Coplanar Waveguide Fed Dual-Band Dual-Sense Circular Polarized Square Slot Antenna

A novel design of a dual-band dual-sense circularly polarized square slot antenna with two rectangular shaped parasitic patches etched on a single substrate for 1.74/2.82 GHz applications is presented. A coplanar waveguide (CPW) fed line with two horizontal branches of different lengths is used, which produce two different frequencies bands. However, good circular polarization (CP) performance is achieved by adjusting the size of the parasitic patches. The two branches of feed line can excite dual-band dual-sense circular polarized wave. The antenna generates right hand circular polarization (RHCP) and left hand circular polarization (LHCP) radiation at 1.74 and 2.82 GHz, respectively. Lower band is obtained due to 90(degrees) phase difference between currents in the two orthogonal branches of the feed line. The lower band of CP is controlled by the size of parasitic patch/element (PE2) and the upper band of CP is controlled by length of right-sided horizontal branch of feed line. The key parameters of the design are investigated to show how to obtain dual CP with impedance matching.