What happens if you “ground” both ends of the shield of a coaxial cable?
“Ground” is in quotes for a reason— in any electrical network, only one point at a time can truly be considered the reference, or ground level. In other words, you can’t really ground both ends of a piece of coax if they aren’t located next to each other.
The point is, the “ground” connection provides a second path for the current that wants to flow through the shield of the coax, and this breaks the symmetry that enables the coax to protect against interference from external magnetic fields—or the outward leakage of the signal’s magnetic field.
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