A DGS-CPW Microwave Sensor Loaded With SRR for Solid Material Measurement

This article proposes a coplanar waveguide (CPW) microwave dielectric constant sensor for solid materials. Compared with conventional microstrip line structures, CPWs complete the element on only one side of the dielectric substrate, simplifying the manufacturing process and providing a compact and simple solution. The split ring resonator (SRR) is loaded onto the defective ground structure (DGS) in the CPW ground plane to construct a high electric field region. The relationship between the permittivity of a solid and its resonant frequency has been further investigated. The sensor is manufactured on a dielectric substrate with the dimensions of $23.4\times 29.4\times 0.762$ mm, and the test results show that the sensor has a no-load resonant frequency of 2.245 GHz. The measured average sensitivity reaches 8.43%, and the average resolution is 189.35 MHz, which provides good performance in the field of dielectric constant measurement.