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| October 2009 Issue |
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Virtual Lift
The new radar revolutionises airpower dominance
By Prasun K. Sengupta |
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| Airborne active electronically steered-array (AESA) radars, already on board the Republic of Singapore Air Force’s Boeing-built F-15SGs and the Royal Australian Air Force’s F/A-18F Super Hornets, are about to revolutionise the regional balance of airpower and air dominance scenarios. Present-day airborne multi-mode radars like the ones on board the Indian Air Force’s (IAF) Dassault Mirage 2000H/TH and MiG-29B-12 (even after they are upgraded) have already attained the limits of technical performance that can be realised by systems with mechanically-scanning antennae. These limits can only be exceeded by an AESA radar that can simultaneously perform up to five functions comprising look-up and shoot-up; look-down and shoot-down; directional jamming of hostile data-links; real-beam ground mapping via Doppler-beam sharpening in the SAR mode; and ground moving target indication. By 2012 there will be available a range of X-band, L-band, and S-band AESA arrays that will all be able to be housed within both the upgraded Su-30MKI (after 2014) and the yet-to-fly fifth generation fighter aircraft (FGFA), with each array being assigned specific taskings, all aimed at not only ensuring the highest degree of survivability, but also full-spectrum air dominance. |
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| In Europe, the newly-developed ‘Caesar’ AESA radar for the Eurofighter EF-2000 Typhoon earlier this year successfully demonstrated the awesome potential of electronic beam-steering during three flight trials campaigns, two on a BAC 1-11 test aircraft and one on board Eurofighter DA5. In an AESA radar, the mechanically-scanning antenna is replaced by a fixed-array consisting of a multiplicity of so-called transmit/receive (T/R) modules with integrated radiating antenna elements. The active array eliminates, moreover, the traditional transmitter, which in most cases comes equipped with a travelling-wave tube (TWT), as well as the high-voltage power supply. Each radiating element can be fed with signals of individual phase-setting determined by the T/R module. If this is applied to the entire array formed by several hundreds or even thousands of elements in an appropriate pattern, a radiating beam can be generated in the far-field, which scans the space. This beam can change its look direction in quasi-real time. Strictly speaking, the beam is not continuously moved any longer but ‘switched’ from one spatial position to the other in roughly 0.1 per cent of the time needed by a mechanical system for the same manoeuvre. The AESA radar on board the M-MRCA offers capabilities that could not be reached up to now. This means, for example, that the search process is no longer dependent on a pre-determined search pattern, but can follow freely selectable sequences of beam positions, and making own-ship detectability considerably more difficult. The tactical requirement for simultaneously scanning a certain space segment in front of the aircraft and tracking the trajectories of as many identified targets as possible (track-while-scan, or TWS) can be fulfilled to much higher performance levels by an AESA radar than by a conventional one. Additionally, almost simultaneous surveillance of air and ground sectors becomes possible. Besides the primary radar operation, separate beams can provide data links to launched air combat missiles or even to other aircraft. |
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[Full Story] |
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