A broadband dual circularly polarized antenna with double incomplete rings

A broadband dual circularly polarized antenna is proposed in this novel. It consists of two incomplete rings, a rectangular ground plane and a microstrip line. The outer incomplete ring is connected with the microstrip line, and the inner incomplete ring is equivalent to parasitic branches, which forms circular polarization radiation characteristics with the external ring. The simulation results show that the impedance bandwidth of the antenna can reach 92.8% (2.3GHz∼6.45 GHz), the circular polarization bandwidth of the low-frequency band reaches 40.1% (2.37GHz∼3.56 GHz), while the high-frequency band is 8.9% (4.52GHz∼4.94 GHz). The antenna has a maximum gain of 7.2dBi in the circularly polarized bandwidth, and the size is only
$40\times 40\times 1.6\ \text{mm}^{3}$
.