Патент USA US2406364код для вставки
OS CILLATI ON GENERATOR Filedl Nov. e, 1941v > H. 7.' FRI/S /NvE/vroRs y C, R/DEOÈUT ' ATTORNEY 2,406,364 Patented Aug. 27, 1946 UNITED STATES 'PATENT oFFlCE OSCILLATION GENERATOR Harald .T. Friis, Rumson, and Vincent C. Rideout, Red Bank, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application November 6, 1941, Serial No.` 418,018 4 claims. (ci. 25o-36) 1 This invention relates to vacuum tube `oscilla tors and more particularly to oscillators for the generation of ultra-high frequency currents for which the corresponding wave-lengths may be comparable to the dimensions-ofl the Vacuum tube electrodes and their associated leads. The principal objects of the `invention are to ensure the establishment of the oscillation fre quency at a definite desired value and to prevent the generation of oscillations at frequencies other than that desired. Another object is to improve the efñciency of ultra-short wave oscillation of the feedback type. When the frequency of oscillation corresponds to a wave-length of the order of 10 centimeters it may be found that the distributed inductance >and capacity of the vacuum tube electrodes and their lead-in conductors Vare suchlthat a portion of a standing wave representing a-substantial n fraction of a wave-length may be set up within 20 the vacuum 4tube, leaving lonly a small part of the Wave to ’be established in the conductors eX Y 2 vided by the inherent capacity between the plate and cathode or a supplementary capacity may be provided if necessary. Other features of the invention are, first, the use of a vacuum tube having its electrodes so dis posed and connected that they form, vin effect, continuations of the tuning lines and, second, the extension of the tuning lines on both sides of the electrodes. `By virtue of these features the creation of voltage antinodes at the centers of the electrodes becomes possible with a resulting `substantial increase in the output power. The nature of the invention will be more fully understood from the detailed description which follows and by reference to the accompanying drawing of which: Fig. 1 is a simplified schematic of the inven tion; Figs. 2 to 4, inclusive, areV diagrams illustra >tive of the operation of the invention; Fig. 5‘is a somewhat simplified showing «of a preferred form of the invention; and . Figs. 6 and 7 illustrate mechanical and circuit features of the oscillator of Fig. 5. cillation frequency. Where tuning by Lecher 25 Referring to Fig. 1, III is a vacuum tube con -ternal to the tube. This results in a restriction of the range and accuracy of adjustment ofthe os wires or adjustable concentric lines has been used, a common practice has been to extend the lengths of the lines sufliciently to include several half waves at the oscillation frequency. This has the advantages of permitting a wide range of 30 taining a straight ñlamentary cathode II, a con trol grid I2, and an anode I3, disposed in par-_ allel relation to one another. Lead-in wires ex Itend from both ends of the filament and plate through opposite sides of the tube to tuning‘con ductors I4, I5, I6 and I1, which constitute the frequency adjustment and, because of the inher centralconductors of sections of coaxial line ele ently low dissipation of the line structures, of ments I8, I9, Z0 and 2|. Each line section is ensuring a high degree of frequency stability. provided with a sliding short-circuiting bridge However, such arrangements tend to permit the `establishment of >oscillations at the lower natural 35 such las 22, by .means of which its effective length may be varied for tuning purposes. For the sake frequencies ofthe extended lines, with the result of simplicity the connections of the energizing that oscillation at the desired harmonic modes ‘ sources for the cathode and plate have been can be started and rmaintained only with difli omitted from the showing of Fig. 1, but these are 40 shown in Fig. 5. As is usual in thecase of feed- y In accordance with this invention the above back oscillators, the plate is positive with respect noted difficulty is avoided by employing the feed to the filament and thegrid may beat the same back method of oscillation generation using a direct current potential as the filament or .may triode vacuum tube and by tuning two of the be given a negative bias. The control gridis con- . interelectrode circuits by means of lines differing culty. Y - " ' in length by a predetermined fraction of a wave 45 nected directly to the outer conductors of the ~ tuning lines allfof which may be grounded. . length at the operating frequency. With this ar The pair of line sections I3 and I8 together rangement the phase or the magnitude, or both, with the filament Il and grid I2 constitute a of the feedback are such at the lower natural single substantially uniform shielded line short resonances of the lines that oscillations cannot circuitedat both> ends. Likewise, line sections 20 50 be sustained. For the generation of the highest and 2I together with the plate I3 and the grid frequency oscillations we find it advantageous to constitute Ia second substantially continuous operate the vacuum tube with its control- grid at short-circuited line. The two lines are shielded ground potential and to connect the tuning lines from each >other except for the. couplings pro to the grid-cathode> and grid-plate circuits, re spectively. .The feedback coupling may be pro 55 vided bythe direct capacity between the plate . 2,406,364 4 à and filament of the tube, denoted by Cp in the figure, and by the electron stream. The lines are Under stricted. frequency, the lengths diñering from each other They» are also acl plate and filament when standing waves are pro Y duced. With these adjustments rthe system oïscilá" be such as to permit oscillationsin a lower fre quency mode. lates readily at the desired frequency-correspond-V ,v Y Y' ' ï Y - v ' çonstructional features of an oscillator Y,‘embodying,the principles .of the y invention_ areV ing to the half Wave diiTerence inthe »lengths _of ` ’ ,Y tended further to include larger numbers of half waves andïthat the difference in their lengths ceuld be'inore than a single half wave, subject to` the condition that the dilîerence should not thatrvcltage atively to theantinodes mid-pointexist of the at the tubecenters electrodes of the» « ' short-circuiting It will be evident that the lines might be ex justed by positioning the short-circuited ends reln the lines. condition the bridges can be kept well clear of the tube struc ture so that the tuning adjustment is not re adjusted '_so that each is an integral number of half waves in length at the desired oscillation by one or more half waves. this . „shown inlFigs. 5, ,6 and 7. 'I‘he oscillatormay be looked upon as a modi- ' lied form of the well-known C'olpitts oscillator, ` in which the oscillation circuit comprises essen and tiallycathode two capacities and the plate interconnecting and cathode,the`-r respec grid Referring tc Fig. 5, `Ythe vacuum tube comprises a roughly hemispheri ' cal glass envelope 23 sealed to a iiat metallic .base 2d. ' v'The grid l2 is mounted directly on the base .2d and is electrically connected thereto. » Leads from both ends of filament i! and plate tively, and an inductance ,connected betweenrpthe tirare brought out through vglass seals,v,such as plate and the grid. One of the capacities is pro vided'by the plate to cathode tube capacity/1Ds and the other by detuning the cathode line lil, Vl 9 25, ineholes in the base'ëß, The four tuning linesAV I3, le, 29 Yand 2lY haveA their outer conduc ' to-«a frequencyavery slightlybelcw` the _oscilla-> tion frequency so -thatits ._eiïective reactance, ~ tors connected directly to the vacuumtube b_ase 'Ell 'and -extend perpendicularly thereto, The inner conductors Y*of the'li'nesconsist of small’Y measured at Ythe tube electrodes, is capacitive. diameter tubes such as 25, the o_uter surfaces of Correspondingly, the, inductive characterof the » which carry YtheÍhighÍ.'frequency' currents and - plate to'grid impedance maybe realized by Vtuning Vthe.' plateline 2,53, 2l to a frequency’very?slightly greater than-the oscillation frequency. `Y`This. ex» . ' Yplanatio'nof Vthe, character of the. Circuit isV given tentatively in Vthe absence Yof, more'vlexaot knowl-edge .of theactions> atltheextremely high, fl‘e? quencies contemplated.Y „ ' ' ` through which insulated conductorsarethreadedV „ forsupplying the necessary energizing currents to the’ plate" and fñlarnent.V ’These 'inner 'tubes areY held Yin place insiderthe outer conductors by ring" supports such as 2'! which may `be metallic. At'their inner ends, the inner tubes arev provided with ‘special condenser couplings te 'to ther/u1’-` Some of the various standing waveY conditions -`- - rent supply conductors top-rovide low impedance v that mayY existinthe tuninglines _of tlfieoscilla-r ` paths for the high frequency oscillations. ’These are shown diagrammatically in'Fig.'5 and inde tor with diiïerent adjustments of the short-,cir ycuiting `bridges'are shown in Figs. 2, 3 andre. In each of theseñgures the upper and lower hori zontal lines represent,Y respectively,l the? central conductors of the filament ,and plate tuning lines. The curves, designatedby Vr 4and IVD, superim posed thereon illustratethe _voltage distributions along these lines. , The endsof the voltagecurves correspond _to .the positions of the. short-circuit ing bridges.VVA The Ashortest `possible vadjustment ofthe linesis illustratedrbyeFig. 2,7,for whichcase each line supports onlyisingle half wave. _ Be, causeof` the. ìrreeularítiesßf the gemein’. Of the" electrodeY structures the voltage' distributionV ' maybe. expected to diiîer from the simple sinus o_idal Aform _characteristic of .a uniform line. With this mode Vof operation the range of ad justment is limited Yby the dimensions of the tube and the highest frequenciesA cannot bel produced. Fig. 3 illustrates one mode of operation in ac' extendedA cordance withthe on both sides invention. of the The tubeplate sufficiently Aline tail in Fig; 7. Adjustment of the eifective lengths , of the linesV is obtained by meansrof sliding _ bridges such as 28 comprising metallic piston . members drilled through the'center to' slide' over the'inner tubes and provided with >a circular> comb of nexible contact fingers which make cone tact with both line conductors. Direct current is supplied to 'the plate from a source through the inner conductor ofA line 2Q. " The "other termi nal of the plate` extends into the inner conductor of’line 2l but is insulated therefrom bycondenser coupling 30. Filament‘cu'rrent 'is supplied from a sourceV 3l, grounded atits positive terminal,` through >conductors threading the inner tubes of lines I3 and lil and is controlled by a circuit in cluding resistors 32 and 33, potentiometer 34, and ballast lamp 35. These elements also serve to provide a suitable Ynegative bias Yvoltage for the grid, the amount of which may beV controlled by the choice vof the values of resistors 32 and 33. > ‘An output circuit isindicated by a branching concentric line 36 connected to line 2E) .close to Ato accommodate three half waves and the y_fila Qment line is4 extended on one side only so thatl ` the base of the tube. When this output circuit it includes two half Waves.. VI'f the ñlament line ` wereY extended equally on the other side of the connection is used the impedance ofthe con nected circuit should be high and preferably but, with the two linesv V'differing by one-half should be so tuned as to prevent any substantial effect on the standing wave pattern in the oscil lator lines. Other well-known types of coupling , wave-"en_gth, oscillation is possible only at rthe may also be used. tube,_oscillation could take place at a greater Wave-length as indicated, by the „dotted curves, a higher> frequency. ` For the generation of the highest possible’fre quencies it is desirable that each, of thel lines shou1d__ include at _least three half >Waves', in ’ ' As already explained, the showing of Fig. 5 is to some extent diagrammatic»Y Constructional features of an actual oscillator are shown in Figs. ` 5 and A'2. Fig. 6 shows a plan View of' the tube base and electrodes, and Fig'. 7 vis a sectional which case the dimensions of theV tube no ylonger limit> Vthe .positioning of the `short-circuiting ' bridges.` Fig. ¿i illustrates the'stand'ingwavecon-- view showing the details of the line construction. The 'tuning lines, instead Yof being disposed side ditionswherí the filament line includes threeA by side are placed'at the four corners-of a square >half waves vand the plate line includes four. as indicated by the four small circles in Fig. 6. 2,406,1364' 5 section and a diamond-shaped plan. 6 1. An oscillation generator comprising a vac The vacuum tube plate I3 has a roof-like form in uum tube having a cathode, an anode and a con Th'e grid trol grid, a tuning line connected to said anode and said grid and a second tuning line connected to said cathode and said grid, said lines being short-circuited at their ends remote from the vacuum tube electrodes and >having unequal base plate provide supports for the tuning lines. lengths differing by an integral number of h'alf The lines fit over the supporting elements, good wave-lengths at the oscillation frequency, and contact and a firm hold being obtained by slit ting the ends of the outer conductors axially. 10 said electrodes being connected to said lines at points corresponding to voltage loops of the Oth'er familiar methods of attachment may, of standing waves developed in the lines at the os course, be used. The tube terminals take the cillation frequency. form of straight rods coming out through the 2'. An oscillation generator in accordance with centers of the line supporting tubes. Their con nections to the inner conductors of ~the tuning 15 claim 1 in which the tuning lines are extended has the sectional form of a U-shaped channel and has a multiplicity of narrow transverse slits, not shown, giving it a comb-like structure. Short tubular elements 31 welded to the tube on both sides of the vacuum tube electrodes suiii ciently to include on each side at least one half standing Wave in addition to th'e half wave cen tered about the connection of the electrodes to lines and the power supply leads are shown in detail in Fig. '7. Plate supply lead38, passing through the center of the inner conductor and insulated therefrom by glass beads 39 terminates in a tapered circular rod 40 which fits tightly in the end of the inner conductor tube and is insu lated therefrom by a layer of mica 4I. 'I'he end ,of the rod 40 projects beyond the inner conductor tube and is drilled and slitted axially to receive and make contact with plate terminal 42. The layer of mica between the terminal rod and the tube insulates the direct current supply circuit and at the same time provides a capacitive cou pling to the tubular conductor having very low impedance at ultra-high frequencies. The con nections to the other terminals of the tube are made in the same way as described above. For the adjustment of th'e short-circuiting bridges 28, rods 43 are provided which are con nected to the bridges and extend beyond the ends of the tuning lines. What is claimed is: ‘ 20 the lines. . 3. An oscillation generator in accordance with claim 1 in which the tuning lines are extended _ o-n both sides of the vacuum tube electrodes and in which the electrodes are connected to the line 25 extensions at the opposite ends of their major axes whereby -the electrodes are included as por tions of the line conductors. 4. An oscillation generator in accordance with claim l in which the tuning lines comprise co 30 axial conductors, the cathode of the vacuum tube being connected to the inner conductor of one of said lines, the anode being connected to the inner conductor of the other line, and the control grid being connected to the outer conductors of both' 35 of said lines. HARALD T. FRIIS. VINCENT C. RIDEOUT.