A wired pipe system includes a wired pipe segment having a first end and a second end, a first coupler in the first end and a second coupler in the second end and a transmission line disposed in the wired pipe segment between the first and second ends. The transmission line includes a transmission cable that includes an inner conductor and an insulating material disposed about the inner conductor as well as a a wire channel surrounding the insulating material and the inner conductor for at least a portion of a length of the transmission cable. The wire channel and the insulating material are mated together by at least one mating feature.