Compact and Wideband Directional Circularly Polarized Distributed Patch Antenna With High Efficiency

A compact and wideband directional circularly polarized (CP) antenna is presented in this paper. The antenna adopts four distributed micropatches as the radiation structure to realize directional radiation and wideband potential, and a low-loss sequentially rotated feeding network is utilized to provide CP excitation. Because of the good impedance matching between the proposed radiation structure and the feeding network, the antenna obtains wide bandwidths in both impedance and axial ratio (AR), and high efficiency is also achieved in the wide band. A prototype of the antenna is fabricated to validate the proposed method. The antenna's dimensions are 0.418λ
₀
× 0.418λ
₀
× 0.064λ
₀
(λ
₀
is the free-space wavelength at the center frequency of operating band). The impedance bandwidth for VSWR ≤ 2 reaches 42.9% (1.457 ~ 2.253 GHz), and the CP bandwidth for AR ≤ 3 dB reaches 22.8% (1.67 ~ 2.10 GHz). In the overlapped band, the radiation efficiency is more than 96.5%, and the gains are greater than 4.8 dBic.