Research And Application Of The Equivalent Medium Theory In Periodic Structure Composite Materials

Multi scale or multi physical modeling plays an important role in many important problems.In practical work,when modeling electromagnetic simulation of complex targets,there will often be such problems: it is impossible to model the material or coating of the target in detail.In addition,with the rapid development of the material field,the composite material of periodic structure is widely used in real life by virtue of its unique characteristics.For example,microwave absorbing materials for lightweight antenna reflectors and aircraft,and radome materials used to protect antennas are mostly related to composite materials with periodic structure.In the actual process of electromagnetic simulation modeling,considering the microstructure of the materials can not be unlimited,if it can be in the complex environment of inhomogeneous composite materials equivalent to a uniform medium plate,it can reduce the difficulty of electromagnetic simulation in a large extent,save the computer memory and calculation time.Therefore,the research on the application of the theory of equivalent medium in the modeling and Simulation of complex electromagnetic environment has become one of the hot topics in the field of electromagnetic field in recent years.When the periodic size of the periodic structure composite material is much smaller than the wavelength of the electromagnetic wave,from the perspective of electromagnetism,the material can be equivalent to a homogeneous medium,and the medium can be characterized by equivalent electromagnetic parameters.Therefore,the purpose of this paper is to ensure that the periodic structure of the heterogeneous composite material is equivalent to a homogeneous dielectric plate based on the equivalent medium theory under the condition that the electromagnetic properties of the composite remain unchanged.The main contents of this paper are as follows:First,in order to analyze the electromagnetic characteristics of the periodic structure composite,the finite element boundary integral method is adopted in this paper.Therefore,this paper introduces the basic principle of the finite element boundary integral method,the discrete treatment of the finite element boundary integral equation,and the solution to the complete matrix equation.Then,the boundary value problem of periodic structure material is solved in detail.The Galerkin(Galerkin)weak method is used to weaken the restriction of mesh conformal.Then,taking the material of the radome as an example,the free space method is proposed to analyze the equivalent dielectric constant of the radome material.By comparing the transmission parameters and the reflected parameters of the honeycomb material before and after the equivalent,the rationality of the free space method is verified.Finally,a more complex method for analyzing the equivalent electromagnetic parameters of composites is introduced,which is the 4*4 matrix method,which achieves the goal of making the periodic structure of the heterogeneous composite equivalent to the anisotropic medium.Compared with the free space method,the honeycomb material can be regarded as an anisotropic homogeneous material,which achieves a higher accuracy requirement for the equivalence of periodic structure composites.