Design of High Frequency Resonator for Dielectric Spectroscopy

A design for a cost-effective one-port patch antenna for high-frequency (20GHz) dielectric spectroscopy is presented. The sensor comprises a microstrip input line, a quarter-wavelength transformer for impedance matching, and a patch antenna with a milled channel adjacent to its radiating element, allowing fluids to influence its resonant frequency. A circuit model explains the operating principle, showing that shifts in resonant frequency correspond to variations in the real part of the fluid's permittivity. The sensor's performance is assessed through finite element method (FEM) simulations under various material conditions. Results indicate that the sensor's response is predominantly governed by the real part of permittivity, with minimal impact from dielectric losses. Calibration using reference fluids in simulations yields a predictive model with high accuracy (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>> 0.99). Experimental validation and prototyping are planned for future work.