Fire-resistant cable for transmitting high frequency signals
First Claim
1. An unshielded, fire-resistant cable which is suitable for transmission of high frequency signals, said cable comprising:
- a plurality of twisted pairs of insulated conductors, each insulated conductor comprising;
an elongated metallic member; and
an insulation system which is characterized by a dissipation factor that is less than about 0.004 and by an effective dielectric constant which is such that the velocity of propagation of signals at high frequencies along each conductor pair is equal at least to the product of 0.65 and the velocity of light, said insulation system comprising an inner layer which is contiguous to said elongated metallic member and an outer layer which comprises a flame-retardant plastic material; and
a jacket which is disposed about said plurality of insulated conductors and which comprises a plastic material that is characterized by a suitably low dissipation factor and dielectric constant.
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Accused Products
Abstract
A fire-resistant cable (20) which is suitable for the transmission of high frequency signals in a local area network includes a core which comprises a plurality of twisted pairs (22,22) of insulated conductors (24,24) and a jacket (35). Each insulated conductor of each pair includes an elongated metallic member (26) and an insulation system (28). The insulation system which is characterized by a suitable low dissipation factor includes dual layers, an outer one of which includes a flame-retardant plastic material. Also, the insulation system is characterized by a suitably low dielectric constant and by compatibility with a relatively short pair twist scheme. In one embodiment, the insulation system includes an inner layer (30) of a polyolefin plastic material and an outer layer (32) of a flame-retardant polyolefin plastic material. The jacket comprises a plastic material characterized by a suitably low dissipation factor and dielectric constant and in a preferred embodiment comprises a flame-retardant polyolefin plastic material. Preferably, the twist length of each pair does not exceed the product of about forty and the outer diameter of an insulated conductor of each pair.
112 Citations
17 Claims
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1. An unshielded, fire-resistant cable which is suitable for transmission of high frequency signals, said cable comprising:
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a plurality of twisted pairs of insulated conductors, each insulated conductor comprising; an elongated metallic member; and an insulation system which is characterized by a dissipation factor that is less than about 0.004 and by an effective dielectric constant which is such that the velocity of propagation of signals at high frequencies along each conductor pair is equal at least to the product of 0.65 and the velocity of light, said insulation system comprising an inner layer which is contiguous to said elongated metallic member and an outer layer which comprises a flame-retardant plastic material; and a jacket which is disposed about said plurality of insulated conductors and which comprises a plastic material that is characterized by a suitably low dissipation factor and dielectric constant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification