Study Of EM Wave Propagation In The Rock Tube And Effective Parameters Of The Composite Media

Electromagnetic pulse projection (EMP) is of interest in many military and civil applications. In the research field of EMP one of the emphases is on the electromagnetic coupling through a tube. With the development of electromagnetism technology, study of antimagnetic materiel is viewed as more and more important. Antimagnetic materiel is often a composite media. Study of the computation for the effective electromagnetic parameter of composite media is important. Therefore in this dissertation main efforts are put on the computation of the attenuation characteristic of electromagnetic wave in the rock tube and the effective electromagnetic parameter of the composite media. In addition, an effective approach by using the Finite-Different Time-Domain (FDTD) method to compute the resonant frequency of cavity is given.FDTD method is applied to compute the attenuation characteristic of electromagnetic wave in the rock tube. The attenuation characteristic of electromagnetic pulse is analyzed in time-domain and frequency-domain, respectively. The empirical formula of electromagnetic wave attenuation vary with depth of the tube is given. The computational results show that the value of electric field in some range could be estimated by the empirical formula. Besides, the attenuation characteristic of electromagnetic wave in the straight and tortuous rock tube is compared.Reconstruction of the effective electromagnetic parameter of the composite media in the wide band is studied. Using FDTD method, the reflection and transmission coefficients of the composite media is computed. Based on the Propagation Matrix method, we use Genetic Algorithm (GA) to reconstruct the effective electromagnetic parameter of the composite media in the different volume concentration. The curve of the effective electromagnetic parameter vary with the volume concentration is given. The computed results demonstrate the availability of proposed scheme.The method of computation resonant frequency of cavity by using FDTD method is discussed. The computational time can be greatly reduced by introducing an artificial loss into the solution space. The computational results show that the loss should be controlled in a proper range; otherwise it might result in the error.