RTLS: Improved Direction Finding

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]].

Bellini’s and Tosi’s US 943,960 (1909) direction finding system used a fixed orthogonal DF array and a rotatable transformer for beam steering.

[[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.

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