Application of a dual-band metamaterial differential sensor with dual-detection modes for permittivity detection

Abstract This paper presents a dual-band metamaterial differential sensor with dual-detection modes for the permittivity characterization of materials. The design aims to address common limitations in metamaterial sensors, such as susceptibility to environmental factors and reliance on single-mode detection. The sensor employs a differential configuration to suppress common-mode interference from the environment. Furthermore, by integrating a branch-line coupler with a complementary split-ring resonator (CSRR) structure, it achieves the capability to detect permittivity variations through both amplitude changes and frequency shifts. Through theoretical analysis of the sensor structure, the physical mechanism enabling the sensing function is elucidated. The simulation results indicate that the sensor achieves permittivity detection by monitoring amplitude changes at a resonance frequency of 1.54 GHz, with a detection sensitivity of 2.10 dB/permittivity unit (PU). Also, permittivity detection is achieved by monitoring frequency changes within the frequency range of 2–3 GHz, with a detection sensitivity of 39.80 MHz/PU. The consistency between simulation and measurement results confirms the feasibility of the sensor. The sensor’s capability to determine the permittivity suggests its potential as a tool for subsurface target detection.