GB942287A - Improvements in or relating to crossed dipole aerials and arrays - Google Patents

Abstract

942,287. Aerials. BRITISH BROADCASTING CORPORATION. April 11, 1962 [April 19, 1961], No. 14184/61. Heading H4A. Referring to Fig. 1, a turnstile aerial in the form of a pair of crossed half-wave dipoles AC, BD, is made substantially omnidirectional in the plane of the dipoles, i.e. horizontally, by connecting the radiating elements to the conductors X, Y through non-radiating inductive and capacitive impedances a, c; b, d, arranged as shown, each impedance being equal in magnitude to the radiation resistance of a single element at the operating frequency. As shown in Fig. 2, each element A, B, C, D is a hollow cylinder and is separated from the conductors XY by dielectric plugs G. The inductive impedances H are merely conductors joined to the elements A and C through conductive discs H<SP>1</SP>. Similar rods J are separated from the elements BD by a thickness of the dielectric G sufficient to give the necessary capacitive coupling. The conductors X, Y are in the form of a half-wave transmission line short-circuited at each end (Fig. 3, not shown), the dipoles and feeder being connected at the centre of the line. The conductors XY can take other forms for example four L-sections forming a box or two facing channel sections or two facing conductors of semi-circular section. An array is disclosed (Fig. 4, not shown), comprising two or more turnstile aerials stacked end-to-end with each aerial rotated through 90 degrees with respect to the adjacent one.