Design of a 510GHz High-Isolation Multi-Branch Waveguide Coupler

Directional coupler is a widely-used passive component in microwave/millimeter-wave systems. Serving as isolators in terahertz systems with shared antenna for transmitter and receiver, it enables the attainment of considerable isolation between the two paths. In this paper, two high-isolation directional coupler designs operating at 510GHz are presented. The four-branch waveguide coupler demonstrates lower fabrication complexity, while the modified five-branch waveguide coupler offers even higher isolation. Simulation results indicate that both designs achieve isolation better than 30 dB, attesting to their effectiveness in providing high isolation.