Implementation of 180° directional coupler in 220 GHz band based on the DRIE process

Aiming at the application requirements of monopulse antenna to sum-and-difference feeding network in terahertz band acquisition and tracking system, a 180°waveguide directional coupler with easy integrated structure is proposed in this paper, which can realize the power distribution and 180°phase difference of the output port. The device is processed based on silicon-based DRIE technology, and the performance is tested in combination with CNC tooling structure. The main work includes: based on the theory of H-plane crack waveguide directional coupler, the coupler design of symmetrical stepped structure is completed; Based on the silicon-based DRIE technology, the independent device was prepared. This device is tested based on CNC tooling cavity and vector network analyzer. The measurement results exhibit that from 205GHz to 230GHz, the return loss is better than -15 dB, the isolation is better than -20dB, the coupling degree is -3.5 dB ~ -5 dB, the amplitude unbalance is less than 1dB, and the phase difference between the output ports is 180°±7°.The above results verify that the 180°waveguide directional coupler has excellent performance and can provide key technical basis for further design of high-performance sum-and-difference feeding network in terahertz band.