Terahertz waveguide directional coupler with double “Tian-Shape”

The terahertz waveguide directional coupler with double “tian-shape” is designed basing on the directional coupling principle of branch line. The branch lines closed to the waveguide width edge are bolding to increase stress and then the feasibility of processing will be improved. The coupler is analyzed and optimized by professional electromagnetic simulation software high-frequency structure simulator (HFSS). The results show that the coupling degree is 6.3 ± 0.2 dB in the range of 313 GHz to 383 GHz. It is almost close to the straight line in the whole frequency band. The isolation degree is less than -20dB and the average insertion loss is almost close to 0 dB. The return loss in each port of the directional coupler are both less than -20dB. Finally, the process of fabricating the coupler based on MEMS technology is described and the physical model is shown.