An Approximate Analysis of Coaxial Line with a Helical Dielectric Support

Shown in Fig. 1 is a cutaway section of coaxial cable with a helical dielectric support. The particular cable depicted bears the trade name of Styroflex derived from the fact that the dielectric helix is built up in a winding operation from nonplasticized polystyrene tapes giving to the final assembly a tight grip on the center conductor and a good degree of allowable bending capability. The outer conductor in the original design of the cable consists of an aluminum sheath extruded over the dielectric. Other forms of cable with helical dielectric support are also available.