An apparatus for communicating a signal downhole includes a drill pipe configured to be rotated to drill the borehole and a tube under axial tension and secured in the drill pipe, wherein the axial tension occurs at least with the drill pipe not under axial tension. The apparatus further includes a connector sleeve sealed to an end of the tube and configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to. The apparatus further includes a transmission line configured to communicate the signal. The transmission line is disposed in the tube and has a length greater than the length of the tube and extending past the connector sleeve.