Range-ambiguous clutter characteristics in airborne FDA radar

Abstract

Frequency diverse array (FDA) has received much attention in recent years. Different from classic phased-array (PA) that uses the same carrier frequency for all array elements, FDA adopts a small frequency increment across its array elements to produce angle, range and even time dependent transmit beampattern, which provides many promising applications, but it may result in time- and spatial-variant clutter characteristics. Since the impacts of FDA on radar clutter structures and characteristics still have not been systematically investigated, this paper studies range-ambiguous clutter characteristics for airborne FDA radar including FDA multiple-input multiple-output (FDA-MIMO) radar and coherent FDA radar systems. The corresponding receiver filtered signal models are formulated, and the clutter rank in different scenarios are analyzed. Moreover, by exploiting FDA range-dependent beampattern, we propose a method to distinguish range-ambiguous clutter in airborne FDA radar. Both theoretical analysis and simulation results validate the superiority of FDA radar over traditional PA and MIMO radars in suppressing range-ambiguous clutter and FDA-MIMO radar achieves better suppression performance than coherent FDA radar.