Design considerations for the development of the annular ring microstrip antenna

The design considerations for development of the annular ring microstrip antenna are considered and consequently various parameters such as input impedance, VSWR, return loss and radiation pattern have been theoretically investigated as a function of frequency for different feed locations with a view to optimizing the feed location for proper matching and radiation. It has been observed that resonance occurs at 3.285 GHz, which is invariant with feed location. The antenna behaves as an RL network below resonance and as an RC network above resonance and shows perfect matching at a feed location of 3.35 cm from the centre. The percentage bandwidth is found to decrease and radiated power to increase with increasing ratio of outer to inner radius of the ring antenna.