Estimation of EM emissions from coaxial and twin-lead cables attached to A PCB using imbalance difference and asymmetrical dipole models

Cables attached to printed circuit board (PCB) are widely known source of common-mode radiated emissions (CM-RE). Therefore, it is important to estimate these emissions at the design phase of the electronic device to reduce the product cost and to increase the market sharing for electromagnetic compatibility (EMC) compliance. In this paper, a novel analytical method is proposed to estimate CM-RE from coaxial and twin-lead cables attached to PCB. This analytical method involve to perform two procedures; first, the CM voltage is computed at the cable-board junction based on the degree of change between the imbalance factors of the board and the cables connected to PCB; The second procedure is to estimate the CM-RE based on the equivalent asymmetrical dipole antenna. The effectiveness of the proposed method has been verified by comparing the estimated results with the measurement results taken in a semi anechoic chamber. A good agreement with accuracy of more than 90% was observed for the frequencies from 30 MHz to 1 GHz.