On the ground, to obtain directional radio beams with a well-defined navigable course, crossed loop antennas were used initially. The Ford Motor Company developed the first commercially workable application of a loop-based, low-frequency radio range, installing it at their Dearborn and Chicago fields in 1926 and filed the patent for it in 1928.[11][12] Earlier concepts for the system were developed in Germany in 1906[13] which were later experimented with by the US Bureau of Standards and Army Signal Corps in the early 1920s. The technology was quickly adopted by the U.S. Commerce Department, who set up a demonstration range on June 30, 1928, [4][7] and the first series of stations entered service later that year.[14] But the loop antenna design generated excessive horizontally polarized skywaves that could interfere with the signals, especially at night.