Thinned multi-ring arrays using genetic algorithms

Electromagnetic optimization problems generally involve a large number of parameters. Traditional optimization methods are not well suited for optimizing a large number of discrete parameter. This paper focuses on a relatively new approach to optimization, namely, the generic algorithm (GA). Thinning of large antenna arrays is an example of sophisticated multi-parameter optimization problems. In addition to reducing cost and complexity, thinning (randomizing) removes the periodicity in the array excitation and hence results in the cancellation of grating lobes and the possible reduction of sidelobes of the array. This paper deals with the optimal thinning of large planar arrays of the original multi-ring structure using genetic algorithms. The genetic algorithm determines which elements are turned off in a periodic ring array to yield the lowest maximum relative sidelobe level. As an example the paper describes simulation of the proposed technique for a 64-element ring area. The considered original ring array is considered to be excited by two aperture techniques sampling methods described in a previous work. The results shows that the thinned ring array enjoys much lower sidelobe levels, and hence are of great engineering importance.