GB677460A - Improvements in directional radio transmission systems - Google Patents

Abstract

677,460. Directive radio systems. PILLOT DE COLIGNY, G. DE. Dec. 28, 1949 [Dec. 29, 1948], No. 33076/49. Class 40 (vii). A directive radio system, particularly for use as a radio beacon, comprises a reflector as described in Specification 677,457 constructed from a plurality of strips taken from the surfaces of successive ones of a family of paraboloids and having a linear focus, and a plurality of radiating elements transmitting distinguishable signals and situated at spaced intervals along the focal line. Fig. 4 illustrates a continuously rotating beacon whereof the vertical polar diagram comprises a plurality of overlapping beams 68, 69, 70 produced by radiators 58, 59, 60 situated along the focal line of the reflector 63. The radiators comprise waveguide apertures fed from a, common waveguide coupled to a pulsed magnetron transmitter. Gas switches in the coupling guides between the common guide and the apertures are arranged to suppress a selected proportion, different for each gas-switch, of the pulses applied thereto so that the signals radiated from the various apertures are distinguishable by virtue of their different pulse repetition frequencies. In an alternative arrangement each aperture radiates a pulse pair whose spacing is characteristic of the aperture. The different beams may alternatively comprise continuous-wave signals and be distinguished by different modulation signals applied thereto. An aircraft may accordingly determine its angular position with respect to the beacon, azimuthal angle being determined by the interval between reception of a " North " signal and of the beacon transmission and elevational angle being determined by the particular distinguishing characteristic of the received signal. The Specification as open to inspection under Sect. 91 states that, instead of using a plurality of radiators, a single linear radiator comprising a longitudinal slot cut in a waveguide may be used. The Specification as open to inspection under Sect. 91, also discloses matter forming the subject-matter of Specification 677,510. This subject-matter does not appear in the Specification as accepted.