6
Quick Review of the Itty Bitty Radio Telescope
Discuss this article in our forums
Quick Review of the Itty Bitty Radio Telescope
 |
 |
Figure 1 - View of full IBT setup in local park. |
Figure 2 - Close up view with labels for major components. |
The Itty Bitty Radio Telescope (hereafter, IBT) is a simple DIY device that can be used to detect radio waves from the Sun. It primarily consists of a satellite dish, a signal meter, a power source and a mount (often a lazy susan rig). In my case, I purchased an 18” dish off of Craig’s List, the signal meter was obtained via eBay and the remaining items were sourced at Amazon and local hardware stores. Excellent instructions with parts lists are available from several sources including:
2. IBT Instructions at Setileague
3. Alternative IBT Instructions at NRAO
The Society of Amateur Radio Astronomers sells a parts kit that includes most items for a price of $89 (not including the dish). The link is found here: SARA IBT Kit.
Some slight variety exists in terms of how to build the IBT, though the basic template remains the same in the various sources shown above. As with most DIY projects, I made a few tweaks with my setup including the use of a battery pack with an on/off switch (Battery Pack with ON/Off Switch), which is quite convenient.
Some of the items will vary in price (e.g. satellite dish) but my general opinion is that the finished product can be completed for less than $250 in about 2-4 hours once all items are assembled. For me, the greatest challenge was constructing the lazy susan for which I consulted a number of YouTube videos.
The operation of the device is quite simple. The dish is aimed toward the Sun and when an exact alignment between the dish and the Sun occurs the meter gives forth a noticeable change in volume and pitch. (The focus point for my dish is labeled in Figure 2 above.) If the IBT is mounted on a lazy susan, it is easy to simply rotate the device back and forth in a manner that brings it in and out of focus and thereby varying the volume and pitch of the meter. An excellent YouTube video is found at this link: Photonic Radio Astronomy .
Concerning public outreach, I was happily surprised to see the interest expressed by people in the IBT at a recent event. At the event we had the typical white light filtered and H-alpha scopes, which are common tools at solar observing sessions. In addition, I decided to bring along my newly constructed IBT. In the end, I think the IBT was the biggest hit. Folks liked to watch the shadow of the LNB (see Figure 2) cross the centerline of the dish and to listen to the corresponding change in pitch of the meter. One participant even said it was a more interesting instrument than the optical scopes!
In summary, if you are looking for some variety in your daytime solar observing options, the IBT is a good bet.
Author BIO: Michael J. Caba lives in Central Oregon and has been an observer on and off for over 50 years. Counting the IBT, he owns five scopes. He doesn’t have any real biases, except a preference for Tele Vue eyepieces over all others.
- KeithC, Jaimo!, careysub and 15 others like this
24 Comments
Here is a site that explains the whats and whys about what is being detected:
https://physicsopenl...radio-emission/
This detects at 12,200 to 12,700 MHz and it is the solar black body radiation at 6000K, enhanced a bit (probably by the high temperature corona).
It is acting as a microwave thermometer, detecting the Sun's heat. But this is not fundamentally different from when we look at the Sun through solar filters -- we are observing the Sun's thermal emissions in the visible band.
Thanks for the additional info. Do you have one?
No, but this might enter my queue for a club outreach device.
seen one demonstrated
very interesting
Yes, it works great for outreach! It's very simple, so as a day to day tool for an amateur astronomer its kind of a 1 trick pony, i.e, once you have done it a few times you have seen all it has to offer. But the 1 trick is really good for outreach. Highly recommended.
Do you have any quick visual of what you've graphed out with any quick blurbs on what some specific, significant detections mean?
In terms of space objects, it only detects the Sun. Probably the best visual out there is at this link: https://www.youtube....h?v=jyAgRg9EJGU
Thanks. I learned quite a bit from reading this review and then looking up a bit more about amateur radio-astronomy. Turns out you can go a bit further and not for a lot of extra cost. You do need more yard area to strategically position a couple of dipole antennas and then you can check up on how Jupiter is doing in addition to the Sun. (Just more stuff to mow around though.
)
The NASA Radio Jove Project home is: https://radiojove.gsfc.nasa.gov
and the basic DIY Radio Jove kit is $220 + shipping. The DIYer has to supply his own four mounting poles and guy wires for the ends of the two dipoles and their height could go up to 20ft depending on your latitude and the rest depends on Jupiter's declination and elevation.
You might be able to pick up the Moon too. (Particularly interesting because you are actually detecting the thermal radiation from the Moon, not the reflected radiation from the sun). Here is my version with a slightly bigger dish
http://www.threehill...astronomy_1.htm
Cheers
Robin
Interesting. I did not know that about the Moon. I will have to try that some night.
I wonder what software is used to construct images out of the readings taken?
The radio telescope is like a one pixel camera. A picture is built up by taking a series of scans and plotting out the intensity.
Also If you look at a particular frequency eg neutral Hydrogen you can use the doppler shifts eg to map out the arms in the milky way which are moving at different velocities relative to us
Here is an example of nice little project to map the milky way.
http://parac.eu/projectmk3.htm
Cheers
Robin
This is a lot like one the SETI League brought to a SF Convention maybe 20-30 years ago. They claimed it was inspired by a small fusion reactor I had brought to an earlier con. They demonstrated that it could detect body heat. However, the dish was too small to detect SETI signals well. They recommended a 12-ft satellite dish for that. Their system was based on a nice digitally-controlled ICOM microwave receiver that could be set up to scan a band in the microwave spectrum, essentially making a spectrum analyzer. The SETI League is an amateur group, not to be confused with the SETI Institute. I believe their designs for their SETI-specific radiotelescope are on-line. The 12-ft dish is intended to be capable of detecting the "WOW!" event. https://en.wikipedia...iki/Wow!_signal
The SETI League SF Convention one was specifically a public outreach device, and it got a lot of attention.
Facebook friend Mike Geogiopolis spent a career working with NASA gadgets, and appears to have an especially nice homebrew radio telescope in the works.
Ah, here it is.
Stealing an idea from Tom Ligon (see the last two Images of the Week), SETI League executive director H. Paul Shuch set up a simple demonstration radio telescope at the Arisia science fiction convention in Boston the second weekend of January. This device, based upon a Ku-band Direct Broadcast Satellite antenna and low-noise block downconverter, is capable of detecting only the very strongest astrophysical sources. Nevertheless, its presence in the exhibit hall drew in the crowds for Paul's SETI talk.
20 March 1999
In a page of "pictures of the week", 1999. Also in there are many mentions of their more serious amateur SETI observatories. http://www.setileagu...tos/pixwk99.htm
Interesting. Thanks for sharing.
Many thanks. I translated and forwarded your post to Facebook Turkish Amateur Astronomy group (with 22k members).
You are welcome!
My daughter, her friends in high school, and I built a horn antenna that can detect 21cm Hydrogen line following these 2 articles. The first paper is brief but you get idea what the project looks like and the second one has everything you need to complete the project. The second paper is the courtesy from SARA (Society of Amateur Radio Astronomers).
https://lweb.cfa.har...SposterPDF2.pdf
https://www.radio-as...al-Feb-2019.pdf
Great stuff! The Scope in a Box by SARA can also detect the 21cm hydrogen line.
The price tag of this is mostly beyond most of people can afford.
I think the price for the Scope in a Box is $350 at this link:
https://www.radio-as.../scope-in-a-box
The tripod in that kit is pretty flimsy, so an upgrade to something else will add to the cost. I upgraded to an Explore Scientific Twilight I, which sells new for $350. So going that route, the price jumps to $700. Nonetheless, the setup with the upgraded mount works very well, is sturdy and the antenna itself is easy to point. Hope that helps.
Can you please show me the formula to convert 12,200 to 12,700 MHz to 6000K? Thank you.
It sounds like what you are looking for is Planck's law. Every body at any temperature emits photons at every possible frequency, just in varying amounts. The peak of emission is given by Wien's displacement law, and for bodies at 6000 K apparent temperature (like the Sun) that frequency is in green light -- where the human eye is most sensitive. This is not a coincidence. As shown in the chart on the Open Physics site the Sun is about a million times dimmer at 12.5 GHZ.
The radiotelescope would actually be more interesting if it operated at 0.1 to 1 GHZ because solar emissions in this band vary enormously with the solar cycle.
https://en.wikipedia...ki/Planck's_law
https://en.wikipedia...isplacement_law
Thank you. I think I got it.