US2641657A - Radio-frequency transmission device - Google Patents

Description

5 Y RTU www/W M EL VR 0 MEM? w Nv M0. A M Y m. me. or D5 Y B mm. whgwww Lbn D. H. PREIST ETAL RADIO-FREQUENCY TRANSMISSION DEVICE June 9, 1953 Filed April 18, 1949 June 9, 1953 D. H. PREIS-r ETAL RADIO-FREQUENCY TRANSMISSION DEVICE 2 Sheets-Sheet 2 Filed April 18, 1949 INVENTOR` DONALD H. PQE/57' Brno/v 0. ALLoU ATTORNEY Patented June 9, 1953 RADIO-FREQUENCY TRANSMISSION DEVICE Donald H. Preist, Tiburon, and Byron Of. Ballou,

San Bruno, Calif., assignors to Eitel-McCullough, Inc., San Bruno, Calif., a corporation of California Application April 18, 1949, Serial N o. 88,182

2 Claims.

Our invention relates to generators of radiofrequency power, and more particularly to such a generator capable of delivering large orders of power in the higher frequency ranges, say above 100 mcs/sec., using conventional type negat1ve grid tubes.

In the copending application of Donald H. Preist, Serial No. 42,171, filed August 3, 1948, now Patent No. 2,554,500, issued May 29, 1951, there is disclosed a new type of R. F. generator embodying an annular cavity resonator operating in conjunction with a plurality of tube units, whereby the power outputs of the individual tube units are combined without appreciable loss,

'Ihe object of our present invention is to provide an improved construction for such a multiple unit tube generator.

The invention possesses other objects and features of advantage, some of which with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure 1 is a vertical sectional view of a power amplifier embodying the improvements of our invention; and

Figure 2 is a plan view of the same, the line I-I indicating the plane of section of Figure 1.

In terms of broad inclusion, the radio-frequency generator of our invention comprises a plurality of tube units disposed in -a circle about an axis, and a pair of annular cavity resonators l coaxial with the circle and having conductors connected to electrodes of the tube units, each resonator comprising two communicating annular cavity sections. As embodied in an amplifier one of these cavity resonators functions as the input circuit and the other as the output circuit. In our generator of such annular construction improved means are provided for feeding R. F.

power into and out of the resonators. The output transmission line coupled to the output resonator is arranged coaxially with the generator, and the input transmission line coupled to the input resonator is spaced from the generator axis, a plurality of the input lines being provided and so spaced as to lie in the circle defined by the tube units. An output tuning stub is also preferably provided, formed as an extension of the output line and located centrally of the generator.

In greater detail, and referring to the drawings, our improved R. F'. generator constructed as an amplifier comprises a plurality of electron tube units I disposed in a circle about a common axis, which tube units are of like structure and have like characteristics. While four tube units are shown, it is understood that any desired number may be employed, depending upon the power output required. Any conventional type of negative grid electron tube may be used for the units I, the triode type of tube illustrated having a cathode 2, grid 3 andanode 4, the anode being external and all the electrodes being preferably cylindrical and coaxial.

The tube units employed `also preferably have coaxial terminals for the electrodes, such as the cathode terminal 6 opposite the anode and the grid terminal ring 'I interposed in the glass envelope wall between the cathode terminal and anode. The heating structure for the cathode is not shown but may comprise any suitable means such as an inner filament for heating the cathode cylinder 2 by electron bombardment, in which case the filament leads preferably extend out through the tubular cathode terminal 6.

The amplier has a pair of annular cavity resonators common to the tube units I, functioning as the input and output resonant circuits for such units. Each resonator has two communicating annular cavity sections arranged coaxially with the circle of tube units, thus the input resonator has the two annular cavity sections 8 and 9 communicating through spaces between the lower portions of the tube units, and the output resonator has the two annular cavity sections I I and I2 communicating through spaces between the upper portions of the tube units. This symmetrical arrangement of the cavity resonators with respect to the tube units is an important feature in our R. F. generator.

The two cavity sections 8 and 9 of the input resonator extend downwardly from a plane defined by the circle of tube units, say a plane passing through the mid-portions of the units I. Cavity sections I l and I2 of the output resonator also extend downwardly from such plane and surround the input resonator.

The several cavity sections of the resonators are denned by metallic boundary walls or conductors which make up the physical structure yof the amplier. As illustrated, the annular cavity sections of the resonators are defined by six concentric wall conductors I3, I4, I6, I'I, I8 and I9. The shorter walls are connected across the top by ametal ring 20, these parts comprising an inner conductor of the input resonator. I'his inner conductor is connected to the cathode 2 of each of the tube units, preferably by having cathode terminals 6 seated in apertures or sockets in thelring 20.

Suitable leads for the cathode heater means may conveniently extend out through the hollow space formed between the walls I3 and I4.

A transverse conductor member or metal ring 2| extends across the top 4of the input resonator in the plane of the grid terminal rings 'I and is connected .to the vcylinders I6 and l1. .This .transverse conductor comprises the top Wall of the input cavity 8-9 and also forms a common dividing wall between the input and output resonators. v

Cavity sections 8 and 9 of theinput resonator .are thus connected about their circumference by the communicating space formed between the transverse wall members 2D and 2I. Conductor 2| is electrically connected for R.. F. to the grid V3 of each of the tube units through suitable bypass condensers as hereinafter described.

Wall conductors I8 and I9 are joined across the top by a transverse wall conductor 2e. Cavity. sections lI and I2 of the output resonator are thus .also ycorn'iected about their circumference by the communicating space formed between .the 'transverse'wallrneinbers 2l and-24. Conductor .2lI1is electrically connected ,for R. F. to the vanode Azoffeach'of the tube units'through suitable bypass condensersas hereinafter described.

By this :arrangement it will be seen that 'the cavity resonators are `coaxial with the circle vor tube units, and are disposed in such a manner that the `tube units arelocated between the Yannular cavity sections of the resonators, with the cathodes connected to .a conductor of the input resonator, the anodes connected to a conductor of the output resonator and thegrids connected to a common transverse conductor 'between the resonators.

It will thus'be noted .that each resonator cornprises v'two cavity sections, each section being constitutedby the space between a pair of concentric cylinders. The lengthof each'section, 'measured a yaxially of the circle of tube units, is substantially greater than the width of the section, measured radially of the circle of tube units, i. e., the difference in radius of the concentric cylinders which Vdeiine the section (ignoring the thickness of the cylinders). An annulus having a greater 4axial than radial dimension, measured as described, is defined hereinafter as an axially ex-` tending annulus.

The 'several cylindrical conductors of the resonators are held mechanically in position by rings 2.8, 2S, -30 and 3I of suitable insulating material located between the conductors at the bottom of @the generator. Any suitable metal such as brass maybe used for the various cylindrical and transverse conductors described.

Adjustable means are provided for tuning the input and output resonators to the desired resonant frequency. For thispurpose a pair of mov- .able annular metal plungers orshorting bars 32 and 33 are provided inthe input resonator, `forming end walls in the cavity sections and 9 respectively. vThese plungers are slideably mounted on the wall conductors, and axial adjustment is achieved by means of .plunger rods 34 and 35 of insulating material projecting out through the supportsg and 30. These rodsmay be connected externally to insure that the plungers are adjusted in unison.

.In a like manner plungers St and 39 are providedin the cavity sections I I and l2 of the `output resonator, which plungers are slideably mounted on the wall conductors and adjusted by plunger rods lll ande?.

The D. C. voltages may be applied to the tube electrodes in any suitable manner. In the amplifier illustrated, which is essentially a grid-separation type of circuit, the positive D. C. anode potential and bias voltages are applied through suitable leads to the anodes and grid terminal rings. Suitable leadsvfor the cathode heaters for `the several tube units are conveniently brought out through the hollow space between the conductors I3 and Ill.

The D. C. voltages are preferably isolated by suitable .bypass condensers at the anode and grid terminals of the tube units. For example, each anode fi is preferably provided with aterminal disk 46 located below the anode cooler lil; the latter being either of a nned type as illustrated for forced air Acooling or of the jacket type for water cooling. The bypass condenser is conveniently formed by rings I of insulating material separating the terminal disk 4e from the conductor 2d at one side and a retaining ring i9 on the .opposite side. In a like manner a terminal disk 5I is connected to the grid terminal ring 'I and separated from :the 'conductor 2| and a retainingring 52 by .rings 53 of insulating material. For convenience of replacing the tubes, the grid terminal disk 5I preferably has contact iingers 54 for yengaging the grid ring I so that the tube-plugs ,into .this part as a socket, whereby the tube may lbe withdrawn by merely removing the retainingring 49 or having a suitable joint in theterminal disk 46.

An important feature of our present invention Ais themeans .employed for transferring and coupling R. F. power into and out of vanannular generator of the .character described. Driving power from a suitable source tothe input resonator is transferred by a coaxial transmission line '5t extending up through the open space between conductors I3 and IH. and suitably arranged between the tube units I. This line comprises an inner conductor `5'I terminating at the transverse meinber '2| and anouter conductor 58 `terminating at thetransverse member 29, thus .providing the desired coupling for transferring energy from thetransmission line 56 to the input resonator, it being noted that the input transmission line 5t terminates at the communicating space between the cavity sections 8 and 9. At least two of the input lines 56 are preferably incorporated, diamet-rically disposed as illustrated in Figure 2, so Ias lto .provide a balanced coupling. These lines are preferably connected externally to a common transmission line (not shown) which feeds the power from the driving source. In other words,

'the 'input transmission lines 55 are spaced from the'axis of the generator and lie in the same circle as the tube units l. The advantage of this oir"- center arrangement of the input lines is that it provides a satisfactory means for coupling the driving power into the annular input resonator without taking up space along the axis of the generator, which central space may be then utilized for other purposes.

Power is preferably transferred from the output resonator by .a transmission line E5) along the axis of the generator, and comprising an .outer conductor 5I terminating at thetransverse conductor 24 and an inner conductor E52 extending downwardly within the conductory I8. Coupling of energy from the output resonator is established by the circular slot 53 formed between the ends of aligned conductors 6l and I8. The extension of the inner conductor @2 together with the surrounding conductor IB provides an output tuning stub which is tuned by anannular snorting bar 64 adjusted by plunger rods 66. This arrangement of the input and output transmission lines and the output tuning stub provides a very compact generator construction.

In our improved R. F. generator the overall diameter of the generator may be increased indefinitely to accommodate an indenite number of tube units, depending upon the amount of power required. Furthermore, the multiple unit tube generator described will operate well in the higher frequency ranges, say above 500 mcs/sec., without loss of efficiency compared to that obtainable from a single tube unit. The total power output from n tube units, as measured at the load, is substantially n times that obtainable from a single tube unit in an efcient single unit tube generator.

While we have described our generator in connection with triode units, it is understood that tube units having additional electrodes such as tetrodes may be emploged, in which case additional annular, coaxial and symmetrical circuit members are employed.

We claim:

1. A radio-frequency transmission device comprising a plurality of electron tube units disposed in a circle about an axis and each havingr electrodes including an anode and cath-ode, an output cavity resonator common to the tube units and having two communicating, axially extending, annular cavity sections, the output resonator being coaxial with said circle and having a conductor connected to an anode of each of the tube units, an input cavity resonator common to the tube units and having two communicating, axially extending, annular cavity sections, the input resonator being coaxial with said circle and having a conductor connected to a cathode of each of said tube units, the axial dimension of each cavity being substantially greater than the radial dimension thereof, an output transmission line coaxial with said circle and coupled to the output resonator, a tuning stub coaxial with said circle and forming an extension of the output line, and an input transmission line spaced from said axis and coupled to the input resonator.

2. A radio-frequency transmission device comprising a plurality of electron tube units disposed in a circle about an axis and each having electrodes including an an-ode and cathode, an output cavity resonator common to the tube units and having two communicating, axially extending, annular cavity sections, the output resonator being coaxial with said circle and having a conductor connected to an anode of each of the tube units, an input cavity resonator common to the tube units and having two communicating, axially extending, annular cavity sections, the input resonator being coaxial with said circle and having a conductor connected to a cathode of each of said tube units, the axial dimension of each cavity being substantially greater than the radial dimension thereof, an output transmission line coaxial with said circle and coupled to the output resonator by a circular slot, and a tuning stub coaxial with said circle and forming an extension of the output line on the opposite side of said slot.

DONALD H. PREIST. BYRON O. BALLOU.

References Cited in the ile of this patent UNITED STATES PATENTS Number Name Date 2,173,908 Kolster Sept. 26, 1939 2,281,550 Barrow May 5, 1942 2,284,405 McArthur May 26, 1942 2,363,641 Carlson Nov. 28, 1944 2,404,261 Whinnery July 16, 1946 2,407,068 Fiske et al. Sept. 3, 1946 2,412,805 Ford Dec. 17, 1946 2,554,501 Preist May 29, 1951 2,554,502 Prest May 29, 1951

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