Патент USA US3054079код для вставки
Sept‘. 11, 1962 3,054,075 J. R. LOHOAR ANODISED HELICAL TAPE WAVEGUIDE FOR MODULATING ARRANGEMENTS Filed April 29, 1960 v . Il. ' INVENTOR V B. ?uid/Mam, 5mm x ATTQRNEYS United States Patent 0 1 r. ICC 1 3,054,075 AN ODISED HELICAL TAPE WAVEGUIDE FOR , MODULATING ARRANGEMENTS John Ronald Lohoar, Steveuage, England, assignor to Marconi’s Wireless Telegraph Company Limited, Lon don, England, a British company 3,054,075 Patented Sept. 11, 1962 2 Within said length of waveguide and a winding external to said length of waveguide and arranged and adapted to provide a varying magnetic ?eld through said body to modulate, in accordance with the variations of said ?eld, high frequency wave energy transmitted through said length of guide. Filed Apr. 29, 1960, Ser. No. 25,573 Claims priority, application Great Britain Aug. 19, 1959 Claims. (Cl. 333-96) Preferably the tape is aluminium tape anodised to pro vide the insulation between the turns. In order to reduce discontinuities between the helically 10 wound length of guide and the adjoining ends of wave This invention relates to wave energy modulating ar guides between which the length is inserted to form a rangements and more speci?cally to modulating arrange “run” of guide, it is most desirable, if not essential, that ments of the kind in which very high frequency wave the ends of the helically wound length be ?nished ?at, energy is modulated by propagating it along a waveguide i.e. that they terminate in planes at right angles to the in which is a ferrite or similar body and subjecting said 15 axis. One way of doing this is to ?t each end of the body to a modulated or varied magnetic ?eld produced by helically wound length with a cylindrical collar which is a coil system outside the guide. flat at one end and shaped with a step at the other to mate The object of the invention is to provide improved, with the end of the helix proper, the tape of which is simple and efficient modulating arrangements of the kind cut oif square to the length of the tape. Another way is referred to wherein, despite that the coil system is out 20 to solder together the last few turns of the helical guide side the waveguide, there is minimum losses due to the to permit it to be turned off square, i.e. ?at. interposition of the walls of the guide in the path of the Preferably also the outside of said length of guide is magnetic ?ux and minimum interference with the proper covered with a thickness of comparatively rigid insulating _ functioning of the waveguide as such. material, e.g. resin, and the winding is positioned on the It is common practice to effect modulation of a high 25 outside of this insulating material. ‘In one construction, frequency electro-magnetic wave transmitted down a wave the winding is a single layer winding of turns of conductive guide by applying a magnetic ?eld which is varied in ac tape wound directly on the insulating material. cordance with modulation to vary the magnetisation of a The ends of the length of waveguide may be ?tted ferrite body inserted in the waveguide, the modulating with flanges which must be so arranged that, when said magnetic ?eld being generated by a coil system outside 30 length is inserted in a “run” of guide, it is insulated at the guide. One of the dii?culties met with in modulators least at one end from the adjacent guides. Accordingly, of this nature is that, since the varying magnetic ?eld if a ?ange on the end of the helically wound length is to has to pass through the guide walls to reach the ferrite be in metal to metal contact with a ?ange at the end of body, it induces substantial eddy currents in said walls, an adjacent length of guide, the former ?ange should be especially if the modulating frequencies are relatively high. 35 insulated from the helix and a thin insulating shim is These eddy currents of course constitute loss and tend in inserted to avoid contact between the end of the helix and effect to short circuit the magnetic ?eld and oppose proper the adjacent guide. and e?icient modulation. Various expedients have been The invention is illustrated in the accompanying draw proposed to meet this difficulty but it is by no means easy ing which is a simpli?ed sectional view of a preferred to do so without interfering with the proper functioning of embodiment of the invention as applied to a frequency or the waveguide as such, and without resulting in a struc phase modulator of microwave energy. Although the in ture which is mechanically unsatisfactory or unduly ex vention is not limited to its use at any particular band pensive or incapable of handling high power. For ex of frequencies, it is very advantageous for phase or fre ample, it has been proposed to use a guide in the form 45 quency modulation of microwave energy'at comparatively of a very thin ?lm of deposited silver or aluminium on high frequencies and the illustrated embodiment is suitable the inside of an insulating tube, but this construction will for use for phase or frequency modulating microwave not handle high power satisfactorily and is, moreover, ex energy of a frequency of the order of 10,000 mc./s. by a pensive and mechanically weak. It has also been pro modulating frequency of the order of l mc./ s. Practical posed to slot the waveguide with a slot running parallel principal dimensions for the illustrated embodiment when to the axis, but here again such a slot tends to distort the 50 intended for the frequencies stated are: about91A2" overall ?eld, its provision results in an asymmetrical waveguide length and about 0.81" for the inside diameter of the and leakage of high frequency (microwave) energy tends to occur through the slot. Another proposal which has been made is to provide the waveguide with a helical slot, guide, the guide being wound from anodised aluminium tape about 1A0 of an inch wide and about 1/32 of an inch thick. the slotted waveguide being formed by electro-forming it 55 Referring to the drawing, a circularly sectioned guide 1 on a special mandrel and then using the coil, which the is made from anodised aluminium tape which is wound slotted guide in fact constitutes, as the source of the mod— in helical form with the edges of the turns in contact with ulating magnetic ?eld. This expedient avoids the di?’iculty one another as indicated by the parallel lines 1a shown above mentioned by in fact dispensing with the external at the ends of the guide length. It will be understood that 60 modulating ?eld source altogether (since the guide itself the distance between any two adjacent parallel lines 1a is now the ?eld source) but the construction is expensive represents the width of the tape. The anodising of the and again there is a tendency to microwave energy loss aluminium provides insulation so that although the tape through the helical slot. There is also an added limita edges are physically in contact with one another and the tion in design parameters because of the fact that the mag 65 ?nished guide has no gaps or substantially no gaps lead netisation coil and the guide are now one and the same. According to this invention an arrangement of the kind ing to the exterior, the turns are effectively insulated each from the next. The ends of the wound guide are ?nished referred to for modulating very high frequency electro off by ?anges which serve for coupling the length of magnetic Wave energy comprises a length of waveguide guide to other guide lengths (not shown). These ?anges constituted by a helically wound metallic tape with the 70 should be insulated from the guide proper and may be edges of the turns substantially in physical contact with one another but insulated from one another, a ferrite body ?tted thereto in any convenient manner. The most prac tical way of making the glide consists in winding the tape - A, 3,054,075 3 on to'a, mandrel so .that no gaps occur in the winding; clamping it at the ends; and then, after trimming the ends if necessary, ?tting the ?anges in position with suit able insulation between them-and the guide proper. The clamps may then be removed and the mandrel punched out. . 4 ium tape the turns of which are substantially in physical contact with one another, said tape being anodised to provide insulation between the turns whereby energy trans mitted through said length of Waveguide is modulated by the varying magnetic ?eld through said body. 2. An arrangement as claimed in claim 1 wherein the In the illustrated embodiment the waveguide with its end ?anges, which are marked 2, is “potted” with resin or some other suitable insulating compound so that the guide is externally coated to provide it with additional mechan ical: strength and rigidity by a comparatively thick layer of resin or other insulating compound 3. On this layer is wound the modulating magnetizing coil which is con ends of the helically Wound Waveguide terminate in planes at right angles to the guide axis and wherein the last few ends for avoiding sharp impedance discontinuities. The ferrite rod 5 is supported in position in the guide by suit able insulating supports 6, preferably aper-tured as indi cated. tape. turns of said tape are soldered together. 3. An arrangement as claimed in claim 1 wherein the said guide is covered with a layer of insulating material and wherein said coil is positioned on the outside of said insulating material. 4. An arrangement as claimed in claim 1 wherein each ventionally represented at 4 and may conveniently con sist in practice of a few turns of copper tape wound di 15 end of the helically wound length is ?tted with a cylin— drical collar which is ?at at one end and shaped with a rectlyon to the insulation 3. The coil 4 extends at least step at the other to mate with the end of the helix proper, over the length of a ferrite insert which is shown as of the tape of which is cut oif square to the length of the conventional form at 5, i.e. it is a ferrite rod with pointed 5. An arrangement as claimed in claim 1 in which said waveguide length is ?tted at least at one end with a ?ange insulated from the helical winding. , An experimental arrangement as illustrated using ano— dised aluminium tape 0.1" x 0.032” has been successfully used at the frequencies hereinbefore mentioned to handle 25 500 watts C.W. power. I claim: 1. ,A wave energy modulating arrangement in which very high frequency energy is modulated comprising a length of waveguide, a ferrite body located in said wave 30 guide, a magnetic coil positioned outside said length of waveguide arranged and adapted to subject said body to a modulated magnetic ?eld, said waveguide being of circu lar cross-section and comprising ahelically wound alumin References Cited in the ?le of this patent UNITED STATES PATENTS 2,802,134 Fox _________________ __ Aug. 6, 1957 1,031,381 Germany _____________ __ June 4, 1958 FOREIGN PATENTS OTHER REFERENCES Brown, “Proceedings of the IRE,” April 1958, pages 722-726.