Correspondence of common- and differential-mode components on em radiation from surface microstrip line structure

Yoshiki Kayano, Motoshi Tanaka, Hiroshi Inoue

    Research output: Contribution to journalArticlepeer-review

    9 Citations (Scopus)

    Abstract

    It has been demonstrated that a common-mode (CM) current can dominate the EMI processes up to 1 GHz, despite the fact that a CM current is smaller than a differential-mode (DM) current. However, this description is insufficient to describe behavior above 1 GHz. In this paper, the correspondence of CM and DM components for total electromagnetic (EM) radiation from a printed circuit board (PCB) with surface microstrip line, which is commonly used in microwave integrated circuits, at gigahertz frequency is studied experimentally and with finite-difference time-domain (FDTD) modeling. In order to characterize the EM radiation, the frequency response of the CM current, the electric field near the PCB, and the electric far field are investigated. First, the frequency response of the CM current, near and far-fields for the PCB with an attached feed cable are compared up to 5 GHz. Although the CM current decreases above a few gigahertz, near and far electric fields increase as the frequency becomes higher. Second, in order to distinguish between CM and DM radiation at high frequency, the frequency response and the angle pattern of the far-field from a PCB without the feed cable are discussed. The results show that radiation up to 1 GHz is related to the CM component. However, depending on polarization and PCB geometry, radiation may be dominated by the DM rather than the CM component. The results indicate that the DM component may be more significant relative to the CM component, and the increase in EM radiation can not be predicted from only the frequency response of CM current. Therefore, identifying the dominant component is essential for suppressing the EM radiation. This study is a basic consideration to realize a technique which is effective on the suppression of the EM radiation from the PCB with an attached feed cable.

    Original languageEnglish
    Pages (from-to)1688-1695
    Number of pages8
    JournalIEICE Transactions on Electronics
    VolumeE88-C
    Issue number8
    DOIs
    Publication statusPublished - 2005 Aug

    Keywords

    • Common-mode
    • Differential-mode
    • Electromagnetic radiation
    • Far-field
    • Near field
    • PCB

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Electrical and Electronic Engineering

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