Aspects of the development of dielectrics for radio frequency submarine telephone cables

Future insulation requirements for radio-frequency submarine telephone cables are postulated. A new apparatus is described that enables dielectric loss of low-loss (¿¿ 50 ¿¿rad) materials to be measured under factory conditions over the frequency range of 0.1 to 200 MHz with a repeatability of ¿¿ one¿¿rad. Dielectric loss curves for samples of low density polyethylene, high density polyethylene, three propylene-ethylene random copolymers and one propylene homo-polymer are published. A discussion on the relative dielectric, mechanical and extrusion merits is given and an opinion on the preferred candidate for submarine cables operating above 100 MHz is offered.