Active electronically scanned array: Difference between revisions

Revision as of 22:05, 14 December 2024

Revision as of 17:37, 11 January 2025

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+{{short description|Type of phased -array radar}}

{{more citations needed|date=April 2015}}

[[File:ILA Berlin 2012 PD 193-2.JPG|thumb|The [[Eurofighter Typhoon]] combat aircraft with its nose fairing removed, revealing its [[Euroradar CAPTOR]] AESA radar antenna]]

An '''active electronically scanned array''' ('''AESA''') is a type of [[phased -array]] antenna, which is a computer-controlled [[antenna array]] in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna.<ref>{{Citation |title=The Insane Engineering of the F-35B | date=28 January 2023 |url=https://www.youtube.com/watch?v=1lCOgFPtaZ4 |access-date=2024-02-16 |language=en}}</ref> In the AESA, each antenna element is connected to a small solid-state transmit/receive module (TRM) under the control of a computer, which performs the functions of a [[transmitter]] and/or [[receiver (radio)|receiver]] for the antenna. This contrasts with a [[passive electronically scanned array]] (PESA), in which all the antenna elements are connected to a single transmitter and/or receiver through [[phase shifter]]s under the control of the computer. AESA's main use is in [[radar]], and these are known as active phased -array radar (APAR).

The AESA is a more advanced, sophisticated, second-generation of the original PESA phased -array technology. PESAs can only emit a single beam of radio waves at a single frequency at a time. The PESA must utilize a [[Butler matrix]] if multiple beams are required. The AESA can radiate multiple beams of radio waves at multiple frequencies simultaneously. AESA radars can spread their signal emissions across a wider range of frequencies, which makes them more difficult to detect over [[Noise (radio)|background noise]], allowing ships and aircraft to radiate powerful radar signals while still remaining stealthy, as well as being more resistant to jamming. Hybrids of AESA and PESA 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 AESA (e.g., multiple independent beams) can be realized at a lower cost compared to pure AESA.

==History==

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[[File:MAR-I radar.jpg|thumb|An aerial view of the three domes of the Multifunction Array Radar prototype, surrounded by a [[clutter fence]], at White Sands Missile Range, N.M.]]

[[File:Azov array.jpg|thumb|Sketch of the FLAT TWIN antiballistic missile radar]]

[[Bell Labs]] proposed replacing the [[Nike Zeus]] radars with a phased -array system in 1960, and was given the go-ahead for development in June 1961. The result was the Zeus Multi-function Array Radar (ZMAR), an early example of an active electronically steered array radar system.{{sfn|Bell Labs|1975|p=I-35}} ZMAR became MAR when the Zeus program ended in favor of the [[Nike-X]] system in 1963. The MAR (Multi-function Array Radar) was made of a large number of small antennas, each one connected to a separate computer-controlled transmitter or receiver. Using a variety of [[beamforming]] and [[signal processing]] steps, a single MAR was able to perform long-distance detection, track generation, discrimination of warheads from decoys, and tracking of the outbound interceptor missiles.{{sfn|Bell Labs|1975|p=2-3}}

MAR allowed the entire battle over a wide space to be controlled from a single site. Each MAR, and its associated battle center, would process tracks for hundreds of targets. The system would then select the most appropriate battery for each one, and hand off particular targets for them to attack. One battery would normally be associated with the MAR, while others would be distributed around it. Remote batteries were equipped with a much simpler radar whose primary purpose was to track the outgoing [[Sprint missile]]s before they became visible to the potentially distant MAR. These smaller Missile Site Radars (MSR) were passively scanned, forming only a single beam instead of the MAR's multiple beams.{{sfn|Bell Labs|1975|p=2-3}}

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Radar systems generally 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 [[Radar display|display of some sort]]. The transmitter elements were typically [[klystron tube]]s or [[magnetron]]s, 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.

Starting in the 1960s new [[solid state (electronics)|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]] (PESA), 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 were 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. Additionally, 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.

AESAs are the result of further developments in solid-state electronics. In earlier systems the transmitted signal was originally created in a klystron or [[traveling wave tube]] or similar device, which are relatively large. Receiver electronics were also large due to the high frequencies that they worked with. The introduction of [[gallium arsenide]] microelectronics through the 1980s served to greatly reduce the size of the receiver elements until effective ones could be built at sizes similar to those of handheld radios, only a few cubic centimeters in volume. The introduction of [[JFET]]s and [[MESFET]]s did the same to the transmitter side of the systems as well. It gave rise to amplifier-transmitters with a low-power solid-state waveform generator feeding an amplifier, allowing any radar so equipped to transmit on a much wider range of frequencies, to the point of changing operating frequency with every pulse sent out. Shrinking the entire assembly (the transmitter, receiver and antenna) into a single "transmitter-receiver module" (TRM) about the size of a carton of milk and arraying these elements produces an AESA.

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Radar systems work by sending out a signal and then listening for its echo off distant objects. Each of these paths, to and from the target, is subject to the [[inverse square law]] of propagation in both the transmitted signal and the signal reflected back. That means that a radar's received energy drops with the fourth power of the distance, which is why radar systems require high powers, often in the megawatt range, to be effective at long range.

The radar signal being sent out is a simple radio signal, and can be received with a simple [[radio receiver]]. Military aircraft and ships have defensive receivers, called "[[radar warning receiver]]s" (RWR), which detect when an enemy radar beam is on them, thus revealing the position of the enemy. Unlike the radar unit, which must send the pulse out and then receive its reflection, the target's receiver does not need the reflection and thus the signal drops off only as the square of distance. This means that the receiver is always at an advantage [neglecting disparity in antenna size] over the radar in terms of range -– it will always be able to detect the signal long before the radar can see the target's echo. Since the position of the radar is extremely useful information in an attack on that platform, this means that radars generally must be turned off for lengthy periods if they are subject to attack; this is common on ships, for instance.

Unlike the radar, which knows which direction it is sending its signal, the receiver simply gets a pulse of energy and has to interpret it. Since the radio spectrum is filled with noise, the receiver's signal is integrated over a short period of time, making periodic sources like a radar add up and stand out over the random background. The rough direction can be calculated using a rotating antenna, or similar passive array using [[Phase-Comparison Monopulse|phase]] or [[Amplitude-Comparison Monopulse|amplitude comparison]]. Typically RWRs store the detected pulses for a short period of time, and compare their broadcast frequency and [[pulse repetition frequency]] against a database of known radars. The direction to the source is normally combined with symbology indicating the likely purpose of the radar – [[airborne early warning and control]], [[surface-to-air missile]], etc.

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==Limitations==

With a half wavelength distance between the elements, the maximum beam angle is approximately <math>\pm 45</math>°. With a shorter element distance, the highest field of view (FOV) for a flat phased -array antenna is currently 120° (<math>\pm 60</math>°),<ref>{{cite book|url=https://books.google.com/books?id=ANEM6nI3tosC&pg=PA196|title=Introduction to Electronic Warfare Modeling|year=2001|publisher=Artech House|isbn=9781596933118|via=Google Books}}</ref> although this can be combined with mechanical steering as noted above.<ref>{{cite book|url=https://books.google.com/books?id=ANEM6nI3tosC&pg=PA196|title=Introduction to Electronic Warfare Modeling|first=David|last=Adamy|date=26 March 2018|publisher=Artech House|isbn=9781596933118|via=Google Books}}</ref><ref>{{cite web|url=http://www.radartutorial.eu/17.bauteile/bt36.en.html|title=Error 308|access-date=17 June 2015|url-status=dead|archive-url=https://web.archive.org/web/20150506024146/http://www.radartutorial.eu/17.bauteile/bt36.en.html|archive-date=6 May 2015}}</ref>

==List of existing systems==

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[[File:Hanwha Systems APY-016K AESA radar and APS-016K signal processing unit.jpg|thumb|[[Hanwha Group|Hanwha Systems]] APY-016K AESA radar set of [[KAI KF-21 Boramae|KF-21 Boramae]] multirole combat aircraft]]

[[File:LIG Nex1 ESR-500A AESA Radar.jpg|thumb|[[LIG Nex1]] ESR-500A AESA radar]]

===Airborne systems===

* [[Aselsan]]

** [[MURAD AESA Radar|MURAD]], for the [[Baykar Bayraktar Akıncı]], [[F-16]] and [[TAI TF-X Kaan]].

** FULMAR, for the maritime aircraft and helicopters.

* [[Euroradar CAPTOR|Captor-E]] CAESAR (CAPTOR Active Electronically Scanning Array Radar) for the [[Eurofighter Typhoon]]

* [[Defence Research and Development Organisation]]

** [[DRDO AEW&CS|DRDO LSTAR]] -– Radar for Airborne Early -Warning platform.

** [[Uttam AESA]] multifunction radar for [[HAL Tejas]]

** [[Uttam AESA Radar#Virupaaksha|Virupaaksha]] multifunction radar for [[Sukhoi Su-30MKI|Su-30MKI]], an advance variant of [[Uttam AESA Radar|Uttam AESA]]

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** [[Multi-role Electronically Scanned Array]] (MESA), for the [[Boeing E-7 Wedgetail]]

** AN/ASQ-236 Podded AESA Radar

** [[AN/ZPY-1]] STARLite Small Tactical Radar -– Lightweight, for manned and unmanned aircraft

** AN/ZPY-2 [[Multi-Platform Radar Technology Insertion Program]] (MP-RTIP)

** AN/ZPY-3 Multi-Function Active Sensor (MFAS) for [[Northrop Grumman MQ-4C Triton|MQ-4C Triton]]

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** [[Shenyang J-16]]<ref>{{cite web |url=https://nationalinterest.org/blog/the-buzz/chinas-new-j-16d-aircraft-might-have-terrifying-new-military-23427 |title = China's New J-16D Aircraft Might Have a Terrifying New Military Capability {{!}} The National Interest|date = 30 November 2017}}</ref>

** [[Aérospatiale Super Frelon#Variants|Z-8AEW]]

** Vehicle Dismount and Exploitation Radar (VADER)

* [[Phazotron NIIR]]

** [[Zhuk radar|Zhuk-A/AM]], optional for [[Mikoyan MiG-35|MiG-35]]

* [[Raytheon]]

** [[APG-63 and APG-70|AN/APG-63(V)2]] and AN/APG-63(V)3, for the [[F-15 Eagle|F-15C Eagle]], [[Republic of Singapore]]'s [[F-15SG]]

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** [[APG-63 and APG-70#AN/APG-82(V)1|AN/APG-82(V)1]] for the [[F-15E Strike Eagle]] & [[Boeing F-15EX Eagle II|F-15EX Eagle II]]

** [[AN/APG-84 RACR]] (Raytheon Advanced Combat Radar) for F-16 and F/A-18 upgrades.

** [[AN/APQ-181]] upgrade from [[Passivepassive electronically scanned array|PESA]] to AESA, for [[Northrop Grumman B-2 Spirit]] bomber

** [[AN/APS-154]] [[Advanced Airborne Sensor|AAS]] (Advanced Airborne Sensor), AESA follow-on to [[Littoral Surveillance Radar System|LSRS]] (Littoral Surveillance Radar System), [[APS-149|AN/APS-149]]. Also for the [[Boeing P-8 Poseidon]]

** PhantomStrike air-cooled AESA radar for the [[KAI T-50 Golden Eagle|FA-50 Block 20]].

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The first AESA radar employed on an operational warship was the Japanese [[OPS-24]] manufactured by [[Mitsubishi Electric]] introduced on the JDS Hamagiri (DD-155), the first ship of the latter batch of the [[Asagiri-class destroyer]], launched in 1988.

* [[Active Phased Array Radar|APAR]] (active phased -array radar): Thales Netherlands' multifunction radar is the primary sensor of the Royal Netherlands Navy's [[De Zeven Provinciën class frigate|De Zeven Provinciën class]] frigates, the German Navy's [[Sachsen class frigate|Sachsen class]] frigates, and the Royal Danish Navy's [[Ivar Huitfeldt class frigate|Ivar Huitfeldt class]] frigates. [[Active Phased Array Radar|APAR]] is the first active electronically scanned array multifunction radar employed on an operational warship.<ref name="Janes NI">Jane's Navy International, August 2010, "Expanding coverage from sea to sky"</ref>

* [[Aselsan]]

** AKREP, for marine platforms.

** CENK, for marine platforms.

* [[BAE Systems]]

** [[SAMPSON]] multifunction radar for the UK's [[Type 45 destroyer]]s

** [[Type 997 Artisan radar|ARTISAN]] Type 997 multifunction radar for the UK's [[Type 23 frigate|Type 23]] and [[Type 26 frigate|Type 26]] Frigates and the [[Queen Elizabeth-class aircraft carrier|Queen Elizabeth class]] aircraft carriers

* [[Bharat Electronics]]

** RAWL-03 -– Multi -Function Active phased -array Air Surveillance Radar.<ref name="bel-india.com">{{Cite web |url=http://www.bel-india.com/Products.aspx?MId=13&LId=1&CId=19&link=69 |title=BEL &#124; Products |access-date=2016-11-01 |archive-url=https://web.archive.org/web/20161103233710/http://www.bel-india.com/Products.aspx?MId=13&LId=1&CId=19&link=69 |archive-date=2016-11-03 |url-status=dead }}</ref>

** Naval Missile Defense Radar (NMDR) -– S-Band Multi -Function Active phased -array Radar.<ref name="bel-india.com"/>

* [[Cassidian]]

** BÜR -– [[Bodenüberwachungsradar]] by [[Cassidian]], for the [[Bundeswehr]]

** [[COBRA (radar)|COBRA]] Counter-battery radar

* [[CEA Technologies]]

** [[CEAFAR]] a 4th generation, S-Band multifunction digital active phased -array radar, installed on all RAN ANZAC class frigates.

* China

** Road-mobile "Anti-Stealth" JY-26 "Skywatch-U" 3-D long-range air surveillance radar.<ref>{{cite news|url=http://www.defensenews.com/article/20141122/DEFREG03/311220016/China-s-Anti-Stealth-Radar-Comes-Fruition |archive-url=https://archive.today/20141124002410/http://www.defensenews.com/article/20141122/DEFREG03/311220016/China-s-Anti-Stealth-Radar-Comes-Fruition |url-status=dead |archive-date=24 November 2014 |title=China's Anti-Stealth Radar Comes to Fruition |last1=MINNICK |first1=WENDELL |date=22 November 2014 |website=www.defensenews.com |publisher=Gannett |access-date=25 November 2014 }}</ref>

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** [[YLC-2 Radar]]<ref>{{cite web|url=http://www.ausairpower.net/APA-PLA-IADS-Radars.html|title=PLA Air Defence Radars|author=John C Wise|date=13 January 2009|pages=1|access-date=17 June 2015}}</ref>

* [[Defence Research and Development Organisation]]

** [[Ashwini LLTR Radar]]- – 4D AESA radar (used by Indian Air Force).<ref>Low Level Transportable Radar (LLTR) - Ashwini https://www.drdo.gov.in/sites/default/files/inline-files/lltr.pdf</ref>

** [[Arudhra Radar]]- – Multi function AESA radar (used by Indian Air Force).<ref>{{cite web|url=http://www.drdo.gov.in/drdo/labs/LRDE/English/index.jsp?pg=achieve.jsp|title=DRDO Radar List|website=drdo.gov.in|access-date=25 July 2016|url-status=dead|archive-url=https://web.archive.org/web/20140723095010/http://drdo.gov.in/drdo/labs/LRDE/English/index.jsp?pg=achieve.jsp|archive-date=23 July 2014}}</ref>

** [[Swordfish Long Range Tracking Radar]]-– Target acquisition and fire control radar for [[Indian Ballistic Missile Defence Programme|Indian Ballistic Missile Defence]] system.

** [[Air Defence Tactical Control Radar]] (ADTCR) -– Tactical control radar.<ref>{{Cite web|title=Air Defence Tactical Control Radar (ADTCR)|url=https://www.drdo.gov.in/air-defence-tactical-control-radar-adtcr|url-status=live|access-date=2021-10-07|website=Defence Research and Development Organisation, Ministry of Defence, Government of India|archive-url=https://web.archive.org/web/20200708110602/https://www.drdo.gov.in/air-defence-tactical-control-radar-adtcr |archive-date=2020-07-08 }}</ref>

** [[Atulya Air Defence Fire Control Radar]] (ADFCR) -– X-band, 3D Fire control radar.<ref>{{Cite web|title=Air Defence Fire Control Radar|url=https://www.drdo.gov.in/air-defence-fire-control-radar|url-status=live|access-date=2021-10-07|website=Defence Research and Development Organisation, Ministry of Defence, Government of India|archive-url=https://web.archive.org/web/20200815160403/https://www.drdo.gov.in/air-defence-fire-control-radar |archive-date=2020-08-15 }}</ref>

[[Image:ELM 2248 MF-STAR radar onboard INS Kolkata (D63) of the Indian Navy.png|thumb|[[EL/M-2248 MF-STAR]] on board a [[Kolkata class destroyer|''Kolkata''-class destroyer]]]]

* [[Elta Systems|Elta]]

** [[EL/M-2080 Green Pine|EL/M-2080 ''Green Pine'']] ground-based [[early -warning]] AESA radar

** [[EL/M-2106]] ATAR air defense fire control radar

** [[EL/M-2180]] -– WatchR Guard Multi-Mode Staring Ground Surveillance Radar

** [[EL/M-2248 MF-STAR|EL/M-2248 ''MF-STAR'']] multifunction naval radar

** [[EL/M-2258]] Advanced Lightweight Phased -Array ''ALPHA'' multifunction naval radar

** [[EL/M-2084]] multimission radar (artillery weapon ___location, air defence and fire control)

** [[EL/M-2133]] ''WindGuard'' -– ''Trophy'' active protection system radar

* [[Hensoldt]]

** [[TRML-4D]]<ref name=trml-4d-product>{{cite web | url=https://www.hensoldt.net/products/radar-iff-and-datalink/trml-4d/ | title=TRML-4D - Multi-Functional Air Surveillance and Target Acquisition Radar System &#124; HENSOLDT }}</ref><ref name=armyrecognition-trml-4d>{{cite web | url=https://www.armyrecognition.com/defense_news_may_2021_global_security_army_industry/hensoldt_presenting_trml-_4d_multi-function_air_surveillance_and_target_acquisition_radar.html | title=Hensoldt presenting TRML- 4D multi-function air surveillance and target acquisition radar &#124; Defense News May 2021 Global Security army industry &#124; Defense Security global news industry army year 2021 &#124; Archive News year | access-date=2022-05-17 | archive-date=2022-05-26 | archive-url=https://web.archive.org/web/20220526011606/https://www.armyrecognition.com/defense_news_may_2021_global_security_army_industry/hensoldt_presenting_trml-_4d_multi-function_air_surveillance_and_target_acquisition_radar.html | url-status=dead }}</ref><ref name=armada-trml-4d>{{cite web | url=https://www.armadainternational.com/2018/06/hensoldt-presents-new-ground-based-air-defence-radar/ | title=HENSOLDT presents new ground-based Air Defence Radar | date=19 June 2018 }}</ref>

** [[TRML#TRS-4D|TRS-4D]]

* [[Larsen & Toubro]]

** [[Air Defence Fire Control Radar System]]- – 3D surveillance radar.<ref>{{Cite web|title=Defexpo 2016: Larsen & Toubro highlights new Air Defence Fire Control Radar system|url=https://www.armyrecognition.com/defexpo_2016_show_daily_news_coverage_report/defexpo_2016_larsen_toubro_highlights_new_air_defence_fire_control_radar_system_22803162.html|url-status=live|access-date=2021-10-07|website=Army Recognition|date=28 March 2016 |archive-url=https://web.archive.org/web/20160401145102/http://www.armyrecognition.com:80/defexpo_2016_show_daily_news_coverage_report/defexpo_2016_larsen_toubro_highlights_new_air_defence_fire_control_radar_system_22803162.html |archive-date=2016-04-01 }}</ref>

* [[LIG Nex1]]

** [[SPS-550K]] medium-range air and surface surveillance radar for [[Incheon-class frigate]]s and [[Daegu-class frigate]]s

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** [[AN/MPQ-64 Sentinel|AN/MPQ-64A4 Sentinel]]

** [[TPY-4|AN/TPY-4 3DELRR]] Three-Dimensional Expeditionary Long-Range Radar<ref>{{cite web | url=https://www.airforce-technology.com/news/lockheed-martin-tpy-4-radar/ | title=Lockheed Martin completes first AN/TPY-4 radar production | date=5 May 2022 }}</ref>

[[File:Q-53 Counterfire Target Acquisition Radar.jpg|thumb|[[AN/TPQ-53]] [[phased -array radar]]]]

* [[MEADS]]'s fire control radar

* [[Mitsubishi Electric Corporation]]

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** JTPS-P16 Counter-battery radar

* [[National Chung-Shan Institute of Science and Technology]]

** [[Sea eagle eye]]- – Multi function AESA radar<ref>{{Cite web |title=中科院研製「海鷹眼」主動相列雷達 海軍正進行效能審核 -- 上報 / 要聞 |url=https://www.upmedia.mg/news_info.php?Type=1&SerialNo=101855 |access-date=2023-05-02 |website=www.upmedia.mg}}</ref>

* [[NEC]]

** J/TPS-102 Self-propelled ground-based radar, cylindrical array antenna.

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** [[AN/SPY-6|AN/SPY-6 Air and Missile Defense Radar (AMDR)]] multifunction radar for U.S. [[Arleigh Burke-class destroyer|''Arleigh Burke'' destroyers]], {{sclass|Gerald R. Ford|aircraft carrier}}

** Cobra Judy Replacement (CJR)/Cobra King on {{USNS|Howard O. Lorenzen|T-AGM-25}}

** [[AN/FPS-132]] [[Upgraded Early Warning Radar|Upgraded Early Warning Radar (UEWR)]] -– [[PAVE PAWS]] upgrade from PESA to AESA

** [[KuRFS]]<ref>{{cite web |url=https://www.raytheon.com/news/feature/kurfs-radar |title = The Swiss Army knife of radars - For soldiers, the KuRFS radar does it all and all at once {{!}} Raytheon Missiles & Defense}}</ref>

* [[Saab Group]]

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** [[Ground Master 400]]

** [[Ground Master 200 Multi-Mission|Ground Master 200 MM]]

** [[SMART-L]] MM <ref>{{cite web |url=https://www.thalesgroup.com/en/smart-l-mm |title = SMART-L MM {{!}} Thales Group}}</ref>

** [[Sea Fire 500]] on [[FREMM multipurpose frigate|FREMM-ER frigates]]

** [[Sea Master 400]]

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* [[Receiver (radio)|Receiver]]

* [[Passive electronically scanned array]]

* [[Low Probability -probability-of-intercept Intercept Radarradar]] (LPIR)

* [[Terrain-following radar]]

* [[Solid State Phased Array Radar System]]

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==External links==

* [httphttps://www.ausairpower.net/aesa-intro.html Active Electronically Steered Arrays – A Maturing Technology] (ausairpower.net)

* [https://web.archive.org/web/20060718065545/http://flug-revue.rotor.com/FRHeft/FRH9812/FR9812c.htm FLUG REVUE December 1998: Modern fighter radar technology] (flug-revue.rotor.com)

* [https://web.archive.org/web/20071031083529/http://www.mwjournal.com/article.asp?HH_ID=AR_29 Phased -Arrays and Radars – Past, Present and Future] (mwjournal.com)