GB576828A - Improvements in electro-magnetic beam receiving aerial devices - Google Patents

Abstract

576,828. Directive wireless signalling; aerials. DOWSETT, H. M. Aug. 22, 1941, No. 10744. [Class 40 (v)] A dipole for short-wave reception, and particularly for receiving radiation of the kind described in Specification 576,825 (in which a tubular beam of radiation is polarized in all planes containing the line of propagation X, X, and in which the maximum electric stress is on a cylinder P, Q surrounding the line X, X), comprises a linear part A, B at the ends for maximum response to the electric field and a coiled part at the centre, and in the same plane as the linear part, for maximum response to the magnetic field. The linear part may be curved, Fig. 2 (b), and two or more coils may be provided, Fig. 2 (c). For receiving the tubular beam of radiation mentioned above, one or more dipoles may be arranged in separate axial planes around the beam axis at the position of maximum electric stress, or at the focus O of the reflector, curved dipoles as in Fig. 2 (b) being arranged as shown in Fig. 1, or dipoles as in Fig. 2 (c) may have their linear part along the axis X, X and the coiled parts in axial planes. Energy received by the reflector itself may be added to that received by the dipoles, the ends Y, Y of the reflector being earthed through impedances Z to prevent reflection effects. Specification 576,826 also is referred to.