Research On Absorbing Characteristics Of Three-dimensional Metamaterials Based On Electromagnetic Resonance Addition

As an artificial composite material with a sub-wavelength unit structure,metamaterials have flexible electromagnetic control capabilities and are widely used in radar absorption,electromagnetic compatibility,and other fields.With the advancement of detection technology,the investigation of broadband,high-performance microwave absorbing materials is of great significance.Based on the resonance addition mechanism,this paper designs a variety of gradient metal line array patterns,constructs a three-dimensional metamaterial structure absorber,and superimposes the upper and lower layers to achieve the broadening of the absorption frequency band.Broadband and high-efficiency absorption characteristics are studied.The main research contents and conclusions obtained are summarized as follows:Design the metal wire structure model to construct the metal-medium surface,discuss the absorbing mechanism of the metal wire attached to the three-dimensional dielectric plate,summarize and explore the correlation between the geometric parameters of the structure and the absorbing performance.Based on the eigenmode solver,the dispersion curve of the metal wire structure is simulated,the corresponding relationship between the absorption frequency and the cut-off frequency shows that the metal wire structure has a local effect on the cut-off frequency electromagnetic wave.By changing the length of the metal wire,the electromagnetic wave at different frequencies can be absorbed.The graded metal wires are arranged in an orderly manner on the FR-4 substrate,and a three-dimensional metamaterial structure absorber is designed.This structure effectively superimposes the absorption peaks of different frequencies,and the reflectivity is less than-15 d B in the frequency range of 8.0-16.4 GHz when the thickness is 13 mm.The structure has polarization insensitive characteristics and good oblique incidence performance,and still has good loss characteristics for TM waves when the incident angle reaches 60°.The simulation result is consistent with the experimental result.A polarization-insensitive meta-surface structure is designed to achieve high-frequency electromagnetic loss.Then a double-layer absorber based on the superposition mechanism is constructed to obtain the absorbing characteristics covering the X and Ku bands.The simulation results show that the double-layer design can effectively superimpose the absorption bandwidth of the metamaterial structure,and its reflectivity is less than-15 d B in the 7.5-20.0 GHz frequency band when the thickness is 15 mm.The equivalent input impedance is extracted based on the electromagnetic parameter inversion to verify the matching characteristics of the structure and the free space impedance,and the mechanism of its absorption is further explained.The simulation result is in good agreement with the experimental result.According to application requirements,a dielectric layer is covered above the double-layer structure.The correlation between the permittivity and thickness of the dielectric layer and the absorption performance is discussed.The optimized design has a reflectivity of less than-15 d B in the 7.8-19.5 GHz frequency band.The composite metamaterial has certain application prospects in the field of radar wave absorption.