A novel self-diplexing circularly polarized antenna is presented. The antenna is of aperture type with two microstrip line fed ports operating in two frequency bands. Orthogonal senses of circular polarization are achieved by oppositely directing the traveling-wave currents along the exponentially curved edge of the aperture. Promising results were achieved, including a good port isolations 23dB in both bands and a wide operating bandwidths of 12.4% and 10.3% centered at 2.8 GHz and 5.8 GHz, respectively.
