[TowerTalk] SteppIR Redux

[Chuck Lewis]

Rick Karlquist challenges:

> Figure out how to make the elements of retractable
> tubing, so when not in use, they collapse down to
> 3 feet (each side) or whatever.  This would reduce
> the 2 element antenna to the size of a TV antenna when not in
> use.  This might be a big advantage for restricted
> QTH's.  The antenna could have an additional "5 meter"
> band setting which would qualify it as a channel 2
> TV antenna for legal purposes.
>
> For ideas, study those retractable car radio antennas.
>
> Rick N6RK
> (4 element SteppIR owner)


A Canadian Company named Spar Aerospace (which later built the 'Canadian
Arm' for Shuttle) did just that years ago. It was called a "Stem" (Storable
Tubular Extendable Member), and was a slick little mechanism available in
several configurations depending on the application. It was used as an
antenna on Canada's Aluette II, one of their early satellites, then later by
NASA for a number of projects including Skylab, where we used it in the
early '70s  for transferring bulky film canisters during EVAs from one end
of Skylab to the EVA hatch. You can read a little blurb on it at:

http://collections.ic.gc.ca/heirloom_series/volume6/70-73.htm
http://collections.ic.gc.ca/heirloom_series/volume5/160-163.htm

The challenges for ham use were many (believe me, I would have LOVED to try
it), including poor bending strength, enormous cost (even assuming Ham
industry quantities, and questionable longevity in a one-G heavy-weather
environment. But it was a no-brainer for one-of-a-kind zero-g use. The Stem
was the first thing that came to mind when I saw the ads for the SteppIR.
In fact, I wouldn't be surprised if it were a source of inspiration for the
SteppIR. Imagine a steel measuring tape with a curl which, when extended,
subtended not just 15-20 degrees, but curled all the way around to the
adjacent edge and overlapped,  creating a tube; then straightened as it
retracted, rolling up on a reel just like my new Stanley PowerLock tape and
(I think) just like the SteppIR.

Today, with more modern materials and manufacturing processes, it might be a
more viable candidate for a self-supporting element, but there would still
be the weather, wind, ice and high-dollar issues. My best guess is that
Fluidmotion considered and rejected that concept in favor of their
shrouded/supported tape. Or it could still be covered by patents.

Anyone wishing to dig a little on the 'net can probably find a wealth of
historical stuff on this little gem...it's another one of those "why didn't
I think of that"...ideas!


Chuck, N4NM