As a very fast development in Radio astronomy, a subfield of astronomy which studies celestial objects at radio frequencies, radio telescope was invented in a form on directional radio antenna.
In their astronomical role they differ from optical telescopes in that they operate in the radio frequency portion of the electromagnetic spectrum where they can detect and collect data on radio sources.
In 1931, Karl Guthe Jansky, an engineer with Bell Telephone Laboratories, built the first radio antenna which can identify an astronomical radio source. This kind of telescope is basically a very sensitive radio receiver.
Comparing to the communication receivers which are used to extract information and have been intentionally modulated onto the radio wave, radio telescope receivers are designed to measure the intensity of the radio wave over some limited band of frequencies. Therefore, the radio telescope can be seen as an energy measuring device.
The two figures above show the whole system of simple radio telescope. And this is also the system our group used to detect the space.