Design Of High-Performance,Miniaturized Planar Microwave Sensors Based On Complementary Split Ring Resonator

Microwave sensors have a wide range of applications in the fields of food,medical care,agriculture and environment.They are not only used to characterize the electromagnetic properties of samples of magnetic-dielectric materials,but also to the dielectric characterization of electrolyte solutions in microfluidic systems.The thesis is devoted to exploring the research of the microwave sensor based on plane resonance that can be used to measure the complex permittivity and the complex permeability of the material.A series of high-performance,miniaturized planar microwave sensors based on complementary split resonant ring(CSRR)structure are proposed.In the first part,a microwave sensor for detecting the electromagnetic properties of magneticdielectric samples is proposed.The proposed sensor has the two sensing areas.One area is used to measure the complex permittivity and the other area is used to measure the complex permeability.The measurement of the two parameters does not interfere with each other,and the complex permittivity and complex permeability of the sample can be obtained by analyzing the respective resonance frequency points.In the second part,two improved sensors based on the sensor structure in the first part are proposed.The first improved sensor can obtain simultaneously the complex permittivity and complex permeability by loading two same magnetic-dielectric samples in one measurement,the second improved sensor can obtain simultaneously the relative permittivity and relative permeability by loading a magnetic-dielectric sample for one measurement.The improved sensors have high resolution and high quality factor Q value.In the third part,an active microwave sensor for detecting media samples is proposed.The sensor consists of a microstrip complementary split ring resonator(MCSRR)and an active loop.The active feedback loop can generates negative impedance to compensate for the loss of the resonator.The sensor has an ultra-small electrical size,high sensitivity and an ultra-high quality factor Q value.In the fourth part,a differential microwave microfluidic sensor for detecting the complex permittivity of the electrolyte solution is proposed.The differential sensor has two identical sensing units based on the MCSRR structure.One of the two sensing units is used to refer to the other for measurement.A single sensing unit has a smaller electrical size and high sensitivity.The differential sensor has strong anti-interference and stability.In short,a series of microwave sensors based on the CSRR structure are designed and realized the accurate measurement of the complex permittivity,the complex permeability of magneticdielectric sample and the complex permittivity of electrolyte solution in the thesis.