Adaptive beamforming with conjugate symmetric weights

The Hermitian persymmetric maximum likelihood estimator (MLE) is better than the conventional MLE in estimating the covariance matrix of a symmetrically distributed antenna array. Though using the Hermitian persymmetric MLE improves the performance of adaptive beamforming, it increases the computational load due to the forward-backward averaging of array input sample data. By observing that the weight vector obtained from the Hermitian persymmetric MLE is conjugate symmetric if the phase origin is chosen at the array geometry center, methods are developed to reduce the computational load of the direct-form beamformer and the generalized sidelobe canceler (GSC). The weights of both beamformers can be adapted with real computations, with significant savings in computation time.>