Abstract: “In this paper a novel structure of circular microstrip antenna with airgap between ground plane and substrate is analyzed. To enhance the agility of antenna a MOS device is loaded on the patch. Various parameters such as input impedance, resonance frequency, bandwidth, frequency agility, VSWR, radiation pattern etc. of antenna are calculated to investigate the structure. The resonant frequency of proposed 10 mm radius patch with 1 mm airgap is 6.60 GHz. By varying bias voltage of MOS, antenna can be tuned down to 1.571 GHz operating frequency, which makes the antenna suitable for modern communication system such as GPS, UMTS, WiMAX and remote sensing. Frequency agility 76.20% is found for a MOS loaded CMSA with airgap.”

Keywords: Circular patch, airgap, agility, MOS, microstrip