Free-space material characterisation at terahertz frequencies using a vector network analyser

While dielectric properties of many materials have been extensively characterised at low frequencies and into the microwave region of the electromagnetic spectrum, published information is much sparser in the THz region. Knowledge of permittivity is essential for design of photonic waveguides, mixers, modulators and other devices designed to operate at these frequencies. A system based around a vector network analyser was assembled to measure the permittivity of planar samples. The number of components required is vastly smaller than that of time domain spectroscopy systems. The Short-Open-Load-Through (SOLT) calibration procedure is performed on the system to ensure measurement accuracy.