Solid Permittivity Measurement Sensor Based With IDE-ELC Substrate Integrated Waveguide Resonator

Characterization of the dielectric constant of solid materials has many applications. Among them, improving the sensitivity and reducing the error of solid sensors is the key to the design. A design of a highly sensitive substrate-integrated waveguide (SIW) microwave sensor is proposed in this letter. An electric-LC (ELC) resonator is etched on the surface of the SIW to sense changes in the dielectric characteristic. Furthermore, to improve the sensitivity, both sides of the ELC are designed with an interdigital electrodes (IDEs) structure to achieve high electric field confinement in the sensing area. Meanwhile, the permittivity of the material under test (MUT) is calculated by the resonant frequency offset. The experimental results show that the sensor has a sensitivity of 8.33%, a frequency detection resolution (FDR) of 120.5 MHz, and a measurement error of 2.33% with a size of
$16\times20$
mm. This work can be used for the detection of permittivity of solid materials in industrial applications.