基于传输反射法的微尺度等效电磁参数提取技术研究OA

In recent years,conductive components have been increasingly incorporated into wave-absorbing materials to enhance their absorption bandwidth and performance.Meanwhile,microwaves are also being more widely used for sintering of metal powders and metal-powder-containing composite materials.However,when the content of conductive components is relatively high,traditional equivalent permittivity εeff prediction formulas of-ten fail to accurately determine the equivalent electromagnetic parameters of these composites.To address this issue,an innovative micro-scale equivalent electromagnetic parameters extraction technique based on the transmission-re-flection(Nicolson-Ross-Weir,NRW)method is proposed to analyze the equivalent permittivity εeff and equivalent permeability μeff of composites containing conductive components.By applying periodic boundary conditions,a unit simulation model for micro-scale composites with conductive components is established to obtain the S-param-eters,and then to be combined with the NRW method to calculate the equivalent electromagnetic parameters.The effects of metal component volume fraction φ,particle size r,and conductivity σ on the equivalent electromagnetic parameters are investigated.The simulation results indicate that when non-magnetic composites contain a high pro-portion of metal components,the equivalent permeability μeff changes significantly under microwave radiation,the real part μ'eff＜1 and the imaginary part μ″eff＞0.Through the study of the interaction between microwaves and com-posite material structures,it is found that the change in equivalent permeability arises from the induced ring cur-rents on metal particle surfaces under microwave radiation,which functions similar to orbital angular momentum.When the microwave frequency ranges in 2-6 GHz,the real part ε'effand imaginary part ε″effof the equivalent per-mittivity both increase with the increase of metal component volume fraction φ.At constant φ,both μ'eff and μ″eff in-crease with the decrease of particle size r,while the change of μeff disappears when there is a sharp decline of con-ductivity σ.Experimental measurements of εeff and μeff for composites mixing copper powder with paraffin wax with varying φ values showed consistent trends with the simulation results,validating the accuracy of the predictive model.This research provides guidance for the design and optimization of high-efficiency wave-absorbing materials and microwave material processing systems.