Configuration of Hybrid Clustered Structures in Large Planar Arrays for Optimizing Beam Pattern Coverage

Dividing a large planar array aperture (LPAA) into smaller clustered subarrays gives many advantageous in practical implementation of such antenna systems in terms of complexity and cost. In this paper, two new hybrid clustered subarray structures are first proposed to optimize the coverage of the beam patterns (CBP). The hybridization process consists of either 2 by 2 or 4 by 4 clustered subarray structures. The first structure consists of several sub-apertures (i.e., four sub-apertures with 2 by 2 and 16 sub-apertures with 4 by 4), and each sub-aperture is tiled with either irregular clusters or individual radiating elements with specific element excitation amplitudes-only or phases-only. It is also possible that each sub-aperture may contain irregular clusters and individual elements together. The second structure is to hybridize the subapertures with different excitation weights, as each subaperture is fed with an independent excitation of amplitudesonly or phases-only. Then this structure is characterized by hybrid structure and hybrid excitation weights at the same time. Moreover, the thinning technique is included with these hybrid structures to further reduce the array complexity. The process of thinning includes the whole sub-aperture or only a part of it while preserving the characteristics of the original fully optimized CBP such as peak sidelobe level (PSLL) and half power beam width (HPBW). These ideas are implemented through the use of the genetic algorithm (GA) in conjunction with a set of desired constraints such that the required beam pattern coverage can be successfully met. Computational results show that the required CBP can be obtained effectively with the proposed hybrid structures while minimizing the array complexity as small as possible.