GB733763A - Improvements in or relating to delay lines - Google Patents

Abstract

733,763. Delay lines. LIGNES TELEGRAPHIQUES ET TELEPHONIQUES. Nov. 27, 1953 [March 4, 1953], No. 33069/53. Class 40 (8). A delay line comprising a conductor wound in a single layer on a cylinder having ferromagnetic elements inserted therein, has the winding and the shape of elements such that the magnetic flux in the elements is lower than would be caused by a constant pitch winding having the same number of turns per unit length and having a continuous cylinder of the same ferromagnetic material placed within. As shown in Fig. 1, a conductor 1 is wound on a " plastic " tube 2 containing sticks 3 of ferromagnetic material separated by non-magnetic spaces 4. In a modification, Fig. 2, a cylinder 5 of ferromagnetic material is inserted in a " plastic " tube 6 having a winding consisting of helices 7, 8 of the same pitch and having the same number of turns which are alternately right and left-handed. In a further embodiment (Fig. 3, not shown), the sticks of Fig. 1 are used with a winding as in Fig. 2. In a particular example, Fig. 4, a core 15 comprising bundles of iron wires containing 40 per cent nickel, each insulated with alumina, is covered with tapes of polystyrol. The return conductor 17 comprises copper wire, enamelled and braided with silk. The assembly is covered with a layer 18 of polyethylene, then with a braid 19 comprising copper wires in one direction and cotton yarn in the other direction, and finally a protecting sheath 20. The ferromagnetic material may be ferrite or bundles of fine wires manufactured according to the process described in Specification 669,322, [Group XXXVIII]. The conductor 1 may be connected to a second conductor parallel with the cylinder through condensers arranged at intervals along the line (see Fig. 5, not shown). Alternatively the line may be formed as a coaxial line, the second conductor being in the form of a cylindrical tube surrounding the conductor 1. Where the core comprises fine wires it may be used as the second conductor.