Unidirectional Circularly Polarized Slot Antenna Backed with Miniaturized AMC Reflector

This paper investigates a low profile circularly polarized (CP) slot antenna with unidirectional radiation. The antenna includes a coplanar waveguide (CPW)-fed square slot radiator loaded by two L-shaped strips around two diagonal corners, underneath which is an artificial magnetic conductor (AMC) reflector with an air gap in between. The AMC reflector is polarization independent and miniaturized by using lumped capacitors to accommodate sufficient unit cells within restricted electrical dimension. The antenna was analyzed numerically, and the simulated 10-dB impedance bandwidth and 3-dB axial ratio (AR) bandwidth are 16.0% and 3.0%, respectively, relative to the center frequency of 2.68 GHz. The overall size of the antenna is 0.54 lambda(0) x 0.54 lambda(0) x 0.08 lambda(0) with a maximum gain of 6.7 dBic.