Broadband circularly-polarized square slot antenna fed by coplanar waveguide

A novel circularly polarized slot antenna fed by coplanar waveguide (CPW) is presented in this paper. The proposed antenna consists of a square slot cut on the ground and a CPW feed line with a stepped impedance transformer. Two stubs are embedded in the CPW feed line to excite circular polarized wave while a slit is cut on the ground to enhance the impendence bandwidth. The measured impendence bandwidth ranges from 4.4 GHz to 7.9 GHz, with the AR bandwidth from 4.5 GHz to 7.5 GHz, which cover wlan (5.15~5.25,5.725~5.825), wimax (5.25~5.85) and Chinese Dedicated Short Range Communications (DSRC) for Electronic Toll Collection (ETC) systems.