Abstracts of Technical Articles by Bell System Authors (01 January 1945)

Abstracts of Technical Articles by Bell System Authors Jour. Applied Physics, October 1944. FM and Television, November 1944. 157 158 BELL SYSTEM TECHNICAL JOURNAL coaxial cables will provide for broad-band transmission sendee such as is required for television. A cable is now being installed between Terre Haute and St. Louis which contains six coaxial tubes to provide telephone circuits, and which may, in the future, find use in connection with the provision of intercity television networks. 

The structure of the tubes used with coaxial cables consists of a central copper conductor within a copper tube about f in. in diameter, made from flat copper strip which is formed around the insulating discs. Around each copper tube are two steel tapes which supplement the shielding of the copper tube in preventing interference between tubes in close proximity. The central conductor is separated from the outer conductor by slotted insulating disks which are forced onto the wire. The cables are formed with an appropriate number of these tubes along with some small gauge pairs used for control and operating purposes. 

In the case of underground cables buried directly in the earth, jute or plastic protective coverings are used to assist in reducing sheath corrosion. In some parts of the country it is essential to add a metal covering outside the lead sheath and the plastic or jute to protect the cables against the operations of ground squirrels or pocket gophers. In certain areas these animals have been found to carry away long sections of the jute covering and will chew holes in the lead sheath unless other metal protection is provided.