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Akyra

DIY Radio Telescope?

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Do mirror's reflect radio waves? If they do, could we not convert our scopes into radio scopes with the use of a microphone placed at the point in the focuser where light comes to focus?

Radio waves can penetrate through clouds can they not? So those with GOTO would be able to collect data regardless of weather - permitting it isnt raining of course! Which means they could also gather information about objects lost in the suns light during the daytime, like mercury for example.

Am I just talking s**t again or is this possible?

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It depends what you make the mirror out of. If you're looking at radio waves then the mirror will have to be made of a much thicker metal, because the thickness of the metal has to be comparable to the wavelength of the radiation. That's actually how satellite dishes work. They're basically a big curved mirror that concentrates all of the microwaves coming down from the satellite. They're often full of holes to keep the weight down, and this doesn't matter because the wavelength of the waves is larger than the holes. This is the same principle as seeing a light on in your microwave. You can see the light escaping through the door but the microwaves aren't escaping becuase they're too long. Once you get beyond visible light into the shorter wavelengths; ultraviolet light is easy to make mirrors for, but x-rays are very difficult. And so making x-ray telescopes is very difficult. Sometimes they do it by using a bag of gas to act like a lens rather than mirrors. Mobile phone waves are at the microwave end of radio waves, and a sheet of aluminium would work nicely as a mirror for those.

Hope this helps :D

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But surely the coating on the mirror is metal (usualy some alloy of aluminium)

so twhat i would have thoughthis must reflect some of the radio spectrum

so its just a matter of finding out what part of the radio spectrum is reflected

and positioning the correct reciever in the right place

at least thats what i would have thought

mike

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Many electronic experimenters have built their own radio telescopes. In fact, the world's second radio telescope was built by an amateur radio operator, Grote Reber, in 1937. Amateurs use a variety of equipment, sometimes modified satellite receivers and dishes, to build their radio telescopes. For more detailed information about amateur radio telescopes, contact the Society of Amateur Radio Astronomers.

http://www.radio-astronomy.org/

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It depends what you make the mirror out of. If you're looking at radio waves then the mirror will have to be made of a much thicker metal, because the thickness of the metal has to be comparable to the wavelength of the radiation. That's actually how satellite dishes work. They're basically a big curved mirror that concentrates all of the microwaves coming down from the satellite. They're often full of holes to keep the weight down, and this doesn't matter because the wavelength of the waves is larger than the holes. This is the same principle as seeing a light on in your microwave. You can see the light escaping through the door but the microwaves aren't escaping becuase they're too long. Once you get beyond visible light into the shorter wavelengths; ultraviolet light is easy to make mirrors for, but x-rays are very difficult. And so making x-ray telescopes is very difficult. Sometimes they do it by using a bag of gas to act like a lens rather than mirrors. Mobile phone waves are at the microwave end of radio waves, and a sheet of aluminium would work nicely as a mirror for those.

Hope this helps :D

Sorry, got to disagree with you there, the thickness has got nought to do with it, only the surface of a solid reflector, the diameter of the holes in the mesh, has to do with the wavelength, ( frequency ) of the spectrum you wish to observe. Dipole arrays can be used successfully, as at the Cambridge University array, and the frequency can be in the HF range, i.e. between 3 to 30 MHz, a lot of info can be heard (observed) at about the 27 - 29 MHz band. radio astronomy has a very large part of the electromagnetic spectrum to be explored, compared to what our very inefficient eyes can see, but our ears cannot quite impart the same detail. To interpet this part of astronomy, you need a to be be more inventive. really could be great fun to explore and learn. Your last statement that aluminium would work for mobile phones, is true as it is for long waves, i.e. 300 KHzs as it is for the mirror in our reflectors, after all they are coated in aluminium!!

This opens up a whole new can of worms, but one worth looking at.

Do mirror's reflect radio waves? If they do, could we not convert our scopes into radio scopes with the use of a microphone placed at the point in the focuser where light comes to focus?

Radio waves can penetrate through clouds can they not? So those with GOTO would be able to collect data regardless of weather - permitting it isnt raining of course! Which means they could also gather information about objects lost in the suns light during the daytime, like mercury for example.

Am I just talking s**t again or is this possible?

Also a microphone to pick up radio signals????? How about using an aerial to pick up sound. Sorry just will not work. Also light comes to a different point of focus compared to radio waves, true, a parabolic reflector will reflect all wave lenghts to the same point of focus, but nought is perfect in this world, So why not use a refractor to focus radio waves??? Otherwise all telescopes would be APO's with full Sky Digital reception, and make you a cup of tea coffee. ( They all work with electromagnetic radition, but can you make the quantum leap and combine them??)

The Sun being a massive generator of radio energy, inert generators such as Mercury, would like looking at a broken light bulb against the Wembly stadium floodlights!! Non existant.

naz

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So, joking aside, is there a way to do this for a relatively modest sum? Lets say a couple of hundred UK notes to start the ball rolling. Less would be good and a lot less would be a lot better. :D

A dipole aerial I understand to be a long wire cut in half with the two halves connected to the receiver box. The dipole length is related to the wavelength of the signal that is intended to be picked up. Just a couple of pounds/dollars/euros there then. Next up is the "black box" that the TV aerial style coax connects to. Here I have no idea what it needs to do, other than magically decode the signal into something else. I'm expecting a cat's whisker and Leyden jar come into play but it's been a while.

Next up we need to convert this into computerese so that we can use some kind of software to convert the squawks and whistles into pictures. Black and white will do for now, but colour later would be nice.

Anybody know if the dishes that came out of the golfballs on Fylingdales Moor might be in a skip round the back?

Kaptain Klevtsov

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So, joking aside, is there a way to do this for a relatively modest sum? Lets say a couple of hundred UK notes to start the ball rolling. Less would be good and a lot less would be a lot better. :D

A dipole aerial I understand to be a long wire cut in half with the two halves connected to the receiver box. The dipole length is related to the wavelength of the signal that is intended to be picked up. Just a couple of pounds/dollars/euros there then. Next up is the "black box" that the TV aerial style coax connects to. Here I have no idea what it needs to do, other than magically decode the signal into something else. I'm expecting a cat's whisker and Leyden jar come into play but it's been a while.

Next up we need to convert this into computerese so that we can use some kind of software to convert the squawks and whistles into pictures. Black and white will do for now, but colour later would be nice.

Anybody know if the dishes that came out of the golfballs on Fylingdales Moor might be in a skip round the back?

Kaptain Klevtsov

Well the software I imagine would be some kind of spectral analasys software. What could happen would be that you gather the 'sound' from the scope and record it into your PC as if you was recording your own voice/converting vinyl to MP3 etc etc, then run the recording through the spectral analasys software and the results should show a visual representation of what was picked up. I doubt you could do this in realtime without spending some proper cash.

The Aphex Twin (musician) made a track that sounded like a load of bleeps and squawks and when you ran it through some SA software, it turned out to be his face!

Tony..

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This is a project that I've been looking at for quite a while..

http://radiojove.gsfc.nasa.gov/

I have the room for a long dipole and luckily have the skills to build a

receiver rather than buy one but if you have to buy the kit, it's not

too expensive for what you get...

You need to dig deep into the website to find everything but I reckon

it's a viable project for the to do list :D

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Most of my concerns were answered by various ppl here-namely Microphone, thickness etc. A proper parabola is less dependant on material as it is on size. The radio range has wavelengths in the meters or tens of meters and require an antenna of comparable size. A dipole for any given frequency is "tuned" to recieve an even fraction or harmonic of that frequency. This is why radio telescopes are so big, they need to tune something that's maybe 20 meters wavelength as compared to visible light at nanometers wavelength.

Many amateur radio astronomers have success with a simple Yagi type antenna. The spectrum analysis software at the "business end" is usually cost efficient, as I recall. Some googling "Yagi" and "Amateur radio astronomy" I'm sure will lead you in many different ways to spend your cash. :D

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If anyone is a member, i believe the BAA are developing a radio telescope.

Not sure how its coming along though. Will try to find out

cheers

AT

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Try my little one below. Its quick and easy to make. Costs is very low, and you can make it at home with very few tools. It's not flash or anything, but its enough to get you started. The hoop type antenna with reflecting mesh is good fun, but the simple straight wire dipole antenna is easy and very effective.

Baz.

http://www.aussiepeople.com.au/asignobservatory/Radioastronomy.aspx

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jupitervisradio.jpg

Thats cool, nice one mate. But what exactly has been recorded by the radio-scope in the top image?

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I see the planet in the middle, the reflection of radio waves off the thin ring system and the magnetic field of Jupiter. What do you see? 8)

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Does anyone still have the info contained in that link its gone down, I would love to have a bash at this. I have an old satellite dish could I do something with that?

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You know i wondered where i learned about the wire mesh in a microwave preventing us from being fried when we cooked anything came from. It was this thread!

You know Guys, FYI, i understand the British Astronomical Association have been working on a radio telescope which amateurs like is can use.

Last i heard they were creating one which worked from a serial port on a computer, a little fool hardy IMHO as few computers are made with such ports now. However knowing them i am sure they have planned this.

The Radio Astronomy Group, or RAG as its often called is run by Lawrence Newell. i believe they can be contacted here British Astronomical Association - Radio Astronomy Group

The problem you will all have with this kind of work is as with LP there is Also RP (radio pollution) another reason why the governement is investing less money in the Jodrell Dish project.

All manner to electical items will interfere with your project, TV's Radio's, pretty much anything that is electical.

The extend to which i am unsure of (i recall this from a meeting of the RAG group some time ago)

Then that said there was a way of shielding the instruments as well :-)

HTH

Al

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