Sidelobe reduction of a scanned and broadside central element fed concentric ring array antenna with fixed first null beamwidth using novel particle swarm optimisation

Sidelobe reduction in an array antenna results in increased first null beamwidth. In this paper, the authors present a method based on a novel particle swarm optimisation with time-varying maximum velocity for focusing a beam at any direction in the vertical plane of a concentric ring array antenna with minimum sidelobe level while keeping the first null beamwidth of the array fixed. The excitation amplitude of the array elements along with the central element are radially varied and optimised using the proposed algorithm to reach the goal. Three different cases have been presented to illustrate the potential of the method.