My knowledge and experience with amateur radio astronomy is very limited. Although I do have a background in electrical engineering with a special interest in electromagnetic radiation, I don't yet have any significant experience with astronomical observing at radio frequencies. It is my hope to change this situation. This web page is the first step.
Optical observers also see the universe using electromagnetic radiation. The only difference between optical and radio observing is the frequency of the radiation used to make the observations. Visible light has a frequency that ranges from about 4.3 x 1014 Hz to 7.5 x 1014 Hz. This is a fairly narrow range of frequencies -- less than one octave. Yet the universe produces radiation over a range of frequencies that spans many orders of magnitude. There are many wonderful sights to behold in the sky that are quite invisible to our eyes!
As we turn down the frequency dial of a hypothetical "super" receiver, we would first go from visible light to infrared light. Although the boundary between infrared light and high radio frequencies is fuzzy, I think it's reasonable to say that infrared light goes all the way down to approximately 3.0 x 10 12 Hz (100 micron wavelength). This is 3 THz or 3000 GHz. Below that frequency we enter the domain of millimeter waves. Microwave frequencies kick in around 100 GHz and extend all the way down to, say, 1 GHz. Below 1 GHz we are strictly in the domain of "radio" frequencies. However when I talk about radio observing in this document, I mean (at least potentially) observing at any frequency below infrared frequencies. That is, I mean any frequency below 3000 GHz.
Since our eyes are not sensitive to radiation outside their limited range, we can not directly observe the sky using radio frequencies. Instead we have to rely on electronic (and possibly expensive) equipment to convert the radio information to a form that we can accept: sound, charts, graphic display, etc. This is not really very different than what goes on today among optical observers. Many serious observers rely on CCD devices and computers to collect and process optical information. Many optical observers are also looking at their results on a computer screen!
When one thinks about radio astronomy one usually thinks about large, impressive radio telescopes and expensive, high speed computers. In general it does not sound like something an amateur could get into. I believe that is incorrect. The purpose of this page is to show how an interested amateur, using reasonably modest equipment, can do some exciting radio astronomy. As I write this, I don't know the details of how this will work either. However, it is my hope to figure that out as I go along.
I am one of the advisors to the Astronomy Club at Vermont Technical College. This page is linked into the VTC Astronomy Club page. While amateur radio astronomy is something that interests me personally, it is also something that I'm doing in connection with the VTC Astronomy Club.
To make useful radio observations, there are several issues that must be considered.
It is possible to make interesting observations of meteor showers using a standard FM receiver (88 MHz to 108 MHz range). Since this doesn't require any special equipment it seems like a good way to get started with amateur radio astronomy. Check out the Observing Meteors by Radio page for more information on the theory and technique involved.
Observing meteors by radio requires that you point your FM antenna toward a distance station that you don't normally receive. Locate a frequency that is clear on your dial. What stations use that frequency? Consult the FCC's FM Radio Database Query Program to find out!
There are quite a few pages on the web pertaining to amateur radio astronomy. I direct you particularly to the home page of the Society of Amateur Radio Astronomers (SARA). As you might expect, this site contains quite a bit of information about amateur radio astronomy. SARA's page "Interesting Web Sites for Radio Astronomy Enthusiasts" contains numerous links to other sites of interest. Many amateur radio astronomers have put up web pages detailing the design of their telescopes. Check them out!
Return to the Amateur Astronomer's Notebook.