DESIGN OF SWITCHED BEAM PLANAR ARRAYS USING THE METHOD OF GENETIC ALGORITHMS

Abstract

Abstract—A system consisting of a smart antenna and a processor can perform filtering in both the time and space domain, thus reducing the sensitivity of the receiver to interfering directional noise sources. Smart antennas can be used for further increase in the capacity of a communication system and for variable speed of transmission for multimedia information. Switched beam antenna arrays are a subset of smart antennas that cover either the x-y plane or a portion of it with multiple radiation patterns. A processor can decide which pattern to use for reception or transmission. In this paper the use of genetic algorithms (GAs) is examined in the design of switched beam antenna arrays. The antenna consists of five or six elements and the radiation patterns vary from 4 to 8, covering the x-y plane with the main beams of the radiation patterns pointing at 0◦, 90◦, 180◦, 270◦ and 0◦, 45◦, 90◦, 135◦, 180◦, 225◦, 270◦, 315◦ respectively. The positions of the antenna elements are either chosen exclusively by the GA or are assumed to form a circular array with one central element and the GA decides for the radius and the offset angle of the circle. Furthermore, the GA is asked to design an array covering the first 120◦ of the x-y plane with 4 radiation patterns pointing at 15◦, 45◦, 75◦ and 105◦. Such a configuration can be used in sector antennas, which are widely used in 2G mobile communication systems.