Narrow-band Band-pass Filters for Terahertz Applications

In this work, a WR-1.5 band-pass filter is presented, manufactured using the Polystrata 3D fabrication process. The filter is intended to be integrated into a radiometric receiver to band limit the incoming noise power and encompass an atmospheric spectral window centered at 682.5 GHz. A 10.8 mm diameter waveguide flange is fabricated in Polystrata with a band-pass filter structure running parallel to the flange face. The thickness of this standalone filter “shim” is 0.8 mm. The dimensions of the filter structure itself are 0.4 mm x 0.8 mm x 2.3 mm. The filter has a 3 dB bandwidth of 12 GHz, or 1.7%, and exhibits 4.5 dB insertion loss. These results are compared against standard CNC machine split-block waveguide iris filters at the same frequency to highlight the advantages of micromachined filters for terahertz applications.