US3699379A - Delay lines - Google Patents

Delay lines Download PDF

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Publication number
US3699379A
US3699379A US107787A US3699379DA US3699379A US 3699379 A US3699379 A US 3699379A US 107787 A US107787 A US 107787A US 3699379D A US3699379D A US 3699379DA US 3699379 A US3699379 A US 3699379A
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United States
Prior art keywords
delay line
fingers
structures
exterior tube
comb
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
Application number
US107787A
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English (en)
Inventor
Gerard Kantorowicz
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.)
Thales SA
Original Assignee
Thomson CSF SA
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Filing date
Publication date
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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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/24—Slow-wave structures, e.g. delay systems
    • H01J23/28—Interdigital slow-wave structures; Adjustment therefor
    • 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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/24—Slow-wave structures, e.g. delay systems

Definitions

  • the present invention relates to asymmetrical interleaved or otherwise known as interdigital delay lines, operating in the fundamental mode, and intended for travelling wave tubes.
  • a delay line of this type having the advantages of low dispersion, wide pass band, good heat dissipation, solid structure and straightforward manufacture.
  • a delay line comprising two-comb shaped structures, facing each other and having interleaved fingers, generally shaped as triangles and having aligned openings defining a rectilinear passage for the transfer of an electron beam, said structures being asymmetrical with respect to the axis of said tube.
  • FIGS. 1 and 2 respectively illustrate a transverse and a longitudinal section through a delay line in accordance with the invention
  • FIG. 3 illustrates the dispersion characteristic of a symmetrical interleaved delay line
  • FIG. 4 illustrates the dispersion characteristic of an asymmetrical delay line in accordance with the invention.
  • FIG. 5 illustrates a variant embodiment of a delay line in accordance with the invention.
  • FIGS. 1 and 2 illustrated a metal envelope 1 of reentrant rectangular cross-section, equipped on one of its faces 2 with a series of triangular fingers 3 provided in the neighborhood of their tips 4 with a hole 5, whilst the opposite face 6 of the envelope 1 carries another series of triangular fingers 7 whose base width 8 is larger than the base width 9 of the fingers 3 in the first series.
  • the fingers 7 are provided in the neighborhood oftheir tips 10 with a tubular structure 11 produced by inserting a tube 12 into an opening 13 formed in the finger 7.
  • the tube 12 disposed perpendicularly to the plate forming the finger7 and symmetrically in relation to the said finger, is placed in position there.
  • the axis of the tube 12 coincides with the axis of the holes in the fingers 3.
  • the axis of the beam passing through the delay line will coincide with the common axis of the holes 5 and the tubes 12.
  • FIGS. 3 and 4 clearly shows the difference between the operation of a conventional sym- I 2
  • the dispersion curve representing the variations in the delay ratio c/v of the line as a funcmetrical interleaved delay line shown in FIG. 3 and that tion of the wavelength (c'being the velocity of light and v the speed of propagation of the wave along the delay line), is backwards in the fundamental mode (part I of the curve plotted in FIG. 3); that is to say, c/v
  • phase-shift between two immediately ad- I jacent fingers varies between 0 and 1r when passing from the high frequency cu-off point (A) to the low frequency cut-off point (B) of the line.
  • the fundamental mode has a cut-off point for a phase-shift of 1r/2 between two immediately adjacent fingers, that is to say 1r between two identical consecutive fingers.
  • This fundamental mode has a direct dispersion (section D of the curve in FIG. 4); calling p the pitch of the line, that is to say the distance separating two identical consecutive fingers, then one will have a cut-off point c/v A/2p. i
  • This fundamental mode thus exhibits direct dispersion (section D), in respectof which the electron beam is coupled to the wave having the same delay ratio, and backwards dispersion behavior (section I) in respect of which the beam is coupled to a wave of higher frequency.
  • the line will advantageously be operated in the portion of the curve corresponding to section D, which exhibits a low dispersion.
  • This delay line in accordance with the invention has the advantage of good heat dissipation, thanks to. the
  • the invention is in no way limited to the embodiments described hereinbefore. It will be observed in particular that it may be advantageous, in order further to increase the pass-band, to choose a rectangular section envelope having a re-entrant profile on three of its faces as shown in FIG. 5, that is to say on the face 2 carrying the fingers 3 and on the faces 20 and 21.
  • a structure of this kind modifies the dispersion characteristics of the line and makes it possible to achieve low dispersion throughout the wide frequency band.
  • An interdigital delay line comprising two combshaped structures, defining an exterior tube facing each other and having asymmetrical interleaved fingers, generally shaped as triangles and having aligned openings defining a rectilinear passage for the transfer of an electron beam, said structures being asymmetrical with respect to a central axis of said exterior tube, the fingers of one of said structures carrying respective tubes inserted in said openings, the length of said tubes being greater than the thickness of the fingers.
  • the delay line as claimed in claim 1 further including laterally disposed means mounted to said exterior tube in 1 substantial alignment with said rectilinear passage for modifying the dispersion characteristics of the electron beam transferred through the delay line;
  • each of the interleafed fingers of each of the comb-shaped structures is equal to those of their respective structure but different from those of the other structure, so as to provide asymmetry with respect to the central axis of the exterior tube.

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  • Microwave Tubes (AREA)
US107787A 1970-01-26 1971-01-19 Delay lines Expired - Lifetime US3699379A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7002640A FR2076722A5 (fr) 1970-01-26 1970-01-26

Publications (1)

Publication Number Publication Date
US3699379A true US3699379A (en) 1972-10-17

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Application Number Title Priority Date Filing Date
US107787A Expired - Lifetime US3699379A (en) 1970-01-26 1971-01-19 Delay lines

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US (1) US3699379A (fr)
FR (1) FR2076722A5 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4905268A (en) * 1985-10-25 1990-02-27 Picker International, Inc. Adjustable off-focal aperture for x-ray tubes

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532545A (en) * 1945-03-08 1950-12-05 Everhart Edgar Magnetron oscillator
US2888595A (en) * 1951-03-15 1959-05-26 Csf Travelling wave delay tubes of the magnetron type
US2924738A (en) * 1954-01-14 1960-02-09 Varian Associates Electron beam apparatus
US3068432A (en) * 1952-06-28 1962-12-11 Csf Ladder type delay line

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532545A (en) * 1945-03-08 1950-12-05 Everhart Edgar Magnetron oscillator
US2888595A (en) * 1951-03-15 1959-05-26 Csf Travelling wave delay tubes of the magnetron type
US3068432A (en) * 1952-06-28 1962-12-11 Csf Ladder type delay line
US2924738A (en) * 1954-01-14 1960-02-09 Varian Associates Electron beam apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4905268A (en) * 1985-10-25 1990-02-27 Picker International, Inc. Adjustable off-focal aperture for x-ray tubes

Also Published As

Publication number Publication date
FR2076722A5 (fr) 1971-10-15

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