GB403376A - Improvements in antennae for radio transmitters - Google Patents

Abstract

403,376. Aerials. LORENZ AKT.- GES., C., 1, Lorenzweg, Tempelhof, Berlin. June 16, 1932, No. 17038. Convention date, Oct. 7, 1931. [Class 40 (v).] - To reduce the spacewave component and to radiate energy that is predominantly earthbound, thereby reducing fading effects in broadcast transmission, one or more dipoles are arranged so that the centre of oscillation of the highest dipole is within half a wavelength of the ground. In Fig. 3 three such dipoles Di...Di<11> are arranged one above the other with the intermediate spacing shown, the oscillation centre of the uppermost being five-twelfths of a wavelength above ground. To ensure a constant effective height, an invariable earthstructure is provided below the aerial system having a diameter of at least half a wavelength. As shown in Fig. 9, the geometrical length of the aerial may be shortened by adding horizontal portions N, N1 at the top and bottom, energization taking place at the lower end of the aerial through a non-radiating feed-line F. Figs. 10 and 11 respectively show methods of suspending a single dipole Di, and one or two pairs of dipoles, placed back to back. Fig. 12 illustrates node coupling, and Fig. 13 loop coupling to the feed lines. Or coupling may be to the lowest dipole. The invention is applicable to circular arrangements of aerials designed to emphasize the ground component of radiation such as are described in Specification 396,740. The size of the dipoles and the amplitude and phase-relation of the currents fed to them may also be varied to ensure a favourable distribution of the horizontal field.