| The unique sub-wavelength unit structure and flexible designing of the metamaterial make it extraordinary in electromagnetic field.Its theoretical and applied research have received widespread attention.In view of the thick thickness,low absorption rate and the limited bandwidth of the traditional low-frequency absorbing materials,metamaterials provide a new direction for the study of low-frequency absorbers,and its theoretical and applied research are of great significance.Firstly,introducing the basic concepts and theoretical formulas of metamaterial.A brief summary of the development and application of absorbers are summarized.Meanwhile,the effective medium theory,impedance matching theory,surface current analysis and multiple interference theory are introduced.Secondly,a graphite-loaded metamaterial absorber is proposed.The absorber is designed based on conventional absorber method and loaded with the graphite material.The absorption band from 0.60 GHz to 0.89 GHz is achieved with an absorption rate of 90%.The absorber can keep a high absorption rate under a wide angle of incidence.The absorbing mechanism was analyzed by the magnetic energy distribution and the simulation results were matched with the theoretical calculated results.The effects of loaded and unloaded graphite,resistance,graphite thickness and air layer thickness on the absorption rate were discussed.Finally,a broadband polarization-insensitive split-patch multiple layer metamaterial absorber loaded lumped resisters working at 0.84 GHz-1.64 GHz was proposed.The absorption bandwidth with an absorption rate of 90%is 0.80 GHz.The calculated results are in good agreement with the simulated results.The error of the experiment and simulation is caused by the environmental factors.In this paper,impedance matching theory,surface current analysis and magnetic energy distribution are used to explain the absorbing mechanism.The effects of resistance and air layer thickness on absorption rate are also analyzed in detail. |
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