Measurement of complex permittivity by rectangular waveguide method with simple specimen preparation

The characterization of materials by rectangular waveguide method usually requires a sample holder and a complicated procedure of preparing specimen in order to limit the air gaps between the specimen and the boundaries of the waveguide that will affect the accuracy of measurement. In this paper, we present a technique of complex permittivity measurement with a simple MUT (Material Under Test) preparation technique. The waveguides are first calibrated at the reference planes by the TRL calibration. Then, the scattering parameters in the presence of MUT specimen are measured at two SMA ports of the waveguides by an Agilent VNA. These coefficients are de-embedded to the reference planes by the TRL calibration. Finally, the Nicolson-Ross-Weir (NRW) algorithm is used to extract the dielectric constant and the loss tangent of the MUT. The simulation and measurement are performed at the 1.7-2.7 GHz band. The results demonstrate the validity of the proposed technique.