Using TDIE Method To Calculate The Scattered Field In Time Domain For NURBS Surface

In recent years, the time domain methods were often proposed to calculate electromagnetic fields. This may be due to the short-pulse radar or other related application. It may also be due to the fact that the time domain methods have several advantages over conventional frequency domain methods.The time domain integral equation method (TDIE method) was firstly proposed by S. M. Rao, et al. In this thesis, a new method is given to solve the singular integrals in the TDIE method. It will be easy to get the results for the singular integrals. So, the method of Rao has improved in its calculation. Again, the above method is firstly proposed to calculate the scattered field in time domain for NURBS surface ( non-uniform rational B-spline surface). It is known, the surface of complex object can be designed by use of NURBS surface. Therefore, the above method can be extended to calculate the scattered field in time domain for the complex object.Chapter 1 is the introduction of this thesis. Some basic conceptions and formulas for the scattered field are given in Chapter 2. The TDIE method is introduced in Chapter 3. First, we choose the planar triangular patches to model the body because they have the ability to conform to any geometrical surface. Second, the well-known method of moments (MoM) is used to calculate the surface current, where a special set of basis functions is selected. According to the TDIE method, the scattered field can be expressed by use of the magnetic vector and electric scalar potentials and they can be calculated by using the surface current. In this case, the singular integrals will appear in the calculation. Again, our method is also presented in this chapter for solving the singular integrals in the TDIE method. In fact, by using a special transform the singular integrals will become the conventional integrals and we will obtain its results in the closed form. For our method, the key procedures of the programming are explained in Chapter 4. Several numerical examples are given inthis chapter. Note that the incident pulse in these examples are the Gaussian-impulse plane wave. These results are in quite agreement with Rao's results. It is shown, our method is in the right. In Chapter 5, the expression of NURBS surface is introduced. Then, we calculate the scattered field in time domain for the NURBS surface by use of our method. The numerical examples are also given.