Numerical Calculation Error of Variational Method with Dielectric Measurement Using a Coaxial-probe

This study was conducted to clarify how numerical calculation with higher-mode exclusion affects dielectric property estimation in application with the variational method to calculate S11 using the open-ended coaxial-probe method. Specifically, the dielectric constants of certain liquid types were estimated based on an inverse problem to coincide with S11 values calculated using the variational method (VM) and the finite element method (FEM) at frequencies of 0.50 and 2.50 GHz, respectively. The estimation results were compared with the set dielectric property values associated with S11 calculation using the FEM. Differences of 10.4 to 29.0% in the complex permittivity of tap water were observed with VM application using the coaxial-probe method as compared with FEM application.