Some ideas ...
 

"John Smith I" wrote in message
...
I have been searching the internet, it seems to me someone would have:

1) Constructed an airtight room, filled it with a gas such as neon and
placed an antenna in such a room. The power/freq to the antenna could be
varied and "patterns" observed in how the rf was exciting the gas into
"glowing" in the visible range while observing any visible patterns in
such.


The gas would ionize, conduct, and severely detune the antenna.

Pete