Dual-Band Dual-Sense Circularly Polarized Slot Antenna With a C-Shaped Grounded Strip

A novel dual-band coplanar waveguide (CPW)-fed slot antenna with a C-shaped grounded strip is proposed for dual-sense circularly polarized radiation. The circular polarization in the lower band is achieved by the slots loaded in two opposite corners, and the C-shape grounded strip can offer a current path for the upper band. A rectangular tuning stub protruded into the slot from the signal strip of the CPW is used to obtain good impedance matching over the whole frequency band. Axial-ratio (AR) bandwidth can be significantly enhanced through tuning the horizontal length of the C-shaped grounded strip. The antenna has been investigated numerically and experimentally. Experimental results show that the antenna possesses the measured 10-dB return loss impedance bandwidth of 106.9% (1.01-3.33 GHz). The measured 3-dB AR bandwidths for the lower and upper bands can be up to 32.35% (1.41-1.96 GHz) and 5.6% (2.45-2.59 GHz), respectively.