US2657305A

US2657305A - Traveling wave tube mixing apparatus

Info

Publication number: US2657305A
Application number: US2767A
Authority: US
Inventors: Knol Kornelis Swier; Ziel Aldert Van Der
Original assignee: Hartford National Bank and Trust Co
Current assignee: Hartford National Bank and Trust Co
Priority date: 1947-01-28
Filing date: 1948-01-16
Publication date: 1953-10-27
Anticipated expiration: 1970-10-27

Description

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Oct. 27, 1953 K. s. KNoL ETAL 2,657,305

TRAVELING WAVE TUBE MIXING APPARATUS Filed Jan. 16, 1948 K-s. KNoLaAA/AN DERzlEL x19 lNvENToRs .4, AGENT N :l v Le? Patented Oct. 27, 1953 TRAVELING WAVE TUBE DIIXING APPARATUS Kornelis Swier Knol and Aldert van der Ziel, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford,

Conn., as trustee Application January 16, 1948, Serial N o. 2,767 In theNetherlands January 28, 1947 (Cl. Z50-20) 9 Claims. 1

This invention relates to a mixer circuit-arrangement for centimetre waves, in which use yis made of a so-called travelling wave amplifying tube. A known construction of such atube used for the amplification of centimetre waves comprises a system for producing an electron beam, and in addition a helical conductor along which the waves to be amplified propagate and which is arranged with respect to the said system in such manner that the electrons of the beam move approximately axially with the helix. The waves to be amplified are fed to that end of the helix which is nearest to the electron beam, and the winding pitch of the helix and/or the diameter; the turns and the voltages used for producing the electron-beam are chosen to vbe such that the speed of propagation of the waves measured along the axis of the helix is slightly lower than the mean velocity of the electrons of the beam.

Under these conditions the electrons give off energy to the waves, so that these amplied waves can be taken from the end of the helix remote from the source of electrons.

The invention is based on the recognition that a tube operating on this principle may be used with a given modication, as a mixer tube for centimetre waves.

For this purpose the oscillations to be mixed and an auxiliary oscillation are fed, according to the invention, to the helical conductor in such manner as to produce travelling waves along the helix (helices), these waves moving in the same sense, and preferably at the same velocity or at a slightly lower velocity than the electrons. After having traversed the helix or helices the electrons are separated according to their velocity with the aid of a suitable electrode system from which at the same time the intermediate frequency oscillation is taken. l

The actual occurrence of an intermediate fre- 'quency oscillation in the output circuit is due to the fact that on traversing the helix or helices the electrons of the beam reach different velocities owing to the traversing waves, so that after velocity detection in the said electrode-system' Van oscillation of difference-frequency results in the output circuit.

The oscillation to be mixed and the auxiliary oscillation may jointly be supplied to the end of the same helix nearest to the source of elec- 2 to avoid radiation of oscillations of the frequency of the auxiliary oscillation by avoiding an aerial connected, if any, to the input circuit, the helix to which the oscillation to be mixed is supplied is preferably located nearer to the source of electrons than the helix to which the auxiliary oscillations are fed. Ii desired, the auxiliary oscillation may be produced in the tube itself.

In the drawing,

Figure -1 is a schematic diagram of a iirst preferred embodiment of the invention;

Fig. 2 is a curve explanatory rof the operation of Fig. 1; and

Fig. 3 is a schematic diagram of a second embodiment oi the invention.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing, in'whlch one enibodiment comprising two helices is represented by way of example in Fig. l. The tube l represented therein comprises a system 2 for producing anelectron-beam, two helices il] and H ary ranged coaxially with the tube and Vin line with one another and a system for velocity detection which consists of a cylindrical electrode 3 and a collecting electrode 4 arranged slightly obliquely relatively to the axis of the tube. In this case it is advantageous to apply to the cylindrical electrode 3 a voltage slightly differing from earth potential and to apply a slightly positive voltage to the electrode fi. For the sake of simplicity the sources of potential required for this purpose are not represented. The end of the helix IB located on the side of the source of electrons is earthed through an impedance E at which the input oscillations occurring at the terminals l2 appear. The other end of this helix is earthed through an impedance E, the Value of which substantially corresponds with the surge impedance of the helixv ID, so that travelling waves moving from the left to the right occur therein. The source 'l for the auxiliary oscillation is connected in between the left-hand end of the helix il and earth, whilst the other end of this helix is likewise earthed through an impedance 8, the value of which is adapted to the helix Il, so that in the helix Il travelling waves of the auxiliary frequency occur which move from the left to As indicated by a dotted cylinder 3.

The operation of the circuit-arrangement may be described with reference to Fig. 2. This figure shows a curve representing the relation between the current I4 flowing from the electrode 4 to the output circuit and the velocity of the electrons of the beam. According as this velocity is lower more electrons of the beam will be attracted by the cylinder 3, so that a smaller part will flow to the electrode li. Since the relation between the output current and the electron velocity is not linear, the electrode system 3, 4 will operate as a velocity detector. Owing to the helices it and ll the successive electrons of the beam reach different velocities in accordance with the intensity of the waves on the helices I9 and l l, so that in the output circuit 9 an oscillation may occur, the frequency oi which is equal to the difference between the frequencies of the 1oscillation to be mixed and the auxiliary oscillaion.

Fig. 3 schematically illustrates a mixing ciicuit wherein the traveling wave tube includes but a single section helix I3, the local oscillations l and the input oscillations both being applied to the terminus of the helix adjacent the electron gun.

What we claim is:

1. Apparatus for mixing first and second highfrequency oscillations of different frequency to produce intermediate-frequency oscillations comprising a traveling-wave electron beam tube including a helical conductor for guiding oscillations, an electron beam source adjacent one end of said conductor and a collector electrode adiacent the other end of said conductor, said source being arranged to direct an electron beam along the axis of said helical conductor toward said collector electrode with a velocity which at any point thereon exceeds that of the traveling wave of oscillations as measured along said axis, means to apply said rst and second oscillations to said helical conductor to produce traveling waves thereon which advance in the same direction as said electron beam, and means to derive the intermediate-frequency oscillations from said collector electrode.

2. Apparatus for mixing first and second highfrequency oscillations of different frequency to produce intermediate-frequency oscillations comprising a traveling-wave electron beam tube including a helical conductor for guiding oscillations, an electron beam gun adjacent one end of said conductor and a collector electrode adjacent the other end of said conductor, said gun ybeing arranged to direct an electron beam along the axis of sai-d helical conductor towards said collector electrode with a velocity which at any point thereon exceeds that of the traveling wave of oscillations as measured along said axis, input circuit means to apply said first and second oscillations to said helical conductor at said one end thereof to produce a traveling wave thereon which advances in the same direction as said yelectron beam, an impedance connected to said other 4end of said conductor and having a value matching the surge impedance of said conductor, and output circuit means to derive the intermediate-frequency oscillations from said collector electrode.

3. Apparatus for mixing first and second high frequency oscillations of different frequency to .produce intermediate-frequency oscillations comprising a traveling wave electron beam tube including a helical conductor for guiding oscillations, an electron beam gun adjacent one end of said conductor, a collector electrode adjacent the other end of said conductor and a retarding tubular electrode interposed between said collector electrode and the other end of said tube, said gun being arranged to direct an electron beam along the axis of said helical conductor through said tubular electrode towards said collector electrode with a velocity which at any point thereon exceeds that of the traveling wave ofthe oscillations as measured along said axis, input circuit means to apply said first and second oscillations to said helical conductor at said one end thereof to produce a traveling wave thereon which advances in the same direction as said electron beam, an impedance connected to said other end of said conductor and having a value matching the impedance of said conductor, and output circuit means to derive the intermediatefrequency oscillations from said collector electrode, said last named means including a resonant circuit connected between the collector electrode and said tubular electrode and tuned to said intermediate frequency.

4. An apparatus, as set forth in claim 3, further including means to bias said collector electrode positively with respect to said retarding electrode.

5. An apparatus, as set forth in claim 3, wherein said collector electrode is disposed obliquely relative to the axis of said beam.

-6. Apparatus for mixing rst and second highfrequency oscillations of different frequency to produce intermediate-frequency oscillations comprising a traveling-wave electron beam tube including a helical conductor for guiding oscillations, said helical conductor being constituted by separate first and second sections each having end terminals, an electron beam gun adjacent one end of said helical conductor., a collector electrode adjacent the other end of said conductor, said gun being arranged to direct an electron beam along the axis of said helical conductor successively through the first and second sections thereof toward said collector electrode with a velocity which at any point thereon exceeds that of the traveling wave of oscillations as measured along said axis, means to apply said first oscillations to the terminus of said first section adjacent said gun, means to apply said second oscillations to the terminus of said second section adjacent said gun, and means to derive the intermediate-frequency oscillations from said collector electrode.

'7. Apparatus for mixing first and second highfrequency oscillations of different frequency to produce intermediate-frequency oscillations comprising a traveling wave electron beam tube including a helical conductor for guiding oscillations, said helical conductor being constituted by separate first and second sections, an electron beam gun adjacent one end of said conductor, a collector electrode adjacent the other end of said conductor and a retarding tubular electrode interposed between said collector electrode and said other end of said conductor, said gun being arranged to direct an electron beam along the axis of said helical conductor successively through the first and second sections thereo toward said collector electrode with a velocity which at any point thereon `exceeds that of the traveling wave of oscillations as measured along said axis, nrst input circuit means to apply said nrst oscillations to the terminus of said `iirst ysection adjacent said gun, second input circuit 'means to apply said second oscillations to the terminus' of said second section adjacent said gun, and output circuit means to derive the intermediate-frequency oscillations from said collector electrode, said last named means including a resonant circuit connected between the collector electrode and said tubular electrode an-d tuned to said intermediate frequency.

8. Apparatus for mixing first and second highfrequency oscillations to produce intermediatefrequency oscillations, the frequency of said first oscillations being high relative to said second oscillations, said apparatus comprising a traveling wave electron beam including a helical conductor for guiding oscillations, said helical conductor being constituted by separate rst and second sections, an electron beam gun adjacent one end of said conductor, a collector electrode adjacent the other end of said conductor and a retarding tubular electrode interposed between said collector electrode and said other end of said conductor, said gun being arranged to -direct an electron beam along the axis of said helical conductor successively through the first and second sections thereof toward said collector electrode with a velocity which at any point thereon exceeds that of the traveling Wave of oscillations as measured along said axis, rst input circuit means to apply said rst oscillations to the terminus of said rst section adjacent said gun, a rst matching impedance connected to the other terminus of said rst section, second input circuit means to apply said second oscillations to the terminus of said second section adjacent said gun, a second matching impedance connected to the other terminus of said second section, and means to de- 6 rive the intermediate-frequency oscillations from said collector electrode, said last named means including a resonant circuit tuned to the frequency of said intermediate frequency oscillations an-d connected between saidvretarding and collector electrodes.

9. Mixing apparatus, as set forth in claim 8, wherein said collector electrode is disposed obliquely with respect to the axis of said beam and further including means to apply a constant voltage to said collector electrode which is positive with respect to said retarding electrode.

KORNELIS SWIER KNOL. ALBERT VAN DER ZEL.

References Cited in the lle of this patent UNITED STATES PATENTS Number Name Date 2,064,469 Haeff Dec. 15, 1936 2,233,126 Haeff Feb. 25, 1941 2,289,756 Clavier et al. July 14, 1942 2,300,052 Lindenblad Oct. 27, 1942 2,367,295 Llewellyn Jan. 16, 1945 2,508,228 Coeterier May 16, 1950 2,541,843 Tiley Feb. 13, 1951 2,575,383 Field Nov. 20, 1951 2,578,434 Lindenblad Dec. 1l, 1951 2,580,007 Dohler et al Dec. 25, 1951 OTHER REFERENCES Article by Pierce and Field. pp. 108-111, Proc. of I. R. E. for Feb. 1947, vol. No. 35, No. 2. Copy in U. S. Patent Office, Scientific Library.