context: The first actual radar was built by the German Christian Hülsmeyer, who developed what was called a telemobiloscope in the early 20th century. (Patent granted in 1904.) The device was intended for use on ships. It sent an echo signal if there was an obstacle on the ship's collision course. If the receiver received an echo, it rang an alarm bell. The device covered a few kilometers. The radar developed by Hülsmeyer was based on a broadband radio pulse produced by a spark gap, from which the resonant circuit formed by the antenna only passed through the spectrum of the desired band. However, even after the successful demonstration, the telemobiloscope did not convince the shipowners, apparently because the newly invented radio pilot was believed to guarantee the safety of shipping. Hülsmeyer tried unsuccessfully to market his invention to many others and eventually became bitter, never doing anything for the radar again. [2]
question: Who invented the radar?
answers.text: Christian Hülsmeyer