Research On Electromagnetic Parameters Extraction Of Layered Inhomogeneous Media

Electromagnetic parameters of materials are importance,which have important theoretical significance and applied value to the study of their electromagnetic characteristics.With the development and the application of layered media in different engineering and science fields,many novel functional materials continuously appear,such as bianisotropic media.There are new requirements for the extraction of electromagnetic parameters of materials.Therefore,it is very urgent and necessary to investigate the methods of measuring the electromagnetic parameters of layered and bianisotropic media.First,based on NRW T/R(Nicolson-Ross-Weir Transmission/Reflection)method,we extend the electromagnetic parameters of materials varies from the single-layer medium to the double-layer medium and derive a method for extracting the electromagnetic parameters of any layer of the double-layer medium.The in homogeneous double-layer medium are placed in the rectangular waveguide,the unknown complex relative permittivity and permeability can be got by extracting the scattering parameters of the waveguide port.And we consider the thickness resonance,multivalued disadvantages and other potential problems in such case.The available method is only applicable to the extraction of the electromagnetic parameters of the solid materials,whereas the improved method in this thesis is suitable for the parameter extraction of liquid and powdered solids too.Second,we put forward a method of extracting permittivity and the thickness of double-layer media using GA(Genetic Algorithm).The accuracy of the method are validated by comparing the results with that obtained by the transmission line method.The advantage of the transmission line method is can extracting the electromagnetic parameters of the tested material quickly without iterative optimization.The GA have the advantage of extracting several unknown parameters at the same time,that is the electromagnetic parameters and thickness of the double-layer materials can be simultaneously extracted by using the GA.Finally,we give a method of extracting tensor electromagnetic parameters of bianisotropic media.Solving the scattering field of single axis bianisotropic slab in free space by using the transfer matrix,which can be used to inverse the tensor parameters of a bianisotropic slab by combining with the genetic algorithm.It has been proved that nonmagnetic metal helical coils are bianisotropic.A set of arrays composed of the coils are used to simulate the uniaxial bianisotropic slab.To determine scattering parameters,numerical simulations are performed via the HFSS.The scattering parameters are put into the GA to gain the tensor parameters of the effective bianisotropic media by the inversion method.The results are consistent with the literature,which have proved that the effectiveness of this method.