A multi-band high-sensitivity microwave sensor for simultaneous detection of two dielectric materials

A multi-band high-sensitivity microwave sensor is reported. The two resonance units are based on complementary square spiral resonators (CSSRs) and produce four measurement bands through parasitic resonances. The four frequency bands are 2.001, 2.988, 5.438, and 7.755 GHz, respectively. Through an analysis of the coupling effects between the two CSSR resonance units, it is shown that the sensor is capable of simultaneously characterizing two samples with distinct dielectric properties. By adding a metal patch to the microstrip line, the overall quality factor of the sensor is enhanced, leading to higher sensitivity and accuracy in both real and imaginary part measurements. The measurement results demonstrate that this sensor provides an accurate and efficient solution for solid permittivity measurements.