A Dual-Polarized Cross-Slot Antenna Array on a Parallel-Plate Waveguide With Compact Structure and High Efficiency

A dual-polarized cross-slot antenna array based on the parallel-plate waveguide (PPW) is presented in this letter. A new compact 2 × 2-element subarray consisting of four radiating cross-slots, four out cavities, one coupling cross-slot, and one metallic-block-loaded resonant cavity is first proposed to achieve dual polarization and high efficiency. Two orthogonally arranged H-plane waveguide feed networks combined with the low-loss PPW are used to generate a pair of orthogonal plane waves to feed the subarray. To demonstrate the merits of the antenna, an 8 × 8 array prototype is designed and fabricated. The measured result shows that the aperture efficiency exceeding 60% is obtained throughout the band of 12-12.6 GHz. The isolation between two polarizations is higher than 25 dB over the bandwidth. Therefore, this antenna array can be a good alternative for satellite communications systems in airborne applications.