GB652716A - Improvements in and relating to folded dipole aerials - Google Patents

Abstract

652,716. Aerials. COSSOR, Ltd., A. C., WYNN, A. H. A., and OXENHAM, J. K. Sept. 21, 1948, No. 24732. [Class 40 (vii)] The invention relates to folded dipole aerials of the type comprising a centre-fed dipole and a further conductor or conductors disposed alongside the dipole with connections between points at or near the ends of the dipole and corresponding points at or near the ends of the further conductor or conductors, the structure having a part annular form. According to the invention, the conductors forming the dipole and the further conductor or conductors are arranged on opposite sides of one or more insulating members. Each insulating member may be a flat plate and the conductors applied to the plate by a printing process ; by spraying through a mask; by sputtering; or by providing the plate with recesses, coating the whole surface with a conductor, and then removing the raised portions of the support by grinding. In Figs. 3 and 4, the upper and lower surfaces respectively of an insulating sheet carry thin strips of conducting material (shown shaded). E and F constitute the input terminals and rivets are passed through the sheet to join points J, J<SP>1</SP> and K, K<SP>1</SP>, the whole assembly forming a folded dipole with conductors bent to follow the sides of a square. It is shown that by suitable choice of the points of connection between the dipole and further conductors, the aerial input impedance may be made resistive and that this may occur at a frequency lower than the resonant frequency of the dipole. At a given frequency an aerial constructed according to the invention may have smaller dimensions than a normal dipole. By making the conductor on the under surface broader than that on the top, as shown in Fig. 4, the aerial input resistance is increased. In a second embodiment, Figs. 6 and 7 (not shown), two conductors are provided on the under surface to produce a doubly folded dipole. Multi-folded dipoles are produced by employing a plurality of supports, Figs. 9-11 (not shown). Specification 652,398, [Group XL (b)], is referred to in connection with the methods of applying the conductors to the insulating support.