Analysis Of Cloaking Theories Based On Metamaterials And The Design Of Polarization Converter

Metamaterials are functional materials composed of artificial composite subwavelength structures.By appropriately designing the size and orderly arranging units,metamaterials could have lots of unique electromagnetic properties.The paper makes an intensive research on metamaterials based on the application background of electromagnetic cloaking technology.This paper mainly discusses cloaking theories based on metamaterials,and divides them into two categories: passive and active cloaking technology.Firstly we analyze passive cloaking mechanism based on scattering cancellation,resonant absorption and polarization control.Secondly we study active cloaking mechanism based on equivalent source and boundary element method.Then four methods for obtaining equivalent medium parameters are described in detail: the Lorentz model and its improvement,retrieval method using scattering parameters,calculation by analytic formula for layered materials,and the surface impedance method,etc.What's more,based on polarization control,we design a linear polarization conversion device to achieve cloaking function.All the theoretical analysis,numerical simulation and experimental measurement verify the rationality and feasibility of the design.Finally,we design and simulate a cloaking device by means of an arrangement of the U-shaped array and the mirror array.The final result demonstrates that the polarization conversion device which is based on metamaterials is feasible and efficient in the field of electromagnetic cloaking,and has certain value for carrying out various cloaking mechanism deeply.