Printed circularly polarised antenna with ultra-wide axial-ratio bandwidth

A circularly polarised printed dipole-like antenna employing asymmetrical arms and an orthogonal slit in the ground plane is presented. It is fed by a stepped microstrip line which connects to the shorter arm. By utilising surface currents on the asymmetrical arms and the orthogonal feedline structure, circular polarisation is realised. Experimental and numerical data are in agreement and the measured results show a fractional impedance bandwidth of 41.3% (1.77-2.69 GHz) and a wide axial-ratio bandwidth of 38.4% (1.81-2.67 GHz).