Combined time-delay FIR and 2-D IIR filters for EARS, radar, and imaging applications

A linear antenna array beamforming method which significantly improves the spatial selectivity of conventional phased/timed arrays is presented. A two-dimensional (2-D) infinite impulse response (IIR) digital beam filter is employed as a pre-processing stage to existing phased/timed arrays, thereby mathematically modifying the array transfer function. Introduction of a pre-filter is possible due to multi-input multi-output signal flow structure of the 2-D IIR beam filters, and the improvement in spatial selectivity is presented using closed-form frequency response and array pattern simulations. An example wireless communication scenario shows that the proposed beamformer leads to additional gain of more than 10 dB in terms of the BER vs. SIR performance.