US2917655A - Electric transmission line - Google Patents

Electric transmission line Download PDF

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Publication number
US2917655A
US2917655A US555954A US55595455A US2917655A US 2917655 A US2917655 A US 2917655A US 555954 A US555954 A US 555954A US 55595455 A US55595455 A US 55595455A US 2917655 A US2917655 A US 2917655A
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US
United States
Prior art keywords
line
helix
delay
coupling
transition
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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US555954A
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English (en)
Inventor
Millburn John Richard
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.)
US Philips Corp
North American Philips Co Inc
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US Philips Corp
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Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
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Publication of US2917655A publication Critical patent/US2917655A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H01J23/40—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit
    • H01J23/42—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit the interaction circuit being a helix or a helix-derived slow-wave structure
    • 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

Definitions

  • This invention relates to travelling-wave tubes cornoutput-coupling means.
  • the conductive cylinder surrounding the delay-line helix limits the mode of oscillation of the helix to one mode of oscillation and moreover prevents stray radiation.
  • the inputand output-coupling serve to match the impedance of a coaxial line or hollow wave guide to the impedance of the delay-line helix and moreover to convert the mode of oscillation of the delay-line helix into the mode of oscillation of the inputand output line.
  • the inputand output-coupling should be of simple construction, high mechanical rigidity and, in particular, small axial dimensions.
  • Transition couplings are known, in which the delay-line helix has a pitch angle following an exponential law in order to secure matching to the impedance of a hollow wave guide.
  • inputand output-coupling means are known, by which the pitch angle of the delay-line helix gradually increases to 90 so that the end can be directly coupled to the inner conductor of the coaxial line. Since the helix is usually wound from thin wire, the impedance of the coaxial line formed therefrom at the end would become extremely high. Therefore, it is necessary for the diameter of the transition part to increase with an increase in spacing from the delay-line or for the diameter of the conductive cylinder surrounding the delay-line to decrease with an increase in spacing from the delay-line, since otherwise the impedance does not acquire a suitable value.
  • the end of the delayline helix is connected to a tube having an equal outside diameter, and a helical slot is cut into the tube, the pitch angle of which increases gradually to 90. In this way direct coupling to a coaxial line is possible.
  • the manufacture is extremely diicult, particularly of tubes for frequencies above 10,000 mc./s.
  • the object of the present invention is to provide inputand output-coupling means which are simpler than the existing couplings.
  • the coupling in a travelling-wave tube comprising a delay-line helix, which is spaced from a surrounding conductive cylinder and furthermore comprising inputor output-coupling means, the coupling consists of a helix having an outside diameter equal to that of the delay-line and a constant pitch the conductor length being Vs x to 3A; A, where )t is the wave-length at the centre of the frequency band for which the tube is designed, while the helix has a pitch angle 2 to 6 times that of the delay-line and is connected to a straight cylindrical tube of equal diameter.
  • the invention makes use of the so-called quarterwave Y transformer in travelling-wave tubes and therefore the tation.
  • the axes of the delay-line, transition helix and coaxial conductor coincide.
  • the delay-line helix is preferably between %0 )t andi 11/40 7l long, and the pitch angle is 3 to 5 times that of the delay-line.
  • FIG. 1 shows an inputand output-coupling means to a coaxial line
  • Fig. 2 shows a coupling to a hollow wave guide.
  • the delay-line helix is denoted by 1, the constant-pitch transition by 2 and a cylindrical conductor by 3.
  • the outside diameters of the parts 1, 2 and 3 are equal and these axes coincide.
  • a coaxial -conductive cylinder 4 surrounds the glass wall 7.
  • electron gun or collecting electrode is arranged in the space 5 or 6 according as to whether the beam extends inside or outside the delay-line.
  • the cylindrical conductor 3 passes over, via a conical transition, into a part 8 of greater diameter in order to couple the coaxial line to a hollow wave guide-10 and particularly to its narrow part 11.
  • the impedance of the narrow section 11 is equal to that of the coaxial line 3, 4.
  • the diameter of the trickened part 8 is at least 0.15 a, where a is the width of the normal part 9 of the hollow wave guide 10.
  • Leakage of energy is limited by a quarter wave-length space 12.
  • the delay-line is a helix having a pitch of 0.028 cm. and an axial length of 18.5 cms.
  • the transistion 2 had a pitch of 0.1 cm. and was 0.25 cm. long. In this instance, the length of the transition was only 1.3% of the transition jointly with the delay-line.
  • the helix and the transition may be wound on an ordinary lathe.
  • the transition may only be one quarter wavelength long for a given frequency
  • the travelling-wavetube according to the invention may advantageously be used over a wide frequency band.
  • coupling to a coaxial line proved feasible with a power' loss less than l decibel over a band-width of 2.000 mc./s.,. the centre of this band being situated at 10.000 mc./s.
  • the band-width was 3.000 mc./s. with the same centre and a loss less than 2 decibels.
  • a travelling-wave tube comprising a delay-line helix having a given pitch angle; a cylindrical conductor; a coupling helix having a constant pitch angle and having one end connected to one end of said delay-line helix and the other connected to one end of said cylindricaly conductor, the diameter of said delay-line helix being substantially equal to the diameter of said coupling helix and the diameter of said cylindrical conductor, said con-- stant pitch angle of said coupling helix being between Z and 6 times as great as said pitch angle of the delay-line helix, the length of said coupling helix being between l/ )e and 567s where A is the wave length of the center frequency of the band of frequencies over which the tube operates; and the surrounding conductive cylindel,l coaxial with and extending over at least a portion of said cylindrical conductor.
  • a travelling-wave tube as claimed in claim l in which the length of said delayline helix is between 9/40 A and 11/40 )t and said pitch angle of said coupling helix is between 3 and 5 times the, pitch angle of said delay-line helix.

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  • Microwave Tubes (AREA)
  • Waveguides (AREA)
US555954A 1954-12-31 1955-12-28 Electric transmission line Expired - Lifetime US2917655A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB338911X 1954-12-31

Publications (1)

Publication Number Publication Date
US2917655A true US2917655A (en) 1959-12-15

Family

ID=10358776

Family Applications (1)

Application Number Title Priority Date Filing Date
US555954A Expired - Lifetime US2917655A (en) 1954-12-31 1955-12-28 Electric transmission line

Country Status (7)

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US (1) US2917655A (de)
BE (1) BE544056A (de)
CH (1) CH338911A (de)
DE (1) DE1073636B (de)
FR (1) FR1139162A (de)
GB (1) GB797352A (de)
NL (1) NL203186A (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955224A (en) * 1958-01-16 1960-10-04 Itt Traveling wave electron discharge device

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2575383A (en) * 1946-10-22 1951-11-20 Bell Telephone Labor Inc High-frequency amplifying device
US2637775A (en) * 1948-03-16 1953-05-05 Rca Corp Coupling of a helical conductor to a wave guide
US2673900A (en) * 1946-10-23 1954-03-30 Bell Telephone Labor Inc High-frequency amplifying device
US2708727A (en) * 1952-06-12 1955-05-17 Bell Telephone Labor Inc Helix coupling arrangements
US2719936A (en) * 1949-09-14 1955-10-04 Rca Corp Electron tubes of the traveling wave type
US2724775A (en) * 1949-06-30 1955-11-22 Univ Leland Stanford Junior High frequency oscillators
US2757310A (en) * 1952-01-01 1956-07-31 Hartford Nat Bank And Turst Co Travelling wave tube
US2823333A (en) * 1954-10-29 1958-02-11 Bell Telephone Labor Inc Traveling wave tube
US2828440A (en) * 1950-06-22 1958-03-25 Rca Corp Traveling wave electron tube

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2595698A (en) * 1949-05-10 1952-05-06 Rca Corp Electron discharge device and associated circuit
FR998819A (fr) * 1949-10-14 1952-01-23 Csf Perfectionnements au couplage des tubes à propagation d'onde linéaires avec leurs circuits d'entrée et de sortie

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2575383A (en) * 1946-10-22 1951-11-20 Bell Telephone Labor Inc High-frequency amplifying device
US2673900A (en) * 1946-10-23 1954-03-30 Bell Telephone Labor Inc High-frequency amplifying device
US2637775A (en) * 1948-03-16 1953-05-05 Rca Corp Coupling of a helical conductor to a wave guide
US2724775A (en) * 1949-06-30 1955-11-22 Univ Leland Stanford Junior High frequency oscillators
US2719936A (en) * 1949-09-14 1955-10-04 Rca Corp Electron tubes of the traveling wave type
US2828440A (en) * 1950-06-22 1958-03-25 Rca Corp Traveling wave electron tube
US2757310A (en) * 1952-01-01 1956-07-31 Hartford Nat Bank And Turst Co Travelling wave tube
US2708727A (en) * 1952-06-12 1955-05-17 Bell Telephone Labor Inc Helix coupling arrangements
US2823333A (en) * 1954-10-29 1958-02-11 Bell Telephone Labor Inc Traveling wave tube

Also Published As

Publication number Publication date
GB797352A (en) 1958-07-02
FR1139162A (fr) 1957-06-26
CH338911A (de) 1959-06-15
NL203186A (de)
BE544056A (de)
DE1073636B (de) 1960-01-21

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