A PCB, in which the ground plane has a finite width and the trace has unbalanced positioning, can result in common-mode (CM) radiation. So far, CM current which is generated by the unbalance of a trace and ground plane has been investigated by experiment and numerical method. It was clarified that CM current is well explained the radiation from PCB up to a few hundred megahertz, and addition of a guard band geometry, which is well connected to the ground plane, can be effective in suppressing the CM current. But it is seemed to be insufficient description for the phenomena observed at higher frequency. This study newly focuses on the correspondence of the CM current in total electromagnetic (EM) radiation from a PCB with a guard band up to 5 GHz. In results, although total radiated power and near electric field up to 1 GHz were related to CM current, the increase in EM radiation in higher frequencies (a few gigahertz) could not be predicted from only the frequency response of CM current. There should suggest two radiation components for a PCB configuration; radiation as a result of a CM current due to the current driven mechanism, and direct radiation from a trace. At the higher frequencies, direct radiation from the trace may be more significant relative to the radiation due to the CM current. This research will be very useful and applicable to estimate the detail of EMC radiation problem from PCBs with attached cables.

Meeting Name

International Symposium on Electromagnetic Compatibility (2004: Aug. 9-13, Santa Clara, CA)


Electrical and Computer Engineering

Keywords and Phrases

CM Radiation; EMC Radiation; PCB; Attached Cables; Common-Mode Current; Common-Mode Radiation; Earthing; Electromagnetic Compatibility; Electromagnetic Interference; Electromagnetic Radiation; Finite Width Ground Plane; Guard-Band; Printed Circuit Design; Total Electromagnetic Radiation; Unbalanced Positioning Trace; Feeds; Instruments; Coaxial Cables; Resonance; Geometry; Frequency Response; Electronics Packaging

International Standard Book Number (ISBN)


International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version

Final Version

File Type





© 2004 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Aug 2004