An Optimum Adaptive Single-Port Microwave Beamformer Based on Array Signal Vector Estimation

Abstract

A single-port adaptive beamforming structure based on an optimum perturbation technique is presented. The proposed perturbation technique is based on array signal vector estimation for temporally-correlated array signals. Temporal correlation is generated by jointly reducing the receiver bandwidth and increasing the weighting rate. The error signal is generated using the estimated array signal vector that is estimated in ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> +1) perturbation cycles for an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> -element array. The proposed perturbation technique with the adaptive unconstrained least mean square (ULMS) algorithm achieves a lower misadjustment than previous perturbation techniques and the multi-port ULMS algorithm. With proper gradient step size variations and/or weight clipping the proposed algorithm converges with a larger maximum gradient step size than the multi-port and other single-port algorithms. The new perturbation technique can be implemented with less hardware complexity and speed than previous techniques.