Quadrature Hybrid Coupler implemented in Half-Mode Groove Gap Waveguide

This communication presents a low-loss single-layer half-mode gap waveguide-hybrid branch-line coupler. The working band of the quadrature hybrid coupler ranges from 29 GHz to 31 GHz. The simulated output power of −3 dB is achieved for both the direct port and the coupled port. A level of −20 dB is obtained for the decoupled port. The total dimensions of the device are 10 mm × 10 mm × 14 mm. This design, while simple, is a helpful block that can later be integrated into more complex structures, such as beam-forming networks for mm-wave antenna arrays.