----- Original Message -----
From: "Jim Lux" <jimlux@earthlink.net>
To: "K8RI" <K8RI-on-TowerTalk@tm.net>
Cc: <TOWERTALK@contesting.com>
Sent: Monday, September 24, 2007 9:49 AM
Subject: Re: [TowerTalk] Force12
> (There is prior art on adjustable length antennas, by the way.. there's
> a paper from the 60s describing an adjustable vertical for submarines)
Another related implementation was the extendable antenna on the Canadian
"Alouette" Satellite in 1962:
http://www.nrc-cnrc.gc.ca/education/innovations/sti-inno-stem_e.html
This antenna used a S.T.E.M. (Storable Tubular Extendable Member) made by
Spar Aerospace, the Canadian company also responsible for the remote
manipulators aboard the Space Shuttle and ISS. STEMS expanded on the steel
tape-measure concept; the difference was that the tape was wider and curled
completely...overlapping to assume a cylindrical shape when unfurled...to
become an adjustable-length structural (or radiating) member with surprising
stiffness. It's another of those "Why didn't I think of that?" concepts, and
would seem to have been a natural precedent to the SteppIR.
At NASA we used two large double-barrelled STEMS to transfer massive cameras
and film canisters between EVA astronauts on the Skylab program in the early
'70s. Having been involved in that activity, I had assumed that the STEM
concept had triggered the SteppIR design. However, the SteppIR guys, when
queried at Dayton several years ago, claimed no prior knowledge of the STEM
(but were happy to hear the history).
There's surely not any patent issue here; but it's another example of how a
simple idea whose "time has come" sometimes shows up in multiple places and
at multiple times!
Chuck, N4NM
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