For very low levels of Singal leakage triaxial & double shielded cables are used to minimize this leakage. Triaxial cables are preferred Triaxial shielding construction minimize 10-20%less Leakage in comparision to double shielded,Cables.
The triaxial cable has the usual outer conductor braid.A dielectric layers is provided over it and an additional braid is again provided.outer Jacket is of PVC in normal course depending upon the attenuation,stability requirements and frequency.