Time delay is most often introduced into phased array systems by using phase shifters at the array face and time delay units behind rectangular subarrays as shown in Figure 1. This practice leads to significant quantization lobes that represent severe pattern degradation. Figure 1 illustrates this effect in the pattern of an array of 256 rectangular (4 × 2) subarays. Various subarray techniques have been developed to reduce these lobes. These include interlacing or overlapping the subarrays, procedures that are practical [1], but suffer network losses and are relatively difficult and expensive to build. In addition, thinned array approaches may be used, but they can have significant residual error sidelobes even at center frequency. This paper describes a practical technique for using polyomino-shaped subarrays [2]. A polyomino is a geometric figure made up of N square areas assembled into a given shape. The subarrays are used to completely "tile" the aperture, which means that they completely fill the aperture without any gaps or holes. In this study we use contiguous polyomino-shaped subarrays that are identical, but irregular instead of rectangular, and are assembled into apertures by rotating or rotating and flipping (overturning) each subarray.
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