Some maritime TVRO antennas used a mechanical scan at the feed point. A motor would either rotate an attenuator disk or offset the feed in a circular motion. A resolver kept track of the feed location in relation to received signal strength. The antenna was then slewed in the direction of best signal in both AZ and EL. Sort of a poor mans monopulse system. This works OK for antennas in the microwave region but would not work to well for VHF/UHF low gain arrays. What might work well is to use a pair of antennas with a "doppler scan" circuit that steered the rotor toward the estimated direction of the signal.
Howie AB2S _________________________________________________________________ Windows 7: Simplify your PC. Learn more. http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WLM...
Hi, amsat-bb,
With regard to the very interesting subject of Antennas in Space (in general), I hope some of you will be interested to plan to take up a design for a spaceborne antenna, sounds interesting! To help in that process, I was very impressed to read (well, the non-technical bits!) of the DESCANSO book : http://descanso.jpl.nasa.gov/Monograph/series8/Descanso8_00_thru_acronyms.pd...
There are a wealth of information derived from JPL missions that I believe we could take advantage of in the next 20 years of AMSAT design projects.. other books in the series have a lot of information, and who knows - a Mars project might not be that far off if we look at it in a pragmatic way: small payloads will be sent to Mars for validating a lot of the systems before Humans can go, and the Hams + Amsat projects + Space Geeks + Space missions = public support = public funding support formula is hard to ignore... IMHO
So, why not start a individual track on amsat-bb with a prefix [Phase 5] in the subject header, so that others who are not interested, for now, can tune out.
Any ground rules ? Any publications we can get started on that would add to a scholarly discussion on Phase 5 mission planning.
Samudra, N3RDX
On Fri, Oct 23, 2009 at 5:02 PM, Howie DeFelice howied231@hotmail.com wrote:
Some maritime TVRO antennas used a mechanical scan at the feed point. A motor would either rotate an attenuator disk or offset the feed in a circular motion. A resolver kept track of the feed location in relation to received signal strength. The antenna was then slewed in the direction of best signal in both AZ and EL. Sort of a poor mans monopulse system. This works OK for antennas in the microwave region but would not work to well for VHF/UHF low gain arrays. What might work well is to use a pair of antennas with a "doppler scan" circuit that steered the rotor toward the estimated direction of the signal.
Howie AB2S _________________________________________________________________ Windows 7: Simplify your PC. Learn more. http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WLM... _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (2)
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Howie DeFelice -
Samudra Haque