Seetakt radar The shipborne Seetakt radar was developed in the 1930s and was used by the German Navy during World War II . Development . In Germany during the late 1920s , Hans Hollmann began working in the field of microwaves , which were to later become the basis of almost all radar systems . In 1935 he published " Physics and Technique of Ultrashort Waves " , which was picked up by researchers around the world . At the time he had been most interested in their use for communications , but he and his partner Hans - Karl von Willisen had also worked on radar - like systems . In 1928 Hollmann , von Willisen and Paul - Günther Erbslöh started a company called GEMA . In the autumn of 1934 , GEMA built the first commercial radar system for detecting ships , similar to a system developed by Christian Hülsmeyer . Operating in the 50 cm range it could detect ships up to 10 km away . This early version of the system only provided a warning that a ship was in the general vicinity of the direction the antenna was pointed , it did not provide accurate direction or any sort of range information . The purpose was to provide an anti - collision system at night , in fog , and other times of limited visibility . By order of the German navy , in the summer of 1935 they developed a pulse radar with which they could spot the cruiser " Königsberg " at a distance of 8 km , with an accuracy of up to 50 m , enough for gun - laying . The same system could also detect an aircraft at 500 m altitude at a distance of 28 km . The military implications were not lost this time around , and construction of land and sea - based versions took place as " Freya radar " and " Seetakt " . The navy ' s priority at that time was ranging . Detecting targets and obstacles by night or in bad weather were secondary objectives . Actually using it for gun laying , like the Würzburg radar developed for the German army , was initially not a priority for the " Kriegsmarine " . The two systems were generally similar , although the early Seetakt systems worked on a 50 cm wavelength ( 600 MHz ) , while Freya was designed for much longer ranges and used a 2 . 5 m wavelength that could be generated at high power using existing electronics . These early systems proved problematic , and a new version using improved electronics at 60 cm wavelength ( 500 MHz ) was introduced . Four units were ordered and installed on the " Königsberg " , " Admiral Graf Spee " and two large torpedo boat s ( which in German service were the size of small destroyers ) . The " Admiral Graf Spee " used this unit successfully against shipping in the Atlantic . In Dec . 1939 , after heavy fighting during the Battle of the River Plate , the " Admiral Graf Spee " was severely damaged and the captain scuttled the ship in the neutral harbor off Montevideo , Uruguay . The ship sank in shallow water such that its radar antenna was still visible . These early - model Seetakt systems were followed in 1939 by a modified version known as " Dete 1 " , operating between 71 and 81 . 5 cm wavelength ( 368 to 390 MHz ) at 8 kW peak and a pulse repetition frequency of 500 Hz . Maximum range against a ship - sized target at sea was up to on a good day , though more typically half that . Performance was otherwise similar to the earlier system , with a range accuracy of about 50 m . This was considerably more accurate than the guns they ranged for , which typically had spreads of over 100 m . It was also much better than the optical rangefinding equipment of the era , which would typically be accurate to about 200 m at 20 , 000 m .