Some investigations on annular ring microstrip antenna

166-171The various paramoters of annular ring microstrip antenna such as input impedance, VSWR, return loss, radiation pattern have been theoretically investigated as a function of frequency for different feed locations. It has been observed that resonance occurs at 3.285 GHz which is invariant with feed locations. The antenna behaves as RL network below resonance and as RC network above resonance and shows perfect matching at 3.35 cm feed location from the centre. The percentage bandwidth is found decreasing and the radiated power increasing with increasing b/a ratio