IMPEDANCE MATCHING OF A SWITCHED PARASITIC PLANAR ARRAY USING ADDITIONAL PARASITIC ELEMENTS AND THE METHOD OF GENETIC ALGORITHMS

Switched parasitic planar arrays can be used for the purpose of electronic beam steering. The insertion of a digital word in the antenna's feeding circuit may give a radiation pattern with certain characteristics, which is pointed in a desired direction. This paper presents the initial design of such an array that consists of four elements, one active and three parasitic, forming a square. Furthermore, another more complicated configuration is presented, where those four elements are surrounded by a number of parasitic elements, in order to achieve impedance matching at the element, which is active each time. The positions of the parasitic elements are selected in such a way that each radiation pattern maintains its basic characteristics, while impedance matching is achieved. The genetic algorithms are used to carry out the evaluation of the parasitic elements' coordinates. The numerical results and the diagrams presented here show the advantages and disadvantages of this method.