On Wed, 24 Sep 2008 19:25:37 +0100, Graham. wrote:
But a wooden dish?

How about using trees as antennas?

From http://oai.dtic.mil/oai/oai?
verb=getRecord&metadataPrefix=html&identifier=AD08 89658

Abstract : Communications over short ranges through dense wooded or
jungle terrains remains a major problem for our armies today. An approach
to solving this problem is to use a Hybrid Electromagnetic Antenna
Coupler (HEMAC) toroid as a transformer-coupler to excite secondary
radiation from the vegetation. The combination of the electric and
magnetic fields emitted by the toroid are shown to be as effective as a
whip antenna for communicating in the wooded areas adjacent to Fort
Monmouth. Initial experiments comparing a HEMAC toroid to a whip antenna
are discussed. (Author)

And a Scientific American article at
http://www.rexresearch.com/squier/squier.htm

QUOTE

It is not a joke nor a scientific curiosity, this strange discovery of
Gen. George O. Squire, Chief Signal Officer, that trees --- all trees, of
all kinds and all heights, growing anywhere --- are nature's own wireless
towers and antenna combined. The matter first came to his attention in
1904, through the use of trees as grounds for Army buzzer and telegraph
and telephone sets, which, in perfectly dry ground and in a dry season,
functioned poorly or not at all with ordinary grounds. Right then he
began experiments with a view to seeing what possibilities, if any, the
tree had as an aerial. But in 1904 radiotelegraphy was far more
undeveloped than at present, and vacuum amplifying tubes were not thought
of.

UNQUOTE