Transient Electromagnetic Properties Of Dispersive Media

It is of great importance to study the transient electromagnetic characteristics of dispersive media owing to its promotive effects in many fields of engineering interest. However, due to the complexity of the dispersive media, the study of the transient electromagnetic characteristics, the leading research in the electromagnetic field, remains one of the unsolved problems. In this paper attention is paid to the model theories of transient electromagnetic problems of dispersive media and the study of the transient electromagnetic characteristics.Firstly, based on the digital signal processing, a new frequency-dependent finite-difference time-domain ((FD)2TD) method for arbitrary dispersive media is established and improved. The validity of the new numerical method is improved and the application is extended to dispersive media. The dispersion of media is modeled with the infinite-impulsive response filters (IIR). In this paper two (FD)2TD methods based on the permittivity or conductivity are proposed and their numerical dispersion, stability and applicability are also studied.Secondly, based on the concepts of discrete system a new absorbing boundary condition for arbitrary dispersive media is derived. Its stability and efficiency are also studied.Thirdly, the transient electromagnetic problems of dispersive media are simulated and studied with the new (FD)2TD method builtin this paper. The propagation and scattering characteristics of dispersive media are studied in-depth in time-domain. The (FD)2TD method and Wavlet transform are applied to analyze the transient propagation in dispersive media. The scattering of several objects with different shape and complex objects formed with multi-layer dispersive media are simulated. The simple experiment models for dispersive media are built and the measurement results are compared to the numerical solutions. It is shown that the media information is indicated in the late-time response of the transient response, while the geometry information is indicated in the early-time response.Finally, the method of object identification including the significance of the research in this paper is discussed briefly. The research in this paper has laid a foundation for the object identification.