Homemade radio telescope?

[Allenph]

All right, I am a total noob when it comes to radios. I was hoping you guys could supplement my research.

So, when they came and installed my new cable, they just took off the old dish, and left it in the yard. When I called, they said they didn't want it. I had a "great" idea. I remembered using my optical telescope when I was a bit younger, and thought, "Why can't I make a radio telescope from this?!" After a few hours research, I was drowning in information.

So, here is what I know. I know that, for instance, Jupiter sends radio waves out at 15-30 MHz. I know that my dish, was designed for microwaves, in the GHz range. I know my LNB is designed for high frequencies as well. What I need to know is, is there a LNB that I could put on that dish, that could accept 15-30 MHz? I was unable to find one online. Can the dish even be used for that at all? Second of all, is it possible to just take one of those satellite signal meters, and using it to view the frequencies I am revealing? (One coax to power on the meter, the other end of the meter to the LNB.) If so, is there a way to actually record the data, other than writing it down manually?

What other options do I have? Any advice you can give me is MUCH appreciated. Also, I would like to note, that I am not interested in buying a system, that would ruin the challenge. And, I hope I am posting this in the right place!

[nickcarr]

Radio telescope - Wikipedia, the free encyclopedia

Radio telescopes that operate at wavelengths of 3 meters to 30 cm (100 MHz to 1 GHz) are usually well over 100 meters in diameter. Telescopes working at wavelengths shorter than 30 cm (above 1 GHz) range in size from 3 to 90 meters in diameter.

The only true home-made "radio telescopes" involved the older satellite TV dishes that are fairly large. Additional electronic hardware is required to make them sensitive enough to "hear" anything of interest.

Here are a couple of random links:

http://www.arrl.org/files/file/ETP/R...0Telescope.pdf

http://home.comcast.net/~prutchi/ind.../astronomy.htm

[Allenph]

Originally Posted by nickcarr

Radio telescope - Wikipedia, the free encyclopedia

Radio telescopes that operate at wavelengths of 3 meters to 30 cm (100 MHz to 1 GHz) are usually well over 100 meters in diameter. Telescopes working at wavelengths shorter than 30 cm (above 1 GHz) range in size from 3 to 90 meters in diameter.

All right. Thanks. So, now I have two questions. Is there anything I can use that for, and what can I use to listen to low frequencies then? Like an old yagi?

[Allenph]

All right, so I have two questions then. What can I use to get those wavelengths? An old yagi or something? The other, is there any use for the dish then? Haha.

[ka3jjz]

Let's keep this on topic...

I've heard that it is quite possible to hear the radio noise from Jupiter (actually I believe it's around 20 Mhz or so) on a simple dipole, with a very sensitive receiver (and possibly a very quiet preamp). No need for a radio telescope of any kind. You would need to have the planet very high in the sky for this to possibly work. I'm sure that if you google the subject, you'll get lots of answers

If you wish to pursue questions about what an old dish could be used for, you might try asking in our Scanner Antennas forum (and make the subject more relevant than asking about a radio telescope...) - as that question is WAY outside the intent of these forums.

HTH...Mike

[k9rzz]

The OP unfortunately doesn't say how big his dish is. I'm guessing it's 18 inches and not the more useful 7ft to 10ft C band sized. I'm sure there are some folks that can help steer you in the right direction to get this project off the ground ... but not on these forums. Find an astronomy forum that has a radio section. You'll have better luck there!

[zz0468]

Originally Posted by Allenph

What I need to know is, is there a LNB that I could put on that dish, that could accept 15-30 MHz?

Advanced Receiver Research has LNA's for that frequency range suitable for what you want to do. Prices are affordable, too.

Originally Posted by Allenph

Can the dish even be used for that at all?

Not for listening to Jupiter, but it could be used for monitoring solar activity. You could use the dish, unmodified LNB, and by piling a few more parts around it, you could measure the the solar flux at around 12 GHz. When the sun is active, you'd definitely be able to detect flares with it.

Hearing Jovian noise doesn't take much in the way of an antenna. A dipole is quite sufficient. If you're ever spent much time listening to the HF bands, you've probably already heard Jupiter, you just didn't know it.

Originally Posted by Allenph

Second of all, is it possible to just take one of those satellite signal meters, and using it to view the frequencies I am revealing?

Probably not. At least not without a whole lot of additional gain. What you really need is to down convert the IF output of the LNB to a frequency range where you have a decent quality receiver. It could be HF, or VHF, doesn't matter. But you want to have a quality receiver that an agc that can be switched off. Otherwise, it will mask the variations in sun noise.

Originally Posted by Allenph

If so, is there a way to actually record the data, other than writing it down manually?

There are various tools available to use a computer to record data. Some sort of interface would be necessary, as well as appropriate software.

Originally Posted by Allenph

What other options do I have? Any advice you can give me is MUCH appreciated. Also, I would like to note, that I am not interested in buying a system, that would ruin the challenge.

A Google search on amateur radio astronomy will get you a ton of information. What you're wanting to do is not at all far fetched, or out of reach. You may also want to read up on SETI. Even thought that program is specifically looking for intelligent signals, the techniques are essentially identical, so the SETI league is an excellent source of amateur astronomy info.

Originally Posted by Allenph

And, I hope I am posting this in the right place!

Close enough.

[zz0468]

Originally Posted by k9rzz

I'm sure there are some folks that can help steer you in the right direction to get this project off the ground ... but not on these forums.

LOL... I beg your pardon.

[SkyPager]

KA3JJZ is correct a simple radio telescope may be made from a dipole antenna. The local community college just installed one. The attached link to the news story gives some information. They said it was purchased as a kit from NASA. That could mean parts and/or signal processing software & radios etc.

Sound investment: AACC builds radio telescope - CapitalGazette.com: Living

[majoco]

Here's a list of the HF frequencies that are allocated (but not exclusively) for astronomy and the UHF frequencies for detecting the resonant frequencies atoms - you'll need a slightly better LNB than your sat TV provider gave you!..

Significant Radio Astronomy Frequencies