Discretizing technique for a rectangular grid array with arbitrary shape aperture

The excitation of discrete planar arrays with circular boundaries is often determined by conventional sampling of the continuous aperture distributions. If the number of elements is large, so that the sampling interval is small, this can be a satisfactory procedure so long as some pattern degradation is acceptable. A discretizing process using a perturbation technique due to R.S. Elliot (1981) is extended. The modified technique uses a contour map to describe sidelobe peak topography and the sidelobe topography is used to effect pattern improvement. Many points, instead of a single point, are sampled in the vicinity of each lobe for weighting purposes. A gradual change (towards the desired pattern) algorithm is then introduced to maintain pattern stability. The technique was applied to a 140-element aperture (35 elements per quadrant) to obtain 3-dB Chebyshev-like sidelobes. After the iterations, most of the sidelobes were between 30 and 32 dB.<>