A basic radio telescope has the following attributes:
- A sensitive radio which can receive one of the frequency identified for radio astronomy
- The radio has "No" AGC (automatic gain control) or has the ability to turn it off.
- It uses a high gain low noise pre-amp and a directional antenna which can be pointed at the sky.
- A Data Logger is used to record total signal strength of the radio over a period of time
The signal strength of the radio is recorded over a period of time, signal levels will increase and decrease as a radio emitting object passes across the sky. Over number of days it is possible isolate radio astronomical observations from terrestrial and satellite interference.
Of cause everything is always a little more complicated. But it is possible and there are many examples of success to be found on the internet. The most famous of these is the NASA RadioJove Projects.