I have an application where there is a twisted shielded pair cable with a transformer coupled high frequency communication signal on it. the center taps of the transformers will carry DC for powering the device on the opposite end of the cable. The cable has an outer insulator so the shield is insulated from any other return path.
Unfortunately the ground of the cable will be connected to chassis on both ends.
The load end will have a switching power supply (buck regulator) so the currents on the centertap "phantom mode" will be somewhat noisy.
The differential signal is bidirectional 10Mbit/sec Manchester encoded signal) We do not want this signal to escape the cable either.
A couple of choices.
1) terminate the shield only on one side to make it a Faraday cage and add a separate return wire for the DC power on the CT.I don't like this one because there will certainly be a loop are between the separate return wire and the twisted pair. Also when the transmitter on the far end sends its signal, there is not return path back to the source for the currents that couple between each conductor and the shield.
2) Terminate the shield on both sides and use the shield as the return for the DC currents as wellConnecting the shield on both ends provides the return for HF current generated between the pair and the shield. Also intimately couples the power supply generated high frequency harmonics of the DC power currents with the pair so the loop area is as small as it can be.
Assuming these are the only two choices, which of the two would radiate the least amount of noise to nearby circuitry.