Sensor Design Based on MSL Coupled with HCSRR-Loaded Ground Plane for Material Characterization

Material characterization utilizing electromagnetic planar sensors is a promising area within modern sensing technology. This work introduces a novel sensor design based on a microstrip line (MSL) structure coupled with three hexagonal-shaped complementary split-ring resonators (HCSRR) etched onto the ground plane. The primary purpose of the proposed sensor is to measure the dielectric constant of the material under test (MUT). The MSL-HCSRR sensor is specifically engineered to operate within the Industrial, Scientific, and Medical (ISM) frequency band centered at 2.4 GHz. The total dimensions of the sensor structure are optimized to 0.35 λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.16 λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.01 λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>. The interaction of electromagnetic waves with the MUT induces a shift in resonant frequencies, utilized for material characterization. The proposed MSL-HCSRR configuration exhibits an E-field distribution of about 1.15 x 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> V/m and hence, enhances the sensitivity of the sensor by inducing a resonance response that is influenced by the changing dielectric properties of the MUT. This approach enables precise and reliable characterization of materials, particularly those with varying dielectric constants.