[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: AMSAT-BB On phased arrays with azimuth and elevation beam forming



Hey Bob...

I don't suppose that old ATS-1 repeater can somehow be reprogrammed or
retuned to operate in the amateur two meter band?  -s-  It would sure be a
hoot to have a quasi-geosynchronous FM repeater!

Well, we can dream, right!

Frank
wb2bxo@amsat.org


> Date: Tue, 29 Aug 2000 12:18:26 -0700
> From: Bob Nielsen <nielsen@oz.net>
> Subject: Re: [amsat-bb] On phased arrays with azimuth and elevation beam
forming
>
> The number of bits required is a function of the beamwidth, which is a
> function of the length and width of the array, so it is hard to
> generalize.
>
> Actually the satellite system I was describing used analog phase
> shifters with one varactor for each transmitter and receiver (there
> were 8 each, one per dipole).  The drive waveforms were somewhat
> complex as I recall.  I no longer have any of the documentation,
> unfortunately and the details have faded a bit with time....
>
> I recall there was an article about the system in QST by KH6IJ, who was
> involved in some educational applications using ATS-1 and/or 3 (ATS-3
> had a system similar to ATS-1, but used a linear translator).
>
> The last I heard (several years ago), ATS-1's repeater system was still
> functional and had occasionally been turned on for testing (the array
> defaults to omnidirectional in the absence of a de-spin signal).  The
> satellite had long before lost all its fuel and was drifting quite a
> bit.
>
> Bob
>
> On Tue, Aug 29, 2000 at 02:45:07PM -0400, Bob Bruninga wrote:
> > Bob Nielsen wrote.... about ... phased arrays to create a steerable
"beam"
> >
> > > It could be done at VHF with L-C phase shifters using varactors as
> > > variable capacitors.
> >
> > Wow, I would love to see the analysis and background in an article!
Would
> > 3 bits of precision be sufficient? (3 varactors)  That would give +/-
> > phase increments of say 22 degrees between +/- 45 deg?
> >
> > Can I assume that +/- 90 deg would give you a beam spread of +/- 45 deg?
> > I guess then that for my roof pointed south, I would need +/- 180 phase
> > shifts to get from Moon rise to moon set?  Probably would take 4 bits of
> > precision?
>
> - --
> Bob Nielsen, N7XY                          nielsen@oz.net
> Bainbridge Island, WA                      http://www.oz.net/~nielsen
>
> - ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
> ------------------------------
>


----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home