Abstract
Keywords - CEM, EMC, EMI, RFI, FDTD.
Abstract - Time domain simulation techniques such Finite Difference Time Domain (FDTD) are found to be particularly suitable in 3D full wave electromagnetic modelling of vehicles for EMC/EMI/RFI analysis. The simulation results can be used to optimize vehicle antenna set up and to detect hot spots in the field distribution inside the vehicle which can affect the electronics systems on board.
The simulation work presented in this paper was performed using a radiating antenna placed at different positions inside and outside the car structure. The locations were selected to represent common locations for installed vehicle communication systems and for personal hand-held communication devices. Fields produced by the antennas are very influenced by the geometry of the vehicle. Such effects are very difficult to predict on the basis of simple arguments, but can significantly impact on system performance. A real electromagnetic model of the vehicle is therefore useful in order to determine the whole near field vehicle environment.
The first step was to generate a full-vehicle model. A crash car model was used and, before applying the numerical modelling meshing technique, a simplification was carried out by removing some complexity. Without losing electromagnetic details, the simplification allows us to reduce the amount of meshing problems and the size data. This process results on an overall computational domain of (4.4x2x2.2) m 3 , this space was meshed using a uniform main grid with side dimension of 0.01 m which means more than 19 million cells.
Electric field measurements have been carried out on a SEAT Cordoba frame to validate the simulations results. The probe used to collect data was a commercial isotropic field sensor made up of three orthogonal monopoles with a frequency response up to 5 GHz and a dynamic range from 0.5 up to 800 V/m. In this paper, the set up has been used to measure emissions from a European mobile phone GSM1800. Measurements have been done at the positions where the simulations results in the maximums and minimums values when a continuous signal was generated. A good correspondence is showed between simulations and measurements. The procedure could be applied at other frequency bands used by other systems within a car.
Inside and outside prediction of vehicle electromagnetic environment by numerical simulations could provide manufactures the ability to optimise the selection placement of different components to meet electronic system performance and EMC constrains, reducing design cycle times and cost.