radar (original) (raw)

Above, Huelsmeyer's "telemobiloscope" on display at the Deutsches Museum in Munich. At left is the antenna, in the middle the receiver, and at right the transmitter. After 90 years (1904) the unit was connected to a battery and it still worked flawlessly. Range is 3000 m. A description in English on how his radar system worked is detailed in his US patent 810,150 dated Jan. 16, 1906. Click patents for a free download.

On the 30th April 1904, Christian Huelsmeyer in Duesseldorf, Germany, applied for a patent for his 'telemobiloscope' which was a transmitter-receiver system for detecting distant metallic objects by means of electrical waves. The telemobiloscope was designed as an anti-collision device for ships and it worked well. His interest in collision prevention arose after observing the grief of a mother whose son was killed when two ships collided. After a period teaching in Bremen, where he had the opportunity of repeating Hertz's experiments, he joined Siemens. In 1902 he moved to Duesseldorf to concentrate on his invention. He became acquainted with a merchant from Cologne, was given 5,000 marks and founded the company 'Telemobiloscop-Gesellschaft Huelsmeyer und Mannheim'. The first public demonstration of his 'telemobiloscope' took place on the 18th May 1904 at the Hohenzollern Bridge, Cologne. As a ship on the river approached, one could hear a bell ringing. The ringing ceased only when the ship changed direction and left the beam of his 'telemobiloscope'. All tests carried out gave positive results. The press and public opinion were very favorable. However, neither the naval authorities nor industry showed interest. In June 1904 he was given the opportunity by the director of a Dutch shipping company to display his equipment at various shipping congresses at Rotterdam. His was detecting ships at ranges up to 3,000 m, and he was planning a new 'telemobiloscope' which would function up to 10,000 m. He received a fourth patent on the 11th November 1904 in England. In 1955, he was honored at a congress in Munich on Weather and Astro-Navigation (Flug-Wetter-und Astro Funkortungs-Tagung). His 'telemobiloscope' operated on a wavelength of 40-50 cm. The transmitter used a Righi-type spark gap (part of which was immersed in oil) from an induction coil. The radiated pulses were beamed by a funnel-shaped reflector and tube which could be pointed in any desired direction. The receiver used a coherer detector and a separate vertical antenna, which, because of a semi-cylindrical movable screen, was also directional. Basically, the apparatus was designed to detect the presence of an object in a particular direction. The question of determining distance was later solved, by a modification which aimed at beaming the radiation at any desired angle of elevation. Knowledge of the height of one's own transmitting antenna above the surface of the water and of the angle of vertical elevation at which an object was detected would, by simple calculation, give the range of the object. Perhaps the most ingenious aspect of the inventor's later apparatus was his awareness that the equipment might respond to other than its own transmissions and his safeguarding against it by a time limiting electromechanical mechanism. The receiver responded to a first transmission's signal only if, after a predetermined interval, it received the signal from a second transmission.
Some claims are made that Heulsmeyer had built a second set, a much larger demonstration unit which he is supposed to have build in two month and is claimed did not work! There is no support for this claim. His unit worked and it was in competion with the Marconi spark transmitters. The Marconi Wireless Company had the control of the Navel communication industry in those days and would not tolerate any competition.