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Dissipative Foil Wrap for Noise Protection

IP.com Disclosure Number: IPCOM000111677D
Original Publication Date: 1994-Mar-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Gallagher, R: AUTHOR [+4]

Abstract

A slightly conductive foil wrap is applied to sensitive signal cable bundles as shown in the Figure.

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This is the abbreviated version, containing approximately 100% of the total text.

Dissipative Foil Wrap for Noise Protection

      A slightly conductive foil wrap is applied to sensitive signal
cable bundles as shown in the Figure.

      Induced noise from sources such as Electrostatic Discharge
(ESD) or radiated electromagnetic waves that couple onto the cable
cause a flow of high frequency currents on the conductors.  These
disturbing currents can penetrate imperfect shields or convert to
interfering differential signals at the terminating ends of the
cables and cause faults in data and other sense or control signals.

      The higher frequencies propagate on the outer surfaces of the
conductors on which they are induced, and the foil wrap provides a
path for this interfering current.  Since it is only slightly
conductive, the energy in the induced currents is dissipated in the
resistance of the foil while the signals within the cables are
unaffected.

      Since the resistive foil is not functioning as a highly
conductive shield, termination of the ends of the wrapping is not
critical.

      This can be applied as a low cost upgrade to existing
assemblies to improve noise immunity.  The material can be a
carbon-filled lossy plastic film which can be cut and formed to any
desired shape for the application.  A usable range of resistivity for
this application is 1000 to 10,000,000 ohms.