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Re: Radio Telescope Project-PLEASE Help

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Posted by Kate/">Kate on July 21, 1999 15:55:13 UTC

: : Hello: : : I have a 16-element circularly polarized antenna for 440-460MHZ. I was going to build an interferometer, but someone told me that it was very complicated. I'm still shopping for a receiver. Does anyone know how I can build a basic telescope with which I can do a galaxy survey? Or resources that may be useful? Any help would be VERY much appreciated.

: An interferometer requires multiple antennas, spaced over some distance, which simulates a larger antenna equivalent, in diameter, to the spacing of the fartherest spaced antennas in the array. You not only have the expense of multiple antennas (although, I suppose it could be as few as two antennas) but the antennas must be *very* accurately aimed and driven (unless you fix the antenna's positions and allow the sky to "drift" past the aperature of the antenna). The other major issue is getting the signal from each of the antennas *in the proper phase with one another* (*very* important), detecting the signal and sending the data to some sort of recording device (chart recorder, computer program, etc).

: Such an interferometer is do-able, and can be both fun and a learning experience :>) I built one while in college using four 144MHz yagis spaced over a 30-foot radius...it did work, but the beamwidth (and, therefore the resolution of the telescope) was pretty broad. I could detect gross features but nothing more. Offhand no suggestions for sources of information come to mind, but I will look in my library and see if I can come up with titles. There is, I believe, a company in Florida that sells equipment (including kits) for amateur radio astronomy...I'll see if I can find an address.

: Good luck!

Thanks for the response. Do you think that if I bought one more smaller antenna, mounted them both on stepladders and put the whole thing together to be used as a drift interferometer with the two antennas about 25 feet apart I could get a decent enough resolution to make the endeavor worthwhile? I don't need more than one receiver, do I? As I understand it, I would just have to connect both antennas to one receiver with exactly the same length of coaxial cable on each side of a tee-fitting. How would a voltimeter and a strip-chart recorder work for output? Thanks for any answers you can give.

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