Electromagnetic Fields Technology Research With The Target Impulse Response Characteristics Analysis

In this paper there are some theoretical and applying problems of two numerical computational electromagnetic methods,which are marching-time-method of integral equation in time-domain(IETD) and method of finite difference in time-domain(FDTD),are studied.In chapter one,first we introduce the importance and history of the numerical computational electromagnetics,then introduce status and some researched results of the two methods. At last we introduce the researched results about the two methods in our paper.In chapter two,after introduced the general concepts of the marching-time-method of integral equations,we deduce out the scheme for bodies of revolution by applying their symmetry. This scheme can decrease the cost in computation. The second problem is the stability of the IETD. By the theory of Z transformation of linear system and matrix,we proved the validation of the averaging filter method using in IETD to cancel oscillation. Then we illustrate the disadvantage of using averaging filter and give a new averaging filter that we note as phase-modified averaging filter,which can reduce the disadvantage. At the end of this chapter,we study the potent of reducing the time-cost of IETD by taking account the short duration characteristics of incident impulse.In chapter three,after introduced the method of FDTD in electromagnetic computing,we study the dispersion of several 2 order FDTD methods deducing from the difference for space and time variables by Fourier theory. Result show that the dispersion deduced by space-difference can be modified by the time-difference. By comparing the error of dispersion,it illustrates that the staggered uncolocated grid Yee's scheme is the best one among 2 order schemes. Using the same method for 2 order scheme,we analysis the high order FDTD schemes. The method for constructing good-performance high order FDTD schemes is points out,and a new 4 order scheme which is coincident for E and H is given out. The dispersion of its and two other uncoincident schemes' are illustrate that 4 order schemes are more accuracy than 2 order schemes,two kinds of 4 order schemes have nearly the same dispersion. After study the using perfect conducting boundary conditions and PML absorbing boundary condition,it shows the coincident scheme has more goodadvantages. At the end of this chapter,a new inciding wave source using in simulation regular waveguides by FDTD method is given,. It can cancel the harmonic phenomena along cross directions and deduce the cost of computation.In chapter four using the impulse characteristics of inciding wave,we test the energy peaks in the transient impulse response of radar targets. By using it and the time-domain derivative-fitting estimator,we decompose the scatter centers' response of many targets. Some samples are shown here.In chapter five,the main works are summarized and the future researching areas are pointed out.