US3786301A - Travelling wave tubes - Google Patents

Travelling wave tubes Download PDF

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Publication number
US3786301A
US3786301A US00304992A US3786301DA US3786301A US 3786301 A US3786301 A US 3786301A US 00304992 A US00304992 A US 00304992A US 3786301D A US3786301D A US 3786301DA US 3786301 A US3786301 A US 3786301A
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United States
Prior art keywords
tube
wave
velocity
electrons
helical
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00304992A
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English (en)
Inventor
P Chalmers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Teledyne UK Ltd
Original Assignee
English Electric Valve Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
Application granted granted Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
    • H01J25/36—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and without magnet system producing an H-field crossing the E-field
    • H01J25/38—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and without magnet system producing an H-field crossing the E-field the forward travelling wave being utilised

Definitions

  • ABSTRACT A phase modulated travelling wave tube in which am- 22 :J.S.((:Ill ..315/3.6,315/3I9 ⁇ .3,l; plitude modulation Of the signal passing through the [58] Fntid ..3..15 3% 39/3- tube is reduced by providing a wave retarding Struc 1 0 care l ture which is in two electrically isolated portions arl 8 ranged co-axially in line with one another, and applying modulating d.c. potential to the portion of the [56] uNlTE g gfxfris giqrENTs wave retarding structure nearer the electron gun.
  • This invention relates to travelling wave tubes, and more particularly to forward travelling wave amplifier tubes.
  • Forward travelling wave tubes rely for an amplifying effect on the transfer of energy from a stream of electrons generated by an electron gun to the electromagnetic field of an impressed signal.
  • the required inter-action between the stream of electrons and the impressed signal is achieved by providing a wave retarding structure consisting of a linearly arranged succession of electrically resonant cells having unity coupling factor each to its neighbour through which the beam from the electron gun is directed co-axially, there being provided means for coupling an input signal to the line of cells at the gun end thereof and means for taking off an output signal at the other end of said line of cells.
  • the succession of cells is designed to retard the passage of an RF input wave applied to the input means to such an extent that its velocity down the line of cells at least approximately matches the velocity of the electrons in the beam from the gun.
  • Electrons bunch modulated by the wave near the input means are further bunch modulated successively along the line of circuits.
  • the line of circuits takes the form of a helical coil of wire. Each turn of the helix possessing the necessary capacitance and inductance to conduct the RF wave from turn to turn.
  • phase modulation of the signal passing through the tube may be accomplished. This, however, not only phase modulates the signal passing through the tube but varies the degree of bunch modulation and so results in amplitude modulation of the signal passing through the tube. In many cases this amplitude modulation is objectionable.
  • the present invention seeks to provide improved forward travelling wave tubes in which the aforementioned disadvantage is at least reduced.
  • a forward travelling wave tube in which the wave retarding structure is provided in two electrically isolated portions coaxially in line with one another, means being provided for applying modulating d.c. potential to the portion of the wave retarding structure nearer the gun.
  • the other portion of said wave retarding structure is connected to earth conductively or capacitively at its end nearer the gun.
  • the other portion of said wave retarding structure is connected to a dc. insulated output coupling circuit and means are provided for applying a dc. bias voltage directly to the said second portion whereby the velocity of the electrons in the beam is sustained to maintain approximate equality between the velocity of electrons in the beam and the velocity of the radio frequency wave down the wave retarding structure.
  • the one and other portions of the wave retarding structure may or may not be equal in functional length and an optimum ratio exists which depends upon the accelerating voltage at the electron gun, the velocity maintaining voltage on the one portions, the required signal gain ratio and the maximum permitted degree of amplitude modulation.
  • such attenuating means may consist of resistive coatings over part of the lengths of rods supporting the helix.
  • the attenuating means may be provided at the output end of the one portion of the wave retarding structure or at the output end of the one portion and/or the input end of the second portion.
  • FIG. 1 is a highly schematic diagram of one form of forward travelling wave tube in accordance with the present invention and FIG. 2 is a cross-section taken along the line AA.
  • the tube consists of an en velope l of metal within which is a cathode ray gun 2 and a collector electrode represented by 3. At the gun end of the tube is provided a so-called monitor tee 4 having an input 5 to which modulating voltage may be applied. Between the gun 2 and the collector 3 is a wave retarding structure 6 consisting of helical turns of wire. The helical turns are supported by insulating support rods 7. As so far described the tube is as known per se.
  • the wave retarding structure 6 is divided into two portions 8 and 9.
  • the one portion 8 near the gun 2 is connected to the monitor tee 4 to receive modulating potential therefrom at its end near the gun 2.
  • the other end of the wave retarding structure 8 is isolated from frame earth, i.e., isolated from the metal envelope 1.
  • the end of the other portion 9 of the wave retarding structure 6 is connected at 11 to frame earth, whilst its end adjacent to the collector 3 provides a direct output for connection to a load.
  • attenuating material 12 is provided on the support rods 7 over a portion of the length of the wave retarding structure 6. In this example the attenuating material 12 is provided both at the output end of the one portion 8 and the input end of the other portion 9 of the wave retarding structure 6.
  • the complete tube is made up in two sections; the one to the left of the line AA being united by welding represented by 13 to the other section to the right of the line AA as a final step in the manufacture of the travelling wave tube.
  • a forward travelling wave tube comprising, in combination:
  • wave retarding means in said envelope disposed between said electron gun and said collector electrode for phase modulating said applied signal and amplifying the phase modulated signal without significant amplification of the applied signal
  • said wave retarding means comprising a first helical wave retarding portion extending axially between said electron gun and said collector electrode and a second helical wave retarding portion coaxial of the first portion and extending between it and said collector electrode, means for applying a modulating d.c. potential to said first helical portion, output terminal means connected to said second helical portion, and said first and second helical portions being electrically isolated from each other whereby respectively to phase modulate the applied signal and to amplify the phase modulated signal without significant amplitude modulation of the applied signal.
  • a tube as claimed in claim 10 and wherein said attenuating means may consist of resistive coatings over part of the lengths of rods supporting the helix.

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US00304992A 1971-11-09 1972-11-09 Travelling wave tubes Expired - Lifetime US3786301A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5190771 1971-11-09

Publications (1)

Publication Number Publication Date
US3786301A true US3786301A (en) 1974-01-15

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ID=10461873

Family Applications (1)

Application Number Title Priority Date Filing Date
US00304992A Expired - Lifetime US3786301A (en) 1971-11-09 1972-11-09 Travelling wave tubes

Country Status (8)

Country Link
US (1) US3786301A (de)
CA (1) CA966584A (de)
CH (1) CH558082A (de)
DE (1) DE2254931A1 (de)
FR (1) FR2159425A1 (de)
GB (1) GB1343355A (de)
NL (1) NL7215196A (de)
SE (1) SE380672B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112820611A (zh) * 2020-12-31 2021-05-18 山东微波电真空技术有限公司 一种接地行波管

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2891191A (en) * 1953-11-18 1959-06-16 Bell Telephone Labor Inc Backward wave tube
US2899596A (en) * 1959-08-11 Wide band mixing system
US2999182A (en) * 1952-10-02 1961-09-05 Univ Leland Stanford Junior Amplitude limiters for high frequency radio signals
US3024384A (en) * 1959-06-23 1962-03-06 Sperry Rand Corp Microwave logical decision element
US3028597A (en) * 1959-05-04 1962-04-03 Hughes Aircraft Co Traveling-wave tube with independent phase and amplitude control
US3050657A (en) * 1955-01-12 1962-08-21 Gen Electric Slow wave structures
US3366885A (en) * 1963-12-04 1968-01-30 Microwave Ass Switching system comprising low gain, electron beam coupled helices

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2899596A (en) * 1959-08-11 Wide band mixing system
US2999182A (en) * 1952-10-02 1961-09-05 Univ Leland Stanford Junior Amplitude limiters for high frequency radio signals
US2891191A (en) * 1953-11-18 1959-06-16 Bell Telephone Labor Inc Backward wave tube
US3050657A (en) * 1955-01-12 1962-08-21 Gen Electric Slow wave structures
US3028597A (en) * 1959-05-04 1962-04-03 Hughes Aircraft Co Traveling-wave tube with independent phase and amplitude control
US3024384A (en) * 1959-06-23 1962-03-06 Sperry Rand Corp Microwave logical decision element
US3366885A (en) * 1963-12-04 1968-01-30 Microwave Ass Switching system comprising low gain, electron beam coupled helices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112820611A (zh) * 2020-12-31 2021-05-18 山东微波电真空技术有限公司 一种接地行波管

Also Published As

Publication number Publication date
SE380672B (sv) 1975-11-10
FR2159425A1 (de) 1973-06-22
NL7215196A (de) 1973-05-11
CH558082A (de) 1975-01-15
CA966584A (en) 1975-04-22
DE2254931A1 (de) 1973-05-24
GB1343355A (en) 1974-01-10

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