US2249963A - Impedance transformation means - Google Patents

Impedance transformation means Download PDF

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Publication number
US2249963A
US2249963A US304573A US30457339A US2249963A US 2249963 A US2249963 A US 2249963A US 304573 A US304573 A US 304573A US 30457339 A US30457339 A US 30457339A US 2249963 A US2249963 A US 2249963A
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United States
Prior art keywords
shell
line
transmission line
conductor
inner conductor
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Expired - Lifetime
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US304573A
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English (en)
Inventor
Nils E Lindenblad
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RCA Corp
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RCA Corp
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Priority to US304573A priority Critical patent/US2249963A/en
Priority to DER2932D priority patent/DE919247C/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/02—Coupling devices of the waveguide type with invariable factor of coupling
    • H01P5/022—Transitions between lines of the same kind and shape, but with different dimensions
    • H01P5/026—Transitions between lines of the same kind and shape, but with different dimensions between coaxial lines

Definitions

  • the present invention relates to transmission lines and, more particularly, to a method of, and means for, transforming the impedance of one transmission line to such a value that it may be directly connected to another transmission line of a different impedance.
  • An object of the present invention is to provide a means for matching the impedance of one transmission line to that-of another.
  • Still another object of the'invention is to provide a means for matching the impedance of a pair of transmission lines without introducing losses.
  • Still another object of the present invention is to provide a means for transforming the'impedance of a transmission line without introducing circuits of high volt ampere storage.
  • the present invention includes, among its features, a plurality of short sections of concentric transmission lines which are designed to be connected in series at one end and the series combination directly connected to one trans mission line.
  • the other end of the sections are connected in parallel and connected to the other transmission line.
  • animpedance multiplication which is the square of the number of intermediate sections employed.
  • Figures 1, 2 and 4 illustrate simplified transformation systems useful in explaining the principles of the present invention
  • Figure 3 illustrates a simple embodiment of the present invention whereby an impedance ratio of 4 to 1 is obtained
  • Figure 5 illustrates another embodiment of the invention also resulting in a 4 to 1 impedance transformation ratio
  • Figure 6 illustrates another embodiment of the invention in which an impedance ratio of 9 to l is obtained
  • Figure '7 illustrates a modification of the form of my invenpedance of 2 to 1.
  • the circuit shown in Figure 1 comprises a concentric transmission lineA having an inner conductor I and an outer shell 2.
  • the inner and outer conductors of this transmission line are each connected at one end to the center conductors 3 and 4 of a pair of pushpull concentric line branches.
  • An outer conducting sleeve 6 surrounds the end of line A for a distance equal to a quarter of the operating wavelength and is joined to the outer conductors 5 of the push-pull branches as shown.
  • Figure 2 shows a modification of the form of construction shown in Figure 1 wherein the outer shell 5 of the push-pull concentric line is continued through sleeve 6 as a single piece with a notch cut out of one side in order to enablethe connection of the conductors of line A thereto.
  • Figure 3 shows how Figure 2 may be modified in order to connect the two balanced concentric lines 3 and 4 to a single transmission line B for impedance shell 3
  • a phase shifting loop I is connected in series with one of the balanced lines, conductor 3, in the figure, said loop I having a length equal to a half the length of the operating wave. Therefore, at the point of connection of conductor 9 of transmission line B the current in ly connected to branches 3 and 4 in parallel it.
  • Each branch 3, 4 of the U circuit then contains a current I.
  • the center conductor currents and the corresponding shell currents in the two branches add up in the common line A which they feed, as illustrated by the arrows.
  • the inner conductor 3 of one branch is connected to the inside of the outer shell 2 while the inner conductor 4 of the other branch is connected to the outside of the inner conductor 1.
  • the outer shell of the branch containing conductor 3 is, for convenience, in this figure shown as a continuation of the centercondu'ctor I of transmission line A.
  • the voltage at the termination of thecommon line A is equal to that of each branch line 3 and 4.
  • the impedance of the common line A thus has to be half of the impedance of the branch lines.
  • This figure simply represents an exampleof one principle of my invention since the impedance' of common line A is the same as that of common line B and is shown and described to 'make what follows more clearly understood.
  • This example shown in Figure 4 shows two ways of adding currents and transmission lines at the same voltage.
  • the branch lines 3 and 4 can be considered as added into transmission line A or as into transmission line B.
  • FIG 5 I show how the individual branch lines 3 and 4 may have their currents added in series.
  • the current in the common line A is the same as in the branches but the voltage is doubled.
  • branch line 3 enters the transmission line A as a quarter wave
  • the inner conductor 3 connects to the shell 5 of the left-hand branch then continues along the conductor passing through the aperture in wall 5
  • the center conductor current of 3 continues as a shell current of transmission line A.
  • within the casing l and 2 is then an intermediary point at which the voltage appearing in conductor 3 is connected. in series with that appearing in conductor 4. Due to the quarter wave length of shell 3! current is prevented from flowing along its outside surface. Since the current in line A thus must be equal to the current in each of the branches 3 and 4 and since the voltage is the sum of the voltages, the impedance of line A must be twice that of either of the branch lines.
  • the currents in the branch lines are in phase requiring no phase reversal. They may be connected directly in parallel at their lower end and connected to conductors 8 and 3 of transmission line B as shown.
  • the total circuit from B to A of Figure 5 represents an impedance transformation of 4 to 1 with a system which is matched throughout.
  • Neither the current in conductor 23 which flows to the shell 24 of the center branch and the current in conductor 25 which flows to the shell 26 of the right branch can go to the outside of the respective shell due to the high impedance of the quarter wave section surrounding the shell but must go on the inside and become the shell current as already stated.
  • the shell current of the left-hand branch becomes the center conductor current of the main line A while the center conductor current of the right-hand branch becomes the shell current of the main line A. Since the three branches 22, 24 and 26 are connected in series and are in phase relationship, the impedance of each of these branches should be one-third of the impedance of the line A. At their lower ends each of the branches are connected in parallel and connected to the center conductor 9 and shell 8 of transmission line B. The impedance of transmission line B will thus have to be onethird of the impedance of each of the intermediate sections. The transformation ratio, therefore, becomes 9 to 1 between transmission line A and transmission line B.
  • transmission line A is composed of an outer shell 12 and an inner conductor H).
  • the inner conductor I0 is carried throughout the length of the transformation section and is connected to the inner conductor [9 of transmission line B.
  • the lower portion of conductor I0 is surrounded by a shell H which forms with conductor I!) one of the intermediate matching sections.
  • Shell It is surrounded by another shell l3 thus forming a second transformation section in which shell H acts as the center conductor and shell I3 as the outer conductor.
  • the upper end of shell II is connected to the upper end of conductor 2 of transmission line 13. Due to the quarter wavelength of shell II from its end to its point of connection with shell l3 the current from conductor 20 must flow on the inner surface of shell ll. Likewise, in the upper portion of the figure shell l3 becomes the inner conductor of a transformation section in which the shell I2 of line A forms the outer conductor. The end of conductor 2
  • each portion of current takes as it is divided, at the points where the current-s are brought together they are again in phase, since the total path lengths are equal.
  • means for transforming the impedance of one line to a value equal to that of the other comprising an integral number N of short sections of transmission lines, said sections being connected in a series relationship to said one transmission line and in a parallel relationship to said other transmission line.
  • a first concentric transmission line having an inner conductor and an outer shell, said shell and conductor being connected together at one end
  • a second and a third concentric transmission line each having one end extending into the said end of said first transmission line a distance equal to a quarter of the length of the operating wave
  • the outer shell of said second line forming an extension of the inner conductor of said first line
  • the inner conductor of said third line being connected to the shell of said first line
  • the inner conductor of said second line being connected to the shell of said third line whereby said second and third lines are efiectively connected in series across the conductors of said first line.
  • a first concentric transmission line having an inner conductor and an outer shell, said shell and conductor being connected together at one end
  • a second and a third con-centric transmission line each having one end extending into the said end of said first transmission line a distance equal to a quarter of the length of the operating wave
  • the outer shell of said second line forming an extension of the inner conductor of said first line
  • the inner conductor of said third line being connected to the shell of said first line
  • the inner conductor of said second line being connected to the shell of said third line
  • said second and third lines are efiectively connected in series across the conductors of saidfirst line, means for connecting said second and third lines in parallel at their ends.
  • a first concentric transmission line having an inner conductor and an outer shell, said shell and conductor being connected together at one end
  • a second and a third concentric transmission line each having one end extending into thesaid end 'of said first transmission line a distance equal to an odd multiple, including unity, of a quarter of the length of the operating wave
  • the outer shell of said second line forming an extension of the inner conductor of said first line
  • the inner conductor of said third line being connected to the shell of said first line
  • the inner conductor of said second line being connected to the shell of said third line whereby said second and third lines are effectively connected in series across the conductors of said first line.
  • a first concentric transmission line having an inner conductor and an outer shell, said shell and conductor being connected together at one end
  • a second and a third concentric transmission line eachhaving one end extending into the said end of said first transmission line a distance equal to an odd multiple, including unity, of a quarter of the length of the operating Wave
  • the outer shell of said second line forming an extension of the inner conductor of said first line
  • the inner conductor of said third line being connected to the shell of said first line
  • the inner conductor of said second line being connected to the shell of said third line whereby said second and third lines are effectively connected in series across the conductors of said first line, means for connecting said second and third lines in parallel at their other ends.
  • first and a second transmission line each having an inner conductor and an outer shell, a plurality of short sections of concentric transmission lines connected in series at one end and to said first transmission line, means surrounding said ends for preventing current from flowing on the outside of the shells of said short sections, said sections being connected in parallel to said second line at their other ends.
  • first and a second transmission line each having an inner conductor and an outer shell, a plurality of short sections of concentric transmission lines connected in series to said.
  • first transmission line means surrounding said ends for preventing current from flowing on the outside of the shells of said short sections, said sections being connected in parallel to said second line.
  • An impedance transformer comprising a high impedance section of transmission line having an outer shell and an inner conductor, a second shell surrounding said inner conductor extending within said outer shell a distance equal to one quarter of the length of the operating wave and connected thereto, a third shell extending within said second shell a distance equal to onequarter of the length of the operating wave and also surrounding said inner conductor and connected to said second shell at the end thereof, a low impedance section of transmission line having an outer shell and an inner conductor, means connecting the outer shells of said first mentioned and last mentioned sections of transmission line together, and means for connecting the inner conductor of said last section of transmission line to the inner conductor of said first section of transmission line and to the inner ends of each of said second and third shells.
  • An impedance transformer comprising a high impedance section of transmission line having an outer shell and an inner conductor, a second shell surrounding said inner conductor extending within said outer shell a distance equal to one quarter of the length of the operating wave and-connected thereto, a third shell extending within said second shell a distance equal to a quarter of the length of the operating wave and also surrounding said inner conductor and connected to said second shell at the end thereof, a low impedance section of transmission line having an outer-shell and an inner conductor, means connecting the outer shells of said first mentioned and last mentioned sections of transmission line together, and means for connecting the inner conductor of said last section of transmission line to the inner conductor of said first section of transmission line and to the inner ends of each of said second and third shells, said last mentioned means being so arranged that the current in said last mentioned line is divided equally.
  • An impedance transformer comprising a high impedance section of transmission line having an outer shell and an inner conductor, a second shell surrounding said inner conductor extending within said outer shell a distance equal to a quarter of the length of the operating wave and connected thereto, a third shell extending within said second shell a distance equal to a quarter of the length of the operating wave and also surrounding said inner conductor and connected to said second shell at the end thereof, a low impedance section of transmission line having an outer shell and an inner conductor, means connecting the outer shells of said first mentioned and last mentioned sections of transmission line together, and means for connecting the inner conductor of said last section of transmission line to the inner conductor of said first section of transmission line and to the inner ends of each of said second and third shells, said last mentioned means being so arranged that the current in said last mentioned line is divided equally between said first inner conductor and said second and third shells.
  • An impedance transformer comprising a high impedance section of transmission line having an outer shell and an inner conductor, a second shell surrounding said inner conductor extending within said outer shell a distance equal to a quarter of the length of the operating wave and connected thereto, a third shell extending within said second shell a distance equal to a quarter of the length of the operating wave and also surrounding said inner conductor and connected to said second shell at the end thereof, a low impedance section of transmission line having an outer shell and an inner conductor, means connecting the outer shells of said first mentioned and last mentioned sections of transmission line together, and means for connecting the inner conductor of said last section of transmission line to the inner conductor of said first section of transmission line and to the inner ends of each of said second and third shells, said last mentioned means being so arranged that the current in said last mentioned line is divided equally between said first inner conductor and said second and third shells, said last mentioned means being so arranged that the lengths of current path from said second line to said first line are equal.
  • An impedance transformer comprising a high impedance section of transmission line having an outer shell and an inner conductor, a second shell surrounding said inner conductor extending within said outer shell a distance equal to an odd multiple, including unity, of a quarter of the length of the operating wave and connected thereto, a third shell extending within said second shell a distance equal to an odd multiple, including unity, of a quarter of the length of the operating wave and also surrounding said inner conductor and connected to said second shell at the end thereof, a low impedance section of transmission line having an outer shell and an inner conductor, means connecting the outer shells of said first mentioned and last mentioned sections of transmission line together, and means for connecting the inner conductor of said last section of transmission line to the inner con-- ductor of said first section of transmission line and to the inner ends of each of said second and third shells.
  • An impedance transformer comprising a high impedance section of transmission line having an outer shell and an inner conductor, a second shell surrounding said inner conductor extending within said outer shell a distance equal to an odd multiple, including unity, of a quarter of the length of the operating wave and connected thereto, a third shell extending within said second shell a distance equal to an odd multiple, including unity, of a quarter of the length of the operating Wave and also surrounding said inner conductor and connected to said second shell at the end thereof, a low impedance section of transmission line having an outer shell and an inner conductor, means connecting the 10 outer shells of said first mentioned and last mentioned sections of transmission line together, and means for connecting the inner conductor of said last section of transmission line to the inner conductor of said first section of transmission line and to the inner ends of each of said second and third shells, said last mentioned means being so arranged that the current in said last mentioned line is divided equally between said first inner conductor and said second and third shells.

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US304573A 1939-11-15 1939-11-15 Impedance transformation means Expired - Lifetime US2249963A (en)

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US304573A US2249963A (en) 1939-11-15 1939-11-15 Impedance transformation means
DER2932D DE919247C (de) 1939-11-15 1940-11-16 Einrichtung zur gegenseitigen Anpassung zweier Hochfrequenz-UEbertragungs-Leitungen

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2426633A (en) * 1943-08-12 1947-09-02 Bell Telephone Labor Inc Wave transmission network
US2437244A (en) * 1940-07-11 1948-03-09 Dallenbach Walter Junction between concentric and parallel conductor systems
US2452202A (en) * 1944-08-03 1948-10-26 Rca Corp Radio-frequency distributor apparatus
US2456679A (en) * 1941-05-05 1948-12-21 Emi Ltd High-frequency impedance bridge
US2465843A (en) * 1944-08-16 1949-03-29 Rca Corp Radio frequency power division network
US2473328A (en) * 1944-12-19 1949-06-14 Rca Corp Line balance converter
US2478313A (en) * 1945-07-19 1949-08-09 Rca Corp Antenna construction
US2517968A (en) * 1945-01-17 1950-08-08 Rca Corp Line balance converter
US2524993A (en) * 1945-09-14 1950-10-10 Victor H Rumsey Antenna
US2542844A (en) * 1943-08-14 1951-02-20 Bell Telephone Labor Inc Microwave directive antenna
US2617884A (en) * 1945-08-24 1952-11-11 Int Standard Electric Corp Coupling arrangement between aerial and transmission line
US2635176A (en) * 1949-09-01 1953-04-14 Rca Corp Radio-frequency heating system
US2646505A (en) * 1946-03-01 1953-07-21 Us Sec War Broad band bidirectional antenna
US2877430A (en) * 1954-03-24 1959-03-10 Standard Coil Prod Co Inc Transmission line transformer

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE515121C (de) * 1928-04-14 1931-01-03 Telefunken Gmbh Anordnung zum Anschluss eines Verbrauchers an eine Energiequelle
BE421257A (de) * 1936-04-28

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2437244A (en) * 1940-07-11 1948-03-09 Dallenbach Walter Junction between concentric and parallel conductor systems
US2456679A (en) * 1941-05-05 1948-12-21 Emi Ltd High-frequency impedance bridge
US2426633A (en) * 1943-08-12 1947-09-02 Bell Telephone Labor Inc Wave transmission network
US2542844A (en) * 1943-08-14 1951-02-20 Bell Telephone Labor Inc Microwave directive antenna
US2452202A (en) * 1944-08-03 1948-10-26 Rca Corp Radio-frequency distributor apparatus
US2465843A (en) * 1944-08-16 1949-03-29 Rca Corp Radio frequency power division network
US2473328A (en) * 1944-12-19 1949-06-14 Rca Corp Line balance converter
US2517968A (en) * 1945-01-17 1950-08-08 Rca Corp Line balance converter
US2478313A (en) * 1945-07-19 1949-08-09 Rca Corp Antenna construction
US2617884A (en) * 1945-08-24 1952-11-11 Int Standard Electric Corp Coupling arrangement between aerial and transmission line
US2524993A (en) * 1945-09-14 1950-10-10 Victor H Rumsey Antenna
US2646505A (en) * 1946-03-01 1953-07-21 Us Sec War Broad band bidirectional antenna
US2635176A (en) * 1949-09-01 1953-04-14 Rca Corp Radio-frequency heating system
US2877430A (en) * 1954-03-24 1959-03-10 Standard Coil Prod Co Inc Transmission line transformer

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Publication number Publication date
DE919247C (de) 1954-10-18

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