W-Band Waveguide Impedance Tuner Utilizing Dielectric-Based Backshorts
Kiuru, T¹; Möttönen, V. S.²; Räisänen, A. V.^1
1TKK Helsinki University of Technology; ²National Board of Patents and Registration of Finland

In this paper, design, simulations, fabrication, and measurements of a W-band waveguide impedance tuner are presented. The design consists of a WR-10 waveguide with two E-plane arms for tunable dielectric-based backshorts. The impedance tuner is fabricated using a simple split-block technique and is easily scalable to submillimeter wavelengths. Our design shows an excellent input impedance range, tuning accuracy, repeatability, and a high attainable maximum reflection coefficient over the frequency band of 75-110 GHz, e.g., the maximum attainable reflection coefficient at the center frequency of the band is 0.96 (VSWR = 49). The presented tuner applies dielectric-based backshorts, which provide a tuning accuracy better than that of other waveguide backshorts. The presented tuner can be used in the optimization of the input impedance of, e.g., low-noise amplifiers and mixers and in millimeter wavelength noise-figure measurements.