Study On Electromagnetic Characteristics Of Composite Material Based On Scattering And Loss

As a new electromagnetic material,metamaterial has the characteristics of simple design,flexible and adjustable.The phase gradient metasurface can design specific unit to form a phase gradient at the design frequency point,causing the incident electromagnetic wave to be abnormally reflected,thereby reducing the RCS.The coding metamaterials are designed by a coding unit that satisfies the phase coverage and arranged according to a certain sequence.The RCS can be reduced in a wide frequency band based on the principle of scattering,and the electromagnetic properties can be flexibly changed by changing the coding sequence.The magnetic material based on electromagnetic loss has good absorbing effect,but the absorbing frequency is not easy to control and the impedance is not easy to match.This paper starts from the interaction between electromagnetic waves and materials.,based on the design idea of performance superposition,combined with the dual mechanism of scattering and loss,the electromagnetic properties of metamaterials and composites are studied.(1)Starting from the generalized Snell principle,based on the concept of phase gradient metasurface,designed an abnormal reflection metasurface composed of concentric double ring.The performance of the designed structure was verified by simulation and experiment.Low reflectivity and RCS reduction can be achieved by abnormal reflection at the design frequencies of 6.8 GHz and 16.8 GHz.(2)Based on the theory of coding metamaterials,a 1-bit coding metamaterial based on simple block elements is designed.Obtained different proportions of random coding sequences by random calculation,through simulation calculation and sample measurement,verified the broadband performance of coding metamaterial and the effect of coding sequence on the RCS reduction feature.The RCS can be reduced than 10 dB in the broadband operating bandwidth of 8-16 GHz based on the principle of diffuse reflection.(3)Based on the double mechanism of scattering and loss,a composite material design idea is proposed to reduce the full spatial reflectivity of the material.Explored the regular pattern between various structural parameters and electromagnetic properties of composite materials Using the idea of control variable method,The final composites were designed to have excellent electromagnetic stealth characteristics not found in a single material.In the range of 2-10 GHz,the average reflectance was less than-10 dB,results was verified by samples measurement.