Null Steering Scheme for Wideband Spatial Beamformer

It has been demonstrated that wideband beamforming is successfully performed by using only spatial signal processing without Tapped-delay lines or frequency filters, so called wideband spatial beamformer. In this paper, the enhanced technique is developed to include the null steering scheme into the wideband spatial beamformer. Using multiple beamforming networks, the system is capable of suppressing multiple interference signals using only spatial signal processing. The validity of the proposed technique for interference suppression is demonstrated via computer simulations employing a moderate size array. Also the issue of noise effect on null steering performance is investigated. From mathematical derivation, the performance degradation due to noise signal is unavoidable. The results reveal the relation between signal-to- interference ratio and signal-to-noise ratio which is considerably helpful for a smart antenna designer.