Research On Electromagnetic Properties Of Multivariant Hybrid Microwave Absorbing Materials

Microwave absorbing material is getting more and more concerned for the application in stealth of the weapons equipment and the avoidance of electromagnetic wave radiation. Electromagnetic wave absorbing materials with the properties of low density, strong absorption, wide frequency band and thin thickness have attracted more and more attention. The microwave absorbing material that contain only one kind of absorber is difficult to obtain a wide frequency band absorption properties. Coupling one kind of absorber with another absorber or others maybe can obtain compounded absorbing materials with the properties of wide frequency band and strong absorption. In this article, we proceed from the mechanism of the magnetic loss and dielectric loss, and the absorption propertied of microwave absorbing materials with different kinds of loss mechanism have been studied. The compounded absorbing materials with different loss mechanisms were also studied.The complex permeability of the microwave absorbing materials was increased after pulsed high magnetic field, heat, flattening and orientation process. The complex permittivity of the flaky Fe-based alloy particles is much higher than the permeability and this is not good for impedance match, combing the flaky Fe-based alloys with the magnetic material, non-magnetic inorganic material or organic polymer, the dipole polarization was suppressed and the interface polarization produced, then the complex permittivity of the flaky Fe-based alloy particles decreases greatly, and this is good to get a good impedance match which is useful to get a good microwave absorption.A synergetic effect between absorber and PVDF is benefit to improve the wave absorption properties, The dipole at the surface of the flaky NiCo2O4 are more sensitive to the electric field, when the electric field is incident on the surface of NiCo2O4, the interface polarization between NiCo2O4 and PVDF and the dipole polarization would be arised which would lead to the dielectric loss. The wide electromagnetic wave absorption frequency band can be obtained through change the thickness of the microwave absorbing materials.Reduced graphene oxide (RGO) with the properties of low density, high dielectric loss and high chemical stability can be used as microwave absorber. The ternary composite which is composed of RGO, Nano-alloys and ferrite has been prepared by one-step solvothermal synthesis. There is multiple interface polarization between them due to the different dielectric property, and this would lead more dielectric loss. The good absorption properties are ascribed to the dielectric loss, magnetic loss, quarter-wavelength cancellation and impedance match.The microwave absorption properties of the composite which is compose of metamaterial absorber and the traditional magnetic microwave absorbing materials were studied. The absorption properties can be improved through change the structure, size, configuration of the metamaterial unit or change the electromagnetic parameter and thickness of the traditional magnetic microwave absorbing materials. Within a certain thickness of the traditional magnetic microwave absorbing materials, the frequency band width of 90% absorption rate increased with the thickness of the traditional magnetic microwave absorbing materials. When the thickness of the traditional magnetic microwave absorbing materials is 0.9 mm, the band width of the reflection loss below -10 dB can reach 15.8 GHz.