Compact H-Antenna with Shorting Post for GSM Using Genetic Algorithm and Moment Method

y increasing demand for multi-frequency services in communication, the need for compact and multi-band antennas has been growing recently. Microstrip patch antennas for their special characteristics such as low profile, light weight, conformity and ease of fabrication are widely used. They are manufactured in many different shapes and geometries. Among them, H-shaped microstrip antennas are one of compact structures which have been investigated by Palanisamy and Garg [1]. By using shorting post between the surface patch and ground plane, more miniaturization plus dual-band operation is attainable. This paper presents our computational and experimental studies of the performance of these antennas. Optimized dimensions, Feed and shorting post positions are investigated using genetic algorithm as one of the best engines for thorough searching in problems of many parameters [2]. This very compact H-shaped antenna is optimized to operate in 900 MHz and 1800 MHz for GSM application. We also proposed a flexible and accurate model of coaxial and shorting post in prob-fed microstrip antennas discussed in [3] and is useful for optimization process. The method of analysis is moment with RWG basis functions. More information is provided in [3]. A prototype was designed, fabricated and tested to be used in GSM systems. Good agreement has been obtained between theoretical and experimental results.