Research On Broadband And Miniaturized Metamaterial Absorber In UHF Band

In this paper,research on broadband and miniaturized metamaterial absorber in UHF band will be carried on to solve the problem of large size and narrow absorption bandwidth of traditional absorbing materials in the fields such as RFID systems and 4G communications.In Part I of this paper,a multilayer metamaterial absorber(MA)with several square loops in UHF band is mainly proposed,which can achieve absorption rate higher than 90% for electromagnetic(EM)wave with frequency range from 901 MHz to 947 MHz,and 46 MHz absorption bandwidth.Advantages for this absorber include thin thickness and simple structure used to achieve a superposition of several absorption peaks,thereby broadening its absorption bandwidth.In Part II of this paper,a miniaturized metamaterial absorber(MMA)in UHF band is mainly proposed.Based on the monolayer square loop in part I,miniaturization of cell size and bandwidth expansion of single resonance point is realized by utilizing methods of incurved structure design and loading lumped resistance.The MMA can achieve absorption rate higher than 90% for EM wave with frequency range from 840 MHz to 990 MHz,and 150 MHz absorption bandwidth,and more than 14% relative absorption bandwidth.The cell size is reduced to 20mm×20mm,which is merely about 0.06 ? at the resonant frequency(910MHz).And simple RFID test indicating that it can be used in the RFID systems to reduce incorrect readings and to prevent the phenomenon of reading fleeing codes of neighboring RFID systems.In Part III of this paper,an ultra-wideband MMA in UHF band is mainly proposed.Based on the incurved structure in part II,miniaturization of cell size and ultra-wideband absorption performance is realized by utilizing method of loading more lumped resistance and design method of introducing multiple resonance point by close coupling of curved lines.The MMA can achieve absorption rate higher than 90% for EM wave with frequency range from 0.8GHz to 2.7GHz,and 1.9GHz absorption bandwidth,and more than 108% relative absorption bandwidth.It is insensitive to two polarization mode for transverse electric(TE)and transverse magnetic(TM),and remains good absorption performance for wide angle of incidence.And the cell size is 20mm×20mm which is merely about 0.05 ? at the lowest frequency(0.8GHz).In Part IV of this paper,based on MA in UHF band,a miniaturized microwave black-box is mainly proposed,and this part will pay more attention on the practicability of the MA compared to the former three parts.The black-box is designed to be used to test the quality of electronic labels rapidly.Analysis of electric field simulation inside the black-box is carried on,and based on the UHF-RFID system,tests under different external environments is done.Comparative analysis on the different conditions indicates that there exists an area with low reflection interference that can be used for testing the quality of electronic labels rapidly.The significance of this work is that choosing the MA as the absorbing material for the black-box can absorb EM wave efficiently and at the same time solve the problem of large size of traditional absorbing materials in UHF band.