[Elecraft] Underground Antennas (WAS: Ham Ingenuity)

[Ron D'Eau Claire]

Phil, K2ASP asked:

  I guess that with enough power one can put any antenna underground
  (GWEN) or even underwater (SUBCOMM) but let's not give my wife any
  more ammunition!!

  Has anyone here tried it?

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Oh, yes. Work with subterranean antennas dates back to 1923, at least, in
the Amateur literature. They have also been the subject of various "April's
fools" spoofs that some Hams get the idea that they don't work at all, but
apparently they do with the limitations I described.

It seems that losses go up in direct proportion to the coupling of the
antenna with the earth, so the losses increase as the antenna approaches the
earth and increase with depth in the earth. 

In the 1960's (I think it was, I'm away from my Ham library at the moment)
more experimentation was done on the current HF Ham bands by a US Amateur
with measurements of about 16 dB loss compared to an elevated antenna that
are reported in Hey's book, "Practical Wire Antennas". 

Restricted use of Urban space is not limited to the USA, apparently. A
Russian Ham, Igor Grigorov, RK3ZK, has written a book that also touches on
near-earth and underground antennas. His book, "Urban Antennas" is reviewed
by Cebik at: 
http://www.antennex.com/shack/Nov01/urbanrvw.html

In that review Cebik writes: "Underground antennas, long familiar to those
people who had to operate clandestine radios within occupied regions during
World War II, are attracting professional investigation in the US these
days. Whether in a near-surface location or erected deep within a cave,
underground antennas do work for both short and long distance
communications. No, they will not compete with the long Yagis on towers
reaching the 200' level during a CQ or ARRL DX contest, but that is not
their purpose. They can permit communication of essential information over
various types of propagation paths. Interestingly, it is difficult to get a
bearing on these antennas from any significant distance, thus adding to
their security." 

I may have to add that book to my library <G>.

Ron AC7AC