Signal Leaching...

This question comes from Circuit forums, I run it and did not get a satisfactory answer there. (Hope mods of this board do not mind)

I shall publish answers I get here on my forum, unless you explictly ask me not to do so. It would be good if you could give a contact method...

On two wire lines you can capacitive couple individually to each wire. On coaxial line there is some return current that gets through to the outside. You can put a toroid around the cable and a few turns of your own wire on the toroid. The signal pickup on both cases will be very low. All you will be able to do is detect the presence of a signal. You will not get enough to decode or otherwise use the signal.

Yes it's possible to eavesdrop signals from a coaxial cable, for instance.

Flexible, low-loss cables have bonded metal tape outer conductors with braided overshields. This construction provides better than 90dB shielding. Winding a suitable pickup coil (e.g. tuned) along the coaxial cable, and connecting the coil to a sensitive receiver, will do the trick.

So using a sensitive receiver and amplifiers, I can evesdrop...

but can I tune in into a 10-12 wire LAN cable to leach network signals (star topology type cables) So I individually tune till I get signals from only one of the many cables and do it for each of the cabe.