Analysis and Validation of Fabrication and Assembly Effects on Terahertz Waveguide Bandpass Filter

In this paper, a 560 GHz waveguide bandpass filter manufactured using high precision CNC milling technique is presented, impacts of fabrication and assembly on THz waveguide filters are analysed. In the filter, eighth-order coupling cavities are adopted to achieve a higher rectangular coefficient. For low-loss and convenience fabrication, the filter is split at the E-plane waveguide, and internal angles are rounded. Moreover, since the waveguide splitting and re-assembly introduce additional gaps, dimensions of these cavities are increased correspondingly, and the operating frequency is undesirably offset. These imperceptible factors make the experimental results deviate from expectations at THz frequencies. Therefore, influential parameters are investigated in advance. To verify the design, a 560 GHz waveguide bandpass filter is manufactured and measured. The experimental results are consistent with the simulation results.