A Circularly-Polarized Antenna for 5G Applications Fed by Printed Ridge-Gap Waveguide

In this paper, a multilayered circularly polarized (CP) antenna fed by a printed ridge-gap waveguide (PRGW) is presented. In the PRGW section, a 90-degree hybrid coupler is designed to provide a dual-mode generating CP feature at millimeter-wave (mm-Wave) bands. Then the coupler passes the signal from PRGW to the coaxial which plays an excitation role for the radiation section. The radiation section consists of two-layer of substrates and two square patches. The proposed antenna can cover a frequency bandwidth from 26.3-30 GHz (|S11 < -10 dB|) and it supports CP features in the frequency range from 27-30 GHz with an axial ratio (AR) less than 3-dB.