Search

[Abstract] In this letter, the authors propose an optimization method based on the genetic algorithm (GA) to reconfigure a linear array of vertical half-wavelength dipole antennas to generate two patterns with minimum active impedance variation when the antenna switches from one pattern to other in the presence or absence of a ground plane behind the array. The problem is to find a fixed voltage amplitude distribution that generates two broadside symmetrical beams in the horizontal plane: a pencil beam with zero phases and a flat-top beam with phases in the range from -180deg to +180deg. Mutual coupling effect is taken into account via open circuit mutual impedance matrix

This paper presents a new technique based on optimization tools to design phase only, digitally controlled, reconfigurable antenna arrays through time modulation. In the proposed approach, the on-time durations of the time-modulated elements and the static amplitudes of the array elements are perturbed in such a way that the same on-time sequence and discrete values of static amplitudes for four bit digital attenuators produces either a pencil or a flat-top beam pattern, depending on the suitable discrete phase distributions of five bit digital phase shifters. In order to illustrate the technique, three optimization tools: differential evolution (DE), artificial bee colony (ABC), and particle swarm optimization (PSO) are employed and their performances are compared. The numerical results for a 20-element linear array are presented.

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.