Highly sensitive miniaturized labyrinth shape circular split ring resonator (LC-SRR) based microwave sensor for low permittivity characterization applications

Abstract

This article proposed a labyrinth shape circular split ring resonator (LC-SRR) based microwave sensor for material permittivity characterization at L to S-band applications. The proposed sensor achieved miniaturized dimensions of only 25 × 20 mm2 by utilizing fractal technology. This new design strategy adopts a unique and compact structure and high electromagnetic (EM) field intensity, contributing to a more precise sensing mechanism in the microwave frequency range. The design geometry achieved resonant frequency at 2.57 GHz with a notch depth of −29.5 dB. The design evolution, metamaterial characteristics, equivalent circuit model, and electric (E) and magnetic (H) fields are presented to understand the stopband characteristics at the resonant frequency. A high sensitivity of 10.50 % is achieved for the proposed sensor for the permittivity range from 1 to 2. The reflection and transmission characteristics of the proposed LC-SRR based sensor are validated by fabricating and measuring the prototype. Moreover, the sensor performance is validated using different dielectric materials (Roger RT5880, Roger RO4350B, and FR-4) The measurement results show consistency with simulation results. Finally, the miniaturized low-profile sensor structure and high sensitivity to characterize the permittivity of the material makes the proposed sensor suitable for low-permittivity sensing applications.