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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
172:, which are suitable for amplifying or generating a narrow range of frequencies to high power levels. To scan a portion of the sky, a non-PESA radar antenna must be physically moved to point in different directions. In contrast, the beam of a PESA radar can rapidly be changed to point in a different direction, simply by electrically adjusting the phase differences between different elements of the passive electronically scanned array (PESA).
80:, 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.
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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
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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
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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
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developed an experimental phased array radar called
Electronically Steered Array Radar (ESAR). It was a large two-dimensional phased array with beam steering controlled by computers instead of requiring mechanical motion of the antenna. The first module, a linear array, was completed in 1960. It
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missiles. PESAs quickly became widespread on ships and large fixed emplacements in the 1960s, followed by airborne sensors as the electronics shrank.
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72:. The moving red lines show the wavefronts of the radio waves emitted by each element. The individual wavefronts are spherical, but they combine (
156:. Using a hybrid approach, the benefits of AESAs (e.g., multiple independent beams) can be realized at a lower cost compared to true AESAs.
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return, the radar receiver can determine the distance to the object. The receiver then sends the resulting output to a
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Animation showing how a passive electronically scanned array works. It consists of an array of antenna elements
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used by Nazi
Germany for early warning against Allied bombers (world's first operational phased array radar)
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DARPA's experimental two-dimensional
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antenna), in which all the antenna elements are connected to a single
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132:. Most phased array radars in the world are PESA. The civilian
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combat aircraft with nose fairing removed, showing its
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passive electronically scanned array radar antenna.
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502:. Archived from the original on 2007-09-27
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143:(AESA) antenna, which has a separate
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94:passive electronically scanned array
141:active electronically scanned array
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256:transportable 3D air search radar
278:Northrop Grumman E-8 Joint STARS
136:uses PESA transmit-only arrays.
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451:Multi-function radar of the
213:Cavalier Space Force Station
305:(initial version, now AESA)
187:Starting in the 1960s, new
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519:: CS1 maint: unfit URL (
500:"DRDO LRDE Radar Systems"
139:A PESA contrasts with an
68:controlled by a computer
194:semi-active radar homing
180:formed the basis of the
134:microwave landing system
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476:"Phased Array Radar"
353:systems respectively
162:display of some sort
122:travelling wave tube
102:passive phased array
54:powered by a single
18:Passive phased array
239:Aegis combat system
200:List of PESA radars
260:AN/MPQ-64 Sentinel
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448:, an Iranian PESA
269:Boeing E-3 Sentry
250:Firefinder radars
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504:. Retrieved
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483:. Retrieved
363:Mammut radar
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333:Saab Giraffe
294:Westinghouse
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154:RF front end
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106:phased array
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422:naval radar
361:FuMG 41/42
189:solid-state
145:transmitter
112:(such as a
110:transmitter
56:transmitter
506:2009-07-04
485:2024-01-29
459:References
384:N035 Irbis
343:Tomb Stone
303:B-2 Spirit
300:AN/APQ-181
283:AN/APQ-164
231:Cobra Judy
170:magnetrons
78:plane wave
319:EL/M-2026
292:formerly
254:AN/TPS-75
248:AN/TPQ-37
244:AN/TPQ-36
228:AN/SPQ-11
223:AN/MPQ-65
218:AN/MPQ-53
206:AN/FPQ-16
182:AN/FPS-85
175:In 1959,
124:) and/or
114:magnetron
74:superpose
535:Category
515:cite web
426:Hensoldt
408:SU-30MKI
357:Héraklès
345:for the
339:Flap Lid
274:AN/APY-7
265:AN/APY-1
236:AN/SPY-1
152:its own
149:receiver
126:receiver
118:klystron
434:TRML-3D
323:VSHORAD
147:and/or
453:KM-SAM
420:OPS-12
398:Rafale
378:MIG-31
374:Zaslon
314:ARABEL
309:ARTHUR
130:radars
40:Zaslon
541:Radar
480:DARPA
441:]
414:Su-34
386:(see
351:SA-20
347:SA-10
328:EMPAR
209:PARCS
177:DARPA
120:or a
521:link
430:EADS
406:for
394:RBE2
349:and
341:and
296:ESG)
286:B-1B
276:for
246:and
116:, a
98:PESA
59:(TX)
34:The
446:Asr
267:/2
211:at
168:or
70:(C)
66:(φ)
52:(A)
537::
517:}}
513:{{
478:.
467:^
439:de
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321:B
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92:A
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