GB879920A - Improvements in or relating to selection switch devices - Google Patents

Abstract

879,920. Matching impedances. MARCONI'S TELEGRAPH CO. Ltd. Jan. 7, 1960 [July 23, 1959], No. 25397/59. Class 40(8) [Also in Group XXXVI] A selection switch suitable for selectively coupling each of a plurality of aerials to a V.H.F. receiver comprises a stator S and a rotor R, the stator being a cylindrical conductive shell with a number of longitudinal bores cut away at the inside and accommodating inner conductors with ribbon-like strips SA opposite the cutaway portions and comprising coaxial feeders. The rotor R comprises two conductive hollow drums R1, R2 and a hollow insulating cylinder R5, the latter carrying a segmental pick-up plate R6, of the width of the flat portions of the coaxial feeders CX and of length equal to cylinder R5, and spaced from a conductive terminal plate R7 covering most of the remainder of cylinder R5. A conductive cylinder R8 connects the inner ends of drums R1, R2, and it is connected at R11 through resistor R10 to plate R7. A larger diameter bore R12 of cylinder R8 carries a conductor R13 from the pick-up plate R6 to an insulated conductor R15, to provide a coaxial feeder system which by means of rotary capacity couplings R18, R19 and R20 gives continuity of connection at V.H.F. when the rotor is moved. The lower ends of feeders CX are connected to stubs of short-circuited coaxial cable dimensioned for correct termination of the corresponding aerial, e.g. #/4 at mid-band frequency. The ring of feeder lengths may be inside the drum. Specification 855,614 is referred to.