Ettore Bellini (1876-1943) and Alessandro Tosi devised a much improved direction-finding system in 1907. [[1]] Their scheme deployed two orthogonal arrays similar to those of Stone. The key advantage of the Bellini-Tosi direction finder was a rotating transformer coupling. Rather than rotate a potentially large antenna system, the Bellini-Tosi system uses fixed orthogonal antennas with a rotatable transformer. The Figure (below) shows the Bellini-Tosi array and details of the rotating transformer or “goniometer” coupling. Bellini developed many improvements to their invention including a version with a cardiod pattern (with Tosi) [[2]], and a capacitive goniometer [[3], [4]].
[[1]] Ettore Bellini and Alessandro Tosi, System of directed wireless telegraphy, US Patent 943,960, December 21, 1909.
[[2]] Ettore Bellini and Alessandro Tosi, Directed wireless telegraphy, US Patent 948,086, February 1, 1910.
[[3]] Ettore Bellini, Apparatus for directed wireless telegraphy and telephony, US Patent 1,221,787, April 3, 1917.
[[4]] Ettore Bellini, Apparatus for directed wireless telegraphy and telephony, US Patent 1,297,313, March 18, 1919.
