Pulse Leakage Phenomena during the Propagation on the Inside and Outside of a Coaxial CableAs a Model of Intra/Inter System EMI

Hiroshi ECHIGO  Risaburo SATO  

IEICE TRANSACTIONS on Communications   Vol.E80-B   No.11   pp.1625-1632
Publication Date: 1997/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on EMC Implications of Densely Mounted Electronic Devices)
EMC,  coaxial cable,  leakage,  penetration,  ferrite cores,  

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In this paper, leakage of pulses through the outer sheath of a coaxial cable was examined empirically. Corresponding to two kinds of propagation constants, there must be two modes of propagation, which was observed in the experiments. Because of the difference of their propagation speeds, the leak waveform changes the shape as the propagation. It was shown that a ferrite toroidal core works effectively as a suppressor for the noise current, and the cores work more effectively if they are spreadly located over the cable length because the leaking wave increases during the propagation on tha cable. The penetration phenomena of outer EM waves into the cable were also observed. These empirical results revealed that the EM waves which had once got into the cable were hard to remove. So the cores as the noise reduction parts should be set at the nearer point to the EM source.