Continuous-time 2-D IIR+time-delay linear aperture arrays

Application of continuous-time domain two-dimensional (2-D) infinite impulse response (IIR) filters to improve the spatial selectivity of conventional time-delay beamforming for linear arrays is discussed. The proposed technique mathematically modify the zero-manifold-only time-delay beamformer transfer function by introducing complex pole-manifolds at guaranteed stability. A continuous-time domain 2-D IIR filter is employed as a pre-filtering stage to an existing time-delay beamformer to achieve reduced side-lobe level for the same array size. Improved side lobe performance is verified in terms of frequency response, array pattern, and signal to interference ratio (SIR) simulations. For a 64 element array an SIR improvement of better than 2 dB is verified for varying main beam direction from 0° to 80°.

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