Application of Bio-inspired optimization technique for finding the optimal set of concentric circular antenna array

In this paper the maximum sidelobe level (SLL) reductions of three-ring concentric circular antenna arrays (CCAA) are examined using two different classes of evolutionary optimization techniques to finally determine the global optimal three-ring CCAA design. Apart from physical construction of a CCAA, one may broadly classify its design into two major categories: uniformly excited arrays and non-uniformly excited arrays. The present paper assumes non-uniform excitations and uniform spacing of excitation elements in each three-ring CCAA design and a design goal of maximizing SLL reduction associated with optimal beam patterns and beam widths. The design problem is modeled as an optimization problem for each CCAA design. Binary coded genetic algorithm (BGA) and bacterial foraging optimization (BFO) are used to determine an optimum set of normalized excitation weights for CCAA elements, which, when incorporated, results in a radiation pattern with optimal (maximum) SLL reduction. Among the various CCAA designs the three-ring CCAA containing (N₁=4, N₂=6, N₃=8) elements proves to be global optimal design. BFO yields global minimum SLL (-14.98 dB) and global minimum BWFN (75.8°) for the optimal design.