A Constant Corrugation Circular Waveguide for High-Pass Signal Diagnostics in ECEI System at 75–110 GHz

In this work, a high-pass waveguide filter with constant circular corrugations is presented. The proposed design allows propagation of HE 11 mode which has similar Gaussian characteristics of the signals present in a fusion reactor. The device is designed to operate in W-band, i.e., 75–110 GHz, and it generates a wide passband of approximately 30 GHz. The internal corrugations in the proposed design are kept constant which makes fabrication relatively simpler. The proposed high-pass metallic waveguide is numerically analyzed, simulated, and fabricated for experimental validation. The measured transmission co-efficient (S 21 ) shows good agreement with the simulated result and passband of 28 GHz was obtained. The high-pass filter can be effectively used in the electron cyclotron emission imaging (ECEI) system used in fusion plasma experiments for signal diagnostics.