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Re: [TowerTalk] Force12

To: "Jim Lux" <>,"K8RI" <>
Subject: Re: [TowerTalk] Force12
From: "Chuck Lewis" <>
Date: Mon, 24 Sep 2007 13:11:14 -0500
List-post: <>
----- Original Message ----- 
From: "Jim Lux" <>
To: "K8RI" <>
Cc: <>
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:

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 
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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