Analysis Of Triple-TEM Cell Based On Finite Difference Time Domain Method

In this paper, the basic principle of FDTD(Finite Difference Time Domain)method is summarized, and some important problems related to FDTD Method are discussed in detail such as the partition of grid, the conditions of numerical value stability, the setting of excitation source, as well as the choice and setting of absorbing boundary conditions.In order to researching Triple TEM Cell, which is one kind of new test equipment for EMC, this paper firstly analyzes the basic electrical properties of traditional TEM Cell. First of all, the static state field distributing of TEM Cell's central transmission area is calculated, and the field variational rules along with the cross section's size, inner conductor's width and offset distance are analyzed by using Finite Difference Method. Secondly, this paper calculates the three-dimension field distribution of TEM Cell's central transmission area by using FDTD Method, and knows the usable condition of static state analyze after compare with three-dimension calculation. Finally, three kinds of TEM Cell's characteristic impedance are calculated, and the program's validity is proved through compare the compute result and well-known value, which make good preparation for the studying of TTEM Cell.TTEM Cell has the same pyramidal configuration compare with traditional GTEM Cell; however it has two pieces of inner conductors which are placed orthogonal. We just need to change the load status of core board in order to obtain electromagnetic field which has two different polarized directions. This characteristic makes our test convenient. First, the static state field distributing of TTEM Cell's cross section under different loading conditions are calculated. Second, this paper uses FDTD to simulate the propagation of electromagnetic wave in TTEM Cell's three-dimension space, presents the distribution in cross sections, and illuminates how to choose calculative parameters, boundary conditions and set exciting source. Otherwise, this paper analyzes the effects to field distribution and characteristic impedance in the case of EUT, calculates the upper, lower and exterior electric field intensity of different EUT. At last, the polarization of individual modes in the TTEM Cell is analyzed in full consideration.