Comparative Optimal Designs of Non-Uniformly Excited Concentric Circular Antenna Array Using Evolutionary Optimization Techniques

In this paper the comparative optimal designs for maximum sidelobe level (SLL) reduction of three-ring concentric circular antenna array (CCAA) are determined using two novel Particle Swarm Optimization (PSO) techniques namely Particle Swarm Optimization with Constriction Factor and Inertia Weight Approach (PSOCFIWA), Craziness based Particle Swarm Optimization (CRPSO) and Binary coded Genetic Algorithm (BGA). Apart from physical construction of an array, the CCAA design may be classified into two major categories: uniformly excited arrays and non-uniformly excited arrays. The present paper assumes non-uniform excitation and a design problem of maximizing sidelobe level reduction. So, the design problem is modeled as an optimization problem and subsequently solved using three different evolutionary optimization techniques, BGA, PSOCFIWA and CRPSO. Each technique helps to determine an optimal set of normalized excitation weights for CCAA elements, which, when incorporated, results in a radiation pattern with maximum sidelobe level reduction. Among all the designs, the three-ring structure containing (N₁ = 4, N₂= 6, N₃ = 8) elements proves to be the optimal design owing to the highest SLL reduction achieved by each technique. However, while comparing the optimization efficiencies among the three techniques the newly proposed CRPSO technique yields the best optimum sets of normalized excitation weights with least "Misfitness" objective function values and maximum achievable SLL reductions for all sets of three-ring CCAA designs. CRPSO yields grand maximum SLL reduction (-14.94 dB) for the above optimal set. Further, a reduction of major lobe beamwidth is also observed when compared to a uniformly excited CCAA having equal number of elements and same radii.