Apply A Hybrid Numerical Method To The Radiation From The Aperture

Electromagnetic compatibility has become more and more serious in the electronic system recently. In order to solve such problems, the simulation based on electromagnetic numerical method should be processed at the beginning of the product design. So, this paper takes the electrical machine box on the model, researches the radiation from the aperture on the metallic enclosure, especially the problem of transformation from near to far field. We pick out the hybrid of Finite-Difference Time-Domain (FDTD) and the Method of Moment (MoM) from a lot of electromagnetic numerical methods to solve such electromagnetic compatibility. We first use the FDTD to compute the inner of the metallic enclosure because of the complex. However, when we need to compute the far field away from the aperture, the FDTD is difficult (even cannot) because of the lots compute time and the computer memory. In order to conquer the shortcoming, we present the Mom based on the electric field integral equation (EFIE) to transform the electric field from near to far. With this hybrid method, we solved this radiation from the aperture on the box well and reduced the computer memory and compute time. This paper introduced the basic theory of the FDTD and MoM. We firstly use the FDTD to compute the field inner and outside of the enclosure, the fields outside of the enclosure computed by the FDTD provide the point for the MoM. Then use the EFIE and MoM to get the equivalent magnetic current source. At last we can compute the far field with the equivalent magnetic current source. In this paper we deduced the hybrid formula, procedure and the steps, explained the basic thinking of the hybrid method. In all, we introduced a new method to calculate the radiation from the aperture on the box. In this paper, many models about the aperture on the different box were built. We programmed and computed the models built before with this hybrid method. We also use the time domain extrapolation method to calculate the same model, and we compared these data computed by these two methods, we found that the data were matched very well. At last we summarized the influence of the aperture for the radiation of faraway field and presented many experiences about how to reduce the radiation.