Research On Miniaturized Microwave Sensor Based On Metamaterial

Dielectric constant is an important parameter to describe the electromagnetic properties of dielectric materials,which detection technology plays an increasingly important role in many fields such as industrial manufacturing,biomedical and scientific research.This paper focuses on the development of the practical miniaturized new microwave sensor for dielectric constant measurement,a series of microwave sensors with the miniaturization,high sensitivity and strong anti-interference based on the split ring resonator of metamaterial have been proposed.SRR has excellent properties of sub-wavelength and high-quality factor Q,which classic concentric ring structure is widely used in the design of microwave devices.The difference is that this paper will use the new SRR to design the microwave sensor:1.A two-layer magnetic coupled sensor is proposed,which benefits from the effect of the new SRR agglomerating strong electric field and the advantages of low radiation efficiency and magnetic coupling.The proposed two-layer sensor has ultra-small electrical dimensions(0.067?0 x 0.067?0),high quality factor Q(250),extremely high sensitivity(24.24%relative offset)and strong anti-interference ability(11.4%far-field radiation efficiency);2.Combined with the theory of multi-layer SRR coupling,a three-layer magnetic coupled sensor is proposed to 'solve the radiation problem of the two-layer sensor.The improved three-layer sensor has a smaller electrical size(0.052?0×0.052?0),a higher Q value(345),higher sensitivity(14.54%relative offset)and stronger anti-interference ability(6.3%far-field radiation efficiency);3.Based on the three-layer sensor,a single-port differential sensor is proposed,which single resonator has a maximum far-field radiation efficiency as low as 1.9%while maintaining electrical size and sensitivity that is nearly identical to that of the three-layer sensor,and the anti-interference and stability are greatly improved.Then,the relative frequency offset method is proposed for the inversion of the dielectric constant of the samples under test,which greatly improves the accuracy of the measurement and greatly simplifies the test procedure.Finally,we propose the dual-port differential sensor and its RF circuit measurement system.It enables the measurement of the dielectric constant of a material without using any experimental equipment.