A theoretical investigation is earned out in the field of circular shaped microstrip • antennas by using modal modes model to determine antenna parameters for circular, annular, nner shorted annular and outer shorted annular patches. The work is concerned with the study of the input impedance, bandwidth, radiation pattern, mode excitation and mode suppression of unwanted modes. From the patterns of the circular shaped patches, different concentric circular ring parches arc studied and well worth results arc obtained for gain enhancements. The gain enhancement is experimentally realized by using parasitic elements as well as backfire elements in front of the inner shorted annular ring. The matching problems of this configurations are solved by adjusting the electromagnetic coupling element. Bandwidth brodening is also realized by this technique.