Study On The Metamaterial Absorber And Its Sensing Application

Due to its unique perfect absorption characteristics,metamaterial absorbers have been widely applied in the fields of electromagnetic stealth and electromagnetic compatibility.However,with the continuous improvement of space electromagnetic complexity,the interference of electronic devices is growing more and more serious,and the demand for multi-band absorbers becomes more and more urgent.In addition,metamaterial absorber exhibits potential properties such as rapidity,high efficiency,and nondestructive in the field of sensing technology,its resonant frequency is also sensitive to the dielectric properties of the substrate media.These have attracted widespread attention of researchers and gradually became research hotspots of sensing technology field.Based on traditional electromagnetic wave theory,the thesis designs a new type of six-band metamaterial absorber by utilizing multi-resonator planar arrangement technology,and also reveals its resonance mechanism and absorbing mechanism.Then,based on the successful design experience of metamaterial absorbers,resonant absorption technology of metamaterials can be applied in the field of dielectric media detection.By loading liquid media on microfluidic,a sensor of metamaterial absorber suitable for rapidly non-destructive detection of edible oil is proposed.Then,by utilizing microwave resonators and microfluidic integrated manufacturing process,we can solve the core technical problem that the device must physically contact with the measured medium in the conventional test program,providing a new idea of measuring and identifying dielectric media.(1)Based on the novel Ω-shaped resonator,a six-band absorber was designed.Utilizing the characteristics of Ω-shaped multimode resonators with different absorption bands under the excitation of horizontally polarized waves and vertically polarized waves,a new method of adding absorption bands is proposed by placing four identical Ω-shaped resonators in a centrosymmetric manner.The absorber can achieve perfect polarizationinsensitivity six-band absorption at the frequencies of 3.95 GHz,6.61 GHz,9.17 GHz,11.22 GHz,12.59 GHz,and 15.63 GHz,and the simulated absorption rates are 97.04%,99.57%,and 99.54%,98.95%,99.94% and 99.49%,respectively.By analyzing the distributions of surface current and power loss density,the electromagnetic resonance of the absorber is revealed;Based on the transmission line theory and distribution characteristics of surface current,the equivalent lumped parameters at each absorption frequency are extracted.Then,by utilizing the multi-resonator coupling theory,the exact equivalent circuit model of the absorber can be obtained.Finally,the free-space test platform was built to measure the absorber.The texted absorption rates of 94.35%,99.35%,99.27%,98.33%,98.35% and 93.58% were at 4.01 GHz,6.68 GHz,9.23 GHz,11.17 GHz,12.57 GHz and 15.02 GHz.And the test results were consistent with simulation,verifying the correctness of the design method.(2)An absorber sensor applied in the identification of plant edible oil was proposed.Utilizing four novel W-shaped meander line resonators,a narrow-band absorber,with absorption frequency of 9.887 GHz and Q value of 147,was fabricated.Based on the transmission line theory,the equivalent circuit model of the absorber was extracted.Then,the functional relationship between the dielectric constant and the resonant frequency of circuit was deduced.This can help to acquire the regularity on the sensitivity of the absorber,which lays a theoretical foundation for the design of the liquid medium sensor.Finally,the sensor exhibiting high sensitivity to the dielectric constant can be achieved by utilizing the microfluidic technology to load the measured medium on the region of strong induced electric field.Based on the simulation results of the electromagnetic field,the functional relationship between the absorption frequency and the dielectric constant of the measured medium is established.The maximum sensitivity of the sensor is 500 MHz per unit of relative permittivity.After building the test platform,experimental test results show that: compared to without dielectric medium,we loaded rapeseed oil,corn oil,peanut oil,sesame oil and olive oil,the absorber sensor could generate frequency offsets of 461 MHz,458MHz,449 MHz,444MHz and 436 MHz,respectively.Therefore,the absorber sensor based on the characteristic of frequency offset can identify rapeseed oil,corn oil,peanut oil,sesame oil and olive oil.