A coaxial cable [10, 50] includes an inner conductor [11] that is separated from an outer conductor [13] by a layer of insulating material [12]. The outer conductor includes a thin sheet of metallic foil that envelops the insulating material and has a seam [14] that extends in the longitudinal direction of the cable. In a first embodiment, the insulated conductor is axially rotated (twisted) with respect to its own longitudinal axis. In a second embodiment, the outer conductor is wrapped around the layer of insulating material. In both embodiments, there is relative rotation between the insulated conductor and the outer conductor. This practice is referred to as relative insulated conductor rotation, and it significantly improves the structural return loss characteristics of a coaxial cable when the outer conductor includes an asymmetry, such as a seam, that extends in the longitudinal direction of the cable. A braided-wire shield [15] is positioned between the outer conductor and a plastic jacket [16], which provides environmental protection for the cable.