Broadband circularly polarized Z-shaped dipole antenna with parasitic strips

A Z-shaped dipole antenna with parasitic strips is proposed for wideband and unidirectional circular polarization operation in this article. The dipole arms are bent into L-shape for circular polarization, and printed balun is used to achieve good impedance matching. To further extend the axial ratio bandwidth, two parasitic strips are employed to introduce an additional band of circularly polarized operation at the high frequency. Measured results demonstrate that the proposed antenna has a 10-dB impedance bandwidth of 63.3% (1.64-3.16 GHz) and a 3-dB axial ratio bandwidth of 51.1% (1.72-2.9 GHz). Stable radiation patterns with gain around 9 dBic along +z-axis are also observed.