Radio telescope
A radio telescope was a device that used radio waves to observe the heavens. It was far more powerful than an optical telescope.
The radio telescope was officially invented in 1951. However, in 1911 Dr. Laurence Scarman invented a primitive form of this device, which he called a Marconiscope, which intercepted a signal from Mars.
The Fourth Doctor carried a pocket-sized radio telescope, which he used to detect and decode the signal when the Marconiscope was damaged. (TV: Pyramids of Mars)
In 1968, a radio telescope was built near Crook Marsham on the site where the Sentience was dormant. (PROSE: Nightshade)
In the 1970s, the Master attempted to use a radio telescope at Beacon Hill Research Establishment to transport his allies, the Nestene, to Earth as part of his plan to conquer that planet. (TV: Terror of the Autons)
A few years later, Dr. Louis French, a radio telescope director in Australia, developed and tested a radio wave accelerator in the hopes of making instantaneous contact with other planets. Instead, his device disrupted Earth's atmosphere, creating huge storms around the world, and devastated the planet Morrax. (COMIC: Is Anyone There?)
In 1981, the Fourth Doctor and the Tremas Master worked together to use the Pharos Project to reopen the CVEs and save the universe from entropy. (TV: Logopolis)
A former Cold War listening station in the English village of Goblin's Copse was repurposed into a radio telescope after the war's end. In 2009, it was used by the Tycho Project in their search for alien life, under the direction of Professor Nicholas Skinner. (TV: The Last Sontaran)