UWB circularly polarised slot antenna with modified ground plane and L-shaped radiator

An UWB circularly polarised (CP) slot antenna with simple structure is presented in this Letter. By etching a simple C-shaped slot on the planar ground, adopting an L-shaped strip as a radiator, and employing an off-centre-fed structure, the proposed CP antenna can easily be realised with both wideband impedance bandwidth (IBW) and 3 dB axial-ratio bandwidth (ARBW). The impedance and ARBWs of this antenna can be further expanded by adding a matching stub and cutting an L-shaped slit on the lower ground. This antenna can realise a wideband IBW (S 11 < −10 dB) of about 3.62 GHz (124.4%, 1.10–4.72 GHz) and 3 dB ARBW of about 3.6 GHz (115.2%, 1.26–4.68 GHz).