Improved approach using multiple planar complementary split-ring resonators for accurate measurement of permittivity

This paper presents a non-destructive planar single-compound triple complementary split-ring resonator (TCSRR) to improve the measurement of the dielectric constants of a material under test (MUT). This proposed microwave sensor technology requires the multiple-square concentric ring to generate multiple non-identical frequency responses to take estimate for dielectric property measurement, and the cooperated estimate of SC-TCSRR can effectively mitigate the permittivity measurement error. The dielectric constants and thickness of a MUT are dependent on the operational resonance frequency deviation. The CSRR sensor is etched on the ground plane of a microstrip line. The SC-TCSRR sensor operating between 1.5 GHz to 4.6 GHz band is fabricated by specific ratio range and tested for verification. For calculation and analysis, the permittivity of a MUT is extracted by two resonant frequencies (fM, fH). This proposed method uses three sets (fM, fH), fL, fM) and fL, fH) and averages the measured results to improve measurement accuracy. The experiments yielded average measurement errors less than 1.60 % for the permittivity of MUT. And, the result is more accurate than dual ring CSRR's measurement error result [1] 4.63%. This effective TCSRR sensor offers low computational costs, easy fabrication and precise measurement.