Application of Particle Swarm Optimization Technique in Hexagonal and Concentric Hexagonal Antenna Array for Side Lobe Level Reduction

In this paper, particle swarm optimization (PSO) method, which represents a recent approach for optimization problems in electromagnetic, is applied for array pattern synthesis of hexagonal array (HA) and concentric hexagonal array (CHA) of uniformly excited isotropic antennas which can generate directive beam with minimum relative side lobe level (SLL). Two examples has been presented and solved. In first example, the PSO is used to determine an optimal set of ‘ON-OFF’ elements in a 12-element thinned HA and 24-element thinned CHA, and in second example, PSO is used to determine an optimal set of amplitude distributions in a 12-element HA and a 24-element CHA that provide a radiation pattern with maximum SLL reduction. Optimization is done without significant change in the value of first null beam width (FNBW). Simulation results show that, in first example, the number of effective antenna elements can be brought down from 12 to 6 totals with simultaneous reduction in SLL by −23.85 dB for HA and from 24 to 11 totals with simultaneous reduction in SLL by −20.71 dB for CHA. In second example, SLL is reduced to less than −31 and −27 dB for HA and CHA, respectively, by optimizing inter-element spacing and inter-ring spacing along with amplitude using PSO.