GB623748A - Improvements in high frequency cables - Google Patents

Abstract

623,748. Electric cables. TELEGRAPH CONSTRUCTION & MAINTENANCE CO., Ltd., DEAN, J. N., and SMITH, E. W. July 11, 1946, No. 20801. [Class 36] A high-frequency co-axial cable comprises a non-conducting core 1, around which is applied an inner conductive layer consisting of a plurality of metal tapes. 5 applied edge-toedge with a long lay, together with an outer conductive layer consisting of a single metal tape 7 applied longitudinally over and folded around the tapes 5 and held in position by dielectric material applied thereon, e.g. by a stout helical thread 3. The helical thread 3 may serve to support an outer dielectric envelope 4 and an outer conductor (not shown). The tape 7 may be transversely crimped as at 8 to prevent buckling. An inner conductor 9 may be included if desired. The outer conductor may be applied over the dielectric envelope 4 in the form of tape or tapes having a long lay and may be held in position by a pair of superimposed helically-applied metallic binder tapes, the turns of each helix breaking joint and those of the upper helix covering the gaps between the turns of the lower helix. The core may be of polythene or jute, and the main insulation and binder may be of polythene or any flexible, water-resistant thermoplastic insulation such as orientated polystyrene, which may be mixed with polyisobutylene or mixtures of polythene with polyisobutylene. The helical binder may be of insulation having a higher softening point than that used for the dielectric envelope. A multi-start helix may be used for the binder.