The FDTD Study Of Multi-antennas On A Vehicle System Based On UPML Boundary

In this paper, the electromagnetic characteristic of multi-antennas on a vehicular platform is analyzed using the finite-difference time-domain (FDTD) method based on the UPML boundary. The FDTD method is a kind of transient time domain method, which derived directly from the Maxwell's equations in the time domain. The FDTD method can simulate the propagation processing of electromagnetic wave very clearly. If the excitation is a pulse source, the response in frequency domain can be obtained over a wide bandwidth with one FDTD calculation. The UPML absorbing boundary is a more advanced absorbing boundary and has better absorption and simpler operation which is brought forward on the PML absorbing boundary. The EMC problem of the current vehicle communication systems is more and more prominent; The FDTD method can be easily used to deal with such electromagnetic problems with complex figures.This article first introduces the basic theory of the FDTD method, tells the issues which should be paid attention: the step length of space, the step length of time and the excitation setting. Secondly, the principle of the UPML absorbing boundary is discussed detailedly, the UPML iterative formula and its parameters setting is given, the advantages of the UPML absorbing boundary than the others is presented. And then after a discussion of the design idea of the FDTD program based on the UPML boundary using c/c++ language, the correctness of the program is tested by a few simple examples. Lastly, through the introduction of the modeling of the vehicle and the antenna, the coupling between multiple antennas on vehicle is calculated under different condition and the conclusions are educed.