Branch Waveguide Couplers with a frequency of 510 GHz for Terahertz Transmit/Receive Isolation Applications

To address the requirement of functioning as a transmit/receive isolation device in terahertz transceiver systems, in this paper, we present two high-isolation multi-branch waveguide directional couplers operating at a center frequency of 510 GHz. One is a high-performance five-branch directional coupler, and the other is a new type of three-branch waveguide coupler with lower processing difficulty. Both couplers were fabricated using low-cost CNC milling technologies. The performance of these couplers was verified through measurement results, demonstrating high isolation at the center frequency.