Radio astronomy is a fascinating area of technical endeavour and, as this article shows, it is open to people with enquiring minds and some engineering skill. It does not require vast expenditure as much of the equipment can either be home-constructed or obtained from amateur radio outlets.
Some attention to detail is required and patience is needed to assemble and perfect the receiver system to enable the detection of very weak signals with stable gains and a constant low noise background.
Once equipment is in service one can begin by detecting the radiation from the Sun and some planets. Following this, observations can be made of the galactic emissions in the Milky Way. It is interesting to make maps of these emissions.
More exacting measurements can be made of supernova remnants within the galaxy. With amateur equipment it is not possible to map these sources, but detecting them is quite feasible.
Thermal emission nebulae also present a challenge, but again, one within reach of the amateur observer. The best choice is the Orion Nebula.
Pulsars are hard to detect. Only a few amateurs have succeeded using modest sized antennas of around 3m diameter. The configuration of the receiver chain is different from that used to detect steady signals from the sources discussed so far. The pulsed signals mean that integration over a period of time cannot be used as a technique to improve detectability. In the case of pulsars a lot of raw signal is needed - and this means large antennas. The use of purpose designed post detector software algorithms can improve detectability.
Finally, it is possible for an amateur radio astronomer to detect extra-galactic objects. Cygnus A is a very powerful radio source some 600 million light years away and is quite easy to detect. Virgo A, by contrast, is only 53 million light years away but is a much more difficult proposition.
It is hoped that this paper has indicated some of what an amateur observer can achieve and that interested persons will set up a radio telescope - however modest - and explore the fascinating range of radio objects in the sky.
© Dr David Morgan 2011