measuring EM field

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Laurence Davis by way of Terry Fritz <twftesla-at-qwest-dot-net>" <meknar-at-hotmail-dot-com>

Would it be possible to map the EM field from a tesla system
using interferrometry? (sp) Essentially a transmitter / receiver
with a narrow focused RF signal of known frequency and amplitude
aimed through the field you are inspecting. Compare values to determine
field intensity.  I had a lab where microwaves were focused, so I assume
with a little math that a collimated microwave 'beam' would be possible.
however, I would expect that trying to use microwaves to map 200khz 
transmissions would be difficult to see any interferrence. Since the energy 
levels are a magnitude different. And trying to
focus 200khz or near that would be difficult, quarter wavelength being 
1000ft or so. I would expect that attempting to focus that energy, the
lens would need to be at least 1/4 wavelength.

I wonder if I could con the physics lab guy to let me test this.
hmmm...

any of this sound remotely feasible?
larry.