The invention is a system for transmitting data through a string of downhole components. In accordance with one aspect of the invention, the system includes a plurality of downhole components, such as sections of pipe in a drill string. Each component has a first and second end, with a first communication element located at the first end and a second communication element located at the second end. Each communication element includes a first contact and a second contact. The system also includes a coaxial cable running between the first and second communication elements, the coaxial cable having a conductive tube and a conductive core within it. The system also includes a first and second connector for connecting the first and second communication elements respectively to the coaxial cable. Each connector includes a conductive sleeve, lying concentrically within the conductive tube, which fits around and makes electrical contact with the conductive core. The conductive sleeve is electrically isolated from the conductive tube. The conductive sleeve of the first connector is in electrical contact with the first contact of the first communication element, the conductive sleeve of the second connector is in electrical contact with the first contact of the second communication element, and the conductive tube is in electrical contact with both the second contact of the first communication element and the second contact of the second communication element.