Owen Duffy wrote:

I am not familiar with the equipment you have, so ask the question, can
you measure the phenomena without significantly disturbing it? If I was
designing a common mode current probe, I would think of a small self
contained thing with a panel DMM readout, battery powered, and that could
be clamped to a conductor and read remotely with a telescope. Anything
with substantial length of conductors is likely to be a problem.


A strategy that is used in antenna research with bolometers is to use
wires with an impedance of 377 ohms/square so they "look" like free
space and don't perturb the field. I haven't seen these as a
commercial item, so I suspect that they are fabricated by the
researcher: perhaps by cutting from sheets of so called space cloth or
paper (which has the required sheet resistance)

Check out the work by Bolomey, et al., with measuring fields with
"modulated scattering probes" (put a small dipole in the field with a
diode in it that you can turn on and off with a DC bias, supplied by
resistive lines)