Common-Mode Radiated Emission Analysis of Cable-Connected Printed Boards with Adjacent Metal Chassis by Imbalance Difference Model

Abstract

The common-mode antenna (CMA) model and the equivalent differential-mode (DM) circuit are based on the imbalance difference theory. The theory describes the mode conversion between the common mode (CM) and differential mode (DM) by focusing on the imbalance difference. The CMA model has been proven to provide excellent estimations of CM radiated emission. In this work, the CMA model is combined with the equivalent DM circuit to extend the CMA model to practical applications that include the mode conversion in both DM to CM and CM to DM directions and radiation loss. The combined model is applied to cable-connected printed circuit boards (PCBs) with an adjacent metal chassis that imitates a signal transmission system placed close to the metal chassis. The combined model calculated the CM radiated emission using a field-and-circuit co-simulator, considering the mode conversion in both directions and the radiation loss. Simulation results confirmed that the combined model precisely estimated the CM radiated emission by being separated from the DM radiated emission. The combined model also provided physical insights into EMC design that will enable the CM radiated emission to be efficiently reduced.