GB630010A - Centre fed antenna - Google Patents

Abstract

630,010. Impedance transformers. STANDARD TELEPHONES & CABLES, Ltd. May 17, 1946, No. 15009. Convention date, May 24, 1945. [Class 40 (viii)] [Also in Group XL (c)] A vertical dipole aerial, designed to be supported on a conducting mast and fed by means of a balanced transmission line comprises two tubular radiators 1, 2, as shown, a quarter - wavelength long, but which may be any integral multiple of this length, a support structure 3, 4 mounted at 5, an inner continuous tubular conductor 12 and a balanced transmission line extending from the translator 8, through the conductor 12 and passing through openings therein . to make connections, as shown, with the shortcircuiting members 10 and 11, connecting together the members 1 and 4 and the members 2 and 3 respectively, the radiators 1 and 2 and the separate portions 3, 4 of the support being held apart by an insulating member 9. The inner conductor 12, in the embodiment shown, is short-circuited to the support 3, 4 at positions a quarterwavelength distant from the feed points to the dipole by means of conducting members 14 and 16. The radiators 1 and 2 comprise slidable portions 19 and 20, whereby the length of the radiators may be adjusted. The construction is such that at the outer ends of the radiator, a quarter-wavelength away from the short-circuits 10, 11, a high impedance is presented between the radiators and the support so that no coupling between the two exists. Similarly, at the centre of the dipole a high impedance is presented between the support and the conductor 12 so that the transmission line is not unbalanced due to its being coupled into the dipole at a current antinode.