Патент USA US2408897код для вставки
Get.. 8, 1946. _ ' I A. H. TURNER MICROWAVE MULTI'BAND TUNER' Filed Nov. 29, 1945 l 'Bg I v2,408,896 _ v - 2`Sheets-Sheet 1 , Cíttomeg 011 3» 1946- A. H. TURNER 2,408,896 MICROWAVE MULTIBAND TUNER 4 Filed Nov. 29, 1945 2 sheets-sheet 2 3 nDenm t, ./Zgralfjâf. maar'. N CM ~ ’ Cîtt'orneg 2,408,896 Patented Oct. 8, 1946 UNITED STATES PATENT OFFICE 2,408,896 MICROWAVE MULTIBAND TUNER Alfred H. Turner, Collingswood, N. J., assigner to Radio Corporation of America, a corporation of Delaware Application November 29, 1943, Serial No. 512,107 6 Claims. (C1. Z50-40) l This invention relates generally to ultra-high frequency apparatus and particularly to an im proved microwave multiband tuner for covering a plurality of relatively wide microwave bands. One of the conventional methods of tuning at ultra-high frequencies is to employ a resonant line of suitable design across one end of which is connected a variable capacitor having a rela tively high maximum capacity. Such an ar rangement provides a theoretical limit of 1 to 2v between minimum and maximum frequency ad justments. In practice, the theoretical limit is not attainable because of non-uniform circuit constants. In addition, the loading effect of the device to which the tuner is connected reduces the practicable tuning frequency band. ` `The instant invention is an improvement upon applicant’s copending application Serial No. 481,215, filed March 3l, 1.943, entitled “Ultra high frequency tuner,” which is assigned to the same ‘ assignee as the instant application. Both inven tions contemplate the use of a resonant line con nected at one end to a suitable utilization circuit. The opposite ends of the line are connected to gether through one or more variable capacitors and an inductive element having an inductance of the order of that of one of the lines. The re sulting circuit comprises a parallel resonant cir cuit including the utilization device and the reso nant lines, having a series-tuned circuit includ ing the capacitive and the inductive elements connected across the ends of the lines remote from the utilization device. Adjustment of the reactance of the series capacitors effectively pro vides simultaneous adjustment of both the ca pacitive and inductive reactances of the circuit. Such an arrangement provides a theoretical limit of one to three between the minimum and maxi mum tuning frequency limits. Of course, the theoretical limit may not be attainable in actual 2 movable capacitive elements, and may be ar ranged to rotate with them. The eifective in ductanceof the inductive element is of the order of that employed for one of the resonant lines. It should be understood that two or more tuning .units of the type described may be connected to diiferent utilization circuits, such as, for ex ample, the input and output circuits of the same ordiiferent’thermionic tubes. It should also be understood that the rotating capacitive elements may be suitably ganged by means of any con venient mechanical arrangement. The improvements which the instant invention comprises with respect tovapplicant’s copending application described heretofore, include means for tuning over a plurality of relatively wide ultra-high-frequency bands, and especially means „ for maintaining substantially constant the pass band of the tuning apparatus over all portions of each of the tuning ranges. Further more, the inductive coupling between the various tuned circuits is supplemented by capacitive cou pling in the regions of voltage nodes in the tuned circuits, for providing additional coupling be tween said circuits over predetermined portions of the tuning bands. Simple switching means is provided for switching between the various tuning wave bands. , It should be understood-that the instant in vention may employ either open resonant lines or coaxial resonant lines, as described in applicant’s copending application identified heretofore, as portions of the resonant circuits. Among the objects of the invention are to pro videan improved method of and means for tun ing an ultra high frequency circuit. Another object is to provide an improved method of and means for varying simultaneously the inductive and capacitive reactance of an ultra high fre quency circuit. A further object of the inven tion is .to provide an improved method of and means for tuning an ultra high frequency circuit over a relatively wide band of frequencies. An other object is to provide an improved method The tuning means comprises a pair of resonant lines of the order of one quarter to one half wave 45 of andmeans for varying simultaneously the se practice, but the practical limits substantially ex ceed those possible with the conventional tuning arrangement described heretofore. length at the operating frequency which ter minate at one end in the utilization device and at the other end in iixed capacitor electrodes. Two movable capacitor electrodes are disposed invariable capacitive relation to separate ones of. the ñxed capacitive elements and arranged to vary simultaneously the capacity between each fixed and movable-electrode. A lumped induc tive element, such as, for example, a relatively small helix, is connected directly between the ries inductive and capacitive reactance in a plu rality of ultra high frequency tuned circuits. A still further object of the invention is to provide an improved method of and means for tuning a concentric ultra high frequency kline by ad justing simultaneously the series inductive and capacitivereactances connected to said line. Additional objects of the invention include an improved method of and means for tuning micro _wave .apparatus over »a plurality of microwave 2,408,896 3 4 frequency bands. Another object of the inven cated by the phantom capacitors cl, c2, It Will tion is to provide an improved microwave multi band tuner having substantially uniform band pass characteristics and providing substantially uniform coupling between coupled tuned circuits throughout the frequency range of said tuner. be seen that the distributed capacities cI and c2 will supplement the coupling between the reso nant lines at the high frequency end of the tun ing band as illustrated in graph (a) of Figure 2. 'I'he invention Will be described in greater de tail by reference to the accompanying drawings of which Figure 1 is a schematic circuit diagram of a pair of coupled circuits connected according to the invention; Figure 2 is a family of graphs A small fixed capacitor I I is connected between the anode end of the resonant line 4 and the con trol electrode end of the resonant line 5'. A sim ilar fixed capacitor I2 is connected between the control electrode end of the resonant line 4' and circuits of a multiband microwave receiver in the anode end of the resonant line 5. These ca pacitors are connected to the resonant lines at points which correspond to voltage nodes at the high frequency end of the tuning band and hence correspond to regions of voltage maxima at the low frequency end of the tuning band, thereby cluding features of the invention, and Figure 4 providing appreciable coupling at the low fre is a perspective fragmentary view of the struc tural details of a preferred embodiment o1’ the invention as shown schematically in Figure 3. -' Similar reference characters are applied to simi quency end of the tuning band. indicating the voltage distribution on a tuned line comprising one component of the circuit of Figure l; Figure 3 is a schematic circuit diagram of the radio frequency, mixer and local oscillator lar elements throughout the drawing. When additional inductive elements, not shown, are connected in series with the tube ends of the resonant lines at the points marked (x) to provide tuning throughout an additional rela Referring to Figure l, a utilization circuit, com tively lower frequency band, the capacitors II, I2 prising the anode circuits of thermionic tubes 24 and 25, and having an inherent capacitance rep resented by the interelectrode tube capacities and effectively are moved nearer the tube ends of the resonant circuits, thereby improving the mutual coupling between the lines at the low frequency the inter tube capacities, is connected to one end of a first resonant line, represented by an induct ance 4, and to one end of a second resonant ond of the lowest frequency tuning band. 'I'he tuning range of the tuned coupled circuits fur line, represented by a second inductance 5. The remaining terminals of the resonant lines 4 and 5 terminate, respectively, in fixed capacitive ele ments E and l. A first movable capacitive ele ment 8 is disposed in variable capacitive 'relation with the first ñxed capacitive element 6. The juxtaposed capacitive elements 6, 8 form a ca pacitor, which may be varied. A second movable capacitive element 9 is disposed in similar vari able capacitive relation to the second fixed ca pacitive element l. A third inductive element l0, which, for example, may be a small substan tially rigid helix, having an inductance of the order of the inductance of one of the resonant lines, is connected between the first and second movable capacitive elements 8 and 9. The third inductive element I0 may, if desired, be rotated simultaneously with the movable capacitive ele ments 8 and 9, These movable capacitive ele ments may be individually or interdependently rotated. Similarly, the control electrodes, for example, fixed variable capacitors 53, 54 connected, re spectively, between the anodes of the tetrode ther may be adjusted or extended by means of tubes 24 and 25 of the control electrodes of the double triode tube 34 to increase the effective loading capacitances of the utilization devices. Referring to Figure 3, an ultra-high frequency multiband receiver circuit comprising an ultra high frequency amplifier, an ultra high frequency oscillator and an ultra high frequency mixer or iirst detector. is shown in combination with tun ing circuits of the general type illustrated in Fig-, ure l and described in detail heretofore. A con centric transmission line 2| connected, for ex ample, to a suitable receiving antenna, not shown, is connected to one end of an input coupling loop 22. The remaining end of the input coupling loop 22 is connected to ground through a variable tuning capacitor 23. ~ Y An ultra high frequency balanced amplifier _such as, for example, a pair of tetrode tubes 24, 25 is self-biased ¿by means of a conventional common cathode resistor 2B and cathode bypass of a double triode tube 34 are each connected capacitor 21 which are connected between the respectively to one end of third and fourth res cathodes and ground. The control electrodes of onant lines, represented by the inductances 4' each of the tubes are connected to the ends of and 5', respectively, Likewise, the remaining ~ a center-tapped grid inductor 28 which is induc ends'of the third and fourth resonant lines, rep - tively coupled to the input loop 22. The center resented by the inductances 4', 5', respectively, terminal of the grid inductor is grounded. are connected to fixed capacitive elements 6', 1', The anodes of the first and second triodes 24, respectively. Similarly, movable capacitive ele ments 8', 9’ are connected together through a second small substantially rigid helix I0’ having an inductanoe of the order of the inductance of one of the resonant lines. The resonant lines 4, 4', 5, 5', preferably are symmetrically arranged and equidistant from each other to form the diagonally opposite cor ners of a square or a rectangle whereby the mutual inductive coupling between the various resonant lines is maintained at a substantially constant value. Y The mutual inductive coupling between the several resonant lines is supplemented by the dis tributed capacities between the tuning capacitors 6', 8' and 1, 9, respectively, and between the tun ing capacitors 6, 8 and l', 9', respectively, as indi 25 are connected each to one terminal of corre sponding first and second helical low band in ductors I5, I6. The remaining terminals of the low band inductors I5, I6 are serially connected, respectively, to first and second helical high band inductors I1, I8. The remaining terminals of the high band inductors I'I, I8 are connected to the ends of short resonant lines 4, 5. The re maining terminals of the resonant lines 4, 5 are terminated. respectively, in first and second fixed capacitive elements B and 1_ The movable capacitive elements 8 and 9, which are in capacitive relation., respectively,y with the fixed capacitive elements 6, and l, are connected together through a compact bunched helical in ductive element I0 of the type described hereto fore. Operating potentials for the anodes of the '2,408,896 ytwo triodes 24, 25 are provided from any suitable source, not shown, and applied to the respective electrodes through suitable isolating resistors 3l, 6 The gauging of the four swítchesis indicated in the drawings by the dash line 60. The supplementary coupling `capacitors are connected in the same manner as described here ` A mixer or converter stage includes a 'double Ul tofore in the circuit of Figure 1. The capacities ci, c2 are indicated by dash lines between the triode 34 having the two anodes thereof con 32 and 33. nected together and connected to the primary of an intermediate frequency transformer 36. The cathode is connected to ground. The control electrodes of the two triodes of the double triode 34 are each connected to one end of separate resonant circuits comprising second low band in ductors I5’ and I6’ respectively connected in series with second high band inductors I1’ and I8' and resonant lines 4' and 5’. The resonant B., F. amplifier and converter tuned circuits. Similar capacities c3, c4, also shown in dash lines, indicate coupling between the converter and oscillator tuners. The two coupling capacitors Il, i2 are connected between the tube ends of the resonant circuits of the R. F. amplifier and converter in the same manner as indicated in the circuit of Figure l, Similar capacitors II’ >and i3’ couple between the tube ends of the resonant circuits of the converter and oscillator tubes. lines 4' and 5' are inductively coupled to the res Referring to Figure 4, a preferred mechanical onant lines 4 and 5 of the radio frequency am construction employing the several features of pliñer anode circuit. The resonant lines 4', 5' the invention comprises a plurality of variable are tuned by a second tuning unit 6', 1', 8', 9', capacitive elements indicated by reference nu I0', of the type described heretofore, which is 20 merals conforming to the equivalent elements of serially connected to the lines 4', 5', and with the the circuit of Figure 3. The inductive elements corresponding low band and high band inductors I5, I 0', Iü” are shown as small helical inductors I5', I5', Il', I8'. A grounded center-tapped re secured between the rotatable capacitor plates sistor network 31, 38 is connected between the 8, I9, 8', 9', 8", 9", respectively. The low band common terminals of the inductive elements I5', inductors are shown as small substantially rigid I1' and I6', I3', to provide a d-c grid return helices I5, I6, i5', I5', I5" and I6”. rI‘he high circuit for the balanced converter. band inductors are shown as similar small sub An ultra high frequency oscillator includes a stantially rigid helices I1, I8, I1', I8', I1", i8" double triode 44 having its cathode connected to which are supported between the lower contacts ground through a cathode resistor 45 and cathode ~ capacitor 46. The grid circuit of the oscillator is comprised of a single turn loop 41 terminating in the two control electrodes and having its cen ter-point grounded through a grid resistor 48. The anode circuit of the push-pull oscillator in- ‘ cludes a third tuning unit 6", 1", 8", 9", I0" serially connected with corresponding lines 4", 5” and low band and high band inductors I5", I6", I1", I8". Anode potential is applied to the two anodes through anode resistors 49, 50. The three tuning units described heretofore may be ganged as indicated by the dash lines 5I. The balanced oscillator circuit is coupled to the converter input circuit by means of mutual in ductive coupling between the tuned resonant lines in any manner known in the art, It should be understood that the constants of the circuits will be so selected that the desired intermediate fre quency may be derived from the converter anode circuit. For example, the several tuning capacitors may be of a conventional type providing a capacity range of the order of from one to ten micro micro-farads. Circuits of the type described have been constructed to provide suitable tuning over ranges extending from 90 to 130 megacycles and 130 to 230 megacycles. These ranges could be extended readily by proper selection of circuit constants, and by adapting the constructional features to the desired frequency ranges in a manner well known in the art. |The three resonant circuits may be matched, or the low frequency limits thereof extended, by means of variable capacitors 53, 54 and 55 con nected respectively in shunt with the correspond ing tube ends of the resonant circuits. Similarly, band switching of the three resonant circuits is obtained by means of three four-pole, two posi tion wafer type switches 56, 51 and '58 which selectively short-circuit the several low band in ductors I5, I6, I5', I5', I5" and I6"_ The three switches 56, 51 and 58 may be ganged together and ganged to a band switch 59 adapted to iorten the grid loop 41 of the oscillator circuit. of the corresponding wave band switches and one end of the corresponding resonant lines 4, 5, 4', 5', 4", 5”, respectively. It should be noted that the low band helices are secured directly to the cor responding band switch terminals to minimize residual circuit reactances and provide conven ient support. The band switches 58, 51, 58 may be the conventional wafer type band switch em ployed in commercial multiband tuners wherein the various switch wafer elements are insulated from each other. The various fixed capacitor plates B, 1, 5', 1', 5", 1" may be secured to insulating base supports ’53, E5 for convenient mounting to the receiver chassis, not shown. Similarly, the band switches 56, 51, 58 may be supported in any convenient manner by the re ceiver chassis and provided with a suitable actu ating mechanism, not shown. The supplemen tary tuning capacitors 53, 54, 55 and the sup plementary coupling capacitors II, I2, II', I2’ are indicated schematically to simplify the draw ings. lln practice, these capacitors should be the small tubular type well known in the art. Shielding, of the type indicated by the frag mentary shield portion 55, may be employed in accordance with recognized shielding procedure between any of the tuned circuits requiring iso lation. It should be understood that inductive coupling between the various resonant circuits may be adjusted by adjusting the position and size of the shields isolating said circuits. Thus the invention described comprises im provements of the invention described in appli cant’s copending application identified hereto fore, wherein multiband tuning is provided at microwave frequencies, and novel capacitive coupling is included to supplement the inherent inductive coupling between a plurality of circuit tuning elements, thereby to provide substantially uniform band width throughout the tuning range ’ and substantially constant reaction between said coupled circuits. I claim as my invention: 1. Ultra-high-frequency apparatus including a plurality of inductively coupled tuning circuits lmoeras@ 8 each comprising a pair of resonant lines and ad justable means for tuning said lines, a plurality of coupling capacitors, and means connecting said capacitors between the resonant lines of different von said lines to vprovide predetermined'micro ones of said coupled circuits at predetermined points on said lines to provide predetermined including a. plurality of inductively coupled tun ing circuits each including, in combination, a pair of resonant lines, a pair of adjustable capacitive wave coupling between said circuits throughout the tuning range of said circuits. 5. Multiband ultra-high-frequency apparatus `coupling between said circuits throughout the tuning range of said circuits. elements each having at least a fixed electrode 2. Multiband microwave apparatus including a plurality of inductively coupled microwave tuning vand a movable electrode, an inductive element circuits each comprising a pair of resonant lines and adjustable means for tuning said lines, a plurality of coupling capacitors, a plurality of loading inductors, means for selectively and the inductance of one of said resonant lines. having an inductance at least of the order of ' means connecting said inductive element between said movable electrodes of said capacitive ele ments, means connecting one extremity of each of said resonant lines to a different one o1' said iixed electrodes of said capacitive elements, a. utilization device, means connecting the remain ing ends of said lines to said utilization device, simultaneously interposing one of said loading inductors in each of said resonant lines to change the tuning waveband thereof, and means con necting said capacitors between the resonant lines of different ones of said coupled circuits at pre and means for adjusting simultaneously the determined points on said lines to provide pre 20 capacity of all of said capacitive elements to vary determined microwave coupling between said cir cuits throughout the tuning range of said circuits. 3. Ultra-high-frequency apparatus including a plurality of inductively coupled tuning circuits simultaneously the effective series inductive and capacitive reactance of all of said circuits; a plu rality of loading inductors, means for selectively and simultaneously interposing one of said load ing inductors in each of said resonant lines to each comprising a pair of resonant lines and ad justable means for tuning said lines, a plurality change the tuning waveband thereof, a plurality of coupling capacitors, and means connecting said of coupling capacitors, and means connecting capacitors between the resonant lines of diii’erent said capacitors between the resonant lines of ones of said coupled circuits at points on said diiîerent ones of said coupled circuits at prede lines corresponding to the regions of voltage anti 30 termined points on said lines to provide prede nodes at the limits of said circuit tuning ranges termined coupling between said circuits through to provide predetermined coupling between said out said tuning bands. ' circuits throughout said tuning range of said 6. Multiband microwave apparatus including circuits. a plurality of inductively coupled microwave tun 4. Multiband microwave apparatus including ing circuits each including a pair of inductive a plurality of inductively coupled microwave tun ing circuits each comprising a pair of resonant lines and adjustable means for tuning said lines, a plurality of coupling capacitors, a plurality of elements `and adjustable means for tuning said circuits, a plurality of coupling capacitors, a. plurality of loading inductors, means for selec tively interposing said loading inductors in each loading inductors, means including separate 40 of said tuning circuits to change the tuning waveband thereof, and means connecting said ductors for selectively and simultaneously inter capacitors between said inductive elements of dif short-circuiting means shunting each of said in posing one of said loading inductors in each of ferent ones of said coupled circuits to provide said resonant lines to change the tuning wave predetermined microwave coupling between said band thereof, and means connecting said capaci 45 circuits throughout the multiband tuning range tors between the resonant lines of diiîerent ones of said circuits. of said coupled circuits at predetermined points l ~ ALFRED H. TURNER.