The information I got from a reputable engineer was "slightly" different. Basically, I was told that all RF signals (even the return path) travel on the center conductor and that the shield serves as ground and as a means to complete the circuit. The higher the frequency the closer to the outer center conducter it travels (skin effect) and the lower the freq. the closer to center of the conductor it travels (that's why you can use copper clad with satellite signal but you have to use solid copper center conductor with audio - 20hz thru 20khz). Anyways, that's what I've been told and still believe. Be safe ya'll