Microstripline-fed circularly-polarized aperture antenna

A technique to generate a circularly polarized aperture antenna is presented in this paper. This antenna uses a microstrip line to feed a truncated square aperture. A tuning metal strip is placed across the diagonal line of the aperture. Experiment shows that the metal strip will improve both input V.S.W.R. and axial ratio of this antenna. It is found that 20% bandwidth for 10 dB return loss and 5% bandwidth for less than 3 dB bore sight axial ratio can easily be achieved.