Prediction of common‐mode radiation from cables attached to PCB using imbalance difference and asymmetrical dipole antenna models

Abstract

Cables attached to a PCB can produce a significant amount of unintentional common-mode (CM) radiated emissions (REs). Therefore, it is important to predict these emissions at the design stage before the first prototype is fabricated to ensure time and cost savings. In this Letter, a novel method was proposed to estimate the CM RE from two cables attached to a PCB using the imbalance difference model and asymmetrical dipole antenna model. The proposed method consists of two steps: first, the induced CM voltages on the junctions between the cables and PCB are computed using the imbalance difference model; secondly, the CM REs are then estimated separately for each cable related to half of the ground plane using the asymmetrical dipole antenna model. The overall REs are then computed by the superposition of the RE from the two asymmetrical dipoles. The effectiveness of the proposed method has been verified by comparing the predicted results to both 3D high-frequency structure simulator simulation results and measurement results taken in a semi-anechoic chamber. A good agreement with the accuracy of more than 95% is observed for the upper bounds of the measured REs.