Airborne ground moving target indication using non-side-looking antennas

It is well known that detection of moving targets using an airborne radar is complicated by platform-induced spectral spreading of clutter returns. As a result, conventional pulse Doppler radars require a target to have a minimum detectable velocity (MDV) to be clear of mainbeam (and sidelobe) clutter. In recent years, extensive research into side-looking, multi-channel (i.e. multi-aperture) radars employing space-time adaptive processing (STAP) and displaced phase centre antenna (DPCA) processing techniques has been conducted, in order to reduce the requirement on MDV for airborne early warning (AEW) radar applications. GMTI (ground moving target indication) radars like JSTARS also employ similar techniques to detect slow ground moving targets such as tanks and jeeps. Most of the literature deals with side-looking airborne radars (SLAR), which is the case when the aperture phase centres lie along a line parallel to the flight path. This paper considers the design and performance of GMTI radars for the general, non-SLAR case, where the array is oriented away from the side, the extreme case being a forward-looking airborne radar (FLAR). A non-SLAR GMTI radar is attractive because it is applicable to mechanically rotated antenna arrays, often used for wide-angle surveillance; and, as a result, can be considered as an upgrade to existing surveillance radars.