Active Electronically Scanned Array
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An Active Electronically Scanned Array (AESA), also known as active phased array radar is a revolutionary type of radar whose transmitter and receiver functions are composed of numerous small transmit/receive (T/R) modules. AESA radars feature short to instantaneous (millisecond) scanning rates and have a desirable low probability of intercept.
Being immobile, AESA radars have vastly simpler mechanical designs. They require no complex hydraulics for antenna movement nor hinge appendages that are prone to failure. The AESA radar occupies less space than typical radar, because of its lesser infrastructure requirements and of course its absent range of motion. The distributed transmit function also eliminates the most common single-point failure mode seen in a conventional radar. With these improvements, maintenance crews are far less severely taxed, and the radar is much more reliable.
Main advantages over mechanically scanned arrays are extremely fast scanning rate, much higher range, tremendous number of targets being tracked and engaged (multiple agile beams), low probability of intercept, ability to function as a radio/jammer, simultaneous air and ground modes, Synthetic Aperture Radar.
Mechanical steering may be added to AESA radars for increased radar field of view; The movement performance of the antenna would not need to be nearly as great as that of a traditional radar, as the radar sweep is not integral to the contact update rate.
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[edit] Features
AESA radars have:
- High ECM resistance:
- The extremely fast scan of the radar makes it difficult for an ECM device to find the correct azimuth and elevation in which the radar's main lobe is currently directed.
- High gain associated with AESA radars gives them high ERP, which makes it difficult for an active ECM device, using noise jamming techniques, to successfully jam such a radar.
- The extremely fast scan of the emitter gives it LPI features.
- Less suspectibility to voltage failures, due to the relatively very low voltage in which each and every single radiating element operates; This is combined with graceful degradation.
[edit] The difference between AESA and PESA
In a passive electronically scanned array (PESA), the microwave feed network in the back of the antenna is powered by a single RF source (magnetron, klystron, TWT, etc.), sending its waves into phase shift modules (usually digitally-controlled), which, in turn, feed the numerous emitting elements.
An AESA, instead, has an individual RF source for each of its many transmit/receive elements, making them "active".
This provides for a graceful degradation, so that many T/R modules may fail and the radar would not stop functioning.
AESA radars replace the traditional radar RF sources (magnetron/klystron/TWT), which usually require extremely high operating voltage and power with multiple solid-state sources operating at low voltage (40 to 60 volts). Solid state electronics use silicon or gallium-arsenide technology and benefit from mass production techniques developed for consumer electronics.
[edit] List of AESA radars
[edit] Airborne systems
- Northrop Grumman/Raytheon AN/APG-77, for the F-22 Raptor
- Northrop Grumman AN/APG-80, for the F-16E/F Block 60 Fighting Falcon
- Northrop Grumman AN/APG-81, for the F-35 Joint Strike Fighter
- Northrop Grumman Multi-role AESA, for the Boeing Wedgetail (AEW&C)
- Raytheon AN/APG-63(V)2 and AN/APG-63(V)3, for the F-15C Eagle
- Raytheon AN/APG-79, for the F/A-18E/F Super Hornet
- Raytheon AN/APQ-181 (AESA upgrade currently in development), for the B-2 Spirit bomber
- AMSAR, from the European GTDAR consortium, for Eurofighter and Rafale fighters
- SELEX Seaspray 7000E, for helicopters
- Elta EL/M-2075 radar for the IAI Phalcon AEW&C system
- Mitsubishi Electric Corporation AESA for the Mitsubishi F-2 fighter
- Ericsson Erieye AEW&C and NORA AESA for JAS-39 Gripen
- Phazotron NIIR Zhuk-A
- Tikhomirov NIIP Epaulet-A
- Elta EL/M-2083 aerostat-mounted air search radar
[edit] Ground and sea-based systems
- APAR multi-function radar, primary sensor of Dutch De Zeven Provinciën and German Sachsen class frigates
- Elta EL/M-2080 Green Pine ground-based early warning AESA radar
- AN/SPY-3 multi-function radar for U.S. DD(X), CG(X) and CVN-21 next-generation surface vessels
- Raytheon U.S. National Missile Defense X-Band Radar (XBR)
- SAMPSON multi-function radar for UK. Type 45 destroyers
- MEADS's fire control radar
- THAAD system fire control radar
