Impact of wideband channel-to-channel mismatch on adaptive arrays

The wide waveform bandwidths desired for fine range resolution in current and future phased array radars have an impact on the performance of adaptive digital beamforming (ADBF) due to the inevitable frequency response mismatches that occur from channel to channel across the band. In previous work, analytical expressions for the correlation between channels have been developed for a simple two element array with a sinusoidal ripple in either the amplitude or phase response in one of the channels. This paper extends those results to a more general model that allows larger arrays utilizing time delay steering to be modeled. Expressions are developed for the correlation between channels as a function of the parameters of the channel frequency responses. The performance of the adaptive beamformer is characterized with respect to the SINR for waveforms that are flat over the bandwidth and for LFM waveforms processed using stretch processing.