GB880721A - Microwave phase shifter - Google Patents

Abstract

880,721. Waveguide ferrite phase-shifters. HUGHES AIRCRAFT CO. July 25, 1960 [Nov. 2, 1959], No. 25852/60. Class 40(8). A microwave phase-shifter comprises a ferrite element axially aligned within a waveguide and a magnetic circuit including the ferrite element and one or more branch elements also of ferrite, some or all branch elements having windings by means of which the branches may be magnetically saturated in a direction opposite to the direction of magnetization of the internal element. As shown in Fig. 2, the magnetic circuit comprises elements 14, 17, 18, 19, 21 all made of a ferrite material having a square-loop hysteresis characteristic and a low value of magnetic saturation. The phase shifting element 14' is aligned on the axis of a rectangular waveguide 13 and is dimensioned so that its residual magnetism is equal to the residual magnetism of the outer elements 17, 18, the residual magnetisms of the latter being equal. A saturation field is applied by means of the internal winding 23 to provide a desired phase-shift of energy propagated through the device. When this field is removed, the residual magnetism remains close to the saturation value and the phase-shift persists. Energization of branch winding 24 provides a saturation field in the branch 17 equal and opposite to the field established in the branch 18, so that the net field in the internal element 14 is zero and the phaseshift is cancelled. The windings are energized by current pulses, each winding being connected to a separate pulse source. The waveguide may be made of thin metal or of plastic material internally coated with metal. Where the magnetic circuits cross the waveguide broad walls 11, these walls are cut away. and layers 29. of conductive material, e.g. silver paint, are inserted between the elements on either side of the wall. The modification of Fig. 4 uses additional branch elements 41, .43, 61, 62 made of the same ferrite material as the branches 17, 18. The residual magnetisms of the branches on either side of the guide are equal and the sum of the residual magnetisms of the branches is equal to that of the phaseshifting element 14. All the branches are provided with windings which may be selectively energized to vary the net magnetization of the phase-shifting element. A further modification (Fig. 6, not shown) is described in which the phase-shifting element extends completely from one broad wall 11 of the guide of the other. In this construction the tapered end pieces 19 need not be made of ferrite and may consist of a non-magnetic dielectric. The phase-shifting element may be situated in a length of guide of restricted cross-section coupled by stepped sections to standard waveguides.