Cable with high frequency suppresion
First Claim
Patent Images
1. An electrical cable that attenuates high frequency currents comprising:
- an elongated electrically conductive metallic core of high permeability material; and
an electrically semi-conductive layer disposed about said core, the relative resistances and reactances of said core and said layer providing preferential conduction of direct current by said core and providing a greater concentration of high frequency currents into said layer and damping of such high frequency currents by the resistance of said layer, the resistance in respect to direct current of said core in the elongated direction being small relative to the resistance in respect to direct current of said layer in the same direction, and the reactance in respect to high frequency current of said core in said direction being large relative to the reactance in respect to high frequency current of said layer in said direction, the impedance at high frequencies of said layer in said direction being small relative to the impedance at such frequencies of said core in said direction.
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Abstract
An ignition cable which applies ignition current from a power source to a spark plug of a spark ignited internal combustion engine while attenuating radio frequency currents. An inner elongated electrically conductive metallic core made of a high permeability material has an electrically semiconductive layer disposed thereabout and in intimate contact therewith. Insulation surrounds the semiconductive layer. Direct current is effectively and preferentially conducted by the inner core to provide ignition current, while high frequency currents are crowded by the skin effect into the semiconductive layer, where they are damped by the resistance thereof.
138 Citations
13 Claims
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1. An electrical cable that attenuates high frequency currents comprising:
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an elongated electrically conductive metallic core of high permeability material; and an electrically semi-conductive layer disposed about said core, the relative resistances and reactances of said core and said layer providing preferential conduction of direct current by said core and providing a greater concentration of high frequency currents into said layer and damping of such high frequency currents by the resistance of said layer, the resistance in respect to direct current of said core in the elongated direction being small relative to the resistance in respect to direct current of said layer in the same direction, and the reactance in respect to high frequency current of said core in said direction being large relative to the reactance in respect to high frequency current of said layer in said direction, the impedance at high frequencies of said layer in said direction being small relative to the impedance at such frequencies of said core in said direction. - View Dependent Claims (2, 3, 4, 5)
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6. An ignition cable for applying ignition current from a source to a spark plug of a spark ignited internal combustion engine and for attenuating radio frequency currents comprising
an elongated electrically conductive metallic core for conducting ignition current, said core being formed of high permeability material providing said core with electrical impedance at radio frequencies that is high relative to its direct current resistance; an electrically semiconductive layer disposed about said core for attenuating radio frequency currents, said layer having an electrical resistance that is high relative to the resistance of said core for direct current and an electrical impedance that is low relative to the impedance of said core at radio frequencies, whereby direct current is effectively and preferentially conducted by said core to provide ignition current, and radio frequency currents are concentrated in said layer where they are damped by the resistance thereof to reduce radio frequency interference. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
Specification