The Numerical Characteristic Analysis And Application Of The Time-Domain Differential-Equation Method In Computational Electromagism

Time-Domain Differential-Equation Method (TDDE) has been widely used in the numerical computation of electromagnetism, and the most famous one is the Finite-Difference Time-Domain Mehtod. Time-Domain Differential-Equation Method, just as its name implies, is the time-domain form of the differential-equation method in the region of the computational electromagnetism. It is well known that, the numerical computational methods of electromagnetism not only include the time-domain method and the frequency-domain method, but also contain the differential-equation method and the integral-equation method. Time-Domain Differential-Equation Method integrates the excellence of the time-domain method with the one of the differential-equation methods. It can not only calculate the wide-frequency characteristic of the object, but also analysis the object which has the complex boundary. With the fast development of the speed of CPU and the capability of memory, TDDE has rather higher computational speed and precision while simulating the large-scale object.In this paper, FDTD and FETD are studied. Due to the CFL stability limition, ADI technique is added into FDTD, which can make FDTD unconditionally stable. By analysising the scattering problem of the square metal, the unconditional stability of ADI-FDTD is validated. TDDE mainly includes FDTD and FETD. However, FETD has to cacualte a great sparse matrix at every time step, what requires the high-class hadware and brings the computational efficiency down. What's more, the effect of the absorbing boundary condition in FETD is not perfect. Therefore, FETD is not developed as well as FDTD. This paper introduces the uniaxial anisotropic-medium PML used in FETD.Next, this paper studies the numerical stabilities and dispersions of the two time-domain differential-equation methods, proves the unconditionally stability of ADI-FDTD, analysises the stable condition of the different time-difference FETD by Z transform method,growth factor method and reduced order method. Comparing the dispesion of FDTD and that of FETD, it can be found that the dispersive functions of the two methods are same.Finally, this paper applies FDTD into bio-electromagnetism, analysises the radiation impact of the human's head which is caused by the monopole antennas and the microstrip anatennas, compares the results and gives the interrelated conclusions.