Study Of FDTD Method In The Vehicular Communication Multi-antenna System

In this thesis, the EMC characteristic of multi-antennas on a vehicular platform is analyzed using the finite-difference time-domain (FDTD) method. FDTD is a kind of transient time domain method, which is derived directly from the differential form of Maxwell's equations in the time domain. FDTD 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. Moreover, FDTD can be conveniently used to deal with the problem of complicate shape in complicate medium. The procedure of FDTD method is very universal and can be widely applied in different kinds of system. So, it is applied in the simulation of vehicular communication multi-antenna system in this paper. The EMC prediction is achieved successfully according the calculation results.Firstly, the basic principle, the differential form of FDTD and other relative theories are proposed. The main content includes numerical modeling theories, absorbing boundary condition and the technology of excitation, etc. Secondly, the calculation and analysis model of vehicular communication multi-antenna system is built. The establishment of model is composed of two aspects: meshing of the vehicular and model of antennas. The former one is based on the patch and the latter one is FDTD technology of thin wire. Combined all these theories presented above, a FDTD near-zone to far-zone transformation is described in detail. The analysis model of antenna's coupling and radiation characteristic are established in the paper. And, the EMC characteristic analysis of antennas on vehicular platform is achieved. Moreover, the summary for the advantage and disadvantage of FDTD is given. The new method ADI-FDTD which is better than the general FDTD is proposed. The principle and the derivation are demonstrated in detail. Finally, the analysis software of EMC of vehicular multiple antennae system is developed, which is based on the thought of Object-Oriented Programming. The basic idea, overall flow chart and the core design thought is introduced. Some useful conclusions are obtained and the application of FDTD is verified by a few examples.