GB1112402A - Improvements relating to microwave rotating joints - Google Patents

Abstract

1,112,402. Rotatable couplings. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 7 Dec., 1964 [6 Sept., 1963], No. 35352/63. Heading H1W. A rotating microwave joint, e.g. for the feeder of a rotating aerial, comprises a pair of coupled, mutually rotating, annular strip lines. The strip lines are of the triplate kind, i.e. they consist of a line (or double line) conductor printed on one or both sides of a dielectric layer arranged between, and spaced from, two parallel ground planes. Fig. 2 shows two such dielectric layers, an inner, rotatable, annular layer 16 and an outer, fixed, annular layer 3, the layers (as shown) being in the same plane. Corresponding pairs of rotatable and fixed ground planes of annular form (not shown) are connected respectively to the outer conductor 34 of a central rotatable coaxial line and to the outer conductor 32 of a fixed coaxial line. The ground planes overlap each other, one pair being rebated to accommodate the other. The fixed line conductor 4, printed on one or both sides of the layer 3, is connected at one end to the inner conductor of the line 31, 32 and at the other to a dissipative termination 23. A similar (rotating) line conductor 9 is connected to the inner conductor of the rotating line 33, 34. Coupling between the fixed and rotating lines is afforded by an intermediate line 17 and two annular arrays 18 of radial sectors spaced at quarter-wave intervals, all these being printed on the rotating dielectric layer 16. The construction behaves as a O db. coupler. In a modification, the fixed and rotating transmission lines are spaced apart axially (instead of radially, as shown), and are in the form of two parallel, annular triplates having a common intermediate ground plane. This ground plane is apertured at intervals to provide coupling. In this construction, a coupling array of the type indicated by 17, 18 on Fig. 2 may be printed on one of the dielectric layers or may be shared between both of them, e.g. with one array 18 on the fixed layer, the other on the rotating layer and two intermediate line conductors 17 coupled through apertures in the common ground plane.