A wired pipe segment includes a body extending from a box end to a pin end and a coupler located in one of the box end or the pin end, the coupler including a communication element and a coupler connector in electrical communication therewith and extending away from the communication element. The segment also includes a transmission line extending away from the coupler towards the other of the box and pin end, the transmission line including an inner conductor surrounded by an insulating material, the inner conductor of the transmission line having an end with a non-cylindrical shape. The segment also includes a connector that electrically connects the coupler to the transmission line.