Design of circular switched parasitic dipole arrays using a genetic algorithm

Circular switched parasitic dipole arrays are designed in this letter, using the method of genetic algorithms. Three possible configurations are proposed: a simple circular array with one element driven and the others short-circuited, and two implementations of double-ring array. In the latter case, an inner ring of parasitic elements is added. Electronic steering is achieved through switching of the elements by circular permutation. The aim of the design is to obtain a desired radiation pattern, and to achieve impedance matching of the single active element. The arrays are simulated with the SuperNEC2.4 package and the induced emf method. Double-ring arrays offer better patterns and more accurate impedance matching than simple circular arrays at 1.8 GHz. The designed arrays achieve SWR values below 2.5 from 1.7 to 1.9 GHz. The radiation patterns remain satisfying in an average bandwidth equal to 6.5% of the carrier frequency.