A passive electronically scanned array (PESA), also known as passive phased array, is an antenna in which the beam of radio waves can be electronically steered to point in different directions (that is, a phased array antenna), in which all the antenna elements are connected to a single transmitter (such as a magnetron, a klystron or a travelling wave tube) and/or receiver. The largest use of phased arrays is in radars[citation needed]. Most phased array radars in the world are PESA[citation needed]. The civilian microwave landing system uses PESA transmit-only arrays.
The Mikoyan MiG-31 combat aircraft with nose fairing removed, showing its Zaslon passive electronically scanned array radar antenna.
Animation showing how a passive electronically scanned array works. It consists of an array of antenna elements (A) powered by a single transmitter(TX). The feed current for each antenna passes through a phase shifter(φ) controlled by a computer (C). The moving red lines show the wavefronts of the radio waves emitted by each element. The individual wavefronts are spherical, but they combine (superpose) in front of the antenna to create a plane wave, a beam of radio waves travelling in a specific direction θ. The phase shifters delay the radio waves progressively going up the line so each antenna emits its wavefront later than the one below it. This causes the resulting plane wave to be directed at an angle θ to the antenna. The computer can alter the phase shifters to steer the beam to a new direction, very quickly. The velocity of the radio waves is shown slowed down enormously.
A PESA contrasts with an active electronically scanned array (AESA) antenna, which has a separate transmitter and/or receiver unit for each antenna element, all controlled by a computer; AESA is a more advanced, sophisticated versatile second-generation version of the original PESA phased array technology. Hybrids of the two can also be found, consisting of subarrays that individually resemble PESAs, where each subarray has its own RF front end. Using a hybrid approach, the benefits of AESAs (e.g., multiple independent beams) can be realized at a lower cost compared to true AESAs.
Pulsed radar systems work by connecting an antenna to a powerful radio transmitter to emit a short pulse of signal. The transmitter is then disconnected and the antenna is connected to a sensitive receiver which amplifies any echos from target objects. By measuring the time it takes for the signal to return, the radar receiver can determine the distance to the object. The receiver then sends the resulting output to a display of some sort. The transmitter elements were typically klystron tubes or magnetrons, which are suitable for amplifying or generating a narrow range of frequencies to high power levels. To scan a portion of the sky, the radar antenna must be physically moved to point in different directions.
In 1959, DARPA developed an experimental phased array radar called Electronically Steered Array Radar ESAR. The first module, a linear array, was completed in 1960. It formed the basis of the AN/FPS-85.[1]
Starting in the 1960s new solid-state devices capable of delaying the transmitter signal in a controlled way were introduced. That led to the first practical large-scale passive electronically scanned array, or simply phased array radar. PESAs took a signal from a single source, split it into hundreds of paths, selectively delayed some of them, and sent them to individual antennas. The radio signals from the separate antennas overlapped in space, and the interference patterns between the individual signals was controlled to reinforce the signal in certain directions, and mute it in all others. The delays could be easily controlled electronically, allowing the beam to be steered very quickly without moving the antenna. A PESA can scan a volume of space much quicker than a traditional mechanical system. Thanks to progress in electronics, PESAs added the ability to produce several active beams, allowing them to continue scanning the sky while at the same time focusing smaller beams on certain targets for tracking or guiding semi-active radar homing missiles. PESAs quickly became widespread on ships and large fixed emplacements in the 1960s, followed by airborne sensors as the electronics shrank.[citation needed]
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January 11, 2023
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A passive electronically scanned array PESA also known as passive phased array is an antenna in which the beam of radio waves can be electronically steered to point in different directions that is a phased array antenna in which all the antenna elements are connected to a single transmitter such as a magnetron a klystron or a travelling wave tube and or receiver The largest use of phased arrays is in radars citation needed Most phased array radars in the world are PESA citation needed The civilian microwave landing system uses PESA transmit only arrays The Mikoyan MiG 31 combat aircraft with nose fairing removed showing its Zaslon passive electronically scanned array radar antenna Animation showing how a passive electronically scanned array works It consists of an array of antenna elements A powered by a single transmitter TX The feed current for each antenna passes through a phase shifter f controlled by a computer C The moving red lines show the wavefronts of the radio waves emitted by each element The individual wavefronts are spherical but they combine superpose in front of the antenna to create a plane wave a beam of radio waves travelling in a specific direction 8 The phase shifters delay the radio waves progressively going up the line so each antenna emits its wavefront later than the one below it This causes the resulting plane wave to be directed at an angle 8 to the antenna The computer can alter the phase shifters to steer the beam to a new direction very quickly The velocity of the radio waves is shown slowed down enormously A PESA contrasts with an active electronically scanned array AESA antenna which has a separate transmitter and or receiver unit for each antenna element all controlled by a computer AESA is a more advanced sophisticated versatile second generation version of the original PESA phased array technology Hybrids of the two can also be found consisting of subarrays that individually resemble PESAs where each subarray has its own RF front end Using a hybrid approach the benefits of AESAs e g multiple independent beams can be realized at a lower cost compared to true AESAs Pulsed radar systems work by connecting an antenna to a powerful radio transmitter to emit a short pulse of signal The transmitter is then disconnected and the antenna is connected to a sensitive receiver which amplifies any echos from target objects By measuring the time it takes for the signal to return the radar receiver can determine the distance to the object The receiver then sends the resulting output to a display of some sort The transmitter elements were typically klystron tubes or magnetrons which are suitable for amplifying or generating a narrow range of frequencies to high power levels To scan a portion of the sky the radar antenna must be physically moved to point in different directions In 1959 DARPA developed an experimental phased array radar called Electronically Steered Array Radar ESAR The first module a linear array was completed in 1960 It formed the basis of the AN FPS 85 1 Starting in the 1960s new solid state devices capable of delaying the transmitter signal in a controlled way were introduced That led to the first practical large scale passive electronically scanned array or simply phased array radar PESAs took a signal from a single source split it into hundreds of paths selectively delayed some of them and sent them to individual antennas The radio signals from the separate antennas overlapped in space and the interference patterns between the individual signals was controlled to reinforce the signal in certain directions and mute it in all others The delays could be easily controlled electronically allowing the beam to be steered very quickly without moving the antenna A PESA can scan a volume of space much quicker than a traditional mechanical system Thanks to progress in electronics PESAs added the ability to produce several active beams allowing them to continue scanning the sky while at the same time focusing smaller beams on certain targets for tracking or guiding semi active radar homing missiles PESAs quickly became widespread on ships and large fixed emplacements in the 1960s followed by airborne sensors as the electronics shrank citation needed List of PESA radars EditAN FPQ 16 PARCS at Cavalier Space Force Station AN MPQ 53 AN MPQ 65 AN SPQ 11 Cobra Judy AN SPY 1 Aegis combat system AN TPQ 36 and AN TPQ 37 Firefinder radars AN MPQ 64 Sentinel AN APY 1 2 Boeing E 3 Sentry AN APY 7 for Northrop Grumman E 8 Joint STARS AN APQ 164 B 1B Northrop Grumman formerly Westinghouse ESG AN APQ 181 B 2 Spirit initial version now AESA ARTHUR ARABEL EL M 2026B VSHORAD EMPAR Saab Giraffe 40 50 75 S AMB Flap Lid and Tomb Stone for the SA 10 and SA 20 systems respectively FuMG 41 42 Mammut radar used by Nazi Germany for early warning against Allied bombers world s first operational phased array radar Rajendra Radar 2 Zaslon first ever electronically scanned radar in a fighter jet MIG 31 N035 Irbis see Sukhoi Su 35BM RBE2 Rafale NIIP N011M Bars for SU 30MKI Leninets V004 Su 34 OPS 12 naval radar Hensoldt EADS TRML 3D de Asr an Iranian PESA Multi function radar of the KM SAMReferences Edit https www darpa mil about us timeline phased arrays bare URL DRDO LRDE Radar Systems Archived from the original on 2007 09 27 Retrieved 2009 07 04 Wikimedia Commons has media related to Passive electronically scanned arrays Retrieved from https en wikipedia org w index php title Passive electronically scanned array amp oldid 1119990899, wikipedia, wiki, book, books, library,
