Quad-band split ring resonator-based sensor for microwave sensing application.

This study offers a compact size, highly sensitive, and reliable split ring resonator-based sensor for microwave sensing applications. The designed unit cell is assembled on a 1.575 mm width of low-cost dielectric substrate Rogers RT5880. CST software is employed to design and analyze the proposed sensor. The size of the sensor is 8[Formula: see text]8 mm² which is very small and it's a low price. Also, the CST-simulated model was validated using ADS software. The MATLAB is used to extract the effective parameters of the suggested unit cell. Then the prototype is fabricated, and the laboratory measurements are done to validate the simulated results. The obtained resonances from the designed sensor are 2.77, 5.78, 9.82, and 12.29 GHz. Sensing performance is examined by using various materials and thicknesses of FR-4 material. After analysis, the sensor's EMR, quality factor, and figure of merit (FoM) are found to be 13.54, 325, and 6.15 respectively which are effective. The sensitivity of the sensor is 12.03% which means the sensor performance is optimum. The resonances are shifted to 210, 600, and 810 MHz due to permittivity change and 290, 270, and 560 MHz due to materials thickness change. All laboratory results are perfectly matched with the simulated results. Due to its small size, low cost, high sensitivity, and superior performance, the suggested sensor can be used for sensing material thickness as well as glass, plastic, and substrate materials.