An assembly including a span of microwave signals flexible coaxial line, or other form energy transmission media, is provided with generally coextensive, non-metallic longitudinal strength strands to render greater tensile strength to the assembly. Marginal axial end sections of a coaxial cable span are potted in respective polyurethane grip foundation having longitudinal grooves. The grip foundations are inserted into an open-mesh-sleeve type cable-end grip device. The strength strands are seated in the grooves and interlaced in and out of the openings in the open-mesh-sleeves of the grip devices. Co-adjacent marginal end portions of the strength strands are bundled beyond the interlacing, and knotted to the open-mesh-sleeves of the grip devices. In forming the knots the bundled marginal end portions of the strength strands are entwined and bound together and with a pair of the crossing strands of the open-mesh-sleeve.