An Annual Ring Antenna for UWB Communications

An ultrawideband (UWB) annual ring antenna is presented in this letter. The annual ring antenna has a return loss better than 10 dB from 2.8 to 12.3 GHz. It has an average gain of 2.93 dBi and has a maximum gain of 5 dBi at 7 GHz. The antenna radiation patterns are stable within its operation band. The parameters determining the antenna wideband characteristic are discussed and measured results are presented