Suboptimal frequency-domain adaptive antenna processing algorithm for broadband environments

The paper develops an adaptive antenna algorithm that is highly suboptimal and suitable for use in broadband environments. The algorithm is of the LMS beamforming type and is a variation on a frequency-domain adaptive beamformer. Processing is assumed to take place in frequency bands not exceeding one octave. In this band the complex weight vectors Wk are made a simple analytic function of FFT cell number k. The system minimises broadband output power subject to suitable look-direction constraints. The algorithm was tested assuming constant sensor errors, full adaptation and a time-stationary environment. Broadband bearing resolution capability was found to be far superior to that with conventional beamforming. The system proved capable of steering multiple broadband nulls ¿¿40 to ¿¿60 dB in depth. Algorithm degradation occurs when the system is steered at strong sources, but the overall performance is good, particularly when the wanted signal is weak.