US2403252A - High-frequency impedance-matching device - Google Patents

High-frequency impedance-matching device Download PDF

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Publication number
US2403252A
US2403252A US563713A US56371344A US2403252A US 2403252 A US2403252 A US 2403252A US 563713 A US563713 A US 563713A US 56371344 A US56371344 A US 56371344A US 2403252 A US2403252 A US 2403252A
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impedance
line
members
impedances
length
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US563713A
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English (en)
Inventor
Harold A Wheeler
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Hazeltine Research Inc
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Hazeltine Research Inc
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Priority to BE474967D priority Critical patent/BE474967A/xx
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Priority to US563713A priority patent/US2403252A/en
Priority to GB27438/45A priority patent/GB597922A/en
Application granted granted Critical
Publication of US2403252A publication Critical patent/US2403252A/en
Priority to FR951364D priority patent/FR951364A/fr
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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
    • H01P5/04—Coupling devices of the waveguide type with variable factor of coupling

Definitions

  • the present invention relates to, high-frequency impedance-matching devices and, particularly, to
  • the impedance encountered and required to be matched are complex so that a satisfactory result necessitates a matching of the resistance components and a cancellation of the reactance components of the impedances.
  • Transmission lines of either fixed or adjustable lengths have heretofore been widely used as impedance-matching devices, especially in highfrequency wave-signal circuits.
  • a transmission line when so used exhibits the properties of an impedance transformer in that it is able to transform the value of an impedance coupled to one end of the line to a different value of impedance at its other end.
  • the maximum ratio of impedance transformation varies with the ratio between the characteristic impedance of the line and the value of the impedance to be transformed, but both the actual ratio of the impedance transformation and the magnitude and nature of the reactance components after transformation vary with the effective electrical length of the transmission line.
  • a coaxial transmission line one wave length or more long be employed for impedance matching, the line having a characteristic impedance equal to the value of impedance of one or both of the terminal impedances and being provided with two quarterwave sliders which surround the inner conductor of the line and are independently adjustable axially therealong. These sliders modify the characteristic impedance of the line over the length of each slider and effect, over a range of impedances, a matching of the resistance com- 11 Claims. (01. 178-44) ends of the line.
  • This impedance-matching device when once properly adjusted to provide an impedance match at one operating frequency may not maintain even an approximate impedance match over more than a small range of operating frequencies so that the device may be said to be critical of frequency.
  • the reason for this is that the change of phasethrough the line with change of frequency becomes more severe as the line length increases, there being a cumulative phase shift for the reflected wave-signal energy which is produced at a multitude of points along the length of the device described. It is desirable in many applications that an impedancematching device provide an exact impedance match at one frequency and that a closely approximate impedance match be maintained without further adjustment over a substantial range of operating frequencies. Additionally, it is frequently desirable that an impedance-matching device of this type have a physicalsize appreciably smaller than is possible with the device described.
  • the device includes a plurality of members positioned between the conductorsof the line and independently adiustably movable axially therealong.
  • Each of the adjustable members has at the given frequency a predetermined effective electrical length substantially less than one-half the length of the line and has its shape and material so selected as to cause the characteristic impedance of the line over the lengths of the members to diifer from the geometric mean of the aforesaid impedances in opposite sense from the sense in which the line differs there-- from, and by such magnitude as to enable the transmission line for an adjusted position of the members to match the resistance components and to cancel the reactance components of the afore- 20 ends.
  • the present invention is related to that disclosed and claimed in applicant's copending apsaid pair of impedances.
  • the transmission line of the co ending application utilizes a member of magnetic material movable axially along the line to effect an adjustment of the line terminal impedance
  • the impedance-matching device of the present invention utilizes two members of conductive, dielectric or magnetic material axially independently movable along a quarter-wave line for purposes of matching, over a range of values of magnitude and phase, two impedances which are coupled to individual ends of the line.
  • the present invention is also related to the device of applicants copending application entitled Wave-signal. tuning device, Serial No.
  • a member of conductive, dielectric or magnetic material, or a combination of such materials is axially movable along a transmission line having an electrical length of an odd number of quarter-wave length and short-circuited at its remote end to provide a resonant line adjustable to resonance at any frequency in a range of o erating frequencies.
  • Fig. 1 is a longitudinal sectional view of a high-frequency impedancematching device embodying the present invention
  • Fig. 2 is a diagrammatic representation of the device of Fig. 1
  • Fi 3 is a sectional view of amass:
  • the transmission line I I, I2 preferably has an eifective electrical length equal either to one-quarter wave length or to three-quarters wave length since it then is enabled to provide an optimum ratio of impedance transformation between its terminal 13 are held in position by and l8, l8 are provided at opposite extremities of the conductors II and If to permit the impedances Z1, Z2 which are to be matched to be connected in circuit with the device.
  • the impedance-matching device also includes a plurality of members l5, 18 ositioned between the conductors II and I 2 and independently adiustably movable axially along the conductors.
  • Each of the adjustable members 15 and It has at the aforementioned given frequency a predetermined eflective electrical length substantially less than one-half the length of the line II, If, a preferred physical length for optimum range of control being one-quarter the line length but not exceeding a physical length which provides an effective electrical length of one-quarter wave length.
  • the members It, I8 have their shape and material so selected as to cause the characteristic impedance Zo" of the line H, l2 over the lengths of the members l5, It to differ from the geometric mean of the terminal impedances Z1,
  • the members l5 and I8 may be of conductive, dielectric, or magnetic materials, or a combination of these materials and, for a coaxial transmission line, are
  • Fig. 1 is an impedance chart for the devices of Figs. 1 and 3 and is used to demonstrate their capabilities. 1 Referring now more particularly to the drawings, the device illustrated in Fig. 1 and shown diagrammatically in Fig.
  • a high-frequency impedance-matching device which is adapted for connection between, and for matching at a given frequency, a pair of unequal impedances designated Z1 and Z: having any values within a substantial range of magnitude and able members l5 and I8 are movable by the insertion of a suitable tool, througna slot 40 in the outer conductor ll, into engagement with screws 25 which are loosened during adjustment of members-i5 and IE but are tightened thereafter to engage the inner conductor I! for the purpose of maintaining the members I5, 18 in adjusted position.
  • This device comprises a lural-conductor 7 thereof are proportioned with relation tothe inmean values This applies also in the event the members II and It are'of conductive material but electrically engage only the outer conductor ii, there being the difference in this case that the'inner diameter of the members II and II are proportioned with relation to the diameter of the conductor ll so that the amid! "e Considering now the operation of the device, shown schematically in Finland 2, with imconductor I! to eifect the reduction of characteristic impedance last mentioned. If, on the other hand, the members I! and It are of dielectric material, the desired reduction of line characteristic impedance over the lengths of the members is effected by a choice of the dielectric constant of the material used.
  • the transmisslon line l1, I2 is proportioned to have a characteristic impedance substantially less than the geometric mean impedance of Z1 and Z: and the eifective coemcient of magnetic permeability of the material of members I! and I8 is so selected with relation to the efle'ctive dielectric constant of the members that the characteristic impedance Z0" of the line II, I! is substantially greater than the geometric mean impedance of Z1 and Z: over the lengths of these members.
  • the adjustable members having an effective electrical length of approximately one-fourth the length of the line i II, I: and thus a range of movement equal at least to their own length, provide ample flexibility for matching unequal impedances Z1 and Z: over a wide range of impedance ratios.
  • the characteristic impedance given by Equation 1 must be multiplied by the reciprocal of the square root of the effective dielectric constant of the member, the efl'ective dielectric constant taking into account any air gaps between the adjustable member and either or both of the conductors I I and I2.
  • the adjustable member is of magnetic material
  • the characteristic impedance given is of magnetic material
  • Equation 1 Equation 1 must be multiplied by the square 1 pedances Z1 and Z2, the following relation should it pedances Z1 and Z: connected thereto, the-terminal impedances are matched bysliding the adjustable members II and" so as to vary the dis-. tance B, or the distance A, Fig, 2,,or boththe distances A and B.
  • Thefadjustments in'this regard are somewhat similar to thoserequired to balance resistance and reactance components, of an unknown impedancein'an alternating current Wheatstone bridge.
  • K a factor expressing the diflerence of impedance in successive sections of the impedance-matching device.
  • ' members II thus form coaxial connectors for atcaasa I -1 provides an eifectiveelectrieal length'not substantially exceeding one wave length of the trans-
  • Fig. 3 illustrates thigh-frequency impedance matching device for matching one terminal impedance coupled toone end of the device to a pair of terminal impedances connected in paris generally similarto that shown in Fig. 1 and similar elements are designated by similar refer- 21 is inserted through an aperture 30 in thehollow conductor] I.
  • hollowconductor 21 At the extremities of hollowconductor 21 are a a j pair of insulating discs 28, 28 which support a second inner conductor 29 coaxiallywith the outer conductor 21 by means of a pair of :cen-
  • conductive pins 30 One end of conductor I2 is similarly supported in the first hollow conductor II by another disc 28 and a conductive pin 30. The other end of conductor I2 is conductively connected to the mid-portion g5 of conductor 29.
  • Annular conductive members ⁇ I are secured to the outer ends-of hollow conductors H and 21 by means of'screws I to form a rigidunit. The conductive pins 30 and the annular 80 coupling the impedance-matching device of Fig.
  • an impedance-matching device embodying the present invention has been constructed for operation at a frequency near 500 megacycles for matching a -ohm impedance Z: to a 25-ohm impedance Z1 composed of two 50-oh'm impedances each 2Z1 connected in parallel, the geometric mean of the terminal at pedances thus being 35 ohms.
  • This matching problem therefore involves an impedance ratio of 2 to 1.
  • This device when accuratel adjusted at one operating frequency, has been found to maintain a close impedance match over a wide range of operating frequencies or band width of approximately one-third to one-half the mean frequency.
  • the following dimensions aregiven as illustrative of values of the elements whichv were utilized in this impedance-matching device for the application stated above:
  • Fig. 4 there is illustrated on a hemispherical impedance chart a representative v chartat a 8 particular operating frequency for an impedance-matching device embodying thepresent invention and having its dimensions so chosen that the line II, I! has a length of one-quarter wavelength and a char- I acteristic impedance equal 'to 32: while each of the members it and I I has a length of one-sixtecnth wave length and a characteristic impedance equal to 0.82:.
  • a chart of this type is useful indetermining the required settings ofthe adjustable members l5, II in aparticular impedance-matching device.
  • This chart is also useftfl as a graphical representation of the matchingcapabilities of sucha device.
  • the magnitude of any given impedance is expressed as a ratio between the value of that impedance and a value of resistance arbitrarily assigned the unit center of the chart. Ratio values are indicated by the lines of latitude. ratio values greater than unity lying above the straight horizontal line while those less than unity fall below this line.
  • the possible phase angles of the given impedance are represented by the lines of longitude.
  • A-O' curve represents the values 7 of impedance transformation effected by the impedance-matching device with variations of the spacing B for a fixedspacing of zero electrical degrees for dimension A.
  • a high-frequency impedance-matching device embodying the inven- I tioni's of minimum-physical size is not critical the upper left of the figure.
  • the mem I hers II and ii are in abutting relation and peeltioned at .one end of the transmission line ii, I:
  • the impedance-matching device transform an impedance Z1 having a value indicated by the point P on the impedance chart to the valueof impedance Z2, whereby the impedances Z1 and Z: are matched by the device.
  • an' impedance Z1 having the value represented by the point P on the impedance chart is transformed to the value of impedance Z: at the opposite end of the of adjustment, and is not critical with regard to frequency or, expressed in another manner, is able to provide an exact impedance match at a selected operating frequency and a closely approximate impedance match over a wide range of operating frequencies.
  • A- high-frequency impedance-matching device adapted for connection between and for matching at a given frequency a pair of impedtransmission line, or conversely the impedance example, assume that an impedance Z1 having the value represented by the point P' on the impedance chart is to be matched by the impedancematching device to an impedance having the value Z2.
  • an impedance match is effected when the spacing B has a value of approximately 7%; electrical degrees and the spacing A a value of approximately 7 /2 electrical degrees.
  • members i5 and it have been illustrated as closed or solid conductors slidable on the inner conductor, these members may have any of the configurations and mountings of, and may be formed in similar manner as, the adjustable members shown and described in the aforementioned copending applications.
  • the members l5 and it may be entirely of conductive, magnetic, or dielectric materials or may be formed of two or more of these materials in combination to provide an impedance-matching device having a particular desired characteristic.
  • a high-frequency impedance-matching device adapted for connection between and for matching at a given frequency a pair of impedances having any values within a predetermined range of magnitude and phase comprising, a plural-conductor transmission line adapted to be connected between said impedances and having a predetermined electrical length less than one wave length at said given frequency and a Predetermined characteristic impedance differing in one sense from the geometric mean of said impedances, and a plurality of members positioned between the conductors of said line and independently adjustably movable axially therealons.
  • each of said adjustable members having at said given frequency a predetermined effective electrical length substantially less than one-half the length of said a line and having its shape and material so selected as to cause the characteristicimpedance of said line over the lengths of said members to be less than said geometric mean of said impedances by such magnitude as to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel thereactance components of said pair of impedances.
  • a high-frequency impedance-matching device adapted-for connection between and for matching at a given frequency 'a pair of impedances having any values within a predetermined range of magnitude and phase comprising, a plural-conductor transmission-line adapted to be connected between said impedances and having a predetermined electrical length less than:
  • each of said adjustable members having at said given frequency a predetermined effective elec- 1 trical length substantially less than one-half the 1 length of said line and having its shape so selected 1 as to cause the characteristic impedance of said 1 line over the lengths of said members to be less 1 than said geometric mean of said impedances by i such magnitude as to enable said transmission line for an adjusted position of said members to 1 match the resistance components and to cancel the reactance components of said pair of im- 1 pedances.
  • a high-frequency impedance-matching device adapted for connection between and for 1 matching at a given frequency a pair of impedances having any values within a predetermined range of magnitude and phase comprising, f a plural-conductor transmission line adapted to be connected betweensaid impedances and hav- 1 ing a predetermined electrical length less than 1 one wave length at said given frequency and a A predetermined characteristic impedance greater 1 than the geometric mean of said impedances, and
  • eachof said adjustable members having at said given frequency apredetermh ied eifective electrical length substantially less than one-half the length of said line and having its shapeso selected'as to cause the characteristic impedance of said line over the lengths of said members to be less than said geometric mean of said impedances by such magnitude as to enable said a transmission line for an adjusted position of said members to match the resistance components and to cancel the reactance components of said 6.
  • a high-frequency impedance-matching device adapted for connection between and for matching at a given frequency a of impedances having any values within a predetermined range of magnitude and phase comp g, a plural-conductor transmission line adapted to be connected between said impedances and h ving a predetermined electrical length less than one wave length at said given frequency and a predetermined characteristic impedance less than the geometric mean of said impedances, and a plurality of members positioned between the.
  • each of said adjustable'members having at said given frequency a predetermined eifective' electrical length substantially lem thanone-half the length of said line and having its shape and material so selected as to cause the characteristic impedance of said line over the lengths of said members to be greater than said geometric mean of said impedances by such magnitude as to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel the reactance components of said pair of impedances.
  • a high-frequency impedance-matching device adapted for connection between and for matching at a given frequency a pair of imped ances having any values within a predetermined range of magnitude and phase comprising, a plural-conductor transmission line adapted to be connected between said impedances and having a predetermined electrical length less than one wave length at said given frequency and a predetermined characteristic impedance less than the geometric mean of said impedances.
  • each of said adjustable members having at said given frequency a predetermined eflective electrical length substantially less than one-half the length of said line and having its shapeso selected as to cause the characteristic impedance of said line over the lengths of said members to be greater than said geometric mean of said impedances by such magnitude as to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel the reactance components of said pair of impedances.
  • a high-frequency impedance-matching device "adapted for connection between and for matching at a given frequency a pair of impedances having any values within a predetermined range of magnitude and phase com-' 13 than one wave length at said given frequency and a predetermined characteristic impedance differing in one sense from the geometric mean of said impedances, and a plurality of members positioned within said line between the conductors thereof and independently adjustably movable axially along said line, each of said adjustable members having at said given frequency a predetermined eifective electrical length substantially less than one-half the length of said line and having its shape and material so selected as to cause the characteristic impedance of said line over the lengths of said members to differ from said geometric mean of said impedances in the opposite sense from the sense in which said line differs therefrom and by such magnitude as to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel the reactance components of said pair of impedances.
  • a high-frequency impedance-matching device adapted for connection between and for matching at a given frequency a pair of impedances having any values within a predetermined range of magnitude and phase comprising, a coaxial transmission line adapted to be connected between said impedances and having a predetermined electrical length less than one wave length at said given frequency and a predetermined characteristic impedance differing in one sense from the geometric mean of said impedances, and a plurality of members each enclosing the inner conductor of said line and independently adjustably movable axially along said line, each of said adjustable members having at said given frequency a predetermined effective electrical length substantially less than one-half the length of said line and having its shape and material so selected as to cause the characteristic impedance of said line over the lengths of said members to differ from said geometric mean of said impedances in the opposite sense from the sense in which said line differs therefrom and by such magnitude as to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel the reactance components of said pair
  • a high-frequency impedance-matching device adapted for connection between and for matc ing at a given' frequency a pair of impedances having any values within a predetermined range of magnitude and phase comprising, a plu- .14 rel-conductor transmission line adapted to be connected between said impedances and having an electrical length of approximately one-quarter wave length at said given frequency and a predetermined characteristic impedance differing in one sense from the geometric mean of said impedances, and a plurality of members positioned between the conductors of said line and independently adjustably movable axially therealong, each of adjustable members having at said given frequency an effective electrical length of approximately one-sixteenth wave length and having its shape and material so selected as to cause the characteristic impedance of said line over the lengths of said members to differ from said geo- -metric mean of said impedances in the opposite sense from the sense in which said line differs therefrom andby such magnitude as to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel
  • a high-frequency impedance-matching device adapted for connection between and for matching at a given frequency a pair of impedances having any values within a predetermined range of magnitude and phase comprising, a plural-conductor transmission line adapted to be connected between said impedances and having an electrical length of approximately one-quarter wave length at said given frequenc and a predetermined characteristic impedance differing in one sense from the geometric mean of said impedances, and a plurality of members positioned between the conductors of said line and independently adjustably movable axially therealong, each of said adjustable members having at said given frequency an effective electrical length of approximately one-sixteenth wave length and having its shape and material so selected as to' cause the characteristic impedance of said line over the lengths of said members to differ from said geometric mean of said impedances by approximately the same amount as that of said line but in the opposite sense from the sense in which said line differs therefrom to enable said transmission line for an adjusted position of said members to match the resistance components and to cancel the

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US563713A 1944-11-16 1944-11-16 High-frequency impedance-matching device Expired - Lifetime US2403252A (en)

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Application Number Priority Date Filing Date Title
BE474967D BE474967A (pt) 1944-11-16
US563713A US2403252A (en) 1944-11-16 1944-11-16 High-frequency impedance-matching device
GB27438/45A GB597922A (en) 1944-11-16 1945-10-18 High-frequency impedance-matching device
FR951364D FR951364A (fr) 1944-11-16 1947-08-06 Dispositif d'adaptation d'impédance à haute fréquence

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US563713A US2403252A (en) 1944-11-16 1944-11-16 High-frequency impedance-matching device

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2484798A (en) * 1945-12-29 1949-10-11 Philco Corp Signal transmission system
US2492404A (en) * 1945-11-10 1949-12-27 Rca Corp Construction of ultra high frequency broad-band antennas
US2496321A (en) * 1945-10-29 1950-02-07 Motorola Inc Tunable resonant system
US2557567A (en) * 1946-03-19 1951-06-19 Victor H Rumsey Coaxial transmission line filter system
US2594983A (en) * 1945-08-30 1952-04-29 Us Sec War Transmission line
US2623946A (en) * 1947-03-29 1952-12-30 Sperry Corp Transmission line transition
US2627550A (en) * 1949-05-18 1953-02-03 Bell Telephone Labor Inc Adjustable impedance transformer
US2711517A (en) * 1945-09-14 1955-06-21 Krutter Harry Corrugated wave guide
US2900610A (en) * 1955-05-19 1959-08-18 Richard W Allen Variable impedance transformer
DE1146144B (de) * 1961-08-11 1963-03-28 Fuba Antennenwerke Hans Kolbe Impedanzwandler
US3124747A (en) * 1964-03-10 hermach
US3200355A (en) * 1961-11-24 1965-08-10 Itt Electrical connector having rf filter
US3792385A (en) * 1972-11-06 1974-02-12 Rca Corp Coaxial magnetic slug tuner
US4700159A (en) * 1985-03-29 1987-10-13 Weinschel Engineering Co., Inc. Support structure for coaxial transmission line using spaced dielectric balls
WO1993001627A1 (de) * 1991-07-05 1993-01-21 Ant Nachrichtentechnik Gmbh Abstimmbares anpassungsnetzwerk
US20030156001A1 (en) * 2002-02-15 2003-08-21 Echols Billy G. Thirty-degree length impedance transformer
FR2888670A1 (fr) * 2005-07-18 2007-01-19 Centre Nat Rech Scient Adapteur d'impedance automatique coaxial
US20080200068A1 (en) * 2007-02-21 2008-08-21 Kyocera America, Inc. Broadband RF connector interconnect for multilayer electronic packages

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124747A (en) * 1964-03-10 hermach
US2594983A (en) * 1945-08-30 1952-04-29 Us Sec War Transmission line
US2711517A (en) * 1945-09-14 1955-06-21 Krutter Harry Corrugated wave guide
US2496321A (en) * 1945-10-29 1950-02-07 Motorola Inc Tunable resonant system
US2492404A (en) * 1945-11-10 1949-12-27 Rca Corp Construction of ultra high frequency broad-band antennas
US2484798A (en) * 1945-12-29 1949-10-11 Philco Corp Signal transmission system
US2557567A (en) * 1946-03-19 1951-06-19 Victor H Rumsey Coaxial transmission line filter system
US2623946A (en) * 1947-03-29 1952-12-30 Sperry Corp Transmission line transition
US2627550A (en) * 1949-05-18 1953-02-03 Bell Telephone Labor Inc Adjustable impedance transformer
US2900610A (en) * 1955-05-19 1959-08-18 Richard W Allen Variable impedance transformer
DE1146144B (de) * 1961-08-11 1963-03-28 Fuba Antennenwerke Hans Kolbe Impedanzwandler
US3200355A (en) * 1961-11-24 1965-08-10 Itt Electrical connector having rf filter
US3792385A (en) * 1972-11-06 1974-02-12 Rca Corp Coaxial magnetic slug tuner
US4700159A (en) * 1985-03-29 1987-10-13 Weinschel Engineering Co., Inc. Support structure for coaxial transmission line using spaced dielectric balls
WO1993001627A1 (de) * 1991-07-05 1993-01-21 Ant Nachrichtentechnik Gmbh Abstimmbares anpassungsnetzwerk
US5430417A (en) * 1991-07-05 1995-07-04 Aft Advanced Ferrite Technology Gmbh Tunable matching network
US20030156001A1 (en) * 2002-02-15 2003-08-21 Echols Billy G. Thirty-degree length impedance transformer
US6844803B2 (en) * 2002-02-15 2005-01-18 Mci, Inc. Thirty-degree length impedance transformer
FR2888670A1 (fr) * 2005-07-18 2007-01-19 Centre Nat Rech Scient Adapteur d'impedance automatique coaxial
WO2007010134A1 (fr) * 2005-07-18 2007-01-25 Centre National De La Recherche Scientifique - Cnrs Adapteur d'impedance automatique coaxial
US20090146757A1 (en) * 2005-07-18 2009-06-11 Centre National De La Recherche Scientifique-Cnrs- Coaxial automatic impedance adaptor
US7936233B2 (en) 2005-07-18 2011-05-03 Centre National de la Recherche Scientifique - CRNS Coaxial automatic impedance adaptor
US20080200068A1 (en) * 2007-02-21 2008-08-21 Kyocera America, Inc. Broadband RF connector interconnect for multilayer electronic packages
US7808341B2 (en) 2007-02-21 2010-10-05 Kyocera America, Inc. Broadband RF connector interconnect for multilayer electronic packages

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GB597922A (en) 1948-02-05
BE474967A (pt)
FR951364A (fr) 1949-10-24

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