Patent GB-937843-A (GB)
Title: Improvements in or relating to line matching arrangements
IPC: H01P5/10
Filed: 1959-03-26
Abstract: 937,843. Impedance matching. G. GUANELLA. March 26, 1959 [March 28, 1958], No. 10551/59. Class 40 (8). A H.F. transmission line impedance matching arrangement has the conductors of a two-wire line or connections thereto passing in parallel relation through a ferrite body or a body consisting of ferromagnetic material such as iron powder or a body having similarly high permeability at the frequencies to be transmitted. The opening in the body can be of circular, rectangular or elliptical cross-section. The body can be of annular or tubular form and the conductors can pass through several openings in the body or through a plurality of the bodies. The conductors can be embedded in a flat strip of insulating material, the line where it passes through the body can have the same characteristic impedance as the line outside the body and the distance between the two conductors within the body can be less than the distance between them outside the body. The length of the line can equal one quarter wavelength of a transmitted H.F. oscillation and the characteristic impedance of the line can equal the geometric mean of external impedances at its ends. An electrical screen between the line and the body can consist of at least one metal strip which at least partly surrounds the line within the body. The line can consist of two flat strip conductors arranged side-by-side on or on opposite sides of an insulating support and can be formed by printed circuit techniques. The conductors of the line can be connected to the inner and outer conductors of a coaxial line, the body of high permeability being at least partly surrounded by the outer conductor. There can be at least two two-wire transmission lines which are connected on one side in series and on the other side in parallel and at least one of which passes through the body or bodies of high permeability. All the two-wire lines except one can pass through bodies of high permeability and the beginning and end of said one line can be at the same potential. The interconnected lines can be composed of a double length of flat cable, the beginnings of which are connected to the interchanged ends, one conductor being divided in the middle. At least two two-wire H.F. lines can pass through at least two separate openings in a body of high permeability which is composed of two parts, the openings lying on both sides of the separating surface between the parts. A first group of series-parallel connected lines can be connected in cascade with a second group of series-parallel connected lines with specified relationships between the characteristic impedances of the lines and the external impedances. Various arrangements of connections of the conductors of the lines to imput and output terminals for voltage transformation are described. In the construction shown in Fig. 36 the conductors H 1 , H 2  of a two-wire line embedded in an insulating support S are located in a helical groove in the cylindrical ferrite element K 7 , the magnetic circuit around the twowire line being closed by the ferrite tube K 8 . In the construction shown in Fig. 37 the line system 1, 2 is inside a casing E of high permeability and is wound on a cylindrical support F. The casing E can be made of powdered ferromagnetic material such as iron powder which is formed into a solid body by a binding medium. The core F can be made of high permeability material such as a ferrite. An external ferrite tube can be provided coaxially with F. In the construction shown in Fig. 38 a common core F is provided for two separately wound line systems W 1 , W 2  which can be in series-parallel connection to effect an impedance transformation of 4: 1. In the construction shown in Fig. 39, three two-wire systems W 1 , W 2 , W 3  are shown in coiled arrangement, with additional connecting conductors V 1 , V 2 , V 3 , on a core D of high permeability. An electrical screen comprising a metal wire wound around the coiled line can be provided-this has a high resistance in the direction of the line and a low resistance perpendicular thereto. Both conductors of the line can be wound about a common longitudinal axis. The H.F. line can be made by a process in which the line is wound around a core of high permeability and is encased in a foil of material of high permeability, the interstices between the turns being filled with a material of high permeability. The line can be wound in several layers which are separated by a foil of high permeability material. In a modification, wound H.F. line can be dipped in a mass of ferromagnetic material in plastic state which subsequently solidifies. In a further modification the H.F. line can be sprayed with ferromagnetic material or such material can be pressed around it.