US2425352A - Ultra high frequency electron discharge device system - Google Patents

Description

Aug. 12, 1947. I

ULTRA HIGH FREQUENCY ELECTRON DISCHARGE DEVICE SYSTEM Fild Aug. 2e, 1944 2 sheets-sheet 1 .H Ud

Aug. l2, 1947. R. sLoss 2,425,352

ULTRA HIGH FREQUENCY ELECTRON DISCHARGE DEVICE SYSTEM n Filed Aug. 26, 1944 4 2 sheets-sheet 2- ATTORNEY Patented Aug. 12, 1947 ULTRA HIGH FREQUENCY ELECTRON DISCHARGE DEVICE SYSTEM Robert Sloss, Audubon, N. J., assignor to Radio Corporation of America, a corporation of Dela- Ware Application August 26, 1944, Serial No. 551,289

(CL. Z50-36) 4 Claims.

The present invention has for its primary object to provide a frequency converter or mixer circuit suitable for use at very high frequencies of the order of 3000 megacycles.

Another object is to provide a compact, very high frequency converter system suitable for use in a radio relaying system adapted to receive angular velocity modulated waves and to convert l these waves to waves of another frequency.

The frequency converter of the invention includes a concentric line resonator at whose high voltage end there is mounted a non-linear device in the form of a crystal detector bridging the space between the inner and outer conductors of the resonator. This detector is connected at one end to the outer conductor of the resonator and has its other end protrude into the interior of the hollow, inner conductor through an aperture in the inner conductor. The resonator is fedwith waves of two different very high frequencies so as to cause the detector to produce a beat frequency equal to the difference frequency. Both waves develop voltage on the line resonator, and hence, voltage at both very high radio frequencies is developed across the terminals of the crystal rectifier. i

A feature f the invention lies in the mounting of the local oscillator and its associated cavity resonator, as a result of which it is possible, by a simple adjustment, to move as an integral unit the entire oscillator assemblage including the output probe.

A description of the invention follows in conjunction with a drawing, wherein:

Fig. 1 schematically illustrates the frequency converter or mixer circuit of the invention, in-

' cluding the associated local beating oscillator;

Fig. 2 illustrates in detail the mechanical assemblage of the circuit elements of Fig. 1, particularly the local oscillator and frequency converter, and the manner in which thelocal oscillator unit can be moved by a simple adjustment, in accordance with the invention; and

Fig. 3 is a side View of the apparatus of Fig. 2

as seen looking in the direction of the arrow 3 with the oscillator removed.

Throughout the figures, the same or equivalent parts are given the same reference characters.

Although the present invention is hereinafter described with particular reference to a radio relaying system adapted to receive angular velocity modulated waves, it should be clearly understood that it is not limited thereto and has more general uses.

Referring to Fig. 1 in more detail, there is shown a source of input waves of a mean frequency of 3000 megacycles in the form of a transmission line 100. This line may extend to a suitable receiving antenna (not shown), or any other source of waves. The energy of 3000 megacycles impressed upon the line may be suitably modulated as to frquency, such that the input frequency varies plus and minus 1.17 megacycles, by way'of example. Line 100 is provided with a surrounding metallic conducting shield 102 which is grounded at 104. The frequency converter c-r mixer comprises a metallic cavity resonator 106 which is preferably cylindrical in shape. This resonator has its external surface grounded at 104. Coupling between the cavity resonator 106 and the input line 100 is made by means of loop 105. In the alternative, line 1D0 may be replaced by a wave chute or guide.

Extending within the resonator 106 and connected to one of its bases is cylindrical line section 190 whose base 19| is adjacent and spaced from the metal circular base 192 carried by metal bellows 1I I. The line section 190 acts as an inductance and is tuned by means of this cylindrical metallic bellows 1II having, as indicated, springy corrugated side walls. By means of the bolt 1 I3 and nut 1 I 5, the capacity between plates 19| and 192 is adjusted as is also the volume or internal cubical content of the resonator. Preferably the line section 190 is approximately one-quarter wave-length long-here about 3A of one inch. This line section is tuned by adjustment of plate 192 to the frequency of the `waves received and fed in at loop 105. A crystal detector 198 is mounted as shown at the high voltage end of the line section 190 with one terminal 195 in electrical contact with a wall of resonator 106 and its other terminal 196 protruding through opening 191 in the cylindrical' line section 190. Terminal 136 is connected to conductor or line 1I0. As a result, the crystal detector recties the waves fed in at 105 and 1I8 and feeds the resulting difference frequency of about 30 megacycles into line 1 I 0.

The cavity resonator 106 is also supplied with high frequency oscillations by means of a capacity end plate 1|8 located in the interior of the cavity resonator and fixed to the inner conductor of an exposed section of coaxial transmission line 122 which inner conductor extends into the resonator. The conductor 120 is excited by an automatic frequency controlled high frequency oscillator operating in the neighborhood of either 3030 megacycles or 2070 megacycles. The oscillator will be described more fully later.

3 The crystal detector 108 recties the waves fed in at 105 and 1I8 and produces a lbeat frequency of 30 megacycles which is fed through line 1I0 shielded by the surrounding conductor 1 I2 to the pirrnary coil 1 I 5 of a transformer whose secondary coil 126 is tuned by condenser 128. The output of the tuned circuit 126, 128 is fed through line 132 to the first stage of suitable intermediate fre-v quency amplifiers and limiters.

The high frequency oscillator 138 operates in the neighborhood of 2070 megacyclesv or 3030 megacycles. The oscillator comprises an evacuated container 138, a cathode 134 grounded at 136, a negatively biased plate 156, a cavity resonator 142 charged with voltage of a positive polarity from -battery 298, and a grid 144 connected to the resonator 142. The resonator 142 (shown in cross section) is cylindrical in shape and is made of metal. This resonator has end plates or bases 152, 154 which are perforated and to which are attached the hollow metallic inner tubular conductors 146, 150. The metallic tubes 145, 150 are separated at an intermediate point so as to provide a gap 148. Oscillations are set up in the cavity resonator 122 and wave output is derived from the inductive loop 100 coupled to the space Within the cavity'resonator 142. The

external surface of the cavity resonator 152 is` hence, its frequency of operation. Or, if. desired,`

a metallic bellows adjustment, such as that provided for the cavity resonator 106 may be proand the capacity plate vided for cavity resonator 142, but in this case,

of course, the container 138 should be hermetically sealed to resonator 142 so that a portion of its external surface containing and otherwise supporting the metallic bellows structure would be exposed for external adjustment.

'I'he outputappearing in the tuned circuit 120, 128 .would be, for the example chosen, a Wave having a mean frequency of 30 megacycles and maximum frequency deviation of L1.1'1 megacycles. This wave is fed to suitable intermediate frequency amplifying, limiting and discriminator detector stages.

Figs. 2 and 3 show in greater detail a mechanical arrangement of apparatus which the oscil` lator 138 and mixing and detecting system 106 of Fig. 1 may take. Fig. 2 is a plan view of the oscillator 138 and the mixing and detecting apparatus 106, the latter being shown in cross section for a clearer understanding of the apparatus. Fig. 3 is a View of Ythe apparatus of Fig. 2 seen looking in the direction of arrow 3 with the oscillator 138 removed. In Fig. 2, oscillator tube 138 is of the '126A-B type manufactured by the Western Electric Company. Adjusting bolt or screw A100 is used for the purpose of adjusting the volume of the cavity resonator Within the oscillator tube, and hence the frequency of operation.

By rotating bolt A102, bracket A104 may be m'oved vertically along the grounded metallic support A106 in order to control the position of the conductor 120 and capacity plate 1I8 within the cylindrical housing 105 of the cavity resonator. Movement of the bracket A104 will move the entire oscillator tube `assemblage including oscillator tube 138 and its associated cavity resonator 4 1I8, as a result of which the space within cylinder 106 between line section 190 and the capacity plate will be varied.

Crystal detector 108 has` its upper terminal connected to the lead 1I0 corresponding to the internal conductor 1 I 0 of Fig. l. vThis connection is mad/e by way of the spring contact A1I0 contacting the upper terminals of the crystal 108 and insulatingly supported upon the base of and passing through the metal cylinder 106. The lower terminal of the crystal 103 is in direct/contact with the grounded cylinder 106.

As shown in Fig. 3, the antenna lead within the external grounded conductor 102 is held within the split clamp. A which is locked against the external conductor 102 by adjustment of theY nut A122. It will be noted that the internal conductor100 is looped at 105 and soldered or otherwise xed to and connected directly to the eX- ternal conductor 102. Hence bysimply moving external conductor 102 to the right orto the left, as shown in Fig. 3, the antenna coupling may be adjusted. It will be noted thatrthe antenna coupling loop 105 projects into cylinder 10B inv a direction substantially at right angles tothe positionV of the conductor 120, the latter of which establishes communication with the high frequency oscillator 138,. i

The discriminator detector is diagrammatically illustrated at 208 in Fig. 1 across the output terminalsof which are. connected resistors 102, 184, which, as will be explained more fully later, pro-- vide automatic frequency controlling voltages. These voltages may then be used to control the frequency of oscillator 138 so as to maintain the beat frequency waves within the pass band of intermediate frequency amplifying and limiting stages.

The frequency controlling circuit fo-r the oscillator 138 from which the `automaticfrequency controlling voltages are derived, is illustratedV schematically in Fig. Vl in connection .with vacuum tube 160. More specifically, a source 'of voltage 165 is connectedacross the leads or terminals 116, 118, and these terminals are connected to a potentiometer 114. By properly adjusting the tap 112 on potentiometer 114, and by proper choice of values for other circuit elements, the current 'flow through, or the conductivity of tube 160, having the anode 182, grid 164, andthe cathode 168, may be controlled so that the voltage'applied through leadk 158 upon the plate 156 'is of adesired value, such as vfor example, vo1ts. As indicated, the plate circuit for tube 160 is returned to ground through a resistor 15| shunted by condenser 102erv and through the ground'connection 163 to the source of potential 165. It should, therefore, be clear that the automatic frequency controlling voltages appearing across resistors 182 and 184 will vary the -current flow through the tube 160 and hence its effective resistance. Consequently, the voltage in lead 158 will vary in such' ed in angle frequency or phase deviation with the modulated common sub-carrier wave. This reproduced sub-carrier at the relaying point, employing the frequency converter of the invention, was then used to directly frequency modulate a new high frequency carrier having a value and frequency suitable for retransmittal. Such a relaying system was found effective in minimizing cross-modulation and distortion.

Various alteration and modifications of the present invention may become apparent to those skilled in the art and it is desirable that any and all such modifications and alterations be considered within the purview of the present invention except as limited by the hereinafter apl pended claims.

Having now described my invention what I claim is:

1. An ultra high frequency device including a hollow electrically closed metallic chamber adapted to have periodically repeating electromagnetic waves produced therein, a bracket mounted on the exterior of said chamber, an electron discharge device circuit assemblage supported from said bracket in spaced relation to said chamber, said assemblage including an electron discharge device, an energy coupling element carried by said assemblage and extending into the interior of said chamber through an aperture in said chamber, and means for adjusting the position of said assemblage and coupling element as an integral unit relative to said chamber.

2. An ultra high frequency device including a hollow electrically closed metallic chamber adapted to have periodically repeating electromagnetic waves produced therein, a bracket mounted on the exterior of said chamber, an electron discharge device circuit assemblage supported from said bracket in spaced relation to said chamber, said assemblage including an electron discharge device and hollow metallic resonator supported by said Ibracket, an energy coupling element carried by said assemblage and extending into the interior of said chamber through an aperture in said chamber, and means for adjusting the position on said bracket of said assemblage and coupling element as an integral unit relative to said chamber.

3. An ultra high frequency device including a hollow electrically closed metallic chamber adapted to have periodically repeating electromagnetic waves produced therein, a bracket mounted on the exterior of said chamber, an oscillator circuit assemblage supported from said bracket in spaced relation to said chamber, said assemblage including an electron discharge device and a frequency controlling metallic resonator, an energy coupling element carried by said assemblage and extending into the interior of said chamber through an aperture in said chamber, means on said assemblage for changing the operating frequency of said frequency controlling resonator, and means for adjusting the position of said assemblage and coupling element as an integral unit relative to said chamber.

4. An ultra high frequency device including a hollow electrically closed metallic chamber adapted to have periodically repeating electromagnetic waves produced therein, a bracket mounted on the exterior of said chamber, an oscillator circuit assemblage supported by said bracket in spaced relation to said chamber, said assemblage including an electron discharge device and a frequency controlling metallic resonator, an energy coupling probe carried by said assemblage and extending into the interior of said chamber through an aperture in said chamber, means on said assemblage for changing the operating frequency of said frequency controlling resonator, and a rotatable element carried on said bracket for adjusting the position of said assemblage and probe relative to said chamber, to thereby vary the coupling between said oscillator circuit and said chamber.

ROBERT SLOSS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,106,713 Bowen Feb. 1, 1938 2,191,271 Carter Feb. 20, 1940 2,223,835 Smith Dec. 3, 1940 2,350,907 Kroger June 6, 1944

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