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Re: 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
 
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