radio telescope

A radio telescope is an instrument designed to sense radio electromagnetic radiation at a distance, analogous to an "ordinary" telescope's ability to sense visible light at a distance. Many are reflector telescopes with a dish-shaped reflector directing radio waves to a small antenna that produces a corresponding oscillating electronic signal which can be recorded and analyzed. Radio astronomy, dealing with radio telescopes, radio sources, and methods and results of radio observations has become a major portion of astronomy. Example radio telescopes:

• Green Bank Telescope (GBT)
• Arecibo Observatory (NAIC)
• IRAM 30m Telescope
• Parkes Observatory

The Atacama Large Millimeter Array (ALMA) uses radio-telescope techniques to view a wavelength-range that spans the border between radio and infrared (1 mm is the border generally used regarding astronomy), a regime termed millimeter waves, or submillimeter astronomy waves, or millimeter/submillimeter waves.