Broadband CPW-Fed Circularly Polarized Square Slot Antenna With Lightening-Shaped Feedline and Inverted-L Grounded Strips

A novel design is described for a circularly polarized square slot antenna (CPSSA). Circular polarization (CP) operations can be attained using a lightening-shaped feedline protruded from the signal line of the feeding coplanar waveguide (CPW). The CP bandwidth can be significantly enhanced by implanting a pair of inverted-L grounded strips into the slot and adjusting the dimensions of the lightening-shaped feedline, whereas the impedance bandwidth can be greatly enlarged through tuning embedded vertical and horizontal stubs. The designed antenna was measured to exhibit a CP bandwidth of as high as 48.8%.