Theoretical And Experimental Study On CSRR Characteristics

The left-handed material is a relatively special artificial electromagnetic material that is composed of periodic sub-wavelength-scale structural units.In a certain frequency range,the left-handed material exhibits a negative dielectric constant and a negative magnetic permeability.Left-handed materials also have some exotic electromagnetic properties,such as negative refractive index,inverse Doppler effect,and perfect lenses.At present,various sensors based on left-handed material structure have attracted more and more attention.This sensor can have the advantages of non-separating component measurement,small physical volume,high sensitivity etc,and can be integrated into other microwave devices,which is beneficial to realize miniaturization and integration of microwave devices.With the deepening of the study of left-handed material structure,a new type of left-handed material structure Complementary Split Resonant Ring(CSRR)is proposed and applied to the design of modern sensors.The complementary Split Resonant Ring is a special left-handed material.This thesis discusses the research background and development process of left-handed materials,and summarizes the application status of left-handed materials.The research on the application of CSRR to sensing design in recent years is summarized and analyzed.It is found that applying CSRR to the sensor design is beneficial to improve the performance of the sensor.In order to improve the measurement accuracy of the sensor and realize the minia turization of the sensor,two new structures CSRR are proposed in this paper,which can respectively improve the measurement accuracy of the sensor or miniaturize the sensor.The basic theory of transmission line,Split Resonant Ring(SRR)and Complementary Split Resonant Ring is introduced.The equivalent circuit model of CSRR sensor is studied.The basic principle of microwave detection and method of using S parameter to extract the electromagnetic parameters of the material medium are introduced,which is beneficial to the further study of the CSRR sensor.Based on the relevant theory of transmission line and Complementary Split Resonant Ring,in order to improve the accuracy of dielectric constant measurement of CSRR microstrip sensor,a hexagonal CSRR s tructure is proposed and the simulation analysis is carried out.The measurement accuracy is about 1.4 times higher than that of the traditional quadrilateral CSRR,the quality factor at no load is increased by about 30% compared to that of the quadrilateral structure,so that the performance of the CSRR microstrip sensor is effectively improved;then the sensing performance of the sensor is simulated and analyzed;finally,the experimental system is set up.The designed dielectric sensor is used to test the dielectric constant of different materials,and the influence of the external environment is eliminated as much as possible to reduce the measurement error.In order to realize the miniaturization of the sensor,a new structure of the miniaturized CSRR structure is proposed.At the same operating frequency,the compact CSRR structure is about half of the conventional CSRR structure in physical area occupying,effectively utilizing the internal space of the complementary split resonant ring,reducing the physical area of the sensor,and realizing the modern sensor miniaturization;This chapter also briefly analyzes the complex permittivity of materials,and uses the compact CSRR microstrip sensor to simulate the complex permittivity of materials.The simulation results show that the microstrip resonant sensor loaded with compact CSRR structure can realize measurement of material complex dielectric constant.A method is provided for the study of complex dielectric constant measurement of subsequent materials.