US Patent 7265296 Flame retardant plenum cable

The present invention is a flame retardant cable having an insulated conductor and at least two insulation layers. The cable demonstrates a composite dielectric constant less than or equal to about 2.6 and a composite dissipation factor less than or equal to 0.005 even though one of the insulation layers has a dielectric constant greater than 2.6 or a dissipation factor greater than 0.005. The presently invented cable is achieved with a non-halogenated polyolefin as an insulation layer polymer, where the polyolefin having relatively poor dielectric/dissipative properties and the insulation layer composition being substantially free of halogenated or antimony trioxide flame retardant additives.