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Re: Idea for more satellites in short time


Well, I think the evolution may be a bit surprising.  Firstly, 3.4 GHz
isn't an international ham allocation so probably very unlikely candidate
for satellite.  Next both 5.6 and 10 GHz are equally easy to get on (there
are several mw vendors that make convertors).  I would say that 10.450 GHz
is more attractive since there is a space allocation there.  Also 10 GHz is
the most rapidly growing mw band above 1296 MHz.  A really attractive mode
would be mode-S/X as one can make a dual-band feed horn and use one dish.
A transmitting convertor for 2.4 GHz in the 1 to  5w range is not terribly
difficult or expensive.

24 GHz is a bit harder to do right now.  Also remember that Doppler is
magnified by operating frequency.  It is really too bad the x-band
transmitter failed on AO-40, as mode-S/X might have been used.  Apparently
this is "history" for now.

A comment to Dan Shultz's observations:  It is true that the unfortunate
failures of the V and U transmitters pressed many folks up onto 2.4 GHz.
The "difficutly" (or lack of) to do this was helped greatly by the
availability of inexpensive surplus convertors that took little work (or
test equipment) to make them usuable.  I doubt that AO-40 would have seen
near the population if only the 24 GHz tranmitter were available.  I do
agree that having working mw satellites does promote getting people onto
those bands.  Many folks (like me) are not near the regional centers of
terrestrial mw activity, so motivation to get on higher freq. is a tough
sell.  Satellite overcomes this issue (someone to talk to).

I do think AO-40 was overly ambitious (I understand the opportunity of the
launch platform and the mindset), but now Amsat should realize that perhaps
less ambitous projects on a more frequent schedule will have greater
overall benefit.  The new reality is what kind of launch capability is
available to us.  I like the idea of making "modular" designs that may be
"packaged" as the opportunity presents itself.  Not having to re-invent
every time has some advantages (especially if the frequency of launches is
not extended over a decade).

Amsat-NA has a new board and lots of recent "experience" to benefit from.
The membership is watching closely the decisions that will be made.

73s, ED - AL7EB

At 12:00 PM 3/1/2004 -0800, Emily Clarke wrote:
>At 02:03 PM 3/1/2004 -0500, Dan Schultz wrote:
>>Most hams will never be on 24 GHz unless we provide them a reason for going
>>there. One of the missions of the amateur satellite program is to provide
>>with good reasons to get on the higher frequency bands. If we fail to do
>>most hams will never have a reason to get on 24 GHz.
>At first glance evolution would seem to be 2.4, then 3.3, 5.6, 10 and then 
>24. The move from 2.4 to 24GHz initially seems fairly substantial though 
>when you think about it, it's probably no more substantial than going from 
>6 meters to 70cm.  My only concerns about 24 GHz would be availability of 
>parts and path loss.  Given the problem people seem to have with 2.4G and 
>trees it would appear to me that at 24GHz your average pine tree would 
>appear to be a Faraday cage.
>W0EEC - CM87tm
>AMSAT Area Coordinator - San Francisco Bay Area
>http://www.projectoscar.net    http://www.PlanetEmily.com 
>Help Launch Echo - http://www.amsat.org/amsat/sats/echo/index.html
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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