GB929562A - Improvements in and relating to radio aerials - Google Patents

Abstract

929,562. Aerials. G.S.V. (MARINE & COMMERCIAL) Ltd. Nov. 2, 1959 [Aug. 1, 1958], No. 24946/58. Class 40 (7). A wide-band unipole or dipole aerial is provided with an internallyarranged stub element. The stub is of shortcircuited quarter-wavelength type but a shortcircuit at a distance other than a quarter-wavelength may sometimes be preferred. An advantage of the stub is that a D.C. path to earth is provided from every part of the aerial enabling protection against lightning and improved mechanical strength to be obtained. In a dipole embodiment the upper arm 10 of the dipole contains a coaxially arranged tube 12, a quarter-wavelength stub being formed between these two units and being short-circuited at its upper end by conductive disc 13. The tube 12 extends downwardly through the lower dipole arm 11 and forms a support for the aerial. A coaxial feeder is led up through the tube 12 and is passed through an aperture 15 in the wall thereof opposite the gap between the dipole elements. At this point the inner conductor of the feeder is coupled to the upper dipole element as at 17 and thus to the outer conductor of the stub. The outer of the feeder is connected to the tube 12 and to the dipole element 11 which may be supported from the tube 12 by conductive flange 14. A unipole embodiment, described with reference to Fig. 2 (not shown), is similar but the element 11 is not present and the flange 14 is extended to form the ground plane for the unipole.