2633:. There is an appealing intuitive interpretation of this relationship in a radar. Matched filtering allows the entire energy received from a target to be compressed into a single bin (be it a range, Doppler, elevation, or azimuth bin). On the surface it appears that then within a fixed interval of time, perfect, error free, detection could be obtained. This is done by compressing all energy into an infinitesimal time slice. What limits this approach in the real world is that, while time is arbitrarily divisible, current is not. The quantum of electrical energy is an electron, and so the best that can be done is to match filter all energy into a single electron. Since the electron is moving at a certain temperature (
457:
61:
883:
774:
3434:
4133:, require liquid coolant. The electron beam must contain 5 to 10 times more power than the microwave output, which can produce enough heat to generate plasma. This plasma flows from the collector toward the cathode. The same magnetic focusing that guides the electron beam forces the plasma into the path of the electron beam but flowing in the opposite direction. This introduces FM modulation which degrades Doppler performance. To prevent this, liquid coolant with minimum pressure and flow rate is required, and deionized water is normally used in most high power surface radar systems that use Doppler processing.
3536:
2789:(PPI) radar with a rotating antenna, this will usually be seen as a "sun" or "sunburst" in the center of the display as the receiver responds to echoes from dust particles and misguided RF in the waveguide. Adjusting the timing between when the transmitter sends a pulse and when the receiver stage is enabled will generally reduce the sunburst without affecting the accuracy of the range since most sunburst is caused by a diffused transmit pulse reflected before it leaves the antenna. Clutter is considered a passive interference source since it only appears in response to radar signals sent by the radar.
683:
45:
2989:
detect. This could be offset by using more pulses, but this would shorten the maximum range. So each radar uses a particular type of signal. Long-range radars tend to use long pulses with long delays between them, and short range radars use smaller pulses with less time between them. As electronics have improved many radars now can change their pulse repetition frequency, thereby changing their range. The newest radars fire two pulses during one cell, one for short range (about 10 km (6.2 mi)) and a separate signal for longer ranges (about 100 km (62 mi)).
2849:(AGC), is a method that relies on clutter returns far outnumbering echoes from targets of interest. The receiver's gain is automatically adjusted to maintain a constant level of overall visible clutter. While this does not help detect targets masked by stronger surrounding clutter, it does help to distinguish strong target sources. In the past, radar AGC was electronically controlled and affected the gain of the entire radar receiver. As radars evolved, AGC became computer-software-controlled and affected the gain with greater granularity in specific detection cells.
2704:
1614:
3505:
target location in three dimensions. Most 2D surveillance radars use a spoiled parabolic antenna with a narrow azimuthal beamwidth and wide vertical beamwidth. This beam configuration allows the radar operator to detect an aircraft at a specific azimuth but at an indeterminate height. Conversely, so-called "nodder" height finding radars use a dish with a narrow vertical beamwidth and wide azimuthal beamwidth to detect an aircraft at a specific height but with low azimuthal precision.
3221:" capability required to improve military air combat survivability. Pulse-Doppler is also used for ground based surveillance radar required to defend personnel and vehicles. Pulse-doppler signal processing increases the maximum detection distance using less radiation close to aircraft pilots, shipboard personnel, infantry, and artillery. Reflections from terrain, water, and weather produce signals much larger than aircraft and missiles, which allows fast moving vehicles to hide using
3559:
2985:, accurate distance measurement requires high-speed electronics. In most cases, the receiver does not detect the return while the signal is being transmitted. Through the use of a duplexer, the radar switches between transmitting and receiving at a predetermined rate. A similar effect imposes a maximum range as well. In order to maximize range, longer times between pulses should be used, referred to as a pulse repetition time, or its reciprocal, pulse repetition frequency.
3176:
3009:
3023:
broadcasting at the time the reflected signal arrives back at the radar. By comparing the frequency of the two signals the difference can be easily measured. This is easily accomplished with very high accuracy even in 1940s electronics. A further advantage is that the radar can operate effectively at relatively low frequencies. This was important in the early development of this type when high-frequency signal generation was difficult or expensive.
3353:
2300:
634:
4302:
1002:
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instead of broadcasting and receiving from an aimed antenna, CH broadcast a signal floodlighting the entire area in front of it, and then used one of Watson-Watt's own radio direction finders to determine the direction of the returned echoes. This fact meant CH transmitters had to be much more powerful and have better antennas than competing systems but allowed its rapid introduction using existing technologies.
586:
2868:). This clutter type is especially bothersome since it appears to move and behave like other normal (point) targets of interest. In a typical scenario, an aircraft echo is reflected from the ground below, appearing to the receiver as an identical target below the correct one. The radar may try to unify the targets, reporting the target at an incorrect height, or eliminating it on the basis of
5868:
2966:
3095:
kilowatts. On reception, the signal is sent into a system that delays different frequencies by different times. The resulting output is a much shorter pulse that is suitable for accurate distance measurement, while also compressing the received energy into a much higher energy peak and thus reducing the signal-to-noise ratio. The technique is largely universal on modern large radars.
4021:, subdivided as below. Oxygen in the air is an extremely effective attenuator around 60 GHz, as are other molecules at other frequencies, leading to the so-called propagation window at 94 GHz. Even in this window the attenuation is higher than that due to water at 22.2 GHz. This makes these frequencies generally useful only for short-range highly specific radars, like
3472:
4316:
622:
971:, are too strongly attenuated. Weather phenomena, such as fog, clouds, rain, falling snow, and sleet, that block visible light are usually transparent to radio waves. Certain radio frequencies that are absorbed or scattered by water vapour, raindrops, or atmospheric gases (especially oxygen) are avoided when designing radars, except when their detection is intended.
2981:: transmit a short pulse of radio signal (electromagnetic radiation) and measure the time it takes for the reflection to return. The distance is one-half the round trip time multiplied by the speed of the signal. The factor of one-half comes from the fact that the signal has to travel to the object and back again. Since radio waves travel at the
2695:(SNR). SNR is defined as the ratio of the signal power to the noise power within the desired signal; it compares the level of a desired target signal to the level of background noise (atmospheric noise and noise generated within the receiver). The higher a system's SNR the better it is at discriminating actual targets from noise signals.
3704:'s effective aperture figure means that for any given antenna (or reflector) size will be more efficient at longer wavelengths. Additionally, shorter wavelengths may interact with molecules or raindrops in the air, scattering the signal. Very long wavelengths also have additional diffraction effects that make them suitable for
3134:, military radar). The Doppler effect is only able to determine the relative speed of the target along the line of sight from the radar to the target. Any component of target velocity perpendicular to the line of sight cannot be determined by using the Doppler effect alone, but it can be determined by tracking the target's
3214:. Coherency requirements are not as strict as those for military systems because individual signals ordinarily do not need to be separated. Less sophisticated filtering is required, and range ambiguity processing is not normally needed with weather radar in comparison with military radar intended to track air vehicles.
3549:
Applied similarly to the parabolic reflector, the slotted waveguide is moved mechanically to scan and is particularly suitable for non-tracking surface scan systems, where the vertical pattern may remain constant. Owing to its lower cost and less wind exposure, shipboard, airport surface, and harbour
2896:
Jamming is problematic to radar since the jamming signal only needs to travel one way (from the jammer to the radar receiver) whereas the radar echoes travel two ways (radar-target-radar) and are therefore significantly reduced in power by the time they return to the radar receiver in accordance with
2873:
certain height. Monopulse can be improved by altering the elevation algorithm used at low elevation. In newer air traffic control radar equipment, algorithms are used to identify the false targets by comparing the current pulse returns to those adjacent, as well as calculating return improbabilities.
856:
to monitor vehicle speeds on the roads. Automotive radars are used for adaptive cruise control and emergency breaking on vehicles by ignoring stationary roadside objects that could cause incorrect brake application and instead measuring moving objects to prevent collision with other vehicles. As part
667:
Given all required funding and development support, the team produced working radar systems in 1935 and began deployment. By 1936, the first five Chain Home (CH) systems were operational and by 1940 stretched across the entire UK including
Northern Ireland. Even by standards of the era, CH was crude;
3582:
Phased array antennas are composed of evenly spaced similar antenna elements, such as aerials or rows of slotted waveguide. Each antenna element or group of antenna elements incorporates a discrete phase shift that produces a phase gradient across the array. For example, array elements producing a 5
3201:
to produce the display showing different frequencies. Each different distance produces a different spectrum. These spectra are used to perform the detection process. This is required to achieve acceptable performance in hostile environments involving weather, terrain, and electronic countermeasures.
3085:
The two techniques outlined above both have their disadvantages. The pulse timing technique has an inherent tradeoff in that the accuracy of the distance measurement is inversely related to the length of the pulse, while the energy, and thus direction range, is directly related. Increasing power for
3050:
riding on the receive signal is proportional to the time delay between the radar and the reflector. The frequency shift becomes greater with greater time delay. The frequency shift is directly proportional to the distance travelled. That distance can be displayed on an instrument, and it may also be
2988:
These two effects tend to be at odds with each other, and it is not easy to combine both good short range and good long range in a single radar. This is because the short pulses needed for a good minimum range broadcast have less total energy, making the returns much smaller and the target harder to
2596:
Noise is also generated by external sources, most importantly the natural thermal radiation of the background surrounding the target of interest. In modern radar systems, the internal noise is typically about equal to or lower than the external noise. An exception is if the radar is aimed upwards at
3070:
Terrestrial radar uses low-power FM signals that cover a larger frequency range. The multiple reflections are analyzed mathematically for pattern changes with multiple passes creating a computerized synthetic image. Doppler effects are used which allows slow moving objects to be detected as well as
3022:
Another form of distance measuring radar is based on frequency modulation. In these systems, the frequency of the transmitted signal is changed over time. Since the signal takes a finite time to travel to and from the target, the received signal is a different frequency than what the transmitter is
2872:
or a physical impossibility. Terrain bounce jamming exploits this response by amplifying the radar signal and directing it downward. These problems can be overcome by incorporating a ground map of the radar's surroundings and eliminating all echoes which appear to originate below ground or above a
2792:
Clutter is detected and neutralized in several ways. Clutter tends to appear static between radar scans; on subsequent scan echoes, desirable targets will appear to move, and all stationary echoes can be eliminated. Sea clutter can be reduced by using horizontal polarization, while rain is reduced
3238:
processing is required to identify the true range of all reflected signals. Radial movement is usually linked with
Doppler frequency to produce a lock signal that cannot be produced by radar jamming signals. Pulse-Doppler signal processing also produces audible signals that can be used for threat
3229:
to avoid detection until an attack vehicle is too close to destroy. Pulse-Doppler signal processing incorporates more sophisticated electronic filtering that safely eliminates this kind of weakness. This requires the use of medium pulse-repetition frequency with phase coherent hardware that has a
356:
was the first to use radio waves to detect "the presence of distant metallic objects". In 1904, he demonstrated the feasibility of detecting a ship in dense fog, but not its distance from the transmitter. He obtained a patent for his detection device in April 1904 and later a patent for a related
3619:
As the price of electronics has fallen, phased array radars have become more common. Almost all modern military radar systems are based on phased arrays, where the small additional cost is offset by the improved reliability of a system with no moving parts. Traditional moving-antenna designs are
781:
The information provided by radar includes the bearing and range (and therefore position) of the object from the radar scanner. It is thus used in many different fields where the need for such positioning is crucial. The first use of radar was for military purposes: to locate air, ground and sea
3504:
weather radar uses a symmetric antenna to perform detailed volumetric scans of the atmosphere. Spoiled parabolic antennas produce a narrow beam in one dimension and a relatively wide beam in the other. This feature is useful if target detection over a wide range of angles is more important than
1084:
consists of three flat surfaces meeting like the inside corner of a cube. The structure will reflect waves entering its opening directly back to the source. They are commonly used as radar reflectors to make otherwise difficult-to-detect objects easier to detect. Corner reflectors on boats, for
3699:
Opposing the move to smaller wavelengths are a number of practical issues. For one, the electronics needed to produce high power very short wavelengths were generally more complex and expensive than the electronics needed for longer wavelengths or didn't exist at all. Another issue is that the
3209:
to measure radial wind velocity and precipitation rate in each different volume of air. This is linked with computing systems to produce a real-time electronic weather map. Aircraft safety depends upon continuous access to accurate weather radar information that is used to prevent injuries and
3090:
often operating in the tens of megawatts. The continuous wave methods spread this energy out in time and thus require much lower peak power compared to pulse techniques, but requires some method of allowing the sent and received signals to operate at the same time, often demanding two separate
801:
screens by operators who thereby give radio landing instructions to the pilot, maintaining the aircraft on a defined approach path to the runway. Military fighter aircraft are usually fitted with air-to-air targeting radars, to detect and target enemy aircraft. In addition, larger specialized
416:
discovered that ships passing through the beam path caused the received signal to fade in and out. Taylor submitted a report, suggesting that this phenomenon might be used to detect the presence of ships in low visibility, but the Navy did not immediately continue the work. Eight years later,
3094:
The introduction of new electronics in the 1960s allowed the two techniques to be combined. It starts with a longer pulse that is also frequency modulated. Spreading the broadcast energy out in time means lower peak energies can be used, with modern examples typically on the order of tens of
601:
and turned the request over to
Wilkins. Wilkins returned a set of calculations demonstrating the system was basically impossible. When Watson-Watt then asked what such a system might do, Wilkins recalled the earlier report about aircraft causing radio interference. This revelation led to the
3583:
degree phase shift for each wavelength across the array face will produce a beam pointed 5 degrees away from the centerline perpendicular to the array face. Signals travelling along that beam will be reinforced. Signals offset from that beam will be cancelled. The amount of reinforcement is
2240:
As an example, a
Doppler weather radar with a pulse rate of 2 kHz and transmit frequency of 1 GHz can reliably measure weather speed up to at most 150 m/s (340 mph), thus cannot reliably determine radial velocity of aircraft moving 1,000 m/s (2,200 mph).
524:, produced an experimental apparatus, RAPID, capable of detecting an aircraft within 3 km of a receiver. The Soviets produced their first mass production radars RUS-1 and RUS-2 Redut in 1939 but further development was slowed following the arrest of Oshchepkov and his subsequent
3668:, such multiple aperture arrays, when used in transmitters, result in narrow beams at the expense of reducing the total power transmitted to the target. In principle, such techniques could increase spatial resolution, but the lower power means that this is generally not effective.
3145:(CW radar), by sending out a very pure signal of a known frequency. CW radar is ideal for determining the radial component of a target's velocity. CW radar is typically used by traffic enforcement to measure vehicle speed quickly and accurately where the range is not important.
3696:. This provides a strong incentive to use shorter wavelengths as this will result in smaller antennas. Shorter wavelengths also result in higher resolution due to diffraction, meaning the shaped reflector seen on most radars can also be made smaller for any desired beamwidth.
2584:
amplification. Another reason for heterodyne processing is that for fixed fractional bandwidth, the instantaneous bandwidth increases linearly in frequency. This allows improved range resolution. The one notable exception to heterodyne (downconversion) radar systems is
3792:
Very long range, ground penetrating; 'very high frequency'. Early radar systems generally operated in VHF as suitable electronics had already been developed for broadcast radio. Today this band is heavily congested and no longer suitable for radar due to interference.
2892:
tactic, or unintentional, as with friendly forces operating equipment that transmits using the same frequency range. Jamming is considered an active interference source, since it is initiated by elements outside the radar and in general unrelated to the radar signals.
425:(NRL) observed similar fading effects from passing aircraft; this revelation led to a patent application as well as a proposal for further intensive research on radio-echo signals from moving targets to take place at NRL, where Taylor and Young were based at the time.
2690:
Radar systems must overcome unwanted signals in order to focus on the targets of interest. These unwanted signals may originate from internal and external sources, both passive and active. The ability of the radar system to overcome these unwanted signals defines its
3000:, reflect off a target, and return to the radar antenna. Since a nautical mile is defined as 1,852 m, then dividing this distance by the speed of light (299,792,458 m/s), and then multiplying the result by 2 yields a result of 12.36 μs in duration.
3925:
radar; short-range tracking. Named X band because the frequency was a secret during WW2. Diffraction off raindrops during heavy rain limits the range in the detection role and makes this suitable only for short-range roles or those that deliberately detect rain.
3304:
Historical information is accumulated and used to predict future position for use with air traffic control, threat estimation, combat system doctrine, gun aiming, and missile guidance. Position data is accumulated by radar sensors over the span of a few minutes.
789:, aircraft can be equipped with radar devices that warn of aircraft or other obstacles in or approaching their path, display weather information, and give accurate altitude readings. The first commercial device fitted to aircraft was a 1938 Bell Lab unit on some
3606:. The massive redundancy associated with having a large number of array elements increases reliability at the expense of gradual performance degradation that occurs as individual phase elements fail. To a lesser extent, Phased array radars have been used in
1060:
Radar waves scatter in a variety of ways depending on the size (wavelength) of the radio wave and the shape of the target. If the wavelength is much shorter than the target's size, the wave will bounce off in a way similar to the way light is reflected by a
361:. It operated on a 50 cm wavelength and the pulsed radar signal was created via a spark-gap. His system already used the classic antenna setup of horn antenna with parabolic reflector and was presented to German military officials in practical tests in
1085:
example, make them more detectable to avoid collision or during a rescue. For similar reasons, objects intended to avoid detection will not have inside corners or surfaces and edges perpendicular to likely detection directions, which leads to "odd" looking
808:
are used to measure the bearing and distance of ships to prevent collision with other ships, to navigate, and to fix their position at sea when within range of shore or other fixed references such as islands, buoys, and lightships. In port or in harbour,
3106:
is the change in distance to an object with respect to time. Thus the existing system for measuring distance, combined with a memory capacity to see where the target last was, is enough to measure speed. At one time the memory consisted of a user making
2473:
1065:. If the wavelength is much longer than the size of the target, the target may not be visible because of poor reflection. Low-frequency radar technology is dependent on resonances for detection, but not identification, of targets. This is described by
3453:
for reception, each on a different display. The maximum return would be detected with an antenna at right angles to the target, and a minimum with the antenna pointed directly at it (end on). The operator could determine the direction to a target by
3441:
Radio signals broadcast from a single antenna will spread out in all directions, and likewise a single antenna will receive signals equally from all directions. This leaves the radar with the problem of deciding where the target object is located.
717:
had an article in which a U.S. scientist speculated about the
British early warning system on the English east coast and came close to what it was and how it worked. Watson-Watt was sent to the U.S. in 1941 to advise on air defense after Japan's
536:
dive bombers. More than 230 Gneiss-2 stations were produced by the end of 1944. The French and Soviet systems, however, featured continuous-wave operation that did not provide the full performance ultimately synonymous with modern radar systems.
3877:
Moderate range surveillance, Terminal air traffic control, long-range weather, marine radar; 'S' for 'sentimetric', its code-name during WWII. Less efficient than L, but offering higher resolution, making them especially suitable for long-range
1649:
rely on the
Doppler effect to enhance performance. This produces information about target velocity during the detection process. This also allows small objects to be detected in an environment containing much larger nearby slow moving objects.
861:, fixed-position stopped vehicle detection (SVD) radars are mounted on the roadside to detect stranded vehicles, obstructions and debris by inverting the automotive radar approach and ignoring moving objects. Smaller radar systems are used to
3148:
When using a pulsed radar, the variation between the phase of successive returns gives the distance the target has moved between pulses, and thus its speed can be calculated. Other mathematical developments in radar signal processing include
1073:. Early radars used very long wavelengths that were larger than the targets and thus received a vague signal, whereas many modern systems use shorter wavelengths (a few centimetres or less) that can image objects as small as a loaf of bread.
564:
3458:
the antenna so one display showed a maximum while the other showed a minimum. One serious limitation with this type of solution is that the broadcast is sent out in all directions, so the amount of energy in the direction being examined is
3300:
A Track algorithm is a radar performance enhancement strategy. Tracking algorithms provide the ability to predict future position of multiple moving objects based on the history of the individual positions being reported by sensor systems.
5227:
But by 1940, it was the
British who had made a spectacular breakthrough: the resonant cavity magnetron, a radar transmitter far more powerful than its predecessors.... The magnetron stunned the Americans. Their research was years off the
4588:
3196:
Pulse-Doppler signal processing includes frequency filtering in the detection process. The space between each transmit pulse is divided into range cells or range gates. Each cell is filtered independently much like the process used by a
1249:
1922:
Only the radial component of the velocity is relevant. When the reflector is moving at right angle to the radar beam, it has no relative velocity. Objects moving parallel to the radar beam produce the maximum
Doppler frequency shift.
2924:
and cannot fully be eliminated when directly facing a jammer which uses the same frequency and polarization as the radar. Sidelobe jamming can be overcome by reducing receiving sidelobes in the radar antenna design and by using an
2263:
of the wave. For a transmitted radar signal, the polarization can be controlled to yield different effects. Radars use horizontal, vertical, linear, and circular polarization to detect different types of reflections. For example,
5197:
It not only changed the course of the war by allowing us to develop airborne radar systems, it remains the key piece of technology that lies at the heart of your microwave oven today. The cavity magnetron's invention changed the
3329:
Radar video returns from aircraft can be subjected to a plot extraction process whereby spurious and interfering signals are discarded. A sequence of target returns can be monitored through a device known as a plot extractor.
1625:
Frequency shift is caused by motion that changes the number of wavelengths between the reflector and the radar. This can degrade or enhance radar performance depending upon how it affects the detection process. As an example,
1653:
Doppler shift depends upon whether the radar configuration is active or passive. Active radar transmits a signal that is reflected back to the receiver. Passive radar depends upon the object sending a signal to the receiver.
492:, and the United States, independently and in great secrecy, developed technologies that led to the modern version of radar. Australia, Canada, New Zealand, and South Africa followed prewar Great Britain's radar development,
4000:
Mapping, short range, airport surveillance; frequency just above K band (hence 'a') Photo radar, used to trigger cameras which take pictures of license plates of cars running red lights, operates at 34.300 ± 0.100 GHz.
1568:
2721:
Clutter refers to radio frequency (RF) echoes returned from targets which are uninteresting to radar operators. Such targets include man-made objects such as buildings and — intentionally — by radar countermeasures such as
3038:
or sawtooth pattern at audio frequencies. The signal is then sent out from one antenna and received on another, typically located on the bottom of the aircraft, and the signal can be continuously compared using a simple
376:
used radio technology to provide advance warning of thunderstorms to airmen and during the 1920s went on to lead the U.K. research establishment to make many advances using radio techniques, including the probing of the
3333:
The non-relevant real time returns can be removed from the displayed information and a single plot displayed. In some radar systems, or alternatively in the command and control system to which the radar is connected, a
2565:
Noise typically appears as random variations superimposed on the desired echo signal received in the radar receiver. The lower the power of the desired signal, the more difficult it is to discern it from the noise. The
1833:
2235:
3187:
axis represents each successive transmit pulse interval during which samples are taken. The Fast
Fourier Transform process converts time-domain samples into frequency domain spectra. This is sometimes called the
2887:
Radar jamming refers to radio frequency signals originating from sources outside the radar, transmitting in the radar's frequency and thereby masking targets of interest. Jamming may be intentional, as with an
6466:
3496:
Parabolic reflectors can be either symmetric parabolas or spoiled parabolas: Symmetric parabolic antennas produce a narrow "pencil" beam in both the X and Y dimensions and consequently have a higher gain. The
4154:
and formation of highly flammable alcohol. The loss of a U.S. Navy aircraft in 1978 was attributed to a silicate ester fire. Coolanol is also expensive and toxic. The U.S. Navy has instituted a program named
1916:
165:
to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds.
5992:, National Imagery and Mapping Agency, Bethesda, MD 2001 (US govt publication '...intended to be used primarily as a manual of instruction in navigation schools and by naval and merchant marine personnel.')
3980:
on either side used instead for surveillance. K-band is used for detecting clouds by meteorologists, and by police for detecting speeding motorists. K-band radar guns operate at 24.150 ± 0.100 GHz.
958:
The weak absorption of radio waves by the medium through which they pass is what enables radar sets to detect objects at relatively long ranges—ranges at which other electromagnetic wavelengths, such as
2519:
Radar sensitivity and the power of the return signal as computed in the radar equation. This component includes factors such as the environmental conditions and the size (or radar cross section) of the
947:
Radar receivers are usually, but not always, in the same location as the transmitter. The reflected radar signals captured by the receiving antenna are usually very weak. They can be strengthened by
3489:"dish" to create a tight broadcast beam, typically using the same dish as the receiver. Such systems often combine two radar frequencies in the same antenna in order to allow automatic steering, or
4592:
2835:
that subtracts the received signal from two successive pulses using phase to reduce signals from slow-moving objects. This can be adapted for systems that lack a coherent transmitter, such as
1337:
3613:. As of 2017, NOAA plans to implement a national network of Multi-Function Phased array radars throughout the United States within 10 years, for meteorological studies and flight monitoring.
660:; without it, significant numbers of fighter aircraft, which Great Britain did not have available, would always have needed to be in the air to respond quickly. The radar formed part of the "
4029:
or use in space where attenuation is not a problem. Multiple letters are assigned to these bands by different groups. These are from
Baytron, a now defunct company that made test equipment.
5641:
2640:
Noise is random and target signals are not. Signal processing can take advantage of this phenomenon to reduce the noise floor using two strategies. The kind of signal integration used with
3711:
The traditional band names originated as code-names during World War II and are still in military and aviation use throughout the world. They have been adopted in the United States by the
2123:
656:" along the East and South coasts of England in time for the outbreak of World War II in 1939. This system provided the vital advance information that helped the Royal Air Force win the
1076:
Short radio waves reflect from curves and corners in a way similar to glint from a rounded piece of glass. The most reflective targets for short wavelengths have 90° angles between the
507:(CSF) headed by Maurice Ponte with Henri Gutton, Sylvain Berline and M. Hugon, began developing an obstacle-locating radio apparatus, aspects of which were installed on the ocean liner
2831:, so individual signals can be separated from multiple reflectors located in the same volume using velocity differences. This requires a coherent transmitter. Another technique uses a
5320:
3118:
If the transmitter's output is coherent (phase synchronized), there is another effect that can be used to make almost instant speed measurements (no memory is required), known as the
618:, was very impressed with their system's potential and funds were immediately provided for further operational development. Watson-Watt's team patented the device in patent GB593017.
436:
test unit, operating at 50 cm (600 MHz) and using pulsed modulation which gave successful laboratory results. In January 1931, a writeup on the apparatus was entered in the
298:
rather than radio waves. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents.
1037:, or a significant change in atomic density between the object and what is surrounding it, will usually scatter radar (radio) waves from its surface. This is particularly true for
2307:
5424:
4714:
is actually an acronym that stands for RAdio Detection and Ranging. It was officially coined by U.S. Navy Lieutenant Commanders Samuel M. Tucker and F.R. Furth in November 1940
3517:
Secondary Scan: A scanning technique where the antenna feed is moved to produce a scanning beam, examples include conical scan, unidirectional sector scan, lobe switching, etc.
3520:
Palmer Scan: A scanning technique that produces a scanning beam by moving the main antenna and its feed. A Palmer Scan is a combination of a Primary Scan and a Secondary Scan.
4613:
McGraw-Hill dictionary of scientific and technical terms / Daniel N. Lapedes, editor in chief. Lapedes, Daniel N. New York; Montreal : McGraw-Hill, 1976. , 1634, A26 p.
349:
caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation.
2666:
3660:
techniques, using an array of separate dishes that are phased into a single effective aperture, are not typical for radar applications, although they are widely used in
3449:, with directional receiver antennas which were pointed in various directions. For instance, the first system to be deployed, Chain Home, used two straight antennas at
932:
possible in certain cases. The radar signals that are reflected back towards the radar receiver are the desirable ones that make radar detection work. If the object is
1363:
5816:
2153:
2059:
2032:
2005:
1978:
1951:
1736:
1709:
1682:
2576:
is produced by electrons in transit across a discontinuity, which occurs in all detectors. Shot noise is the dominant source in most receivers. There will also be
920:
in many directions, although some of them will be absorbed and penetrate into the target. Radar signals are reflected especially well by materials of considerable
440:
maintained by the Royal Engineers. This is the first official record in Great Britain of the technology that was used in coastal defence and was incorporated into
4811:
Verfahren zur Bestimmung der Entfernung von metallischen Gegenständen (Schiffen o. dgl.), deren Gegenwart durch das Verfahren nach Patent 16556 festgestellt wird.
3827:), ground penetrating, foliage penetrating; 'ultra high frequency'. Efficiently produced and received at very high energy levels, and also reduces the effects of
1122:
1097:, are very reflective but do not direct the scattered energy back toward the source. The extent to which an object reflects or scatters radio waves is called its
1573:
This shows that the received power declines as the fourth power of the range, which means that the received power from distant targets is relatively very small.
504:
3807:'P' for 'previous', applied retrospectively to early radar systems; essentially HF + VHF. Often used for remote sensing because of good vegetation penetration.
1756:
4079:
High voltage switch for non-coherent keyed power-oscillators These modulators consist of a high voltage pulse generator formed from a high voltage supply, a
4726:
4159:(P2) to eliminate or reduce the volume and toxicity of waste, air emissions, and effluent discharges. Because of this, Coolanol is used less often today.
7123:
698:
in the UK, which allowed the creation of relatively small systems with sub-meter resolution. Britain shared the technology with the U.S. during the 1940
983:
emitted by the target objects themselves, such as infrared radiation (heat). This process of directing artificial radio waves towards objects is called
4102:
waveform. This waveform can be generated by low power/low-voltage input signals. In this case the radar transmitter must be a power-amplifier, e.g., a
3514:
Primary Scan: A scanning technique where the main antenna aerial is moved to produce a scanning beam, examples include circular scan, sector scan, etc.
1458:
521:
610:
shortwave transmitter as the source and their GPO receiver setup in a field while a bomber flew around the site. When the plane was clearly detected,
3712:
5165:
357:
amendment for estimating the distance to the ship. He also obtained a British patent on 23 September 1904 for a full radar system, that he called a
5648:
4827:
741:
The war precipitated research to find better resolution, more portability, and more features for radar, including small, lightweight sets to equip
6679:
3623:
Phased array radars are valued for use in aircraft since they can track multiple targets. The first aircraft to use a phased array radar was the
734:, Cambridge, Massachusetts which developed microwave radar technology in the years 1941–45. Later, in 1943, Page greatly improved radar with the
4694:
3205:
The primary purpose is to measure both the amplitude and frequency of the aggregate reflected signal from multiple distances. This is used with
6812:
1764:
5934:
4845:
3921:, weather, medium-resolution mapping and ground surveillance; in the United States the narrow range 10.525 GHz ±25 MHz is used for
401:
model after noting its manual's description of a "fading" effect (the common term for interference at the time) when aircraft flew overhead.
5980:
5822:. Melbourne, Australia: Aeronautical Research Laboratory, Defense Science and Technology Organisation, Department of Defense. Archived from
5328:
3594:), but electronic device limitations led to poor performance. Phased array radars were originally used for missile defence (see for example
2969:
Pulse radar: The round-trip time for the radar pulse to get to the target and return is measured. The distance is proportional to this time.
2554:
that affect range performance. Reflectors that are too far away produce too little signal to exceed the noise floor and cannot be detected.
2161:
5938:". Privateline.com. (Anecdotal account of the carriage of the world's first high power cavity magnetron from Britain to the US during WW2.)
3394:
that serves as a switch between the antenna and the transmitter or the receiver for the signal when the antenna is used in both situations.
644:
Development of radar greatly expanded on 1 September 1936, when Watson-Watt became superintendent of a new establishment under the British
6109:
The invention that changed the world: how a small group of radar pioneers won the Second World War and launched a technological revolution
2637:) this noise source cannot be further eroded. Ultimately, radar, like all macro-scale entities, is profoundly impacted by quantum theory.
2551:
2805:
802:
military aircraft carry powerful airborne radars to observe air traffic over a wide region and direct fighter aircraft towards targets.
5683:
5413:
5139:
2065:, since the returned frequency otherwise cannot be distinguished from shifting of a harmonic frequency above or below, thus requiring:
1853:
4194:
based on the comparison of reference signals with radio signals reflected, or retransmitted, from the position to be determined. Each
5701:
4909:
Hyland, L.A, A.H. Taylor, and L.C. Young; "System for detecting objects by radio," U.S. Patent No. 1981884, granted 27 November 1934
5876:
2828:
652:, near Felixstowe, Suffolk. Work there resulted in the design and installation of aircraft detection and tracking stations called "
7143:
7133:
6390:
5549:
3616:
Phased array antennas can be built to conform to specific shapes, like missiles, infantry support vehicles, ships, and aircraft.
540:
Full radar evolved as a pulsed system, and the first such elementary apparatus was demonstrated in December 1934 by the American
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6802:
6003:
5117:
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of that transmitted. To get a reasonable amount of power on the "target", the transmitting aerial should also be directional.
3034:. In these systems a "carrier" radar signal is frequency modulated in a predictable way, typically varying up and down with a
1587:= 1 is a simplification for transmission in a vacuum without interference. The propagation factor accounts for the effects of
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3719:. Most countries have additional regulations to control which parts of each band are available for civilian or military use.
3716:
3317:
2836:
2509:
Line of sight, which depends on the height above the ground. Without a direct line of sight, the path of the beam is blocked.
1029:
from the first, the waves will reflect or scatter from the boundary between the materials. This means that a solid object in
731:
5399:
4742:"Performance Assessment of an Integrated Radar Architecture for Multi-Types Frontal Object Detection for Autonomous Vehicle"
6622:
5279:
4276:
3635:
3055:. This signal processing is similar to that used in speed detecting Doppler radar. Example systems using this approach are
2726:. Such targets also include natural objects such as ground, sea, and — when not being tasked for meteorological purposes —
2516:. The maximum non-ambiguous range is the distance the pulse can travel to and return from before the next pulse is emitted.
4940:
The Origins and Development of Radar in the Royal Navy, 1935–45 with Particular Reference to Decimetric Gunnery Equipments
4663:
3338:
is used to associate the sequence of plots belonging to individual targets and estimate the targets' headings and speeds.
6807:
6672:
6641:
A set of 10 video lectures developed at Lincoln Laboratory to develop an understanding of radar systems and technologies.
6015:
5823:
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or a solid state transmitter. In this way, the transmitted pulse is intrapulse-modulated and the radar receiver must use
3642:
2930:
5280:"Scotland's little-known WWII hero who helped beat the Luftwaffe with invention of radar set to be immortalised in film"
2539:
Signal noise is an internal source of random variations in the signal, which is generated by all electronic components.
6536:
6476:
5441:
4556:
4227:
Radar come in a variety of configurations in the emitter, the receiver, the antenna, wavelength, scan strategies, etc.
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Used as a visual sensor for experimental autonomous vehicles, high-resolution meteorological observation, and imaging.
2502:
sinks below the horizon. Furthermore, the signal is attenuated by the medium the beam crosses, and the beam disperses.
1293:
615:
6487:
2490:
A radar beam follows a linear path in vacuum but follows a somewhat curved path in atmosphere due to variation in the
7020:
6638:
6422:
6403:
5904:
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17:
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still widely used in roles where cost is a significant factor such as air traffic surveillance and similar systems.
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An electronic section that controls all those devices and the antenna to perform the radar scan ordered by software.
2901:. Jammers therefore can be much less powerful than their jammed radars and still effectively mask targets along the
5378:
2071:
1630:
can interact with Doppler to produce signal cancellation at certain radial velocities, which degrades performance.
1069:, an effect that creates Earth's blue sky and red sunsets. When the two length scales are comparable, there may be
3231:
3043:
modulator that produces an audio frequency tone from the returned signal and a portion of the transmitted signal.
1057:. This is the radio equivalent of painting something a dark colour so that it cannot be seen by the eye at night.
7113:
4215:
3259:
3170:
2685:
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2034:. As a result, the Doppler measurement is only non-ambiguous if the Doppler frequency shift is less than half of
1013:). The radar's frequency, pulse form, polarization, signal processing, and antenna determine what it can observe.
5771:
5091:
2570:
is a measure of the noise produced by a receiver compared to an ideal receiver, and this needs to be minimized.
711:
showed an example of a radar unit using the Watson-Watt patent in an article on air defence. Also, in late 1941
66:
Radar of the type used for detection of aircraft. It rotates steadily, sweeping the airspace with a narrow beam.
7108:
6665:
4393:
4156:
4091:, a special type of vacuum tube that converts DC (usually pulsed) into microwaves. This technology is known as
3879:
3692:
Antennas generally have to be sized similar to the wavelength of the operational frequency, normally within an
3267:
3211:
2259:, the electric field is perpendicular to the direction of propagation, and the electric field direction is the
456:
4920:
4798:
Patent DE165546; Verfahren, um metallische Gegenstände mittels elektrischer Wellen einem Beobachter zu melden.
7103:
7098:
2468:{\displaystyle H=\left({\sqrt {r^{2}+(k_{e}a_{e})^{2}+2rk_{e}a_{e}sin(\theta _{e})}}\right)-k_{e}a_{e}+h_{a}}
858:
3047:
2909:). Jammers have an added effect of affecting radars along other lines of sight through the radar receiver's
528:
sentence. In total, only 607 Redut stations were produced during the war. The first Russian airborne radar,
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7007:
7002:
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by post-processing motion data from a single moving source, on the other hand, is widely used in space and
3263:
2542:
Reflected signals decline rapidly as distance increases, so noise introduces a radar range limitation. The
1041:
materials such as metal and carbon fibre, making radar well-suited to the detection of aircraft and ships.
895:
5945:
4095:. In this way, the transmitted pulse of RF radiation is kept to a defined and usually very short duration.
3526:: The radar beam is rotated in a small circle around the "boresight" axis, which is pointed at the target.
3401:. Knowing the shape of the desired received signal (a pulse), an optimal receiver can be designed using a
6896:
5753:
5006:
Frederick Seitz, Norman G. Einspruch, Electronic Genie: The Tangled History of Silicon – 1998 – page 104
3646:
3312:
2882:
1093:, especially at longer wavelengths. Half wavelength long wires or strips of conducting material, such as
869:
for computer interaction. Automatic door opening, light activation and intruder sensing are also common.
817:
754:
746:
500:
322:
882:
6982:
6941:
5015:
John Erickson. Radio-Location and the Air Defence Problem: The Design and Development of Soviet Radar.
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794:
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Satellite transponders; a compromise (hence 'C') between X and S bands; weather; long range tracking
3347:
3275:
3052:
2902:
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2746:
trails. Radar clutter can also be caused by other atmospheric phenomena, such as disturbances in the
2256:
1577:
1018:
773:
545:
461:
422:
268:
256:
6519:
5790:
4823:
3115:. Modern radar systems perform the equivalent operation faster and more accurately using computers.
782:
targets. This evolved in the civilian field into applications for aircraft, ships, and automobiles.
4849:
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1634:
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798:
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283:
264:
6576:
Robert Calderbank; S. Howard; Bill Moran (2009). "Waveform diversity in radar signal processing".
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3535:
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3446:
3150:
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2852:
Clutter may also originate from multipath echoes from valid targets caused by ground reflection,
2786:
2739:
2647:
921:
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386:
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at long distances. Through his lightning experiments, Watson-Watt became an expert on the use of
131:
428:
Similarly, in the UK, L. S. Alder took out a secret provisional patent for Naval radar in 1928.
6880:
6776:
5498:
4283:
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2498:. Even when the beam is emitted parallel to the ground, the beam rises above the ground as the
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1094:
810:
719:
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31:
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act to provide the waveform of the RF-pulse. There are two different radar modulator designs:
1348:
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353:
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1038:
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185:, which allowed the creation of relatively small systems with sub-meter resolution. The term
51:
5687:
5147:
1244:{\displaystyle P_{r}={\frac {P_{t}G_{t}A_{r}\sigma F^{4}}{{(4\pi )}^{2}R_{t}^{2}R_{r}^{2}}}}
212:
The modern uses of radar are highly diverse, including air and terrestrial traffic control,
157:, a receiving antenna (often the same antenna is used for transmitting and receiving) and a
6585:
5956:
5847:
ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.100, definition:
5571:
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2010:
1983:
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87:
3945:
High-resolution, also used for satellite transponders, frequency under K band (hence 'u')
2589:
radar. Here a single cycle, or transient wave, is used similar to UWB communications, see
979:
Radar relies on its own transmissions rather than light from the Sun or the Moon, or from
777:
Commercial marine radar antenna. The rotating antenna radiates a vertical fan-shaped beam.
8:
6837:
6797:
6715:
6705:
5705:
5540:
4885:
4746:
2018 IEEE International Conference on Automatic Control and Intelligent Systems (I2CACIS)
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to detect precipitation). Other methods attempt to increase the signal-to-clutter ratio.
2798:
2673:
2672:, which reduces the noise floor by the number of filters. These improvements depend upon
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1022:
866:
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industries, have replaced the traditional military designations with their own systems.
3590:
Phased array radars have been in use since the earliest years of radar in World War II (
2272:
returns usually indicate metal surfaces. Random polarization returns usually indicate a
1591:
and shadowing and depends on the details of the environment. In a real-world situation,
7049:
6710:
6601:
6507:
6468:
Signal design for good correlation: for wireless communication, cryptography, and radar
6433:
6216:
Kaiser, Gerald, Chapter 10 in "A Friendly Guide to Wavelets", Birkhauser, Boston, 1994.
5525:
M. Castelaz. "Exploration: The Doppler Effect". Pisgah Astronomical Research Institute.
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233:
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103:
5647:. Syracuse Research Corporation; Massachusetts Institute of Technology. Archived from
3086:
longer range while maintaining accuracy demands extremely high peak power, with 1960s
560:
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4479:
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which makes use of the change of frequency of returns from moving targets ("chirp").
3080:
2934:
2751:
2062:
1980:, the resulting frequency spectrum will contain harmonic frequencies above and below
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758:
723:
713:
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553:
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346:
6605:
5125:
4809:
4796:
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3687:
3012:
Continuous wave (CW) radar. Using frequency modulation allows range to be extracted.
1576:
Additional filtering and pulse integration modifies the radar equation slightly for
1416:
In the common case where the transmitter and the receiver are at the same location,
865:. Examples are breathing pattern detection for sleep monitoring and hand and finger
397:
to conduct an extensive review of available shortwave units. Wilkins would select a
393:
transmission. Requiring a suitable receiver for such studies, he told the "new boy"
202:
6593:
6564:
4765:
Kostenko, A.A., A.I. Nosich, and I.A. Tishchenko, "Radar Prehistory, Soviet Side,"
4643:
4437:
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in predetermined directions. When these signals contact an object they are usually
821:
790:
762:
695:
481:
469:
341:. In 1897, while testing this equipment for communicating between two ships in the
307:
272:
260:
237:
178:
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6644:
5184:
3175:
987:, although radio waves are invisible to the human eye as well as optical cameras.
559:
at night. This design was followed by a pulsed system demonstrated in May 1935 by
6931:
6926:
6761:
6756:
6007:
5949:
5607:
5584:
4251:
4207:
4125:
Coherent microwave amplifiers operating above 1,000 watts microwave output, like
4018:
3962:
3661:
3603:
3428:
3295:
3031:
2817:
Doppler processing, which uses filters to separate clutter from desirable signals
2716:
2580:
caused by electron transit through amplification devices, which is reduced using
1844:
1646:
1563:{\displaystyle P_{r}={{P_{t}G_{t}A_{r}\sigma F^{4}} \over {{(4\pi )}^{2}R^{4}}}.}
936:
either toward or away from the transmitter, there will be a slight change in the
929:
862:
849:
735:
707:
569:
485:
229:
213:
154:
119:
99:
95:
6546:
E. Fishler; A. Haimovich; R. Blum; D. Chizhik; L. Cimini; R. Valenzuela (2004).
4202:
in which it operates permanently or temporarily. Typical radar utilizations are
3550:
surveillance radars now use this approach in preference to a parabolic antenna.
206:
7088:
6832:
6335:
Not an Ordinary Life. How Changing Times Brought Historical Events into my Life
5575:
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4231:
3755:
3701:
3653:
3628:
3402:
3119:
2982:
2978:
2960:
2804:
Clutter moves with the wind or is stationary. Two common strategies to improve
2586:
2505:
The maximum range of conventional radar can be limited by a number of factors:
964:
941:
825:
699:
661:
638:
597:
In 1935, Watson-Watt was asked to judge recent reports of a German radio-based
533:
445:
409:
318:
291:
182:
158:
146:
6612:
5796:. Madrid, Spain: Instituto de Física Aplicada, CETEF "L. Torres Quevedo", CSIC
5669:
4045:
Very strongly absorbed by atmospheric oxygen, which resonates at 60 GHz.
3708:. For this reason, a wide variety of wavelengths are used in different roles.
3638:
radar was considered to be the world's most powerful fighter radar, until the
1613:
813:
radar systems are used to monitor and regulate ship movements in busy waters.
7082:
6771:
6700:
6657:
4535:
4346:
4266:
4256:
4241:
4203:
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axis represents individual samples taken in between each transmit pulse. The
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2495:
1642:
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649:
405:
244:
127:
123:
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5583:(Technical report). RADC Technical Reports. Vol. 1980. Rome, New York:
5449:
4779:
4098:
Hybrid mixers, fed by a waveform generator and an exciter for a complex but
793:
aircraft. Aircraft can land in fog at airports equipped with radar-assisted
7067:
6437:
4092:
3918:
3854:
3723:
3610:
3591:
3584:
3576:
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2567:
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1580:, which can be used to increase detection range and reduce transmit power.
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611:
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225:
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111:
6143:
Secret Location: A witness to the Birth of Radar and its Postwar Influence
5929:". The Radar Pages. (History and details of various British radar systems)
5731:
5298:
1021:
travelling through one material meet another material, having a different
664:" for collecting reports of enemy aircraft and coordinating the response.
6967:
6781:
4530:
4457:
4246:
4147:
3969:
3624:
3450:
3365:
2921:
2920:
Mainlobe jamming can generally only be reduced by narrowing the mainlobe
2559:
2543:
1828:{\displaystyle F_{D}=2\times F_{T}\times \left({\frac {V_{R}}{C}}\right)}
1090:
901:
887:
556:
241:
138:
6645:
A set of educational videos created for air traffic control (ATC) staff.
5925:
5817:"Polyalphaolefins: A New Improved Cost Effective Aircraft Radar Coolant"
4563:
2668:
for each stage. The signal can also be split among multiple filters for
337:
tube for detecting distant lightning strikes. The next year, he added a
321:
showed that radio waves could be reflected from solid objects. In 1895,
282:
Other systems which are similar to radar make use of other parts of the
6545:
6462:
5967:
5030:"The history of radar, from aircraft radio detectors to airborne radar"
4511:
4361:
4151:
4072:
4026:
4022:
4013:
3848:
3141:
It is possible to make a Doppler radar without any pulsing, known as a
3112:
2861:
2797:(meteorological radars wish for the opposite effect, and therefore use
2763:
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2735:
2731:
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1618:
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905:
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441:
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342:
115:
77:
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6345:(Pages 36–67 contain the experiences of a WAAF radar plotter in WWII.)
2597:
clear sky, where the scene is so "cold" that it generates very little
2230:{\displaystyle |V_{R}|<{\frac {F_{R}\times {\frac {C}{F_{T}}}}{4}}}
228:
to locate landmarks and other ships, aircraft anti-collision systems,
6822:
6766:
6555:
Mark R. Bell (1993). "Information theory and radar waveform design".
5146:(Press release). The Patent Office. 10 September 2001. Archived from
5095:
4664:"Remote Sensing Core Curriculum: Radio Detection and Ranging (RADAR)"
4648:
4623:
4084:
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as they combine good reception qualities with reasonable resolution.
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Waveform design for active sensing systems: a computational approach
4962:
Butement, W. A. S., and P. E. Pollard; "Coastal Defence Apparatus",
3352:
633:
6992:
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6870:
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6090:
A radar history of World War II: technical and military imperatives
4442:
4301:
4146:) was used in several military radars in the 1970s. However, it is
4140:
4136:
4130:
4103:
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3455:
3391:
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surface, such as rocks or soil, and are used by navigation radars.
1592:
1089:. These precautions do not totally eliminate reflection because of
925:
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107:
5672:
on 30 October 2021 – via YouTube; jaglavaksoldier's Channel.
5414:"Stopped Vehicle Detection (SVD) Comparison with Automotive Radar"
3071:
largely eliminating "noise" from the surfaces of bodies of water.
1657:
The Doppler frequency shift for active radar is as follows, where
6013:
Swords, Seán S., "Technical History of the Beginnings of Radar",
4120:
3986:
3931:
3922:
3914:
3607:
3154:
3135:
3111:
marks on the radar screen and then calculating the speed using a
3060:
2965:
2857:
2827:. Doppler separates clutter from aircraft and spacecraft using a
2273:
1911:{\displaystyle F_{D}=F_{T}\times \left({\frac {V_{R}}{C}}\right)}
833:
362:
334:
91:
82:
5471:
5037:
1001:
552:
successfully tested a primitive surface-to-surface radar to aim
275:
and are capable of extracting useful information from very high
267:
for geological observations. Modern high tech radar systems use
44:
6860:
6441:
6010:
Early development and production by Chrysler Corp. during WWII.
5942:
5542:
A Canadian Perspective on High-Frequency Over-the-Horizon Radar
4925:
History of Communications-Electronics in the United States Navy
4050:
4034:
3903:
3866:
3836:
3632:
3627:. The first fighter aircraft to use phased array radar was the
3498:
2869:
1290:(area) of the receiving antenna; this can also be expressed as
1062:
1034:
585:
404:
By placing a transmitter and receiver on opposite sides of the
5120:[New obstacle detection system and its applications].
6725:
5972:
5726:
5118:"Nouveau système de repérage d'obstacles et ses applications"
4591:. Public Works and Government Services Canada. Archived from
4494:
4489:
4484:
4462:
4143:
3767:
3368:
that generates the radio signal with an oscillator such as a
3103:
3056:
1116:
returning to the receiving antenna is given by the equation:
621:
525:
464:, Anacostia, D. C., from the late 1930s (photo taken in 1945)
295:
287:
6178:
2814:
Moving target indication, which integrates successive pulses
2785:
between the radar transceiver and the antenna. In a typical
2512:
The maximum non-ambiguous range, which is determined by the
7062:
6613:
Mark A. Richards; James A. Scheer; William A. Holm (2010).
6460:
5926:
All you ever wanted to know about British air defence radar
5352:"These High-Tech Sensors May Be the Key to Autonomous Cars"
3064:
3408:
A display processor to produce signals for human readable
496:
and Sweden generated its radar technology during the war.
6531:. London: The Institution of Engineering and Technology.
6431:
6071:
RDF1: The Location of Aircraft by Radio Methods 1935–1945
5609:
Investigation of Terrain Bounce Electronic Countermeasure
4087:. They generate short pulses of power to feed, e.g., the
3812:
3781:
3234:
which prevents range from being determined directly, and
2992:
Distance may also be measured as a function of time. The
738:
that was used for many years in most radar applications.
607:
173:
use by several countries in the period before and during
6529:
Waveform design and diversity for advanced radar systems
6412:
6337:, Cardiff Centre for Lifelong Learning, Cardiff, 2009.,
4872:"Making waves: Robert Watson-Watt, the pioneer of radar"
2758:
events. This phenomenon is especially apparent near the
955:
are also used in order to recover useful radar signals.
820:
and wind. It has become the primary tool for short-term
6527:
Fulvio Gini; Antonio De Maio; Lee Patton, eds. (2012).
6365:
Britain's shield: radar and the defeat of the Luftwaffe
6260:
The radar war: Germany's pioneering achievement 1904-45
6219:
4557:"Chapter I – Terminology and technical characteristics"
3587:. The amount of cancellation is side-lobe suppression.
3262:, moving target detection processors, correlation with
499:
In France in 1934, following systematic studies on the
5642:"Ground Surveillance Radars and Military Intelligence"
5256:
5254:
6947:
RIM-174 Standard Extended Range Active Missile (SM-6)
6238:
3565:: Not all radar antennas must rotate to scan the sky.
2996:
is the time it takes for a radar pulse to travel one
2650:
2310:
2268:
is used to minimize the interference caused by rain.
2164:
2134:
2074:
2040:
2013:
1986:
1959:
1932:
1856:
1767:
1744:
1717:
1690:
1663:
1461:
1351:
1297:
1125:
1005:
Brightness can indicate reflectivity as in this 1960
797:
systems in which the plane's position is observed on
637:
Memorial plaque commemorating Robert Watson-Watt and
6295:
6276:
4297:
3968:, meaning 'short'. Limited use due to absorption by
3831:, making them useful in the missile detection role.
3242:
3122:. Most modern radar systems use this principle into
201:
has since entered English and other languages as an
54:, used to track space objects and ballistic missiles
6489:
Signal Design for Active Sensing and Communications
5814:
5251:
5089:
3230:large dynamic range. Military applications require
5732:"Multi-function Phased Array Radar (MPAR) Project"
5497:
4739:
4586:
3282:processing are also used in clutter environments.
3164:
2823:The most effective clutter reduction technique is
2660:
2484:θe : elevation angle above the radar horizon
2467:
2229:
2147:
2117:
2053:
2026:
1999:
1972:
1945:
1910:
1827:
1750:
1730:
1703:
1676:
1562:
1357:
1331:
1243:
6314:
5247:. Bonnier Corporation. December 1941. p. 56.
3713:Institute of Electrical and Electronics Engineers
1332:{\displaystyle {G_{r}\lambda ^{2}} \over {4\pi }}
516:During the same period, Soviet military engineer
7080:
6179:Derek Howse; Naval Radar Trust (February 1993).
5577:A model for high frequency radar auroral clutter
5299:"The Wizard War: WW2 & The Origins of Radar"
5079:. Bonnier Corporation. October 1935. p. 29.
4740:Fakhrul Razi Ahmad, Zakuan; et al. (2018).
4725:: CS1 maint: bot: original URL status unknown (
2781:Some clutter may also be caused by a long radar
2770:produces convection patterns in the ionospheric
2738:, animals (especially birds), turbulence in the
6639:MIT Video Course: Introduction to Radar Systems
6362:
6257:
6241:Principles of radar and sonar signal processing
6033:The radar army: winning the war of the airwaves
5534:
5532:
5268:. Hearst Magazines. September 1941. p. 26.
5212:"How the search for a 'death ray' led to radar"
5172:Improvements in or relating to wireless systems
5128:on 16 January 2009 – via radar-france.fr.
4996:. Hearst Magazines. December 1935. p. 844.
4767:Proc. of IEEE APS International Symposium 2001,
3722:Other users of the radio spectrum, such as the
1953:) is pulsed, using a pulse repeat frequency of
574:in Germany and then another in June 1935 by an
6813:Joint Tactical Information Distribution System
6687:
6485:
5686:. Applied Technology Institute. Archived from
5615:(Thesis). Wright-Patterson AFB, Dayton, Ohio:
4568:. International Telecommunications Union (ITU)
2929:to detect and disregard non-mainlobe signals.
6902:Space Tracking and Surveillance System (STSS)
6876:AN/SPY-6 Air and Missile Defense Radar (AMDR)
6673:
6159:
6106:
6068:
5990:Radar Navigation and Maneuvering Board Manual
5548:(Technical report). Ottawa, Ontario, Canada:
4990:"Radio Waves Warn Liner of Obstacles in Path"
3857:; 'L' for 'long'. Widely used for long range
2486:ha : height of the feedhorn above ground
2118:{\displaystyle |F_{D}|<{\frac {F_{R}}{2}}}
1403:= distance from the transmitter to the target
757:), and complementary navigation systems like
505:Compagnie générale de la télégraphie sans fil
6615:Principles of Modern Radar: Basic Principles
6554:
6388:
5529:
4964:Inventions Book of the Royal Engineers Board
4700:. Archived from the original on 2 March 2023
3285:
1053:substances, is used on military vehicles to
629:tower in Great Baddow, Essex, United Kingdom
197:for "radio detection and ranging". The term
6181:Radar at sea: the royal Navy in World War 2
6087:
5788:
5262:"Odd-shaped Boats Rescue British Engineers"
5182:
3387:that links the transmitter and the antenna.
3250:is employed in radar systems to reduce the
2774:. Radar clutter can degrade the ability of
2478: r : distance radar-target
1412:= distance from the target to the receiver.
7124:Science and technology during World War II
6680:
6666:
6220:Colin Latham; Anne Stobbs (January 1997).
6197:
6049:
5959:Introduction to Naval Weapons Engineering.
5564:
1388:, or scattering coefficient, of the target
6140:
5905:Learn how and when to remove this message
5124:(in French). 20 July 1934. Archived from
5110:
5062:, Doubleday Anchor, New York, 1962, p. 66
4772:
4647:
102:of objects relative to the site. It is a
27:Object detection system using radio waves
6277:Merrill Ivan Skolnik (1 December 1980).
6030:
6020:, Vol. 6, London: Peter Peregrinus, 1986
5952:The secret development of British radar.
5605:
5538:
5019:, vol. 2, no. 3 (Jul. 1972), pp. 241–263
4979:, Peter Peregrinus, Ltd, 1986, pp. 71–74
4977:tech. History of the Beginnings of Radar
4548:
3598:). They are the heart of the ship-borne
3575:Another method of steering is used in a
3557:
3534:
3470:
3432:
3418:A link to end user devices and displays.
3351:
3308:There are four common track algorithms.
3174:
3007:
2964:
2702:
2298:
1612:
1000:
928:, and wet ground. This makes the use of
881:
772:
681:
632:
620:
584:
455:
6557:IEEE Transactions on Information Theory
6548:MIMO radar: an idea whose time has come
5636:
5634:
5550:Defence Research and Development Canada
5524:
5495:
5321:"AIS vs Radar: Vessel Tracking Options"
5209:
4541:
4180:International Telecommunication Union's
3254:. Signal processing techniques include
3003:
2949:
2622:is bandwidth (post matched filter) and
2562:by at least the signal-to-noise ratio.
1104:
532:, entered into service in June 1943 on
14:
7081:
6803:Aegis Ballistic Missile Defense System
5570:
5504:. SciTech Publishing Inc. p. 98.
5296:
4937:
4918:
4382:Acronyms and abbreviations in avionics
4083:, and a high voltage switch such as a
3466:
2284:
671:
648:, Bawdsey Research Station located in
606:of 26 February 1935, using a powerful
451:
6661:
5552:. p. 38. DRDC Ottawa TM 2006-285
5349:
4474:Similar detection and ranging methods
3717:International Telecommunication Union
3179:Pulse-Doppler signal processing. The
732:Massachusetts Institute of Technology
472:, researchers in the United Kingdom,
6853:
6382:
5978:Penley, Bill, and Jonathan Penley, "
5861:
5666:"AN/PPS-5 Ground Surveillance Radar"
5631:
5606:Strasser, Nancy C. (December 1980).
5185:"Briefcase 'that changed the world'"
5176:
5083:
4780:"Christian Huelsmeyer, the inventor"
4277:Synthetically thinned aperture radar
3636:Passive electronically scanned array
3530:
3485:More modern systems use a steerable
3098:
3074:
2944:
2711:from a target cause ghosts to appear
886:3D Doppler radar spectrum showing a
816:Meteorologists use radar to monitor
522:Leningrad Electrotechnical Institute
312:
6897:Space-Based Infrared System (SBIRS)
6808:Active electronically scanned array
6413:Nadav Levanon; Eli Mozeson (2004).
5140:"British man first to patent radar"
4554:
3853:Long range air traffic control and
3643:Active electronically scanned array
3437:AS-3263/SPS-49(V) antenna (US Navy)
2558:requires a signal that exceeds the
2279:
317:As early as 1886, German physicist
24:
6907:Space Surveillance Telescope (SST)
6352:. Cardiff. Candy Jar Books. 2011.
5668:. 29 December 2009. Archived from
5539:Riddolls, Ryan J (December 2006).
5036:. 17 February 2015. Archived from
3681:
3447:omnidirectional broadcast antennas
616:Air Member for Supply and Research
25:
7155:
6942:RIM-161 Standard Missile 3 (SM-3)
6632:
6363:David Zimmerman (February 2001).
5728:National Severe Storms Laboratory
5617:Air Force Institute of Technology
5430:from the original on 9 June 2024.
5379:""AWACS: Nato's eyes in the sky""
5350:Quain, John (26 September 2019).
5318:
4634:(3857): 391–392. 2 October 1943.
4222:
3422:
3251:
3243:Reduction of interference effects
2837:time-domain pulse-amplitude radar
1598:
589:The first workable unit built by
333:, developed an apparatus using a
169:Radar was developed secretly for
5935:Telephone History: Radar History
5866:
5684:"Fundamentals of Radar Tracking"
5092:"The story of RADAR Development"
4692:
4314:
4300:
3508:
3325:Interactive Multiple Model (IMM)
3210:accidents. Weather radar uses a
2601:. The thermal noise is given by
951:. More sophisticated methods of
106:method used to detect and track
59:
43:
6578:IEEE Signal Processing Magazine
6258:David Pritchard (August 1989).
5961:". (Radar fundamentals section)
5857:
5841:
5808:
5782:
5764:
5746:
5720:
5694:
5676:
5658:
5599:
5518:
5489:
5464:
5434:
5406:
5392:
5371:
5343:
5312:
5297:Goebel, Greg (1 January 2007).
5290:
5272:
5233:
5210:Harford, Tim (9 October 2017).
5203:
5183:Angela Hind (5 February 2007).
5154:
5132:
5065:
5052:
5022:
5009:
5000:
4982:
4969:
4956:
4931:
4912:
4903:
4878:
4864:
4838:
4816:
4803:
4790:
4216:radiolocation-satellite service
3825:ballistic missile early warning
3776:(OTH) radars; 'high frequency'
3553:
3376:and controls its duration by a
3260:Pulse-Doppler signal processing
3171:Pulse-Doppler signal processing
3165:Pulse-Doppler signal processing
3030:and is often found in aircraft
2954:
2686:Interference (wave propagation)
2679:
2670:pulse-Doppler signal processing
2244:
1839:Passive radar is applicable to
1578:pulse-Doppler radar performance
974:
877:
768:
460:Experimental radar antenna, US
408:in 1922, U.S. Navy researchers
7144:Wireless communication systems
7134:Radio stations and systems ITU
6881:Sea-based X-band Radar (SBX-1)
6471:. Cambridge University Press.
6446:. Cambridge University Press.
6417:. John Wiley & Sons, Inc.
6317:Introduction to airborne radar
6239:François Le Chevalier (2002).
5500:Introduction to Airborne Radar
4759:
4733:
4695:"History of Radar Meteorology"
4686:
4656:
4616:
4607:
4580:
4394:Amplitude-comparison monopulse
4162:
3880:ground controlled interception
3341:
3318:Probabilistic Data Association
3268:space-time adaptive processing
3026:This technique can be used in
2905:from the jammer to the radar (
2808:in a clutter environment are:
2420:
2407:
2360:
2336:
2181:
2166:
2091:
2076:
1621:caused by motion of the source
1595:effects are also considered.
1534:
1525:
1198:
1189:
940:of the radio waves due to the
432:and P. E. Pollard developed a
389:before turning his inquiry to
325:, a physics instructor at the
13:
1:
6650:Glossary of radar terminology
6296:Merrill Ivan Skolnik (1990).
6279:Introduction to radar systems
6050:E.G. Bowen (1 January 1998).
5917:
5889:and help improve the section.
5241:"Night Watchmen of the Skies"
5073:"Mystery Ray Locates 'Enemy'"
4624:"Radio Detection and Ranging"
4210:, these might operate in the
4067:
2931:Other anti-jamming techniques
1926:When the transmit frequency (
990:
872:
859:Intelligent Transport Systems
503:, the research branch of the
137:A radar system consists of a
7008:Mark 8 Fire Control Computer
7003:Mark I Fire Control Computer
6988:Comprehensive Display System
6741:Ship gun fire-control system
6300:. McGraw-Hill Professional.
6160:Peter S. Hall (March 1991).
6069:Michael Bragg (1 May 2002).
6018:History of Technology Series
5815:Stropki, Michael A. (1992).
5090:Alan Dower Blumlein (2002).
4367:Radar signal characteristics
3445:Early systems tended to use
3322:Multiple Hypothesis Tracking
3264:secondary surveillance radar
2494:of air, which is called the
1394:= pattern propagation factor
896:Radar signal characteristics
840:, precipitation types, etc.
520:, in collaboration with the
177:. A key development was the
7:
6243:. Artech House Publishers.
6202:. Wordsworth Editions Ltd.
5999:Radar – The Great Detective
5587:. p. 9. RADC-TR-80-122
5585:Rome Air Development Center
4942:. Springer. pp. 5–66.
4919:Howeth, Linwood S. (1963).
4587:Translation Bureau (2013).
4293:
4198:shall be classified by the
3715:and internationally by the
3647:Lockheed Martin F-22 Raptor
3313:Nearest neighbour algorithm
2883:Radar jamming and deception
2661:{\displaystyle {\sqrt {2}}}
1452:is the range. This yields:
1374:= gain of receiving antenna
1277:of the transmitting antenna
755:air-to-surface-vessel radar
747:aircraft interception radar
290:, which uses predominantly
80:to determine the distance (
10:
7160:
6983:Naval Tactical Data System
6688:NATO naval weapons systems
6389:M I. Skolnik, ed. (1970).
6315:George W. Stimson (1998).
6198:R.V. Jones (August 1998).
6024:
5442:"The Technology Behind S+"
4333:
4327:
4200:radiocommunication service
4118:
4114:
3728:electronic countermeasures
3688:Radio spectrum § IEEE
3685:
3568:
3542:
3478:
3475:Surveillance radar antenna
3426:
3360:A radar's components are:
3345:
3289:
3252:radar interference effects
3236:range ambiguity resolution
3217:The alternate purpose is "
3168:
3078:
3015:
2977:(ranging) is based on the
2958:
2880:
2876:
2762:, where the action of the
2714:
2698:
2683:
2528:
2514:pulse repetition frequency
2288:
2248:
2128:Or when substituting with
1841:electronic countermeasures
1602:
994:
893:
848:to map the composition of
795:ground-controlled approach
694:A key development was the
690:radar operators in England
675:
548:. The following year, the
369:harbour but was rejected.
305:
301:
189:was coined in 1940 by the
29:
7058:
7032:
6955:
6919:
6889:
6846:
6790:
6749:
6721:Combat information center
6693:
6183:. Naval Institute Press.
4846:"gdr_zeichnungpatent.jpg"
4453:Radar engineering details
4399:Constant false alarm rate
4196:radiodetermination system
4192:radiodetermination system
3539:Slotted waveguide antenna
3348:Radar engineering details
3286:Plot and track extraction
3276:Constant false alarm rate
2843:Constant false alarm rate
2303:Echo heights above ground
2257:electromagnetic radiation
1645:, military aircraft, and
1633:Sea-based radar systems,
846:ground-penetrating radars
546:Naval Research Laboratory
462:Naval Research Laboratory
423:Naval Research Laboratory
269:digital signal processing
259:target locating systems,
207:losing all capitalization
7021:USN early guided weapons
6550:. IEEE Radar Conference.
6222:Radar: A Wartime Miracle
6111:. Simon & Schuster.
6092:. Taylor & Francis.
6054:. Taylor & Francis.
5948:12 December 2005 at the
5496:Stimson, George (1998).
4890:The Lemelson-MIT Program
4874:. BBC. 16 February 2017.
4404:Sensitivity time control
4272:Synthetic-aperture radar
3256:moving target indication
2644:can improve noise up to
2642:moving target indication
2524:
1738:is radial velocity, and
1635:semi-active radar homing
1628:moving target indication
1583:The equation above with
1365:= transmitted wavelength
1358:{\displaystyle \lambda }
1043:Radar absorbing material
799:precision approach radar
751:maritime patrol aircraft
728:MIT Radiation Laboratory
284:electromagnetic spectrum
265:ground-penetrating radar
6598:10.1109/MSP.2008.930414
6492:. Elanders Sverige AB.
6486:M. Soltanalian (2014).
6333:Younghusband, Eileen.,
5791:"Physics of Outgassing"
5702:"Side-Lobe Suppression"
4668:University of Minnesota
4433:Crossed-field amplifier
4342:Terrain-following radar
3772:Coastal radar systems,
3706:over the horizon radars
3631:. The MiG-31M's SBI-16
3151:time-frequency analysis
2927:omnidirectional antenna
2833:moving target indicator
2806:measures of performance
2787:plan position indicator
2740:atmospheric circulation
2552:measures of performance
2482:ae : Earth radius
1758:is the speed of light:
1711:is transmit frequency,
1055:reduce radar reflection
1039:electrically conductive
922:electrical conductivity
488:, the Netherlands, the
395:Arnold Frederic Wilkins
387:radio direction finding
153:domain, a transmitting
7114:Navigational equipment
6932:RIM-67 Standard (SM-2)
6777:Close-in weapon system
6617:. SciTech Publishing.
6348:Younghusband, Eileen.
6319:. SciTech Publishing.
6107:Robert Buderi (1996).
5772:"Fully Coherent Radar"
4284:Over-the-horizon radar
4220:
4025:avoidance systems for
3823:Very long range (e.g.
3801:< 300 MHz
3676:airborne radar systems
3645:was introduced on the
3604:Patriot Missile System
3566:
3540:
3476:
3438:
3357:
3225:flying techniques and
3193:
3013:
2970:
2858:ionospheric reflection
2847:automatic gain control
2776:over-the-horizon radar
2712:
2662:
2500:curvature of the Earth
2487:
2469:
2295:Over-the-horizon radar
2231:
2149:
2119:
2055:
2028:
2001:
1974:
1947:
1912:
1829:
1752:
1732:
1705:
1684:is Doppler frequency,
1678:
1622:
1564:
1359:
1333:
1245:
1014:
924:—such as most metals,
891:
811:vessel traffic service
778:
720:attack on Pearl Harbor
691:
641:
630:
594:
465:
253:flight control systems
76:is a system that uses
32:Radar (disambiguation)
7109:Measuring instruments
7040:Ground-based systems:
6973:Torpedo Data Computer
6963:Radar in World War II
6164:. Potomac Books Inc.
6129:, McGraw Hill, 2005,
6073:. Twayne Publishers.
5704:. MIT. Archived from
5654:on 22 September 2010.
5058:Page, Robert Morris,
4938:Coales, J.F. (1995).
4886:"Robert Wattson-Watt"
4237:Continuous-wave radar
4212:radiolocation service
4188:
4184:ITU Radio Regulations
4127:travelling wave tubes
4081:pulse forming network
3735:Radar frequency bands
3561:
3538:
3474:
3436:
3355:
3280:digital terrain model
3178:
3143:continuous-wave radar
3028:continuous wave radar
3011:
2968:
2959:Further information:
2866:anomalous propagation
2795:circular polarization
2706:
2693:signal-to-noise ratio
2663:
2548:signal-to-noise ratio
2470:
2302:
2266:circular polarization
2249:Further information:
2232:
2150:
2148:{\displaystyle F_{D}}
2120:
2056:
2054:{\displaystyle F_{R}}
2029:
2027:{\displaystyle F_{R}}
2002:
2000:{\displaystyle F_{T}}
1975:
1973:{\displaystyle F_{R}}
1948:
1946:{\displaystyle F_{T}}
1913:
1830:
1753:
1733:
1731:{\displaystyle V_{R}}
1706:
1704:{\displaystyle F_{T}}
1679:
1677:{\displaystyle F_{D}}
1616:
1565:
1444:² can be replaced by
1360:
1334:
1246:
1019:electromagnetic waves
1004:
981:electromagnetic waves
949:electronic amplifiers
900:A radar system has a
894:Further information:
885:
863:detect human movement
776:
726:organized the secret
685:
678:Radar in World War II
636:
624:
588:
501:split-anode magnetron
459:
381:and the detection of
345:, he took note of an
339:spark-gap transmitter
327:Imperial Russian Navy
143:electromagnetic waves
7104:Microwave technology
7099:Aircraft instruments
6088:Louis Brown (1999).
6006:28 July 2020 at the
4542:Notes and references
4468:Travelling-wave tube
4157:Pollution Prevention
3972:at 22 GHz, so K
3859:early warning radars
3219:look-down/shoot-down
3153:(Weyl Heisenberg or
3088:early warning radars
3018:Frequency modulation
3004:Frequency modulation
2975:distance measurement
2973:One way to obtain a
2950:Distance measurement
2648:
2591:List of UWB channels
2308:
2251:Polarization (waves)
2162:
2132:
2072:
2038:
2011:
1984:
1957:
1930:
1854:
1765:
1742:
1715:
1688:
1661:
1459:
1349:
1294:
1123:
1105:Radar range equation
1027:diamagnetic constant
997:Reflection (physics)
852:. Police forces use
352:The German inventor
249:radar remote sensing
222:anti-missile systems
30:For other uses, see
7129:Targeting (warfare)
7119:Air traffic control
6998:Specific equipment:
6838:List of radar types
6818:Historical systems:
6798:Aegis Combat System
6716:Director (military)
6706:Fire-control system
6590:2009ISPM...26...32C
6461:Solomon W. Golomb;
5995:Wesley Stout, 1946
5981:Early Radar History
5965:Hollmann, Martin, "
5286:. 16 February 2017.
5060:The Origin of Radar
4921:"Ch. XXXVIII Radar"
4852:on 24 February 2015
4769:vol. 4. p. 44, 2003
4640:1943Natur.152..391.
4448:Omniview technology
4372:Pulse doppler radar
4330:List of radar types
3737:
3666:thinned array curse
3600:Aegis Combat System
3467:Parabolic reflector
3272:track-before-detect
3128:pulse-Doppler radar
2854:atmospheric ducting
2825:pulse-Doppler radar
2799:linear polarization
2778:to detect targets.
2531:Noise (electronics)
2285:Beam path and range
2270:Linear polarization
2007:with a distance of
1639:active radar homing
1609:Pulse-Doppler radar
1386:radar cross section
1264:= transmitter power
1237:
1222:
1099:radar cross section
1078:reflective surfaces
1067:Rayleigh scattering
1023:dielectric constant
822:weather forecasting
736:monopulse technique
672:During World War II
604:Daventry Experiment
452:Before World War II
399:General Post Office
354:Christian Hülsmeyer
218:air-defense systems
7050:Kerrison Predictor
6711:Fire-control radar
6367:. Sutton Pub Ltd.
6224:. Sutton Pub Ltd.
6141:Ian Goult (2011).
6127:Radar For Mariners
5943:WW2 Shadow Factory
5690:on 24 August 2011.
5357:The New York Times
5331:on 2 February 2019
5122:BREVET D'INVENTION
4589:"Radar definition"
4357:Inverse-square law
4308:Electronics portal
4262:Planar array radar
3804:> 1 m
3733:
3694:order of magnitude
3672:Aperture synthesis
3658:aperture synthesis
3567:
3541:
3477:
3439:
3358:
3227:stealth technology
3194:
3159:chirplet transform
3157:), as well as the
3051:available via the
3014:
2971:
2899:inverse-square law
2890:electronic warfare
2829:frequency spectrum
2752:geomagnetic storms
2713:
2658:
2631:Boltzmann constant
2550:are two different
2488:
2465:
2227:
2145:
2115:
2051:
2024:
1997:
1970:
1943:
1908:
1825:
1748:
1728:
1701:
1674:
1623:
1560:
1355:
1320:
1288:effective aperture
1241:
1223:
1208:
1015:
892:
779:
692:
642:
631:
595:
591:Robert Watson-Watt
582:in Great Britain.
580:Robert Watson-Watt
550:United States Army
466:
419:Lawrence A. Hyland
374:Robert Watson-Watt
234:space surveillance
230:ocean surveillance
191:United States Navy
128:weather formations
104:radiodetermination
7076:
7075:
7045:Gun data computer
6915:
6914:
6569:10.1109/18.259642
6499:978-91-554-9017-1
6453:978-1-107-01969-0
6383:Technical reading
6374:978-0-7509-1799-5
6358:978-0-9566826-2-8
6343:978-0-9561156-9-0
6326:978-1-891121-01-2
6307:978-0-07-057913-2
6288:978-0-07-066572-9
6269:978-1-85260-246-8
6262:. Harpercollins.
6250:978-1-58053-338-6
6231:978-0-7509-1643-1
6209:978-1-85326-699-7
6190:978-1-55750-704-4
6171:978-0-08-037711-7
6152:978-0-7524-5776-5
6145:. History Press.
6135:978-0-07-139867-1
6125:Burch, David F.,
6118:978-0-684-81021-8
6099:978-0-7503-0659-1
6080:978-0-9531544-0-1
6061:978-0-7503-0586-0
6042:978-0-7090-4508-3
6031:Reg Batt (1991).
5968:Radar Family Tree
5915:
5914:
5907:
5789:J.L. de Segovia.
5754:"Radar Modulator"
5511:978-1-891121-01-2
5452:on 27 August 2016
5446:Sleep.mysplus.com
5421:Ogier Electronics
5266:Popular Mechanics
5216:BBC World Service
4994:Popular Mechanics
4949:978-1-349-13457-1
4693:Duda, Jeffrey D.
4595:on 4 January 2014
4565:Radio Regulations
4501:Historical radars
4480:Acoustic location
4288:Chirp transmitter
4108:pulse compression
4065:
4064:
3997:0.75–1.11 cm
3958:1.11–1.67 cm
3817:300–1000 MHz
3664:. Because of the
3596:Safeguard Program
3545:Slotted waveguide
3531:Slotted waveguide
3481:Parabolic antenna
3248:Signal processing
3199:spectrum analyzer
3099:Speed measurement
3081:Pulse compression
3075:Pulse compression
2945:Signal processing
2935:frequency hopping
2760:geomagnetic poles
2656:
2423:
2225:
2219:
2113:
2063:Nyquist frequency
1902:
1819:
1751:{\displaystyle C}
1555:
1329:
1239:
969:ultraviolet light
953:signal processing
867:gesture detection
824:and watching for
724:Alfred Lee Loomis
714:Popular Mechanics
658:Battle of Britain
544:, working at the
347:interference beat
313:First experiments
286:. One example is
261:self-driving cars
205:, a common noun,
50:Long-range radar
18:Remote Radar Head
16:(Redirected from
7151:
7139:1940s neologisms
7025:
7019:
6937:MIM-104F (PAC-3)
6851:
6850:
6791:Specific systems
6682:
6675:
6668:
6659:
6658:
6628:
6624:978-1891121-52-4
6609:
6572:
6563:(5): 1578–1597.
6551:
6542:
6523:
6517:
6513:
6511:
6503:
6482:
6457:
6428:
6409:
6397:
6378:
6330:
6311:
6292:
6273:
6254:
6235:
6213:
6194:
6175:
6156:
6122:
6103:
6084:
6065:
6046:
5983:—an Introduction
5923:Barrett, Dick, "
5910:
5903:
5899:
5896:
5890:
5885:Please read the
5881:may need cleanup
5870:
5869:
5862:
5851:
5845:
5839:
5838:
5836:
5834:
5828:
5821:
5812:
5806:
5805:
5803:
5801:
5795:
5786:
5780:
5779:
5776:radartutorial.eu
5768:
5762:
5761:
5758:radartutorial.eu
5750:
5744:
5743:
5741:
5739:
5724:
5718:
5717:
5715:
5713:
5708:on 31 March 2012
5698:
5692:
5691:
5680:
5674:
5673:
5662:
5656:
5655:
5653:
5646:
5638:
5629:
5628:
5626:
5624:
5619:. pp. 1–104
5614:
5603:
5597:
5596:
5594:
5592:
5582:
5568:
5562:
5561:
5559:
5557:
5547:
5536:
5527:
5526:
5522:
5516:
5515:
5503:
5493:
5487:
5486:
5484:
5482:
5468:
5462:
5461:
5459:
5457:
5448:. Archived from
5438:
5432:
5431:
5429:
5418:
5410:
5404:
5403:
5396:
5390:
5389:
5383:
5375:
5369:
5368:
5366:
5364:
5347:
5341:
5340:
5338:
5336:
5327:. Archived from
5316:
5310:
5309:
5307:
5305:
5294:
5288:
5287:
5276:
5270:
5269:
5258:
5249:
5248:
5237:
5231:
5230:
5224:
5222:
5207:
5201:
5200:
5194:
5192:
5180:
5174:
5169:
5168:
5164:
5158:
5152:
5151:
5150:on 19 July 2006.
5136:
5130:
5129:
5114:
5108:
5107:
5105:
5103:
5094:. Archived from
5087:
5081:
5080:
5069:
5063:
5056:
5050:
5049:
5047:
5045:
5026:
5020:
5013:
5007:
5004:
4998:
4997:
4986:
4980:
4973:
4967:
4960:
4954:
4953:
4935:
4929:
4928:
4916:
4910:
4907:
4901:
4900:
4898:
4896:
4882:
4876:
4875:
4868:
4862:
4861:
4859:
4857:
4848:. Archived from
4842:
4836:
4831:
4830:
4826:
4820:
4814:
4807:
4801:
4794:
4788:
4787:
4776:
4770:
4763:
4757:
4756:
4754:
4752:
4737:
4731:
4730:
4724:
4716:
4707:
4705:
4699:
4690:
4684:
4683:
4681:
4679:
4670:. Archived from
4660:
4654:
4653:
4651:
4649:10.1038/152391b0
4620:
4614:
4611:
4605:
4604:
4602:
4600:
4584:
4578:
4577:
4575:
4573:
4561:
4552:
4526:Hohentwiel radar
4438:Gallium arsenide
4428:Cavity magnetron
4352:Radar navigation
4324:
4322:Geography portal
4319:
4318:
4317:
4310:
4305:
4304:
4174:) is defined by
3942:1.67–2.5 cm
3911:2.5–3.75 cm
3895:3.75–7.5 cm
3829:nuclear blackout
3774:over-the-horizon
3747:Wavelength range
3738:
3732:
3524:Conical scanning
3356:Radar components
3239:identification.
3223:nap-of-the-earth
3048:modulation index
3032:radar altimeters
2915:sidelobe jamming
2907:mainlobe jamming
2707:Radar multipath
2667:
2665:
2664:
2659:
2657:
2652:
2618:is temperature,
2492:refractive index
2474:
2472:
2471:
2466:
2464:
2463:
2451:
2450:
2441:
2440:
2428:
2424:
2419:
2418:
2397:
2396:
2387:
2386:
2368:
2367:
2358:
2357:
2348:
2347:
2332:
2331:
2322:
2280:Limiting factors
2236:
2234:
2233:
2228:
2226:
2221:
2220:
2218:
2217:
2205:
2200:
2199:
2189:
2184:
2179:
2178:
2169:
2154:
2152:
2151:
2146:
2144:
2143:
2124:
2122:
2121:
2116:
2114:
2109:
2108:
2099:
2094:
2089:
2088:
2079:
2060:
2058:
2057:
2052:
2050:
2049:
2033:
2031:
2030:
2025:
2023:
2022:
2006:
2004:
2003:
1998:
1996:
1995:
1979:
1977:
1976:
1971:
1969:
1968:
1952:
1950:
1949:
1944:
1942:
1941:
1917:
1915:
1914:
1909:
1907:
1903:
1898:
1897:
1888:
1879:
1878:
1866:
1865:
1834:
1832:
1831:
1826:
1824:
1820:
1815:
1814:
1805:
1796:
1795:
1777:
1776:
1757:
1755:
1754:
1749:
1737:
1735:
1734:
1729:
1727:
1726:
1710:
1708:
1707:
1702:
1700:
1699:
1683:
1681:
1680:
1675:
1673:
1672:
1569:
1567:
1566:
1561:
1556:
1554:
1553:
1552:
1543:
1542:
1537:
1521:
1520:
1519:
1507:
1506:
1497:
1496:
1487:
1486:
1476:
1471:
1470:
1364:
1362:
1361:
1356:
1338:
1336:
1335:
1330:
1328:
1319:
1318:
1317:
1308:
1307:
1296:
1250:
1248:
1247:
1242:
1240:
1238:
1236:
1231:
1221:
1216:
1207:
1206:
1201:
1185:
1184:
1183:
1171:
1170:
1161:
1160:
1151:
1150:
1140:
1135:
1134:
1087:stealth aircraft
1082:corner reflector
930:radar altimeters
844:use specialized
791:United Air Lines
763:RAF's Pathfinder
696:cavity magnetron
573:
470:Second World War
446:Chain Home (low)
308:History of radar
273:machine learning
251:, altimetry and
179:cavity magnetron
96:elevation angles
63:
47:
21:
7159:
7158:
7154:
7153:
7152:
7150:
7149:
7148:
7079:
7078:
7077:
7072:
7054:
7028:
7023:
7017:
6951:
6927:Harpoon missile
6911:
6885:
6842:
6786:
6762:Guided missiles
6757:Naval artillery
6745:
6689:
6686:
6655:
6635:
6625:
6539:
6515:
6514:
6505:
6504:
6500:
6479:
6454:
6425:
6406:
6398:. McGraw-Hill.
6395:
6385:
6375:
6350:One Woman's War
6327:
6308:
6289:
6281:. McGraw-Hill.
6270:
6251:
6232:
6210:
6200:Most Secret War
6191:
6172:
6153:
6119:
6100:
6081:
6062:
6043:
6027:
6008:Wayback Machine
5950:Wayback Machine
5920:
5911:
5900:
5894:
5891:
5884:
5877:Further reading
5871:
5867:
5860:
5855:
5854:
5846:
5842:
5832:
5830:
5826:
5819:
5813:
5809:
5799:
5797:
5793:
5787:
5783:
5770:
5769:
5765:
5752:
5751:
5747:
5737:
5735:
5725:
5721:
5711:
5709:
5700:
5699:
5695:
5682:
5681:
5677:
5664:
5663:
5659:
5651:
5644:
5640:
5639:
5632:
5622:
5620:
5612:
5604:
5600:
5590:
5588:
5580:
5569:
5565:
5555:
5553:
5545:
5537:
5530:
5523:
5519:
5512:
5494:
5490:
5480:
5478:
5476:Atap.google.com
5470:
5469:
5465:
5455:
5453:
5440:
5439:
5435:
5427:
5416:
5412:
5411:
5407:
5402:. 8 April 2019.
5398:
5397:
5393:
5381:
5377:
5376:
5372:
5362:
5360:
5348:
5344:
5334:
5332:
5317:
5313:
5303:
5301:
5295:
5291:
5278:
5277:
5273:
5260:
5259:
5252:
5245:Popular Science
5239:
5238:
5234:
5220:
5218:
5208:
5204:
5190:
5188:
5181:
5177:
5166:
5160:
5159:
5155:
5138:
5137:
5133:
5116:
5115:
5111:
5101:
5099:
5098:on 10 July 2011
5088:
5084:
5077:Popular Science
5071:
5070:
5066:
5057:
5053:
5043:
5041:
5040:on 20 June 2015
5028:
5027:
5023:
5017:Science Studies
5014:
5010:
5005:
5001:
4988:
4987:
4983:
4975:Swords, S. S.;
4974:
4970:
4961:
4957:
4950:
4936:
4932:
4917:
4913:
4908:
4904:
4894:
4892:
4884:
4883:
4879:
4870:
4869:
4865:
4855:
4853:
4844:
4843:
4839:
4834:Telemobiloscope
4828:
4822:
4821:
4817:
4808:
4804:
4795:
4791:
4778:
4777:
4773:
4764:
4760:
4750:
4748:
4738:
4734:
4718:
4717:
4710:Note: the word
4703:
4701:
4697:
4691:
4687:
4677:
4675:
4662:
4661:
4657:
4622:
4621:
4617:
4612:
4608:
4598:
4596:
4585:
4581:
4571:
4569:
4559:
4553:
4549:
4544:
4338:
4334:Main category:
4332:
4320:
4315:
4313:
4306:
4299:
4296:
4252:Monopulse radar
4225:
4208:secondary radar
4165:
4123:
4117:
4070:
4058:2.7–4.0 mm
4055:75–110 GHz
4042:4.0–7.5 mm
4019:Millimetre band
4009:40–300 GHz
3990:
3979:
3975:
3935:
3786:30–300 MHz
3744:Frequency range
3690:
3684:
3682:Frequency bands
3662:radio astronomy
3573:
3556:
3547:
3533:
3511:
3483:
3469:
3431:
3429:Antenna (radio)
3425:
3350:
3344:
3298:
3296:Track algorithm
3290:Main articles:
3288:
3245:
3173:
3167:
3101:
3083:
3077:
3020:
3006:
2963:
2957:
2952:
2947:
2885:
2879:
2766:on the earth’s
2719:
2717:Clutter (radar)
2701:
2688:
2682:
2651:
2649:
2646:
2645:
2635:Planck spectrum
2628:
2607:
2537:
2529:Main articles:
2527:
2485:
2483:
2481:
2479:
2477:
2475:
2459:
2455:
2446:
2442:
2436:
2432:
2414:
2410:
2392:
2388:
2382:
2378:
2363:
2359:
2353:
2349:
2343:
2339:
2327:
2323:
2321:
2317:
2309:
2306:
2305:
2304:
2297:
2287:
2282:
2253:
2247:
2213:
2209:
2204:
2195:
2191:
2190:
2188:
2180:
2174:
2170:
2165:
2163:
2160:
2159:
2139:
2135:
2133:
2130:
2129:
2104:
2100:
2098:
2090:
2084:
2080:
2075:
2073:
2070:
2069:
2045:
2041:
2039:
2036:
2035:
2018:
2014:
2012:
2009:
2008:
1991:
1987:
1985:
1982:
1981:
1964:
1960:
1958:
1955:
1954:
1937:
1933:
1931:
1928:
1927:
1893:
1889:
1887:
1883:
1874:
1870:
1861:
1857:
1855:
1852:
1851:
1845:radio astronomy
1810:
1806:
1804:
1800:
1791:
1787:
1772:
1768:
1766:
1763:
1762:
1743:
1740:
1739:
1722:
1718:
1716:
1713:
1712:
1695:
1691:
1689:
1686:
1685:
1668:
1664:
1662:
1659:
1658:
1647:radar astronomy
1611:
1603:Main articles:
1601:
1548:
1544:
1538:
1524:
1523:
1522:
1515:
1511:
1502:
1498:
1492:
1488:
1482:
1478:
1477:
1475:
1466:
1462:
1460:
1457:
1456:
1443:
1436:
1429:
1422:
1411:
1402:
1373:
1350:
1347:
1346:
1321:
1313:
1309:
1303:
1299:
1298:
1295:
1292:
1291:
1285:
1272:
1263:
1232:
1227:
1217:
1212:
1202:
1188:
1187:
1186:
1179:
1175:
1166:
1162:
1156:
1152:
1146:
1142:
1141:
1139:
1130:
1126:
1124:
1121:
1120:
1114:
1107:
999:
993:
977:
898:
880:
875:
771:
708:Popular Science
705:In April 1940,
680:
674:
567:
561:Rudolf Kühnhold
554:coastal battery
518:P.K. Oshchepkov
454:
438:Inventions Book
430:W.A.S. Butement
359:telemobiloscope
323:Alexander Popov
315:
310:
304:
232:systems, outer
214:radar astronomy
120:guided missiles
100:radial velocity
71:
70:
69:
68:
67:
64:
56:
55:
48:
35:
28:
23:
22:
15:
12:
11:
5:
7157:
7147:
7146:
7141:
7136:
7131:
7126:
7121:
7116:
7111:
7106:
7101:
7096:
7091:
7074:
7073:
7071:
7070:
7065:
7059:
7056:
7055:
7053:
7052:
7047:
7042:
7036:
7034:
7030:
7029:
7027:
7026:
7015:
7010:
7005:
7000:
6995:
6990:
6985:
6980:
6975:
6970:
6965:
6959:
6957:
6953:
6952:
6950:
6949:
6944:
6939:
6934:
6929:
6923:
6921:
6920:Naval missiles
6917:
6916:
6913:
6912:
6910:
6909:
6904:
6899:
6893:
6891:
6887:
6886:
6884:
6883:
6878:
6873:
6868:
6863:
6857:
6855:
6848:
6844:
6843:
6841:
6840:
6835:
6833:List of radars
6830:
6825:
6820:
6815:
6810:
6805:
6800:
6794:
6792:
6788:
6787:
6785:
6784:
6779:
6774:
6769:
6764:
6759:
6753:
6751:
6747:
6746:
6744:
6743:
6738:
6733:
6728:
6723:
6718:
6713:
6708:
6703:
6697:
6695:
6691:
6690:
6685:
6684:
6677:
6670:
6662:
6653:
6652:
6647:
6642:
6634:
6633:External links
6631:
6630:
6629:
6623:
6610:
6573:
6552:
6543:
6538:978-1849192651
6537:
6524:
6498:
6483:
6478:978-0521821049
6477:
6458:
6452:
6429:
6423:
6410:
6404:
6392:Radar Handbook
6384:
6381:
6380:
6379:
6373:
6360:
6346:
6331:
6325:
6312:
6306:
6298:Radar handbook
6293:
6287:
6274:
6268:
6255:
6249:
6236:
6230:
6217:
6214:
6208:
6195:
6189:
6176:
6170:
6157:
6151:
6138:
6123:
6117:
6104:
6098:
6085:
6079:
6066:
6060:
6047:
6041:
6026:
6023:
6022:
6021:
6011:
5993:
5986:
5976:
5963:
5953:
5939:
5930:
5919:
5916:
5913:
5912:
5874:
5872:
5865:
5859:
5856:
5853:
5852:
5840:
5829:on 5 June 2011
5807:
5781:
5763:
5745:
5719:
5693:
5675:
5657:
5630:
5598:
5574:(March 1980).
5563:
5528:
5517:
5510:
5488:
5472:"Project Soli"
5463:
5433:
5405:
5391:
5370:
5342:
5325:portvision.com
5319:Kline, Aaron.
5311:
5289:
5271:
5250:
5232:
5202:
5175:
5153:
5131:
5109:
5082:
5064:
5051:
5021:
5008:
4999:
4981:
4968:
4955:
4948:
4930:
4911:
4902:
4877:
4863:
4837:
4815:
4802:
4789:
4784:radarworld.org
4771:
4758:
4732:
4685:
4674:on 2 June 2021
4655:
4615:
4606:
4579:
4546:
4545:
4543:
4540:
4539:
4538:
4533:
4528:
4523:
4521:Würzburg radar
4518:
4516:Chain Home Low
4509:
4507:List of radars
4503:
4502:
4498:
4497:
4492:
4487:
4482:
4476:
4475:
4471:
4470:
4465:
4460:
4455:
4450:
4445:
4440:
4435:
4430:
4424:
4423:
4419:
4418:
4416:Proximity fuze
4412:
4411:
4407:
4406:
4401:
4396:
4390:
4389:
4385:
4384:
4379:
4377:Mmwave sensing
4374:
4369:
4364:
4359:
4354:
4349:
4344:
4328:Main listing:
4326:
4325:
4311:
4295:
4292:
4291:
4290:
4281:
4280:
4279:
4269:
4264:
4259:
4254:
4249:
4244:
4239:
4234:
4232:Bistatic radar
4224:
4223:Configurations
4221:
4164:
4161:
4119:Main article:
4116:
4113:
4112:
4111:
4096:
4069:
4066:
4063:
4062:
4059:
4056:
4053:
4047:
4046:
4043:
4040:
4039:40–75 GHz
4037:
4031:
4030:
4016:
4010:
4007:
4003:
4002:
3998:
3995:
3994:24–40 GHz
3992:
3988:
3983:
3982:
3977:
3973:
3959:
3956:
3955:18–24 GHz
3953:
3947:
3946:
3943:
3940:
3939:12–18 GHz
3937:
3933:
3928:
3927:
3912:
3909:
3906:
3900:
3899:
3896:
3893:
3890:
3884:
3883:
3875:
3874:7.5–15 cm
3872:
3869:
3863:
3862:
3851:
3845:
3839:
3833:
3832:
3821:
3818:
3815:
3809:
3808:
3805:
3802:
3799:
3795:
3794:
3790:
3787:
3784:
3778:
3777:
3770:
3764:
3758:
3752:
3751:
3748:
3745:
3742:
3702:radar equation
3686:Main article:
3683:
3680:
3654:interferometry
3629:Mikoyan MiG-31
3569:Main article:
3555:
3552:
3543:Main article:
3532:
3529:
3528:
3527:
3521:
3518:
3515:
3510:
3507:
3479:Main article:
3468:
3465:
3427:Main article:
3424:
3423:Antenna design
3421:
3420:
3419:
3416:
3413:
3410:output devices
3406:
3403:matched filter
3395:
3388:
3381:
3346:Main article:
3343:
3340:
3327:
3326:
3323:
3320:
3315:
3287:
3284:
3244:
3241:
3185:Range Interval
3169:Main article:
3166:
3163:
3120:Doppler effect
3100:
3097:
3079:Main article:
3076:
3073:
3041:beat frequency
3016:Main article:
3005:
3002:
2983:speed of light
2979:time-of-flight
2961:Time of flight
2956:
2953:
2951:
2948:
2946:
2943:
2881:Main article:
2878:
2875:
2821:
2820:
2819:
2818:
2815:
2715:Main article:
2700:
2697:
2684:Main article:
2681:
2678:
2655:
2626:
2605:
2587:ultra-wideband
2526:
2523:
2522:
2521:
2517:
2510:
2480:ke : 4/3
2462:
2458:
2454:
2449:
2445:
2439:
2435:
2431:
2427:
2422:
2417:
2413:
2409:
2406:
2403:
2400:
2395:
2391:
2385:
2381:
2377:
2374:
2371:
2366:
2362:
2356:
2352:
2346:
2342:
2338:
2335:
2330:
2326:
2320:
2316:
2313:
2286:
2283:
2281:
2278:
2246:
2243:
2238:
2237:
2224:
2216:
2212:
2208:
2203:
2198:
2194:
2187:
2183:
2177:
2173:
2168:
2142:
2138:
2126:
2125:
2112:
2107:
2103:
2097:
2093:
2087:
2083:
2078:
2048:
2044:
2021:
2017:
1994:
1990:
1967:
1963:
1940:
1936:
1920:
1919:
1906:
1901:
1896:
1892:
1886:
1882:
1877:
1873:
1869:
1864:
1860:
1837:
1836:
1823:
1818:
1813:
1809:
1803:
1799:
1794:
1790:
1786:
1783:
1780:
1775:
1771:
1747:
1725:
1721:
1698:
1694:
1671:
1667:
1600:
1599:Doppler effect
1597:
1571:
1570:
1559:
1551:
1547:
1541:
1536:
1533:
1530:
1527:
1518:
1514:
1510:
1505:
1501:
1495:
1491:
1485:
1481:
1474:
1469:
1465:
1441:
1434:
1427:
1420:
1414:
1413:
1409:
1404:
1400:
1395:
1389:
1378:
1377:
1376:
1375:
1371:
1366:
1354:
1341:
1340:
1327:
1324:
1316:
1312:
1306:
1302:
1283:
1278:
1270:
1265:
1261:
1252:
1251:
1235:
1230:
1226:
1220:
1215:
1211:
1205:
1200:
1197:
1194:
1191:
1182:
1178:
1174:
1169:
1165:
1159:
1155:
1149:
1145:
1138:
1133:
1129:
1112:
1106:
1103:
1049:and sometimes
1011:Hurricane Abby
995:Main article:
992:
989:
976:
973:
965:infrared light
942:Doppler effect
879:
876:
874:
871:
826:severe weather
770:
767:
743:night fighters
700:Tizard Mission
676:Main article:
673:
670:
662:Dowding system
639:Arnold Wilkins
542:Robert M. Page
453:
450:
410:A. Hoyt Taylor
319:Heinrich Hertz
314:
311:
306:Main article:
303:
300:
292:infrared light
257:guided missile
242:meteorological
183:United Kingdom
124:motor vehicles
65:
58:
57:
49:
42:
41:
40:
39:
38:
26:
9:
6:
4:
3:
2:
7156:
7145:
7142:
7140:
7137:
7135:
7132:
7130:
7127:
7125:
7122:
7120:
7117:
7115:
7112:
7110:
7107:
7105:
7102:
7100:
7097:
7095:
7092:
7090:
7087:
7086:
7084:
7069:
7066:
7064:
7061:
7060:
7057:
7051:
7048:
7046:
7043:
7041:
7038:
7037:
7035:
7031:
7022:
7016:
7014:
7011:
7009:
7006:
7004:
7001:
6999:
6996:
6994:
6991:
6989:
6986:
6984:
6981:
6979:
6978:Ship systems:
6976:
6974:
6971:
6969:
6966:
6964:
6961:
6960:
6958:
6954:
6948:
6945:
6943:
6940:
6938:
6935:
6933:
6930:
6928:
6925:
6924:
6922:
6918:
6908:
6905:
6903:
6900:
6898:
6895:
6894:
6892:
6888:
6882:
6879:
6877:
6874:
6872:
6869:
6867:
6864:
6862:
6859:
6858:
6856:
6852:
6849:
6845:
6839:
6836:
6834:
6831:
6829:
6826:
6824:
6821:
6819:
6816:
6814:
6811:
6809:
6806:
6804:
6801:
6799:
6796:
6795:
6793:
6789:
6783:
6780:
6778:
6775:
6773:
6772:Depth charges
6770:
6768:
6765:
6763:
6760:
6758:
6755:
6754:
6752:
6748:
6742:
6739:
6737:
6734:
6732:
6729:
6727:
6724:
6722:
6719:
6717:
6714:
6712:
6709:
6707:
6704:
6702:
6701:Naval warfare
6699:
6698:
6696:
6692:
6683:
6678:
6676:
6671:
6669:
6664:
6663:
6660:
6656:
6651:
6648:
6646:
6643:
6640:
6637:
6636:
6626:
6620:
6616:
6611:
6607:
6603:
6599:
6595:
6591:
6587:
6583:
6579:
6574:
6570:
6566:
6562:
6558:
6553:
6549:
6544:
6540:
6534:
6530:
6525:
6521:
6509:
6501:
6495:
6491:
6490:
6484:
6480:
6474:
6470:
6469:
6464:
6459:
6455:
6449:
6445:
6444:
6439:
6435:
6430:
6426:
6424:9780471473787
6420:
6416:
6415:Radar signals
6411:
6407:
6405:0-07-057913-X
6401:
6394:
6393:
6387:
6386:
6376:
6370:
6366:
6361:
6359:
6355:
6351:
6347:
6344:
6340:
6336:
6332:
6328:
6322:
6318:
6313:
6309:
6303:
6299:
6294:
6290:
6284:
6280:
6275:
6271:
6265:
6261:
6256:
6252:
6246:
6242:
6237:
6233:
6227:
6223:
6218:
6215:
6211:
6205:
6201:
6196:
6192:
6186:
6182:
6177:
6173:
6167:
6163:
6158:
6154:
6148:
6144:
6139:
6136:
6132:
6128:
6124:
6120:
6114:
6110:
6105:
6101:
6095:
6091:
6086:
6082:
6076:
6072:
6067:
6063:
6057:
6053:
6048:
6044:
6038:
6034:
6029:
6028:
6019:
6017:
6012:
6009:
6005:
6002:
6000:
5994:
5991:
5987:
5984:
5982:
5977:
5974:
5970:
5969:
5964:
5962:
5960:
5954:
5951:
5947:
5944:
5940:
5937:
5936:
5931:
5928:
5927:
5922:
5921:
5909:
5906:
5898:
5895:November 2014
5888:
5887:editing guide
5882:
5878:
5873:
5864:
5863:
5850:
5849:radar / RADAR
5844:
5825:
5818:
5811:
5792:
5785:
5777:
5773:
5767:
5759:
5755:
5749:
5733:
5729:
5723:
5707:
5703:
5697:
5689:
5685:
5679:
5671:
5667:
5661:
5650:
5643:
5637:
5635:
5618:
5611:
5610:
5602:
5586:
5579:
5578:
5573:
5567:
5551:
5544:
5543:
5535:
5533:
5521:
5513:
5507:
5502:
5501:
5492:
5477:
5473:
5467:
5451:
5447:
5443:
5437:
5426:
5422:
5415:
5409:
5401:
5395:
5387:
5380:
5374:
5359:
5358:
5353:
5346:
5330:
5326:
5322:
5315:
5300:
5293:
5285:
5281:
5275:
5267:
5263:
5257:
5255:
5246:
5242:
5236:
5229:
5217:
5213:
5206:
5199:
5186:
5179:
5173:
5163:
5157:
5149:
5145:
5141:
5135:
5127:
5123:
5119:
5113:
5097:
5093:
5086:
5078:
5074:
5068:
5061:
5055:
5039:
5035:
5031:
5025:
5018:
5012:
5003:
4995:
4991:
4985:
4978:
4972:
4965:
4959:
4951:
4945:
4941:
4934:
4927:. Washington.
4926:
4922:
4915:
4906:
4891:
4887:
4881:
4873:
4867:
4851:
4847:
4841:
4835:
4825:
4819:
4813:
4812:
4806:
4800:
4799:
4793:
4785:
4781:
4775:
4768:
4762:
4747:
4743:
4736:
4728:
4722:
4715:
4713:
4696:
4689:
4673:
4669:
4665:
4659:
4650:
4645:
4641:
4637:
4633:
4629:
4625:
4619:
4610:
4594:
4590:
4583:
4567:
4566:
4558:
4551:
4547:
4537:
4536:SCR-270 radar
4534:
4532:
4529:
4527:
4524:
4522:
4519:
4517:
4513:
4510:
4508:
4505:
4504:
4500:
4499:
4496:
4493:
4491:
4488:
4486:
4483:
4481:
4478:
4477:
4473:
4472:
4469:
4466:
4464:
4461:
4459:
4456:
4454:
4451:
4449:
4446:
4444:
4441:
4439:
4436:
4434:
4431:
4429:
4426:
4425:
4421:
4420:
4417:
4414:
4413:
4409:
4408:
4405:
4402:
4400:
4397:
4395:
4392:
4391:
4387:
4386:
4383:
4380:
4378:
4375:
4373:
4370:
4368:
4365:
4363:
4360:
4358:
4355:
4353:
4350:
4348:
4347:Radar imaging
4345:
4343:
4340:
4339:
4337:
4331:
4323:
4312:
4309:
4303:
4298:
4289:
4285:
4282:
4278:
4275:
4274:
4273:
4270:
4268:
4267:Pulse-doppler
4265:
4263:
4260:
4258:
4257:Passive radar
4255:
4253:
4250:
4248:
4245:
4243:
4242:Doppler radar
4240:
4238:
4235:
4233:
4230:
4229:
4228:
4219:
4217:
4213:
4209:
4205:
4204:primary radar
4201:
4197:
4193:
4187:
4185:
4181:
4177:
4176:article 1.100
4173:
4169:
4160:
4158:
4153:
4150:, leading to
4149:
4145:
4142:
4138:
4134:
4132:
4128:
4122:
4109:
4105:
4101:
4097:
4094:
4090:
4086:
4082:
4078:
4077:
4076:
4074:
4060:
4057:
4054:
4052:
4049:
4048:
4044:
4041:
4038:
4036:
4033:
4032:
4028:
4024:
4020:
4017:
4015:
4012:1.0–7.5
4011:
4008:
4005:
4004:
3999:
3996:
3993:
3991:
3985:
3984:
3971:
3967:
3964:
3960:
3957:
3954:
3952:
3949:
3948:
3944:
3941:
3938:
3936:
3930:
3929:
3924:
3920:
3916:
3913:
3910:
3908:8–12 GHz
3907:
3905:
3902:
3901:
3897:
3894:
3891:
3889:
3886:
3885:
3881:
3876:
3873:
3870:
3868:
3865:
3864:
3860:
3856:
3852:
3850:
3846:
3844:
3840:
3838:
3835:
3834:
3830:
3826:
3822:
3819:
3816:
3814:
3811:
3810:
3806:
3803:
3800:
3797:
3796:
3791:
3788:
3785:
3783:
3780:
3779:
3775:
3771:
3769:
3765:
3763:
3759:
3757:
3754:
3753:
3749:
3746:
3743:
3740:
3739:
3736:
3731:
3729:
3725:
3720:
3718:
3714:
3709:
3707:
3703:
3697:
3695:
3689:
3679:
3677:
3673:
3669:
3667:
3663:
3659:
3655:
3652:Phased-array
3650:
3648:
3644:
3641:
3637:
3634:
3630:
3626:
3621:
3617:
3614:
3612:
3609:
3605:
3601:
3597:
3593:
3588:
3586:
3580:
3578:
3572:
3564:
3560:
3551:
3546:
3537:
3525:
3522:
3519:
3516:
3513:
3512:
3509:Types of scan
3506:
3503:
3502:Pulse-Doppler
3500:
3494:
3492:
3488:
3482:
3473:
3464:
3462:
3457:
3452:
3448:
3443:
3435:
3430:
3417:
3414:
3411:
3407:
3404:
3400:
3396:
3393:
3389:
3386:
3382:
3379:
3375:
3371:
3367:
3363:
3362:
3361:
3354:
3349:
3339:
3337:
3336:radar tracker
3331:
3324:
3321:
3319:
3316:
3314:
3311:
3310:
3309:
3306:
3302:
3297:
3293:
3292:Radar tracker
3283:
3281:
3277:
3273:
3269:
3265:
3261:
3257:
3253:
3249:
3240:
3237:
3233:
3228:
3224:
3220:
3215:
3213:
3208:
3207:weather radar
3203:
3200:
3191:
3186:
3182:
3177:
3172:
3162:
3160:
3156:
3152:
3146:
3144:
3139:
3137:
3133:
3132:weather radar
3129:
3125:
3124:Doppler radar
3121:
3116:
3114:
3110:
3109:grease pencil
3105:
3096:
3092:
3089:
3082:
3072:
3068:
3066:
3062:
3058:
3054:
3049:
3044:
3042:
3037:
3033:
3029:
3024:
3019:
3010:
3001:
2999:
2998:nautical mile
2995:
2990:
2986:
2984:
2980:
2976:
2967:
2962:
2942:
2940:
2936:
2932:
2928:
2923:
2918:
2916:
2912:
2908:
2904:
2903:line of sight
2900:
2894:
2891:
2884:
2874:
2871:
2867:
2863:
2859:
2855:
2850:
2848:
2844:
2840:
2838:
2834:
2830:
2826:
2816:
2813:
2812:
2811:
2810:
2809:
2807:
2802:
2800:
2796:
2790:
2788:
2784:
2779:
2777:
2773:
2769:
2768:magnetosphere
2765:
2761:
2757:
2756:space weather
2753:
2749:
2745:
2741:
2737:
2733:
2729:
2728:precipitation
2725:
2718:
2710:
2705:
2696:
2694:
2687:
2677:
2675:
2671:
2653:
2643:
2638:
2636:
2632:
2625:
2621:
2617:
2613:
2610:
2604:
2600:
2599:thermal noise
2594:
2592:
2588:
2583:
2579:
2578:flicker noise
2575:
2571:
2569:
2563:
2561:
2557:
2553:
2549:
2545:
2540:
2536:
2535:Noise (radio)
2532:
2518:
2515:
2511:
2508:
2507:
2506:
2503:
2501:
2497:
2496:radar horizon
2493:
2476:Where :
2460:
2456:
2452:
2447:
2443:
2437:
2433:
2429:
2425:
2415:
2411:
2404:
2401:
2398:
2393:
2389:
2383:
2379:
2375:
2372:
2369:
2364:
2354:
2350:
2344:
2340:
2333:
2328:
2324:
2318:
2314:
2311:
2301:
2296:
2292:
2277:
2275:
2271:
2267:
2262:
2258:
2252:
2242:
2222:
2214:
2210:
2206:
2201:
2196:
2192:
2185:
2175:
2171:
2158:
2157:
2156:
2140:
2136:
2110:
2105:
2101:
2095:
2085:
2081:
2068:
2067:
2066:
2064:
2061:, called the
2046:
2042:
2019:
2015:
1992:
1988:
1965:
1961:
1938:
1934:
1924:
1904:
1899:
1894:
1890:
1884:
1880:
1875:
1871:
1867:
1862:
1858:
1850:
1849:
1848:
1846:
1842:
1821:
1816:
1811:
1807:
1801:
1797:
1792:
1788:
1784:
1781:
1778:
1773:
1769:
1761:
1760:
1759:
1745:
1723:
1719:
1696:
1692:
1669:
1665:
1655:
1651:
1648:
1644:
1643:weather radar
1640:
1636:
1631:
1629:
1620:
1615:
1610:
1606:
1605:Doppler radar
1596:
1594:
1590:
1586:
1581:
1579:
1574:
1557:
1549:
1545:
1539:
1531:
1528:
1516:
1512:
1508:
1503:
1499:
1493:
1489:
1483:
1479:
1472:
1467:
1463:
1455:
1454:
1453:
1451:
1447:
1440:
1433:
1430:and the term
1426:
1419:
1408:
1405:
1399:
1396:
1393:
1390:
1387:
1383:
1380:
1379:
1370:
1367:
1352:
1345:
1344:
1343:
1342:
1325:
1322:
1314:
1310:
1304:
1300:
1289:
1282:
1279:
1276:
1269:
1266:
1260:
1257:
1256:
1255:
1233:
1228:
1224:
1218:
1213:
1209:
1203:
1195:
1192:
1180:
1176:
1172:
1167:
1163:
1157:
1153:
1147:
1143:
1136:
1131:
1127:
1119:
1118:
1117:
1115:
1102:
1100:
1096:
1092:
1088:
1083:
1079:
1074:
1072:
1068:
1064:
1058:
1056:
1052:
1048:
1045:, containing
1044:
1040:
1036:
1032:
1028:
1024:
1020:
1012:
1008:
1007:weather radar
1003:
998:
988:
986:
982:
972:
970:
966:
962:
961:visible light
956:
954:
950:
945:
943:
939:
935:
931:
927:
923:
919:
915:
911:
910:radar signals
907:
903:
897:
889:
884:
870:
868:
864:
860:
855:
851:
850:Earth's crust
847:
843:
839:
838:winter storms
835:
831:
830:thunderstorms
827:
823:
819:
818:precipitation
814:
812:
807:
806:Marine radars
803:
800:
796:
792:
788:
783:
775:
766:
764:
760:
756:
752:
748:
744:
739:
737:
733:
729:
725:
721:
716:
715:
710:
709:
703:
701:
697:
689:
684:
679:
669:
665:
663:
659:
655:
651:
650:Bawdsey Manor
647:
640:
635:
628:
623:
619:
617:
613:
609:
605:
600:
592:
587:
583:
581:
577:
571:
566:
563:and the firm
562:
558:
555:
551:
547:
543:
538:
535:
531:
527:
523:
519:
514:
512:
511:
506:
502:
497:
495:
491:
487:
483:
479:
475:
471:
463:
458:
449:
447:
443:
439:
435:
431:
426:
424:
420:
415:
411:
407:
406:Potomac River
402:
400:
396:
392:
388:
384:
380:
375:
370:
368:
364:
360:
355:
350:
348:
344:
340:
336:
332:
328:
324:
320:
309:
299:
297:
293:
289:
285:
280:
278:
274:
270:
266:
262:
258:
254:
250:
246:
245:precipitation
243:
239:
235:
231:
227:
226:marine radars
223:
219:
215:
210:
208:
204:
200:
196:
192:
188:
184:
180:
176:
172:
167:
164:
160:
156:
152:
148:
144:
140:
135:
133:
129:
125:
121:
117:
113:
109:
105:
101:
97:
93:
89:
85:
84:
79:
75:
62:
53:
46:
37:
33:
19:
7068:Naval combat
7039:
7024:}}
7018:{{
7012:
6997:
6977:
6827:
6817:
6735:
6730:
6654:
6614:
6584:(1): 32–41.
6581:
6577:
6560:
6556:
6547:
6528:
6488:
6467:
6442:
6438:Petre Stoica
6414:
6391:
6364:
6349:
6334:
6316:
6297:
6278:
6259:
6240:
6221:
6199:
6180:
6161:
6142:
6126:
6108:
6089:
6070:
6051:
6032:
6014:
5998:
5989:
5979:
5966:
5958:
5933:
5924:
5901:
5892:
5880:
5858:Bibliography
5848:
5843:
5831:. Retrieved
5824:the original
5810:
5798:. Retrieved
5784:
5775:
5766:
5757:
5748:
5736:. Retrieved
5722:
5712:11 September
5710:. Retrieved
5706:the original
5696:
5688:the original
5678:
5670:the original
5660:
5649:the original
5621:. Retrieved
5608:
5601:
5589:. Retrieved
5576:
5566:
5554:. Retrieved
5541:
5520:
5499:
5491:
5479:. Retrieved
5475:
5466:
5454:. Retrieved
5450:the original
5445:
5436:
5420:
5408:
5394:
5385:
5373:
5361:. Retrieved
5355:
5345:
5333:. Retrieved
5329:the original
5324:
5314:
5302:. Retrieved
5292:
5284:Daily Record
5283:
5274:
5265:
5244:
5235:
5226:
5219:. Retrieved
5215:
5205:
5196:
5189:. Retrieved
5178:
5171:
5156:
5148:the original
5144:Media Centre
5143:
5134:
5126:the original
5121:
5112:
5100:. Retrieved
5096:the original
5085:
5076:
5067:
5059:
5054:
5042:. Retrieved
5038:the original
5033:
5024:
5016:
5011:
5002:
4993:
4984:
4976:
4971:
4963:
4958:
4939:
4933:
4924:
4914:
4905:
4893:. Retrieved
4889:
4880:
4866:
4854:. Retrieved
4850:the original
4840:
4833:
4818:
4810:
4805:
4797:
4792:
4783:
4774:
4766:
4761:
4749:. Retrieved
4745:
4735:
4711:
4709:
4702:. Retrieved
4688:
4676:. Retrieved
4672:the original
4667:
4658:
4631:
4627:
4618:
4609:
4597:. Retrieved
4593:the original
4582:
4570:. Retrieved
4564:
4555:ITU (2020).
4550:
4226:
4199:
4195:
4189:
4175:
4171:
4167:
4166:
4135:
4124:
4093:pulsed power
4071:
3970:water vapour
3965:
3919:marine radar
3892:4–8 GHz
3871:2–4 GHz
3855:surveillance
3734:
3724:broadcasting
3721:
3710:
3698:
3691:
3670:
3651:
3622:
3618:
3615:
3611:surveillance
3592:Mammut radar
3589:
3585:antenna gain
3581:
3577:phased array
3574:
3571:Phased array
3563:Phased array
3554:Phased array
3548:
3495:
3490:
3484:
3461:a small part
3451:right angles
3444:
3440:
3359:
3332:
3328:
3307:
3303:
3299:
3246:
3216:
3204:
3195:
3190:bed of nails
3189:
3184:
3181:Range Sample
3180:
3147:
3140:
3117:
3102:
3093:
3084:
3069:
3045:
3040:
3025:
3021:
2993:
2991:
2987:
2972:
2955:Transit time
2939:polarization
2919:
2914:
2906:
2895:
2886:
2851:
2845:, a form of
2841:
2822:
2803:
2791:
2780:
2720:
2689:
2680:Interference
2639:
2623:
2619:
2615:
2611:
2608:
2602:
2595:
2572:
2568:noise figure
2564:
2541:
2538:
2504:
2489:
2291:Beam forming
2261:polarization
2254:
2245:Polarization
2239:
2127:
1925:
1921:
1847:as follows:
1838:
1656:
1652:
1632:
1624:
1584:
1582:
1575:
1572:
1449:
1445:
1438:
1431:
1424:
1417:
1415:
1406:
1397:
1391:
1381:
1368:
1280:
1267:
1258:
1253:
1110:
1108:
1075:
1059:
1016:
985:illumination
984:
978:
975:Illumination
957:
946:
933:
909:
899:
878:Radar signal
815:
804:
784:
780:
769:Applications
761:used by the
740:
712:
706:
704:
693:
666:
646:Air Ministry
643:
612:Hugh Dowding
596:
593:and his team
578:team led by
576:Air Ministry
557:searchlights
539:
515:
509:
498:
490:Soviet Union
467:
437:
427:
414:Leo C. Young
403:
371:
358:
351:
316:
281:
247:monitoring,
211:
198:
186:
175:World War II
168:
136:
81:
73:
72:
36:
6968:Rangekeeper
6782:Naval mines
6736:Historical:
6516:|work=
6035:. R. Hale.
5973:Radar World
5941:Ekco Radar
4966:, Jan. 1931
4856:24 February
4458:Radar tower
4410:Application
4388:Definitions
4247:Fm-cw radar
4163:Regulations
4148:hygroscopic
4110:techniques.
4027:helicopters
3625:B-1B Lancer
3366:transmitter
3342:Engineering
3138:over time.
3053:transponder
2922:solid angle
2736:dust storms
2560:noise floor
2544:noise floor
1091:diffraction
906:radio waves
904:that emits
902:transmitter
888:Barker code
686:East Coast
568: [
468:Before the
139:transmitter
78:radio waves
7083:Categories
6956:Historical
6463:Guang Gong
6052:Radar Days
5918:References
5879:" section
5738:8 February
5623:2 December
5591:2 December
5572:Elkins, TJ
5556:2 December
5481:29 October
5456:29 October
5335:1 February
5187:. BBC News
4895:1 December
4599:8 November
4512:Chain Home
4362:Wave radar
4152:hydrolysis
4073:Modulators
4068:Modulators
4023:power line
3917:guidance,
3491:radar lock
3232:medium PRF
3113:slide rule
3091:antennas.
2994:radar mile
2862:refraction
2764:solar wind
2750:caused by
2748:ionosphere
2732:hail spike
2582:heterodyne
2574:Shot noise
2289:See also:
1619:wavelength
1617:Change of
1109:The power
1071:resonances
1009:image (of
991:Reflection
873:Principles
854:radar guns
842:Geologists
688:Chain Home
654:Chain Home
627:Chain Home
442:Chain Home
434:breadboard
379:ionosphere
343:Baltic Sea
329:school in
238:rendezvous
151:microwaves
141:producing
116:spacecraft
7013:Navboxes:
6823:Nike Zeus
6767:Torpedoes
6518:ignored (
6508:cite book
5988:Pub 1310
5932:Buderi, "
5800:12 August
5221:9 October
5191:16 August
5162:GB 593017
4751:9 January
4531:H2S radar
4186:(RR) as:
4131:klystrons
4089:magnetron
4085:thyratron
3741:Band name
3640:AN/APG-77
3487:parabolic
3385:waveguide
3378:modulator
3374:magnetron
3266:targets,
3130:systems (
3036:sine wave
2911:sidelobes
2783:waveguide
2754:or other
2674:coherence
2556:Detection
2430:−
2412:θ
2202:×
1881:×
1798:×
1785:×
1589:multipath
1532:π
1509:σ
1353:λ
1326:π
1311:λ
1196:π
1173:σ
1047:resistive
938:frequency
918:scattered
914:reflected
908:known as
834:tornadoes
599:death ray
513:in 1935.
510:Normandie
391:shortwave
383:lightning
372:In 1915,
367:Rotterdam
331:Kronstadt
240:systems,
203:anacronym
163:processor
88:direction
7094:Avionics
6871:AN/SPY-3
6866:AN/SPY-1
6606:16437755
6465:(2005).
6440:(2012).
6432:Hao He;
6004:Archived
5985:". 2002.
5946:Archived
5833:18 March
5425:Archived
5304:24 March
5044:28 April
5034:kret.com
4824:GB 13170
4721:cite web
4572:24 March
4443:Klystron
4422:Hardware
4294:See also
4141:silicate
4137:Coolanol
4104:klystron
4100:coherent
3602:and the
3456:rotating
3399:receiver
3392:duplexer
3370:klystron
2614:, where
1593:pathloss
1448:, where
1051:magnetic
1033:or in a
926:seawater
828:such as
787:aviation
530:Gneiss-2
279:levels.
171:military
159:receiver
108:aircraft
7033:Related
6890:Optical
6847:Sensors
6750:Weapons
6694:General
6586:Bibcode
6434:Jian Li
6025:General
5400:"Terma"
5388:. 2007.
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