Design and Fullwave Analysis of Bridge Edge Coupled H-Waveguide Based Directional Coupler at Sub-THz Frequencies

This paper reports design and analysis of edge coupled H-guide based directional coupler. It is proposed to fabricate the designed coupler using Form lab 3D stereo lithography (SLA) printer where gray resin will be used as polymer material. Dispersion characteristics of the H. guide in the frequency range of 250 GHz - 400GHz have been obtained using CST Microwave studio. A broadband transition has also been designed to excite LSM mode of H-guide using rectangular waveguide. Edge coupled H-guide has been analyzed to obtain even and odd mode characteristics. The designed coupler has 11.7 dB coupling at 330 GHz. The geometry of edge coupled H guide has been modified by introducing a bridge between them to enhance mechanical stability. The presence of bridge alters coupling with frequency.