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Re: SUISAT forensics...



I have been reading the Suitsat Forensics comments which many have been
posted since my analysis early this morning (in Alaska).  I have just
returned home from work so just catching up on my e-mail.

Looking at the photos in Bauer's article, it appears the antenna is a whip
which uses a BNC-male connector and also has a ground-plane (counter-poise)
attached between the antenna connector and an adaptor or the radio (unclear
from photos).  They appear to be embedded in plastic (or mylar) for
flexibility and insulation.  One could also describe this as a centerfed
dipole, though the antenna appears longer than the counter-poise.

There has been a bit of conjecture why there is periodic and deep fading.
The suit probably is made from a metallic material and that shields the
antenna from earth at points in the Suitsat's rotation (tumbling).
Radiation pattern might be slightly directed above and away from the
helmet, as well.  I think this is adequate to produce the fading effects.

I believe there is evidence to support that the battery is operating
normally (with telemetry=24v now received).  Also, I suspect the radio and
recorder are functional as a signal is being modulated on frequency.
Therefore, the weakness of signal received on earth would point to a fault
occurring in the feedline or antenna.

73's Ed - KL7UW
I have seen high failure rates in commercial HT radios at the antenna
support or base (hairline cracks) that reduce 5w radios to mw levels of
output.  Several of you have run calculations using my signal report and
station parameters that all point to 1-2mw as the apparent effective
radiated power being transmitted by Suitsat.  Signal at this level are
detectable by large VHF stations using sensitive LNA's over direct LOS
paths (which exits with Suitsat).

We can only conjecture at this point since little more engineering data is
available.  Continued monitoring of the signal to determine its life term
will add a little more evidence.

Hopefully, Suitsat-2 will be fabricated and lessons learned incorporated.
This it exactly in the normal evolution of space exploration that we
try-try again.

73's Ed - KL7UW

At 08:07 PM 2/8/2006 -0500, A.J. Farmer (AJ3U) wrote:
>Hello,
>
>Details of the construction can be found here:
>
>http://www.amsat.org/amsat-new/articles/BauerSuitsat/index.php
>
>To answer your main question, the antenna is exterior, mounted on top
>of the helmet.
>
>A.J.
>
>On 2/8/06, Joe Leikhim <rhyolite@nettally.com> wrote:
>> Is the antenna for Suitsat exterior to the space suit or is it mounted
inside? Is the Orlan spacesuit metallized for blocking radiation and/or
retaining body heat? What is the antenna type? A 1/2 wave dipole or a
"rubber duck"? These could be explanations for the apparently low ERP.
>
>--
>A.J. Farmer, AJ3U
>SuitSat Audio Files Available at: http://www.aj3u.com
>----
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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