I'm having an electrician fish an Ethernet cable through a wall. I can put shielded or unshielded cat6. However, the electrician doesn't know how to crimp Ethernet cable so I agreed to do that part myself, and I only have materials on hand and experience for plastic crimps. Thus if I put shielded cable, the shield will be left floating. Can a floating shield potentially have worse characteristics than an unshielded cable?
Electronic – Can floating cat6 shield be worse than unshielded
emcethernet
Related Solutions
The shield does not assist against EMI - its protects against ESI - although the two are liable to walk hand in glove in this case.
ie the shield is an electrostatic shield and reduces capacitive coupling
and not an electromagnetic shield which would reduce magnetic coupling.
Needless to say, an electromagnetic field would be a bad thing [tm] for the interior of a transformer.
The shield is effective wherever it places a grounded capacitively coupled sheet between any primary and secondary parts that would otherwise be capacitively coupled. Even imperfect couplig reduction is useful
Electrostatic shields - Canada transformers
A pure square wave of amplitude 3.3 volts p-p when perfectly filtered to remove its harmonics will result in a sinewave whose amplitude is 27% higher at 4.2 volts p-p: -
Notice that the fundamental is higher amplitude than the perfect square wave. If you do the math you'll find that the fundamental is \$\dfrac{4}{\pi}\$ times higher that the square wave.
Somewhere between perfect filtering and the filtering provided by your o-scope you get what you get.
Best Answer
Usually the cable goes to patch panel where you wrap the shield wire on the metal case that is grounded. The other end goes to metal socket and similarly the shield is connected on metal case. If you don't connect the shield, then there is no benefit using FTP over UTP