All I know about this is that during grad school, I had to crawl under a multi-ton supercooled superconducting magnet (an NMR machine) and turn two knobs to mak

All I know about this is that during grad school, I had to crawl under a multi-ton supercooled superconducting magnet (an NMR machine) and turn two knobs to make a number get as small as possible- this was adjusting the impedance of the RF (NMR works by putting a sample in a huge magnetic field and then bombarding it with RF, then switching from transmitter to receiver and detecting the faint echos of energy leaving your system). The magnetic field is so strong you can't have any digital electronics within meters of the NMR- but you can put some impedance matching analog network along with a couple potentiometers and 7-segment displays so a human brain and hands (which are much less affected by magnetism) can reduce radio reflections. RF (and all AC) still seems like spooky magic to me, fortunately I don't deal with signals above 100khz.