Compact circularly-polarised slot antenna for UWB applications

A simple compact broadband circularly-polarised square slot antenna (CPSSA) fed by a coplanar waveguide is presented. A CP bandwidth larger than 38.2% can be attained simply by embedding two inverted-L grounded strips around two opposite corners whereas the impedance bandwidth can be greatly improved through the tuning stubs. The designed CPSSA antenna is 25 × 25 × 0.8 mm³, which is 56% smaller than previous CPSSA structures operating over the frequency band between 2.9 and 11.2 GHz for VSWR <; 2.