Recent Development in Small-Core Coaxial Cable

摘要

Deliberations of the CCITT, leading to the preparation of a standard specification for a 4.4 mm coaxial communication cable have stimulated considerable design activity in the field of small core cables. Two novel solutions are described in this paper, taking as principal requirements the achievement of: (a) low attenuation, (b) constancy of electrical parameters. The first design, which meets the CCITT requirements, has an outer conductor comprising a folded tape with a longitudinal seam, and is separated from the inner conductor by a series of polythene discs within a polythene tube. The latter are produced and applied by a novel process, in which a strip of polythene with contiguous half-discs is continuously extrusion moulded, folded round the centre conductor, and heat sealed. The manufacturing process is described, and the advantages and performance with this type of construction discussed. (Author)