EMI antenna model based on common-mode potential distribution for fast prediction of radiated emission

Abstract

In this paper, an improved common-mode antenna model is proposed to quickly predict a common-mode excitation and radiation of printed circuit boards (PCBs). The improved common-mode antenna model is based on a common-mode potential distribution over the two-dimensional plane. Although the original common-mode antenna model explains the commonmode excitation well by introducing a "current division factor (CDF)" of a one-dimensional parameter which represents a degree of imbalance of a transmission line, but it is applicable for limited cases of PCB shapes. To remove the shape limitation, the improved model proposed here uses a "common-mode potential conversion factor (CPCF)." The CPCF is a two-dimensional parameter expanded from the CDF. The improved commonmode antenna model attains good accuracy with experimental measurements and numerical calculations using FDTD method in terms of electromagnetic interference (EMI). The calculation done using this model was extremely fast compared to that with the real structure.

Fast and Accurate Estimation of Radiated Emission from Printed Circuit Board Using Common-mode Antenna Model Based on Common-Mode Potential Distribution

“…Therefore, the common-mode antenna model has the advantage of reducing calculation costs. In addition, the common-mode radiation results obtained numerically from the approach based on the common-mode antenna model were in good agreement with the results from the experiment and from the simulation using the finite difference time domain (FDTD) analysis [6]. This paper discusses superposition of common-mode excitation sources.…”

“…The authors named the imbalance parameter h(u) "commonmode potential conversion factor (CPCF)" [6]. The change in h(u) in lateral position u should generate common-mode electromotive force ∆V C as h does in the transmission direction.…”

“…The model has the advantage of reducing calculation costs for radiated emission because the signal traces and dielectric can be ignored. According to Sakai et al [6], the radiation calculation time with the common-mode antenna model is reduced to approximately 1/80 of that of the real structure model. The radiation intensity in the simulation with the common-mode antenna model stays within about 3 dB of the radiation intensity as measured in a 3-meter semi-anechoic chamber except for dips.…”

“…1(c), which is specially designed for estimating common-mode radiation from PCBs quickly and accurately, "the common- mode antenna model" [4]- [6]. This model focuses only on common-mode radiation from PCBs and therefore consists of a common-mode excitation source and a common-mode antenna element.…”

“…To estimate the common-mode radiation, the authors have studied the electromotive force that causes the common-mode current and deduced a common-mode excitation mechanism by which the common-mode potential difference becomes a common-mode excitation source [4]- [6]. The common-mode potential is a virtual potential on PCBs and is thought to be non-uniformly distributed over the PCB.…”