Coherent FDA Receiver and Joint Range–Space–Time Processing
Wenkai Jia, Andreas Jakobsson, Wen-Qin Wang
Abstract
When a target is masked by mainlobe clutter with the same Doppler frequency, it is difficult for conventional airborne radars to determine whether a target is present in a given observation using regular space–time adaptive processing (STAP) techniques. Different from phased-array and multiple-input multiple-output (MIMO) arrays, frequency diverse arrays (FDAs) employ frequency offsets (FOs) across the array elements, delivering additional range-controllable degrees of freedom, potentially enabling suppression for this kind of clutter. However, the reception of coherent FDA systems employing small FOs and achieving high transmit gain can be further improved. To this end, this work proposes an coherent airborne FDA radar receiver that explores the orthogonality of echo signals in the Doppler domain, allowing a joint space–time processing module to be deployed to separate the aliased returns. The resulting range STAP allows for a preferable detection performance for coherent airborne FDA radars as compared with current alternative techniques.