l strength The phase delay/frequency characteristic of a coaxial cable is very member of high tensile steel wires which can tolerate the loads of smooth and consequently the group delay distortion is low across a 10 tons or more arising when a repeatered cable is recovered in a telephony or wideband data channel. However, both baseband and rough sea. This is covered in a copper tape welded longitudinally carrier TV transmission will require group delay equalisation, but forming the inner conductor. The dielectric is solid polyethylene the dominant contributions arise from band limiting components of which, as well as having excellent electrical properties, is virtually the system and not from the cable. incompressible. The outer conductor is a single metal tape closed in a longitudinal overlap. 15.3.4 Standard coaxial pair cables This can be of copper, but aluminium is often used. The attenua- tion is then increased by 6%, as is the number of repeaters, but the Three sizes of coaxial pair have been standardised by the CCITT for overall system costs will be lower. Finally, an overall polythene telecommunication use. These are designated by the diameter of the sheath is extruded to apply compression to the outer conductor and inner conductor and inside diameter of the outer conductor. The provide some abrasion resistance. The dimensions of such a cable largest 2.6mm/9.4mm, is the oldest design and is in extensive use in are considerably greater than standard land-line cable. Thus the many parts of the world. Initially installed for low capacity analogue inner conductor has an outside diameter of approximately 9.3mm, systems (600/960 channel) it has been successfully exploited for the dielectric a diameter of 37.3mm, the outer tape a thickness of high capacity analogue systems (up to 60MHz for 10,800 channel 0.46mm and the overall diameter over the sheath is 44.5mm. systems) and for 560Mbit/s digital systems. The 1.2mm/4.4mm design has been particularly successful as a bearer for short and medium haul routes operati