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Matching Cable Junctions With Negative Resistance

IP.com Disclosure Number: IPCOM000084127D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Owen, CE: AUTHOR

Abstract

A junction of n cables may be matched by using series resistors but has the disadvantage of introducing voltage attenuation. However, a junction of n cables, each having a resistive characteristic impedance Ro is matched by shunting the junction by a negative resistance of value Ro/(n-2). All the cables are matched and there is no attenuation in passing the junction.

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Matching Cable Junctions With Negative Resistance

A junction of n cables may be matched by using series resistors but has the disadvantage of introducing voltage attenuation. However, a junction of n cables, each having a resistive characteristic impedance Ro is matched by shunting the junction by a negative resistance of value Ro/(n-2). All the cables are matched and there is no attenuation in passing the junction.

This may be used to match coaxial cables in a tree layout of a communication system covering the aisles of a factory floor. As shown in the diagram a cable is taken from a junction along each aisle and to a controller making a total of n cables at the junction.

This junction is matched by a negative resistance Ro/( n-2).

The negative resistance may be an integrated circuit with taps to select the negative resistance required for a particular number of cables n, and may be powered by a direct current via the coaxial cables. For a speech communication system, the negative resistance is required to operate only at speech frequencies and does not have to operate down to zero frequency.

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