A new wide frequency band feeding technique of annular slot antenna

A new wide frequency bandwidth feeding technique of the annular slot antenna (ASA) in circular polarization is reported. An experimental prototype of the antenna operating in the WLAN 5 GHz band and fed with the new feeder is designed and tested. The radiation pattern is similar to that obtained by a conventional ASA feed. Approximately 19% bandwidth of VSWR <2 and 3.5% axial ratio (AR) bandwidth at 3 dB have been measured. Experimental results agree well with theoretical predictions.