Detuned Magnetic Dipoles Induced Transparency in Microstrip Line for Sensing

Detuned magnetic dipoles analog electromagnetically induced transparency (EIT) effect in a microstrip transmission line is theoretically and experimentally investigated. Only a single unit cell consisting of two detuned split ring resonators (SRRs) placed on the microstrip line is sufficient for inducing the classical EIT-like effect, which is verified by numerical simulation and experimental measurement. The excited principle and resonance nature of the EIT-like effect in the microstrip line are well elucidated by theory and simulation. It was found that the significant suppression of induced currents in SRR resonators played a key role and resulted in the classical EIT-like effect. The influences of the coupling between SRRs and the detuning of sizes for SRRs on the resonant frequency, the peak magnitude, and the line width of the transparency window are numerically and experimentally analyzed. In addition, it is numerically and experimentally demonstrated that the EIT-like structure based on microstrip line couplings can be employed as a sensor based on refractive index variations and yields a sensitivity of 14.2 mm/RIU and a figure of merit (FOM) of 6.17, which allows our design to offer an excellent potential for high resolution of sensing situations.