GB601353A - Improvements in radio antennae - Google Patents

Abstract

601,353. Aerials. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Nov. 1, 1945, No. 29065. Convention date, May 3, 1944. [Classes 40 (v) and 40 (vii)] In a system for both coupling a balanced dipole antenna to an unbalanced coaxial feeder and for providing a support for the dipole, the dipole elements 43, 49 are supported upon insulated bushings midway along a halfwavelength tubular conductor 15 within which extend two tubular quarter-wavelength conductors 25, 31 connected to the opposite ends of the conductor 15 by conductive plugs 23, 30, the adjacent ends of the inner conductors being connected through the insulated bushings each to a respective dipole element. The aerial is fed from an unbalanced coaxial transmission line (not shown), through the fitting 29 and a quarter-wavelength coaxial line comprising the members 25 and 27. The elements 15 and 25 comprise a short-circuited quarter-wavelength coaxial line, the outer conductor of which is earthed and consequently the free end of 25 is isolated from earth. The free end of the inner conductor 27, being connected to the free end of conductor 31, is similarly isolated and consequently a balanced input is obtained. A flange 17 is secured to the tubular conductor 15 by brazing or welding so that the structure may be bolted to a conductive reflector. The elements 43, 49 are detachable and may be replaced by radiators of special form. In Fig. 3 (not shown) is illustrated a radiator element, the lower end of which is provided with a flat plate to give capacitive loading of the dipole. In Figs. 3a, 3b (not shown), hollow cylindrical radiators are illustrated with centre rods passing down them through which energy is fed to the radiators and which act as inductive shunts across the dipole. Projecting lugs by which the radiators are attached to the input circuit are provided to enable the dipole to be spaced farther from the reflector.