Will laying a piece of coaxial cable on a metal surface affect the RF signal? Will coiling coax cause additional cable loss? Open

Coiling coax or laying it on metal has little or no effect on loss. Even if the coax is terminated poorly, all fields are internally contained in the coax. The only time you will have currents on the coax is from the antenna at the end radiating back to the shield. Coax is a truly balanced cable in that the currents on the center conductor and on the shield are exactly the same and in opposite directions. This is true at least to the limits of shielding and copper resistance.

Since the magnetic and electric fields are self contained, the outside world doesn't "see" any current flow and coiling the cable or even wrapping it around a piece of iron makes little or no difference. The prohibition against coiling coax has been around for a long time. I know that, because many years ago I read an article that disabused "yours truly" of that firm belief.

The worst thing about a coiled cable is that the signal has to go through a longer piece of cable and has a little more loss than a straight shot. A one foot diameter coil is harmless for the coax that we all use.

However, coiling cables in a very small coil deforms or even damages the cable, and will mess up the cable impedance.

Posted 3 years agoby LectroAdmin

You must be logged in to post an answer