Comparison of TRL Calibration Standards and Techniques for Waveguide S-parameter Measurements up to Terahertz Frequencies

This paper describes a comparison of measurements to evaluate the effectiveness of different implementations of the Thru-Reflect-Line (TRL) calibration scheme specially developed for S-parameter measurements of terahertz waveguides. A WM-380 (500-750 GHz) vector network analyser (VNA) was calibrated using a 1/4-wave TRL technique utilising novel silicon micromachined standards, and this was benchmarked against a 3$/_{4}-$wave TRL technique utilising conventionally manufactured standards. The calibrations were applied to measurements of a set of devices with a broad range of characteristics. The results from each scheme were then compared, both directly and against reference values of various kinds. The comparison results give a clear indication of the viability of each calibration scheme and each set of standards for providing accurate measurements at these frequencies.