Enabling DPCA via Supervised Reciprocal Filter in OFDM Radar Onboard Moving Platforms

This paper introduces an innovative displaced phase center antenna (DPCA) technique to enable clutter cancellation and slow-moving target detection in Orthogonal Frequency-Division Multiplexing (OFDM) radar systems installed onboard moving platforms. The DPCA approach exploits two receiving antennas displaced along the platform motion direction and provides cancellation of the stationary scene by subtracting properly delayed versions of the range compressed signals obtained at the two channels. In principle, exploiting continuous-wave transmissions should allow to select an appropriate delay to effectively suppress clutter echoes, based on the platform velocity and the array inter-element distance. However, without setting very strict constraints on the platform velocity, this delay might not be a multiple of the OFDM symbol duration. This forces the range compression stage to operate using batches of arbitrary length. Whilst the previously introduced supervised reciprocal filter techniques allow to handle this condition while controlling the system response to a point-like scatterer, they carry out the supervision separately across the two receiving channels, yielding unacceptable clutter cancellation loss. To tackle this issue, we propose a DPCA approach that exploits a new supervision technique for the reciprocal filter, which operates jointly over the two receiving channels. The new approach works with arbitrary batch durations, thus enabling an efficient application of the DPCA approach independently of the platform velocity. The benefits of the proposed approach are validated via numerical analysis.