Broad-Band Dielectric Probe with a Coaxial Line - Circular Waveguide Junction

A model of a broad-band dielectric probe for permittivity measurements of liquids and powdered materials at microwave frequencies is presented in the paper. The coaxial line - circular waveguide junction, built in the probe, is studied using full-wave analysis. A layer of material under test is placed in the circular waveguide of arbitrary radius The probe has been modeled in order to predict the relationship between reflection coefficient at the input and the complex permittivity of any dielectric sample. The developed model was verified with measurements on air, methanol and distilled water.