A Reactance-Domain Concurrent Blind Beamformer

Abstract

The electronically steerable parasitic array radiator (ESPAR) is a smart antenna suited for low-cost user terminal applications. Beamforming is achieved by adaptively adjusting the load reactances at parasitic elements surrounding the active central element. The main goal is to establish nulls in the interfering directions of the array radiation pattern. This paper presents a new blind beamformer for use with reactance domain controlled arrays, such as ESPAR antennas. The new beamformer is based on the concurrent operation of two stochastic gradient algorithms, one which minimizes a cost function that measures the received signal energy dispersion and other which minimizes the Euclidean distance between the received digital modulation symbols and the ones in the reference constellation. Results show that the new blind beamformer presents a faster convergence and a lower steady state mean squared error when compared with classical blind deconvolution algorithms, such as the Maximum Moment Criterion or the Constant Modulus Algorithm.