Miniaturised design of coplanar waveguide-fed broadband circularly polarised slot antenna

A novel miniaturised design of broadband circularly polarised (CP) antenna using a coplanar waveguide feed is presented. To realise CP characteristic, a pair of inverted-L strips around two opposite corners of the slot is protruded. By properly folding the modified ground plane, the 3-dB axial-ratio (AR) band is shifted to around a lower-frequency location, whereas the input impedance band is shifted downwards through the Y-shaped loading strip. The overall size of the antenna is about 0.34 λ₀ × 0.34 λ₀ × 0.009 λ₀ at 1.7 GHz. Measured results show that the proposed design can deliver 3-dB AR bandwidth of 36.8% (1.55-2.25 GHz) and 10 dB impedance bandwidth of 63.2% (1.17-2.25 GHz).