A Novel Dielectric Detection System Based on Wire-Loaded Waveguides

A novel dielectric sensing method that utilizes the highly selective frequency response of a wire-loaded waveguide structure is proposed. The sensing scheme consists of two interconnected waveguides that are coupled through a narrow aperture containing metallic wires. The dielectric sensing is accomplished by detecting the shift in the resonant frequency when the dielectric samples are placed at high intensity field locations around the wires. The effect of various waveguide parameters on the sensitivity of the detection system is also studied using finite-element full-wave simulations. Some of the presented concepts are verified practically by constructing a 3-D waveguide setup and detecting frequency shifts for three dielectric samples that have relative permittivities between 2.2 and 3.3.