A High-gain Dual Circularly Polarized Antenna Using Gap Waveguide

This paper proposes a dual circularly polarized antenna based on gap waveguide (GWG) technology. Circular polarization is achieved by double layers of circular patch antenna feeding by two metal probes. A 90° tripline bridge connected to the two feeding probes is introduced to switch the left hand and the right hand circular polarization. The GWG above the circular patch antenna is formed by an array of metal squares. The proposed antenna unit has an axial ratio (AR) less than 3dB from 28.5 to 31.2 GHz with return loss
$< -\boldsymbol{15}\ \mathbf{dB}$
. Especially, the gain of the antenna is more than 10 dBi from 28.6 to 30.9 GHz, which is higher than that without GWG.