Contents
How does current flow in a coaxial cable?
The RF current in a coaxial cable flows from the signal source (e.g. a transmitter), through the center conductor to the load and then back through the outer conductor of the coax, to the signal source.
Does coax shield need to be grounded?
The shield must be grounded to be effective. The shield should be electrically continuous to maximize effectiveness, which includes cables splices. In shielded signal cables the shield may act as the return path for the signal, or may act as screening only.
Can coax cable electrocute you?
You should never get a big shock from a coax cable. If you get shocked by a coax cable, call an electrician NOW. While it would work for a short time, carrying 110 volts and up to 10 amps would create a lot of heat which would cause the cable to fail.
Does current flow through neutral?
Normal circuit currents flow only in the neutral, and the protective earth conductor bonds all equipment cases to earth to intercept any leakage current due to insulation failure.
Do coax cables get hot?
Cable modems have a tendency to get very hot, some of that heat is radiating out through the cable terminator. Totally normal.
Where does the current go in a coax shield?
The shield (outside) stays at ground potential, and there no outside current flow. But if the antenna or balun is not symmetrical, the current will divide between the inside and the outside of the coax shield.
Where is the current located in a coaxial cable?
So the picture is that an ideal coaxial cable has a current +I on the surface of the inner conductor and a current -I on the inner surface of the shield. (at any give location and moment of time) From the outside of the coax, you don’t see any electric or magnetic fields — they are contained inside the shield.
How does the skin effect affect the coax?
However, the electric and magnetic fields responsible for skin effect can reach across the dielectric of the coax as well: any common-mode current on the center conductor will create eddy currents that cancel the center conductor’s current, replacing it with a current on the shield.
Thus, the shield is also the return current path. The geometry of the shield relative to the center conductor also defines the characteristic impedance of the cable. If there are any discontinuities in the shield, the signal will be distorted by reflections.