Method of Measuring Common-Mode Current Conversion Coefficient for Estimating Variation in Radiated Emission from Printed Circuit Board Components

• Main Authors: Cheng-Yu Ho, 何承諭
• Other Authors: Tzyy-Sheng Horong
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/97977793511870205264

博士 === 國立中山大學 === 電機工程學系研究所 === 101 === This dissertation proposes a novel measurement method using a network analyzer with a bulk current injection (BCI) probe that is used in standard electromagnetic susceptibility (EMS) test to estimate the far-field radiated emissions from printed circuit board (PCB). Generally speaking, radiated emission from PCBs is very complex and difficult to resolve. The proposed method is used to predict the common-mode radiated emission caused by the DC supply loops on a driver PCB of thin film transistor-liquid crystal display (TFT-LCD) panel, which highly correlates with the radiated emission measurements obtained for the TFT-LCD panel in a fully anechoic chamber (FAC). The proposed technique is also successful to estimate the reduction of a specific peak in the radiated emission spectrum by shielding the DC supply loops. Electromagnetic simulation and equivalent-circuit modeling approaches are developed to confirm the common-mode radiation mechanism in this study. As the operating frequency has reached the gigahertz range for an RF PCB, the on-PCB microstrip components radiate more efficiently than ever at low frequencies. The proposed method can also be to measure the common-mode current conversion coefficient of microstrip components in an RF PCB. Based on the proposed measurement method, far-field radiated emissions from microstrip components are obtained, which closely corresponds to measurements in a FAC. The proposed method also estimates the radiated emission reduction by miniaturizing the physical size of microstrip bandpass filters (BPFs). Full-wave electromagnetic simulation further demonstrates the effectiveness of the measurement method.