Poor Man's Radio Telescope

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Introduction: Poor Man's Radio Telescope

About: I like to tinker and I like to learn, and if one can support the other then thats great.

A way to peer into the radiosky using little more then junk found on the side of the road.

Remembering back to my 10th birthday. I recall receiving a book on outer space. I believe it was published by National Geographic. This was by far my most prized book in my somewhat limited collection of the time.

In it there was a rough outline of a radio telescope. This diagram so intrigued me that for years in the back of my mind I dreamed of being able to play with one.

Indeed years have past, careers, children, and everyday life was by far the most important of responsibilities. Then it happened. I spotted a 10 foot satellite dish in someone's trash.. I quickly made off with it and all its components.

The mount was in pretty bad shape. It appears to have some serious wind damage, and the pedals of the dish are in less then what I would consider acceptable shape.

None the less I slapped it all together. In the picture you can see my stinky trashcan mount. It was good for a quick test but boy did it stink.

Step 1: An Examination of the Feed Assembly

Here we see the feed horn and low noise amplifier. All the dish components were hauled to the curb except the actual receiver unit. The bolts holding the wave guide and the amp onto the feed horn had to be purchased. Getting this feed horn back into working order took a little bit of time. It seems that the feed horn assembly was home to a community of wasps. I never realized this before but wasps build there nests to last. It took a good bit of probing and a little 409 to clean it up nice.

This is basically the meat of the system. It takes the focused energy of the dish and downconverts it into a usable signal and then amplifys it.

How is all this powered you might ask? The voltage actually travels down the coax cable that is delivering the signal to the next stage.

The polorizing servo is basically left alone, but for those of you that are curious it's a little motor that turns the antenna inside the feedhorn for better reception.

Step 2: An Examination of the Electronics

Here we see the power supply and a satellite finder meter.

The power supply is home made, 15 volts regulated. I actually picked up the greater quantity of this at a junk store for 3 dollars.Its not as clean as I want it to be but I'm working on it.

The little fat coil hooked up on the right of the power supply is a choke I placed in the voltage path so the signals coming from teh dish do not seep back into the power supply.

The satellite finder meter I just received in the mail a few days ago. It receives from 950-2250Mhz. This is the second most important part of the arrangment. This takes the total power of all the signals that are coming from the dish and converts them into a meter reading. This is known as a Total Power Receiver .

I hooked all this equipment up together and was ready to start.

I passed about 12 volts through it and would get a decent meter readings whenever I swiped my hand in front of the feedhorn assembly. I was convinced that it worked.

Step 3: A Test Run of the Sun

I tried pointing the dish at the sun. As you can see in the picture to the right the meter was pegged. It only did this when the dish was pointing at the sun. I deduced that, "Yes indeed, it was picking up the sun." Note the dB knob turned all the way down. It seems the sun packs a mean punch!

Step 4: I Still See Radio Sunshine on a Cloudy Day

Next a meter reading when some clouds passed in front of the sun. Still a decent amount of signal but definitely not like the unobscured sun reading. Note that I turned the knob up a bit to actually see the signal. The meter shot back up once the clouds were gone.

Step 5: And So...

this isn't an awesome, peer into the unknown type of radio telescope. Right now it only sees the sun. I plan on trying it on the moon and some star systems a little later on.

Believe me there is MUCH room for improvement on this system. But it was good enough to teach me some basics and to strike my curiosity a little further.

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    48 Discussions

    can you produce images with a radio telescope?

    That is a very cool assembly, even if it only sees the sun. Space is always fascinating

    Radio telemetry is defined as sending and receiving; product's that do are each a technology today. For directional antenna (those that aim in a direction) a satellite dish is the antenna; a microwave is what it is designed to receive, of the many different waveform's, or carrier waves, it does this the best; and the bigger it is, the weaker the signal it can pick-up. It will also pick-up sound from a certain direction (bigger the dish, the louder it is) using a microphone as the "feedhorn or radio wave receiver"; it will pick-up (by reflection) any form of light (from visible to invisible) which it can reflect into an opening. The dish pictured can receive over 300 free HDTV channels, legally.

    Any antenna of its size and type also reflects all energies it can aim at; so light from the moon is detected by it just like light from the sun. It also has the ability to receive radar, DBS freq.; and the bigger it is; the more signals it can receive that are weaker; and the smaller the dish is; the less signals it can receive. What they receive depends solely on what type of reception device you focus the dishes reflector on; how good it works is how big the dish is that you aim at what you want to detect. Compare a dish to the energy collected by a cmos device; the dish reflector works exactly like a camera (or telescope); the cmos focuses on the light, then says, or saves every bit of the light as every wavelength it received, making up the entire picture of its "reception" of many colors (wavelengths) and patterns (saved in the defined size of the picture; a square of a certain dimension). The satellite dishes use the round part (circle) focusing of the energy to any pickup device; is a satellites dishes "gain or amplification" of the signal it is aimed at and receiving. If you aim a satellite dish at your neighbors window and have a microphone at the right spot; you will be doing something illegal listening to them; but you can be miles away with a bigger dish and it will still work at where it aims; like at a eagles nest to hear/study their nature!

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    LeeR28

    1 year ago

    This technical Talk is all well n Good ! .. but if your a complete Novis you need guidance .. sending people to other sites to look up info is not exactly helping .. why cant you just lay down the basic components so one can go out and source them ..? is this really too difficult ..?

    I suppose the dog poops are essensial right? Great project.

    Can you help me with the forums. I tried google to find forums where i can ask questions related to radioastronomy projects but i couldnot. I am an begineer in his field and hence want to learn more on the subject

    1 reply

    wow this was a great help to me as i am trying to make a radio telescope with serial connection of 5 dishes located at 50 meters away from each other so as to make a large telescope hope that it works out

    Awesome project ! I'm wondering if I could make one out of a regular dish :)

    ahhhh yes, my RTL dongle is attached to a Raspberry Pi

    easy 1420mhz receiver, a RTL dongle with the R820T chipset. Mount it at the feedhorn. No coax neede just shielded Cat5. Yes they do drift a bit but it is cheap and you can always add a Roman Black crystal heater.

    http://www.gb.nrao.edu/epo/ambassadors/ibtmanualshort.pdf

    I have made similar radio telescopes using satellite TV LNBs, at 4 GHz (C-band) and at 11 GHz (Ku-band). All work well.
    I am confused to read that your C-band radio telescope was sensitive to cloud cover. It should not be, clouds and rain affect only Ku-band.
    Using the Sat Finder is possible but as this device is designed to indicate satellite signals, solar noise response is quite non-linear with the knob setting. I prefer in my designs adding an inline IF amplifier ($4 at MCM Electronics), and I make a detector followed by an opamp, to adjust zero and gain for an analog indicator.
    In addition to solar-noise demonstrations, such simple radio telescopes are interesting remote sensors. One can indicate his/her body temperature, emission of microwaves by walls, vegetation, clouds/rain and fluorescent tubes.

    I did a spit-take on my keyboard when I saw that you labeled the dog crap.

    Just shows my maturity level tonight.

    Anyway, great idea. I have no idea of the electronics involved, but if you ever get some coherent images, i would love to see them.

    Hi zOrb,

    Thankyou for uploading this project. My father-in-law installs dishes and decoders. He's going to love doing this project with me.

    Thankyous to the people who have added comments for this project


    Regards

    is there a way to conect this to s screen to see the shapes of the radio transmitations of extra terrestrial phenomena?
    Ouch
    ...to see the shapes of radio tranmission of other worldly objects....

    You can use this setup for more than seeing the sun. Just plug the raw feed into an oscilloscope and jack up the 21cm bandwidth and you've basically got yourself a high powered radio telescope. Not sure how the LNB is affecting your signal, might want to take that off to get raw analogue goodness.