GB864800A - Improvements in or relating to electromagnetic wave transmission devices - Google Patents

Abstract

864,800. Pulsing carrier frequencies. HUGHES AIRCRAFT CO. Oct. 24, 1958 [Nov. 29, 1957], No. 34179/58. Class 40(5) [Also in Groups XXXV and XL(b)] A non-reciprocal waveguide transmission device for, e.g. pulse modulation purposes includes, in addition to the usual ferrite element, a second ferrite element (which may be integral with the first) for providing a magnetic flux return path. By situating both elements within the waveguide it is possible to reduce the reluctance of the magnetic circuit and to obviate eddy current losses. A Faraday-rotation element in the form of a ferrite rod 50, Fig. 3, is axially arranged in a circular or square waveguide 10. Embedded within the element is a solenoid 52 arranged so that the magnetic field lies entirely within the ferrite material. In another arrangement (Fig. 1), the return flux path comprises a ferrite cylinder 24 contiguous to the waveguide wall. A solenoid 22 is situated in the annular space between the cylinder 24 and the Faraday element 18. The device shown has a rectangular waveguide input 12 and two output terminals 14, 16 of the circulator type having their minor axes displaced at 45 degrees or any other convenient angle from the minor axis of the input guide 12. The device is normally biased to provide the wave rotation necessary to couple the input terminal with one of the output terminals, periodic switching to the other output terminal being obtained by pulsing the solenoid. The output waveguide 14 may be replaced by a resistive vane positioned radially within the waveguide 10. By this means it is possible to operate the device as an isolator. Pairs of circulator terminals may be arranged at both ends of the waveguide 10. In a modification (Fig. 4, not shown), the return magnetic flux path is provided by a number of C-shaped ferrite yokes radially arranged around the element 18 and each carrying its own solenoid. In the modification of Fig. 6, the Faraday element 18 is supported in a square waveguide 70 by four symmetrically arranged conductive vanes 72. These are provided with apertures to accommodate a solenoid 22 and a cylindrical ferrite element 24 which provides the return path. The vanes 72 are provided with steps to improve matching.