US2382217A - Concentric transmission line termination - Google Patents

Concentric transmission line termination Download PDF

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Publication number
US2382217A
US2382217A US479347A US47934743A US2382217A US 2382217 A US2382217 A US 2382217A US 479347 A US479347 A US 479347A US 47934743 A US47934743 A US 47934743A US 2382217 A US2382217 A US 2382217A
Authority
US
United States
Prior art keywords
conductor
line
transmission line
outer conductor
length
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
US479347A
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English (en)
Inventor
Henry B Fancher
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.)
General Electric Co
Original Assignee
General Electric Co
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
Priority to BE474521D priority Critical patent/BE474521A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US479347A priority patent/US2382217A/en
Application granted granted Critical
Publication of US2382217A publication Critical patent/US2382217A/en
Priority to FR941279D priority patent/FR941279A/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/08—Dielectric windows
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/202—Coaxial filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/38—Impedance-matching networks
    • H03H7/383—Impedance-matching networks comprising distributed impedance elements together with lumped impedance elements

Definitions

  • My invention relates to concentric transmission lines, and it has for an object to provide an improved and simplified means for terminating such lines and connecting them with exterior circuits.
  • a carrier wave source Ill supplies carrier waves through a concentric transmission line H to an antenna 12 from which such wavesare radiated. Oscillations from the source III are impressed across the terminals of an output circuit I3, of which one terminal is grounded.
  • the outer conductor ll of the on line I l is grounded at various points along its length, and one end it of the inner conductor I6 is connected to a point on the tuned circuit l3 between'the terminals thereof. At the other end of the ton line, a continuation of the inner conductor It forms the antenna II.
  • each end of the transmission line H is terminated by a termination structure II.
  • structure I! comprises a tubular conductor it having a diameter somewhat larger than that of the outer conductor H of transmission line H and a length equal to the length of a quarter wave at the operating frequency of the source ill.
  • a cup-shaped insulating disk 20 is secured to the free end of conductor l8 and supports the end ii of inner conductor It in rigid relation with respect toouter conductor M of line i l.
  • Disk 20 may be formed of any suitable insulating material, for example, a ceramic-bonded mica insulating material, such as Mycalex, and may be united to conductors l5 andit in any well known manner.
  • Conductor l8, member is which supports it on the outer conductor l4, and insulator 20 are structurally rigid. enough to resist both lateral and longitudinal motions of the inner conductor it with respect to the outer conductor l4. Furthermore, these parts form a closure over the end of the outer conductor M, so that the transmission line II is hermetically sealed. By such sealthe entrance of moisture by condensation,
  • the seal formed by the elements", It and Hot the structure I! is of a type capable of withstanding such gas pressure and preventing leakage of the gas.
  • the structure l1 therefore presents between the outer conductor l3 and the inner conductor I! an extremely highimpedance in series with the capacitance of the insulator 20, the effect of the capacitance of this combination on the line I I being rendered substantially negligible by the series resistance.
  • the length of the conductor l8 whilehaving a length equal to a quarter wave length at carrier frequency, may be somewhat different from a quarter wave in length at side band freqencies widely removed from the carrier frequency.
  • the impedance of the short section of line formed by conductors l3 and I3 is very much higher than the reactance of the insulator even at side band frequencies widely removed from the frequency of waves from the source III.- The eflect of the capacitance of the insulator 20 therefore remains negligible at all frequencies to be transmitted, even when such frequencies are considerably different from that frequency at which the conductor I 8 is exactly a quarter wave length.
  • the effect of the reduced impedance of the above mentioned short section of transmission line at frequencies widely spaced from the carrier frequency may be minimized by choosing afrequency in the middle of the band to be transmitted, and making conductor l8 of such length that this section of transmission line has a length exactly equal to a quarter wave length at this chosen frequency. This is especially important in television applications where single sideband transmission is normally used; in such applications, the chosen frequency will be dinerent from thenominal carrier frequency.
  • similar to the structure I1, is utilized to maintain the inner conductor II in fixed relation with outer conductor H at that end of the line I I.
  • the end of the line ll adjacent the antenna I2 is vertically disposed and, in some cases, may extend a considerable distance above the earth.
  • outer conductor I may be additionally supported, as from a tower, and the structure 21 may be utilized as means to'support the inner conductor IS in a fixed position within the outer conductor H.
  • , grounded at a central point 32 transmits waves through a pair of transmission lines 33 and 34 respectively to the two halves of a dipole antenna 35 and 36.
  • the inner conductor 31 of the tron line 33 is connected to the tuned output circuit 3
  • the other end of the inner conductor 31 is extended toform the element 33 of the dipole antenna, and the inner conductor 33 is extended similarly in the opposite direction to form the other element 33 of the antenna.
  • each line 33 and 34 are grounded throughout the major portion of their length, and each line is terminated at each end by a structure 40, which is similar to the structure ll of Fig. l.
  • a concentric transmission line for high frequency oscillations having inner and outer conductors
  • means for supporting said conductors in spaced relation at an end of said line comprising, a substantially inflexible tubular conductive sheath surrounding said outer conductor and having its end remote from the end 0! said line rigidly attached and conductively connected to said outer conductor, said sheath throughout its inner and outer conductors comprising.
  • a tubular metal sheath encircling said outer conductor at said end and extending along said outer conductor for a distance substantially equal to a quarter wave length at the operating frequency of said line, the end of said sheath remote from said end of said line being conductively connected to said outer conductor, and insulating means supporting said inner conductor in coaxial relationship with said sheath at its other end.
  • a concentric transmission line for high frequency oscillations having an inner conductor and a tubular outer conductor, and means for sealing an end of said line and for reducing reflection of oscillations at said end, said means comprising, a tubular conductive sheath surrounding said inner conductor at said end and having a length equal to a quarter wave length at the frequency of said oscillations, the end of said sheath remote from said end of said line being conductively connected to said outer conductor to form therewith a section of a tron line having a length equal to a quarter wave length at said frequency, and insulating means seallngly engaging both said inner conductor and the other end of said sheath and presenting an undesirable reactance therebetween, said section of transmission line presentinga high impedance in series with said reactance between said inner and outer aemon 3 4.
  • a gas-iiiied concentric transmission line for high irequencr oscillations having an inner conductor and a tubular outer conductor
  • said means comprising, a tubular conductive sheath surrounding said inner conductor at said end and having r. length equal to'a quarter wave length at the frequency of said oscillations, the end of said sheath remote from said end of said line being 'conductiveiy connected to said outer HENRY B. FANC'HER.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Waveguides (AREA)
US479347A 1943-03-16 1943-03-16 Concentric transmission line termination Expired - Lifetime US2382217A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE474521D BE474521A (en:Method) 1943-03-16
US479347A US2382217A (en) 1943-03-16 1943-03-16 Concentric transmission line termination
FR941279D FR941279A (fr) 1943-03-16 1947-01-24 Perfectionnements aux lignes concentriques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US479347A US2382217A (en) 1943-03-16 1943-03-16 Concentric transmission line termination

Publications (1)

Publication Number Publication Date
US2382217A true US2382217A (en) 1945-08-14

Family

ID=23903635

Family Applications (1)

Application Number Title Priority Date Filing Date
US479347A Expired - Lifetime US2382217A (en) 1943-03-16 1943-03-16 Concentric transmission line termination

Country Status (3)

Country Link
US (1) US2382217A (en:Method)
BE (1) BE474521A (en:Method)
FR (1) FR941279A (en:Method)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2434508A (en) * 1942-09-02 1948-01-13 Westinghouse Electric Corp Coupling device
US2463428A (en) * 1945-12-17 1949-03-01 Foster F Rieke Coaxial line termination
US4697191A (en) * 1985-05-08 1987-09-29 Science Applications International Corporation Omniazimuthal antenna

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2434508A (en) * 1942-09-02 1948-01-13 Westinghouse Electric Corp Coupling device
US2463428A (en) * 1945-12-17 1949-03-01 Foster F Rieke Coaxial line termination
US4697191A (en) * 1985-05-08 1987-09-29 Science Applications International Corporation Omniazimuthal antenna

Also Published As

Publication number Publication date
FR941279A (fr) 1949-01-06
BE474521A (en:Method)

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