Sampled line reflectometers for terahertz s-parameter measurements

The design, construction, and investigation of a compact reflectometer suitable for measuring return loss magnitude and phase of biological materials and chemical agents at submillimeter wavelengths is presented. The instrument, which consists of a section of rectangular waveguide and an ensemble of Schottky diode power detectors is designed as a proof-of-principle demonstration and is a relatively simple implementation of the six-port analyzer originally investigated by Engen and coworkers. Design considerations for the reflectometer are presented and measurements in the 270 GHz to 320 GHz range are discussed. In addition, preliminary return loss measurements on sample biological materials (salmon and herring DNA) in the millimeter-wave region are presented and described.