Dielectric Measurement in Liquids Using an Estimation Equation Without Short Termination via the Cut-Off Waveguide Reflection Method

Dielectric constant of various liquids were measured using a method for estimating the dielectric properties for unknown materials with comparison to just three standard materials without the use of short termination at the frequencies of 0.50 and 1.0GHz. The sample was inserted into a coaxial-feed-type cut-off circular waveguide, thereby facilitating determination of permittivity in small amounts of scarce liquids. Moreover, the complex permittivity of various liquids was also estimated at frequencies ranging from 0.50 to 3.0 GHz. The measured results using this approach were thus compared with outcomes from the conventional method. The results indicated the following advantages from the proposed method: 1. Short termination measurement is unnecessary in permittivity estimation; 2. After kit-based SOL calibration, it is unnecessary to move the reference plane using the electrical delay function of VNA when S₁₁ is measured with replacement to the measuring jig.