Single‐fed broadband circularly polarised dipole antenna with simple structure

Abstract

A new designed single-fed broadband circularly polarised dipole antenna with simple structure is presented. The antenna is composed of a horizontal electric dipole and an equivalent magnetic dipole realised by two vertical patches quarter-wave shorted at the bottom. The electric dipole and equivalent magnetic dipole are positioned along the same axis to excite the orthogonal radiation fields with the same amplitude and 90° phase difference for circular polarisation. A broad impedance bandwidth of 69% (|S 11| < −10 dB) from 1.6 to 3.2 GHz is achieved, which covers the whole 3 dB axial ratio bandwidth of 42.7% from 2.0 to 3.1 GHz. In this operation frequency band, the measured gain is above 6.4 dBi and the peak value is 8.4 dBi.