Calibration of waveguide adapter for multimodal measurement of material characteristics

Waveguide multimodal measurement of material constitutive parameters (permittivity and permeability) is designed for the unique and simultaneous determination of both permittivity and permeability. A rectangular waveguide coupler with 4 coaxial-line probe antennas and square cross section is used to decouple the TE₁₀, TE₀₁, TE₁₁ and TM₁₁ modes. The excitation and measurement of multimodal signal needs special coupling structures that must be calibrated before the measurement can be processed. It is the goal of this paper to present a calibration technique for a waveguide adapter used for multimodal measurement. A good agreement can be observed by comparison of scattering parameters of a material sample, ones using real measurement and once using simulation to produce virtual measurement.