GB1258656A - - Google Patents

Abstract

1,258,656. Aerials. INTERNATIONAL STANDARD ELECTRIC CORP. 27 June, 1969 [22 Jan., 1969], No. 32629/69. Heading H4A. In an aerial system, a turnstile aerial is symmetrically surrounded by a circular loop aerial, all elements of the aerials are flat, and they are arranged substantially in a plane. As described, the turnstile aerial consists of two centre-fed crossed dipoles (d 1 , d 1 ) and (d 2 , d 2 ), Fig. 1, and the loop aerial consists of four centrefed pairs of arcuate sections (r 1 , r 2 ), (r 3 , r 4 ), (r 5 , r 6 ), and (r 7 , r 8 ). The aerials are formed by printed circuit techniques on an insulating base a, Fig. 3, made, for example, of 1À5 mm. epoxyglass fabric, and each half-dipole of the turnstile aerial comprises four conductive strips arranged in spaced apart pairs on each side of the base, through which interconnections p are provided. Bridges B under the base connect together the two parts of each half-dipole and provide terminating points for feeder cables. The sections of the loop aerial are U-shaped, and are formed on the upper side of the base, with the closed ends of each pair adjacent each other. A central coaxial cable feeds each pair of sections individually through radially extending baluns T r , Fig. 4, and inductors L. Said inductors are formed on the lower side of the base under the sections, and their outer ends are connected to the legs of said sections by adjustable sliding bridges S. Tuning capacitors (6), Fig. 8 (not shown), may be connected across the outer ends of each balun, at points x, y, where the inner ends of the inductors L are also connected. The baluns T r are of strip construction, and each comprises two paralleled radially extending tapered conductive strips (1), (1), Figs. 6, 6(a) (not shown), formed on each side of the base (a), two low-loss dielectric spacers (b), (c), over the strips (1), (1), which carry outer conductive strips (2), (3), and two low-loss dielectric spacers (d), (e) over the strips (2), (3), which carry screening conductive strips (4), (5). At the inner end of a balun the inner conductor (C) of the central coaxial feeder cable is connected to the strips (1), (1) and its outer conductor (M) is connected to the strips (2), (3). At the outer end of the balun the strips (1), (1) are connected to the strip (2) and the relevant inductors are respectively connected to the strips (2), (3). A metal housing under the insulating base of the aerial provides shielding, and means for attachment of the feeder cables. The aerials may be coated with protective lacquer and they may be enclosed in a radome. The aerial system may be fitted with a cage of the kind described in Specification 1,258,282, for reducing undesirably polarized radiation. The aerial system is stated to be suitable for use in a VOR beacon, or in a direction-finder with a manually-operated goniometer, or in an automatic direction-finder with a visual indicator.