Antenna adaptivity by direction finding and null steering
John E. Hudson · IEE Proceedings H Microwaves Antennas and Propagation · 1985
A maximum-likelihood procedure, in conjunction with a point-source emitter assumption, is used to estimate the directions of arrival of multiple signals at an antenna; followed by direct calculation of beamweighting coefficients, which will receive one source while steering nulls to all other sources. Estimation of element-sensitivity error is also undertaken, and the beam coefficients are compensated to reduce sensitivity to such unknown variables. The result is a robust, adaptive algorithm, which behaves optimally in coherent or incoherent interference situations even when the desired signal direction is not known a priori, and which is able to operate with less data samples than least-squares methods.