A Center-Fed Dual-Polarized Parallel-Plate Waveguide Slot Array Antenna Based on a Feeding Waveguide With Centered Longitudinal Feeding Slots

A dual-polarized paralle-plate waveguide slot array antenna operating at 24.5 GHz band is proposed in this paper. The radiating panel using a 5mm-thick expanded dielectric substrate (
$\epsilon _{r}=1.12$
) consists of two orthogonally oriented
$20\times 19$
radiating slot arrays, where the slots are positioned collinearly. The centered longitudinal feeding slots are introduced into the feeding waveguides, which offer improved aperture efficiency and higher cross-polarization discrimination (XPD) compared to the conventional tilted feeding slot approach. The antenna achieves a remarkable simulated radiation efficiency of over 95% within the operation bandwidth. A prototype antenna is fabricated and verified through measurements. The measured results demonstrate an impedance bandwidth of 13%, with reflection below -10 dB. Moreover, the antenna achieves a simulated peak aperture efficiency of 54% and a measured peak antenna efficiency of 40%. The measured XPD of the antenna prototype exceeds 26 dB.