LOW SIDELOBE WIDE NULLING DIGITAL BEAMFORMING FOR LARGE PLANAR ARRAY USING ITERATIVE FFT TECHNIQUES

The combination of low peak sidelobe level (PSLL) with wide sector nulling digital beamforming (DBF) is achieved for large planar array antennas. This combination is carried out using the iterative Fourier transform (IFT) method. The method is based on the iterative Fourier technique to derive element excitations from the prescribed array factor using successive forward and backward Fourier transforms. A 1024-element rectangular uniformly spaced array is used as an example to demonstrate the performance of the proposed method. Numerical examples show that the proposed method achieves very low PSLL with very wide nulling sectors up to the half plane of the far-field pattern. Moreover, numerical results show that the proposed method is effectively functional even when the mainbeam is steered to directions other than the broadside.