Design of A Broadband Circularly Polarized Patch Antenna With Differential Feeding

In this paper, a broadband differentially fed circularly polarized (CP) patch antenna is designed. Combined with the field distribution of patch antenna, a double-layer differential microstrip feeding structure is proposed to form a circular polarization. The differential CP antenna works around 28.0 GHz, with a −10 dB impedance bandwidth and 3-dB impedance bandwidth of 13.2% and 7.0%, respectively. Within the achieved bandwidth, the radiation pattern has excellent conformality and symmetry. The height of the antenna is only
$0.049\lambda_{0}$
(
$\lambda_{0}$
is the operating wavelength at 29.0 GHz in the free space), achieving a low-profile design.