Optimization of pattern sidelobes in arrays with regular subarray architectures

An algorithm is developed which yields an optimum low sidelobe illumination for an array antenna which is weighted only at a subarray level and not at the individual element level. This technique can be viewed as a way to manage the amplitude quantization grating lobes that naturally occur when elements are fed in regular groups. The method provides a sidelobe control mechanism for arrays designed with subarrays where the weights at the element level are fixed or in some way constrained. The technique provides this sidelobe control mechanism for difference patterns as well as sum patterns. Additionally, it can be used to synthesize gain optimized "spoiled" or "flat topped" beams. It is extremely conducive to the application of digital beamforming (DBF) at the subarray level and further provides a means for enhancing the performance for any array where the desire to reduce the number control elements is viewed as a figure of merit. The technique is equally applicable to mechanically scanned and electronically scanned arrays with a subarray based feed architecture.