Патент USA US3020454код для вставки
Feb- 6, 1962 H. J. WOLKSTEIN ETAL 3,020,444 TRAVELLING WAVE TUBE COUPLER Filed May 5, 1959 2 Sheets-Sheet 1 /// w w“ LINB ,/mm J.mW.B WmmmmNKDM;M HR/ 5 m?nw 8 ‘ nited States arent "ice 3,020,444 Patented Feb. 6, 1962‘ 2 1 loading at high frequency reduces the wave velocity dis- _ 3,020,444 TRAVELLING WA‘VE TUBE COUPLER Herbert J. Wolkstein, Newark, and Ralph E. Bridge, South Bound Brook, N.J., assignors to Radio Corpora tion of America, a corporation of Delaware Filed May 5, 1959, Ser. No. 811,180 5 Claims. (Cl. SIS-3&3) The present invention relates to an improved ?uted persion in the coupler. This is accomplished by the rows of ridges which preferentially load the low ends of the frequency band. In this manner, the coupler support provides a minimum of lossy material and a maximum of energy transfer between the wire mounted on the sup port and the helix of the travelling wave tube which it surrounds. The coupler of the invention thus meets the need of a low noise traveling wave tube Where a decrease microwave helical coupler support useful in coupling 10 in insertion loss is signi?cant. A more detailed description of the invention follows radio frequency energy to or from the helix of a travel in conjunction with a drawing, wherein: FIGURE 1 illustrates an embodiment of the low loss Known helical coupler supports comprise a hollow helical coupler support of the invention mounted upon relatively short cylindrical tube of insulation having a pro-formed helical groove completely embedded in the 15 the envelope of a traveling wave tube. Only a portion of the traveling wave tube is shown. insulation. his groove accommodates a wire adapted ling wave tube. to carry radio frequency energy. Because of the 'arrange- - FIGURE 2 is a cross-section of FIGURE 1 taken along line 2-2; and ment of the pre-formed embedded helical groove in the FIGURE 3 is a fragmentary view of a longitudinal insulation of the coupler, the Wire in the coupler sup port is also completely embedded in the insulation. As a 20 section of the ?uted hollow tube of insulation of the coupler support, showing the parallel rows of ridges of result, there is a very appreciable loss in the transfer of insulation material on the interior surface of the hollow energy between the coupler and the medium with which tube. 1 the coupler is in energy transfer relation. In using such FIGURES 4 and 5 are graphs relating insertion loss to known coupler supports with travelling wave tubes, it has distance for a known type of helical coupler support been found that each db of loss inserted into the system (FIGURE 4) mounted externally of a traveling wave by the input coupler support results in a db of noise tube as compared to the helical coupler support of the in ?gure. Since travelling wave tubes are designed to carry a wide band of very high frequencies, each added db vention (FIGURE 5). FIGURE 1 shows a portion of a traveling wave tube of noise ?gure resulting from loss in the coupler sup port reduces the ei?ciency and effectiveness of the travel 30 having an evacuated glass, envelope 10 of cylindrical cross-section surrounding, an internal helical conductor ling wave tube. An object of the present invention is to enable the '4 12 through the interior of which an electron beam is adapted to be projected. Since the traveling wave tube ef?cient transfer of energy between the helix of a travel is ‘well known in the art, and no claim is made herein the tube envelope, with a minimum of loss. 35 to it per se, the details thereof including the source of electrons, the collector electrode, and the means for ap Another object is to provide an improved helical _ ling wave tube and a helical coupler support external of coupler support which is relatively rigid and reduces to a ‘ ‘ plying the magnetic fieid have not been vshown in the in spaced rows of ridges arranged parallel to the longitu FIGURE 2. terests of simplicity of illustration. minimum the loss encountered in transferring energy be Surrounding the glass envelope 10 of the traveling tween the external coupler and an internal helix adapted to carry high frequency currents. 40 wave tube is the low loss support for the helical coupler of the invention. The helical coupler support comprises Still another object is to provide for use with a travel a hollow thin tube of insulation 14, such as above-men ling wave tube a ?uted external helical coupler in the tioned “Te?on” manufactured by Dupont, having on its form of a very thin hollow tube of insulation having on interior surface a plurality of rows 16 of ridges 18 of in the interior surface thereof a plurality of spaced rows of ridges arranged to support an exposed wire wound be 45 sulation. The ridges 18 in each row are arranged in series, as shown, and are made of the same insulation tween the rows. material as the thin hollow tube 14. Adjacent ridges 18 In brief the invention comprises a low loss helical cou in each row are separated by an open space or valley 20. pler support for use externally of the glass envelope of The bottom of each open space or valley forms the a travelling wave tube containing an internal helix. The smooth interior wall of the tube 14 of insulation. The coupler support is in the form of a thin hollow tube of three rows extend parallel to the longitudinal axis of in~ insulating material, such as polytetrafluoroethylene known sulatio-n tube 14 and are spaced 120° apart, as shown in as “Te?on,” having on its interior surface a plurality of dinal axis of the hollow tube of insulation. Each row The rows of ridges are so arranged that the coupler wire 22 is threaded in helical fashion be of ridges is composed of a series of raised portions of 55 tween the ridges of the three rows, as shown in FIGURE 1. The ridges 18 are smaller in height ‘than the diameter of helical coupler 22 and constitute a minimum of lossy ridges. These rows, preferably three in number, have material to hold the wire 22 in position. Hence, the their ridges so arranged that a coupler wire can be major portion of the wire 22 is exposed to the interior threaded in helical fashion through the open valleys or slots between the ridges, with the major portion of the 60 of tube 14.- for coupling with the internal helix 12 of the traveling wave tube, which the coupler Wire surrounds. wire exposed to the interior of the hollow tube of in It should be noted that the coupler wire 22 is wound sulation. The coupler wire is thus supported by the sides in opposite sense to the inner helix of the travelling wave of adjacent ridges in the respective rows. This arrange tube. ment permits a greater extension of the electric ?elds surrounding the Wire, thereby increasing the coupling co 65 ' In actual practice, in the manufacture of the coupler support of the invention, the insulation tube 14 is ?rst e?icient between the helix of the travelling wave tube threaded and then the ?utes are made to provide the and the surrounding helical coupler. The total effect is three spaced parallel rows 16, and then the rows are seen in the reduced insertion loss. Further, removal of threaded to cut out the valleys or open spaces 20, thereby a good portion of the insulation of the hollow tube, as compared to previously known coupler supports, signi? 70 forming the ridges 18. Because the larger diameter wire is supported by the sides of the smaller ridges, there is an cantly reduces the dielectric stored energy and enhances increase in the. coupling coe?icient between the two output. In addition to this, the reduction of dielectric insulation with an open valley or slot between adjacent 3,020,444 3 A. 2. The combination with a low loss, electromagnetic energy coupler support comprising a hollow tube of insu~ helices 22 and 12, with a consequent appreciable reduc tion in insertion loss. The removal of a considerable area of insulation around the wire 22, compared to the lation having on the interior surface thereof a plurality embedded type of prior art coupler supports, signi?cantly of spaced rows of ridges of insulation material with said ridges each extending inwardly a given distance away reduces the energy stored in the dielectric and hence en from said interior surface, adjacent ridges in each row being spaced apart by an open valley, said rows being parallel to the longitudinal axis of said tube, of a wire hances output from or input into the coupler, depending on whether the coupler is used as an output or input coupler. The reduction in dielectric loading at the high wound helically around the interior of said tube in con frequencies to be passed by the traveling wave tube also reduces the wave velocity dispersion in the coupler. In 10 tinuous contact with said interior surface and held in posi tion by the sides of the ridges of said rows, the diameter practice, the ridge arrangement in the three parallel rows of said wire being greater than the height of said ridges. load the low end of the microwave frequency band to a 3. The combination with a low loss, radio frequency greater extent than the high end of the band. energy coupler support comprising a hollow tube of insu Surrounding the insulation tube 14 is a cylindrical metallic coupler support 24 to which is fastened a coaxial 15 lation having formed on the interior surface thereof a plurality of spaced rows of ridges with said ridges each line 26 the inner conductor 28 of which is connected to extending inwardly a uniform distance above said interior a point at or near one end of the helical coupler wire 22. surface, adjacent ridges in each row being spaced apart The low loss coupler support of the invention may be used for both feeding input energy to the traveling wave tube and for abstracting energy therefrom. For this pur pose, two couplers of the invention surround the enve by an open valley, said rows being parallel to the longi tudinal axis of said tube, of a wire wound helically around and continuously contacting the interior surface lope 10 as shown in FIGURE 1 and are suitably spaced of said tube, said wire being held in position by the sides of the ridges of said rows, the diameter of said wire be ing greater than the height of said ridges. FIGURE 4 is a graph relating insertion loss to distance 4. In combination, a helix adapted to carry radio fre between a pair of helical coupler supports of the type 25 apart along the length of the envelope 10. quency energy and positioned within an evacuated non~ known in the art, mounted on a traveling wave tube. As indicated on the drawing, the loss per coupler varied electrically conducting envelope, a coupler unit in energy from 3 db at 4800 megacycles to 4.8 db at 7000 mega transfer relation to said helix comprising a hollow tube of insulation having the same general cross-sectional FIGURE 5 is another graph relating insertion loss to 30 shape as that of and surrounding said envelope, a metal lie cylinder surrounding said tube of insulation, said tube distance between a pair of helical coupler supports of having on the interior surface thereof three parallel rows the present invention, mounted on a traveling wave tube. of ridges of insulation material spaced 120° apart, said The improvement, as summarized in the legend on this ridges and tube being made of the same material, adja ?gure, shows that the loss per coupler varied from .9 db at 4000 megacycles to 2.5 db at 7000 megacycles. The 35 cent ridges in each row being spaced apart by an open valley, said rows being parallel to the longitudinal axis reduction in loss by the use of the invention compared of said tube, a wire wound helically around and contact to the prior art coupler supports is highly signi?cant, and ing the interior surface of said tube, said wire being held now permits e?icient use of low noise traveling Wave tubes in position by the sides of the ridges of said rows, the where a decrease in insertion loss is very important. The slanted dotted line curves in FIGURES 4 and 5 40 diameter of said wire being greater than the height of said ridges, and a coaxial line having an inner conductor are continuations or projections of the solid line curves. coupled to one end of said wire. The solid line curves are the results of measurements. cycles. 5. The combination with an electromagnetic wave carrying medium, of a pair of coupler units in energy area because the two couplers could not be brought suf ?ciently close to each other on the envelope of the 45 transfer relation to said medium, said units being spaced apart along the length of said unit, each of said units traveling wave tube to obtain measurements in this area. comprising a hollow tube of insulation having on the in In one embodiment of the invention successfully built terior surface thereof a plurality of spaced ridges of the and tested, the ridges of the ?uted rows had a height of approximately 4 mils, While the diameter of the wire of 50 same insulation material as said tube, adjacent ridges in each row being spaced apart by an open valley, said rows the coupler coil held in position by the ridges was 11 being parallel to the longitudinal axis of said tube, of a mils. Obviously, the low loss coupler support of the in wire wound helically around and contacting the interior vention is not limited to these dimensions. Similarly, surface of said tube, said wire being held in position by insulation material other than Te?on can be used and of various thicknesses depending upon the performance 55 the sides of the ridges of said rows, the diameter of said wire being greater than the height of said ridges. characteristics desired. What is claimed is: References Cited in the ?le of this patent 1. Traveling wave tube apparatus comprising a travel ing wave tube of the kind ‘having a wave propagating UNITED STATES PATENTS helix inside the envelope, and a helical coupler coil ex 2,531,972 Dohler et a1 __________ .._ Nov. 28, 1950 No measurements were made in the dotted line curve ternal to the envelope and adapted to provide for the 60 coupling of radio frequency energy to said helix, a sup port for said helical coupler coil comprising a hollow tube of insulation having on the interior surface thereof a plurality of spaced rows of ridges of insulation ma terial, adjacent ridges in each row being spaced apart by Kompfner ____________ .. Sept. 22, 1953 Goodall _____________ __ June 26, 1956 2,849,651 2,894,168 Robertson ___________ __ Aug. 26, 1958 Wing et a1 _____________ .._ July 7, 1959 984,595 767,563 France ______________ __ Feb. 28, 1951 Great Britain __________ __ Feb. 6, 1957 65 an open valley, said rows being parallel to the longitudi nal axis of said insulation tube, said helical coupler coil being held in place by the sides of the ridges in the dif ferent rows, the diameter of the wire of said helical coupler coil being greater than the height of said ridges 70 and exposed to the envelope of the traveling wave tube which it surrounds. 2,653,270 2,752,523 FOREIGN PATENTS OTHER REFERENCES Magid et al.: “Helix Coupling for Traveling Wave Tube,” RCA Technical Notes No. 197. Received Aug. 18, 1958.