Beam switched loop antennas - square to circular

Systematic investigations for three beam switched antenna configurations, namely, the square loop with middle feeding, the square loop with corner feeding and the circular loop antenna are undertaken and the results focusing on their radiation patterns are presented. All these configurations exhibit two zones of impedance bandwidth in the UWB region (3.1 GHz - 10.6 GHz), however, only one of them generates a distortion free tilted beam pattern. This titled beam can be switched in the different space quadrants by using different feeding points on the antenna. Comparison of the radiation patterns of these configurations reveals that the middle fed square loop antenna exhibits the lowest level of co-polarized side-lobes (< 9.0 dB), leading to a conclusion that for beam switched applications the middle fed square loop is the most suitable choice amongst the three loop antennas. ©2009 IEEE.