An H-Plane High-Flatness Ridge Waveguide Dual-Directional Coupler Based on Copper Additive Manufacturing

This letter introduces a dual-directional coupler fabricated by micro-metal additive manufacturing (M-MAM) technology. The coupler consists of three ridge waveguides operating in the WR-6 frequency range (110–170 GHz). To achieve flat coupling, the main signal path utilizes vertically asymmetric dual-ridge waveguide, while the two auxiliary paths use identical single-ridge waveguides. To facilitate seamless integration with other components, bends were added to each port of the coupler to interface with standard waveguide ports. Full-wave electromagnetic (EM) simulations and electrostatic analysis are employed in the design process. Measurement results show that the fabricated coupler exhibits insertion loss and return loss better than 1.4 and 20 dB, respectively, with a coupling variation less than 1.3 dB and a directivity exceeding 23.4 dB. These excellent performances are attributed to the combination of the coupler design approach and the M-MAM process.