Radio Astronomy Equipment
The Electronics Behind Radio Astronomy
The radio signals that radio astronomers are looking for are so weak that we need sensitive equipment to receive and amplify the tiny signals. The famous astronomer and astrophysicist Carl Sagan said in 1985 that the entire energy detected by all the radio telescopes in the World is less than the energy of a falling snowflake. It is not too difficult mathematically to demonstrate that, at the time this was said, it was probably true.
Professional radio astronomers have been using large dishes to capture radio frequency signals for many years but amateurs can carry out a number of projects that can provide important scientific data without the need for a huge and expensive equipment. There are techniques of carrying out radio astronomy that use both direct and indirect detection methods.
You can do real science using a satellite dish or even a TV aerial with just a few additional electronics. However, there are opportunities for amateurs to use larger dishes for various activities such as studying pulsars remotely. There are links to radio observatories such as Jodrell Bank, ESO and Green Bank in the section on Resources
The basic components of a radio telescope observatory are essentially the same as a conventional radio. An antenna is required to intercept the radio emissions, there must be a means of tuning to a particular frequency, the signal must be amplified so that it is usable by electronic systems, and finally, the resulting signal is converted into a format that is meaningful to humans.
The image below shows a system diagram of a radio telescope, published by Vahid Kouhdaragh from Lancaster University on Researchgate:
Researchgate
Radio telescopes operate at lower frequencies and hence lower energies than conventional radio. A radio telescope dish is parabolic, with a large surface to gather photon energy. The radio signals are focussed onto a receiving horn which is actually a very simple metal tube with a rod to detect the signal.
Electronics are used for filtering unwanted signals and amplifying the desired signals. The antenna is connected to such an amplifier, called a Low Noise Amplifier or LNA. The LNA is positioned very close to the receiver and is usually powered by a small DC voltage that is connected between the Earth and signal of a coax cable. Professional radio telescopes use superconducting components to reduce or elimenate noise.
More powerful amplifiers are needed to boost the signal but due to their power consumption they are positioned further away from the antenna so as not to interfere with the signals. Amateurs radio astronomers now have access to inexpensive Software Defined Radios which amplify and digitise signals ready for processing by software. The output of the amplifier is processed by a computer running appropriate software to display the data in a meaningful format, often as a plot of data points overlaying a map of the sky.
The above describes a typical radio observatory, however in the various sections you will see that amateur radio astronomers also use indirect methods of detection, particularly for solar flare and meteor detection, in which disturbances in the ionosphere are being measured by observing the distortion of a radio signal. Each project in the Project section above describes the equipment in more depth.