Side Lobe Reduction of a Uniformly Excited Concentric Ring Array Antenna Using Evolutionary Algorithms

Reduction of sidelobe level in concentric ring arrays results in wide first null beamwidth (FNBW). The authors propose a pattern synthesis method based on modified Particle Swarm Optimization (PSO) algorithm and Differential Evolution (DE) algorithm to reduce sidelobe level while keeping the first null beamwidth (FNBW) fixed or variable. This is achieved by optimizing both ring spacing and number of elements in each ring of a concentric circular ring array of uniformly excited isotropic antennas. The first null beamwidth is attempted to be made equal to or less than that of a uniformly excited and 0.5 λ spaced concentric circular ring array of same number of elements and same number of rings. The comparative performance of modified Particle Swarm Optimization (PSO) algorithm and Differential Evolution (DE) algorithms based on this particular problem in terms of FNBW, sidelobe level and computational time is also studied.