Wideband annular ring slot microstrip antenna with low impedance feed line

A wideband annular ring slot microstrip antenna with low impedance feed line is proposed. The experimental and simulated results confirm the wideband characteristics of the antenna. The measured bandwidth of this antenna is 127.2% for the S/sub 11/<-10 dB, which is much wider than a conventional annular ring slot antenna. Both return loss and radiation properties of the antenna are considered. Good agreement between experiment and simulation is achieved.