GB407881A - Improvements in or relating to directional radio antenna systems - Google Patents

Abstract

407,881. Directive wireless signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.- (Assignees of Carter, P. S. ; Port Jefferson, Long Island, New York, U.S.A.) Sept. 1, 1933, No. 24308. Convention date, Sept. 1, 1932. [Class 40 (v).] The field from a unidirectional aerial system, comprising a radiator a, Fig. 1, and a reflector b, is reversed in direction by varying the effective reactance of the reflector so as to cause the currents induced therein to lag or lead by such an angle that the incident field in the direction a to b is augmented in that direction instead of being reflected. Fig. 5 shows the change in field strength in the two directions as the reactance in the reflector b is altered. As shown in Fig. 6, a V-shaped aerial a, of the kind described in Specification 373,692, is separated from a similar reflecter b bv an odd number of quarter-wavelengths. To reverse the direction of the transmitted field, a switch S, which may be controlled from a remote point, shortcircuits the section from x to S on the tuning- loop of the reflector b so as to alter the effective impedance. Fig. 7 shows three units, of which the centre one a is energized, the two outer ones being provided with short-circuiting switches Sa, Sb. Fig. 8 illustrates a " boosting" arrangement for advancing the phase of the wave from the energized unit a.