US2819452A - Microwave filters - Google Patents

Microwave filters Download PDF

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Publication number
US2819452A
US2819452A US286763A US28676352A US2819452A US 2819452 A US2819452 A US 2819452A US 286763 A US286763 A US 286763A US 28676352 A US28676352 A US 28676352A US 2819452 A US2819452 A US 2819452A
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US
United States
Prior art keywords
conductor
line
conductors
obstacles
susceptance
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
US286763A
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English (en)
Inventor
Arditi Maurice
Georges A Deschamps
Elefant Jack
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.)
TDK Micronas GmbH
International Telephone and Telegraph Corp
Original Assignee
Deutsche ITT Industries GmbH
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
Application filed by Deutsche ITT Industries GmbH filed Critical Deutsche ITT Industries GmbH
Priority to US286763A priority Critical patent/US2819452A/en
Priority to GB12112/53A priority patent/GB761763A/en
Priority to CH316535D priority patent/CH316535A/fr
Priority to DEI7222A priority patent/DE1139928B/de
Application granted granted Critical
Publication of US2819452A publication Critical patent/US2819452A/en
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
    • H01P3/00—Waveguides; Transmission lines of the waveguide type
    • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
    • H01P3/08—Microstrips; Strip lines
    • H01P3/081—Microstriplines
    • 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
    • H01P1/203—Strip line filters
    • H01P1/2039—Galvanic coupling between Input/Output

Definitions

  • This invention relates to microwave transmission systems and more particularly to microwave filters specially applicable to microwave printed transmission lines and circuitry.
  • a type :of microwave transmission line comprising, in one of its simplest forms, two conductors printed or otherwise disposed in substantially parallel relation on opposite sides of a strip or layer of dielectric material a small fraction of a quarter wavelength thick.
  • One conductor is made narrower than the other, so that the wider planar conductor appears as an infinite conducting surface to the narrower conductor, thereby insuring the mode of propagation tof microwave energy therealong in the TEM mode.
  • the dielectric between the two conductors may be of substantially the same Width as the narrowest of the two conductors or wider according to the relationships desired.
  • filter arrangements utilizing a section of the aforementioned parallel strip type of line and spaced susceptances in the form of conductor obstacles projecting either partway or all the way across the space between the paralle'l strip conductors.
  • An object of this invention is to provide still other microwave filter arrangements which are small, light in Weight, and relatively simple and inexpensive to make, also utilizing a section of the aforementioned parallel type of line.
  • One of the features of this invention is the manner of providing in a parallel strip type of line spaced susceptances of large value disposed as reflecting shunt impedances to define a resonant section or cavity in the parallel strip line.
  • the susceptances may comprise the placing of two obstacles or Iother discontinuity structures in or on one or the other or both of the conductors of the line at spaced points to form a resonant cavity section therebetween. These discontinuities may comprise either a conductor or dielectric obstacle.
  • susceptances may be introduced in the line by placing a piece of conductor cross-wise of the line as ⁇ a lumped impedance.
  • the cross-wise conductor would be in contact with one of the line conductors with its ends either open or shorted to the other line conductor. Also such obstacles may be printed directly on the strip of dielectric along with the line conductors, and if desired, may comprise variations in the shape of the line conductors.
  • Another feature of the invention is the method and means for tuning the resonant spacing formed by such line conductor configurations.
  • this tuning of the resonant spacing or cavity may be accomplished in various ways, including Vernier capacitive screws, line compressors or stretches, lateral line projections or protuberances and the size and position of interconnecting portions of the line conductor configurations.
  • Fig. 1 is a plan view of ⁇ one forni of filter in accordance with the principles of this invention
  • Fig. 2 is a cross-sectional View taken along line 2-2 of Fig. l; l
  • Fig. 3 isa plan view of an alternate form of filter
  • Fig. 4 is a cross-sectional view taken along line 4 -4 of Fig. 3;
  • Fig. 5 is a cross-sectional view similar to Fig. 4 showing another modification of the invention.
  • Fig. 6 is a plan view of another embodiment of the invention.
  • Fig. 7 is a cross-sectional view taken along line 7 7 of Fig. 6;
  • Fig. 8 is a circle diagram based upon the Smith admittance chart used in explaining the susceptance characteristics of the plate-'like obstacles used in the filters of the character disclosed herein;
  • Fig. 9 is a plan View of a directly coupled filter in accordance with the principles of this invention.
  • Fig. 10 is a cross-sectional View taken along line 10- 10 of Fig. 9;
  • Figs. l1 and 12 show still other modifications of this invention.
  • the microwave transmission line shown is of the printed circuit type comprising a first or line conductor 1 and a second or base conductor 2 with a layer 3 of dielectric material therebetween.
  • the conductive material may be applied and/ or shaped or etched on a layer of dielectric material, such as polystyrene, polyethylene, quartz, Teflon, fiberglass, or other suitable material of high dielectric quality, in the form of conductive paint or ink, or the conductive material may be chemically deposited, sprayed through a stencil, or dusted onto selected prepared surfaces of thedielectric, or by any other of the known printed circuit techniques.
  • the spacing of the two conductors is preferably selected a small fraction in the order of about 1/10 ⁇ to about 1/s of a quarterwavelength of the microwave propagated therealong.
  • the microwave line of Figs. l and 2 is shown. provided. with spaced obstacles as lumped impedances in the form of short pieces of conductors 4, S, 6, and 7 disposed crosswise of the line conductor l.
  • These crosswise conductor obstacles provide two resonant cavity sections of lengths 1, the cavity sections being coupled by quarter wavelength sections of line.
  • the crosswise conductors 4 through 7 are shown to be of the same width as the line conductor 1, they may be of other widths either wider or narrower as desired, but always a small fraction of a quarter wavelength, depending upon the susceptance value desired.
  • the lengths of the crosswise conductors may also vary depending upon the susceptance value dev sired.
  • the susceptance value may also be varied by adjusting the position of the crosswise conductor. After the crosswise conductors have been suitably located, they may be secured to the line conductor by means of solder 8. After securing the crosswise pieces, it may be desirable to further tune the susceptances, the cavities idened thereby or the quarter wavelength spaced therebetween by ⁇ some form of Vernier trimming device. Such a trimming device is shown in Figs. l and 2 to comprise a piece of small wire as indicated at 9 and 10. Such piece of wire may be positioned either on the cross pieces 4 to 7 or on the line conductor 1 as may be desired. By adjusting the position of the wire, proper matching may be obtained.
  • the optimum position of trimming pieces or wire may be determined by use of any suitable measuring technique, one satisfactory method of making such measurements being disclosed in the pending application of G. A. Deschamps, Serial No. 333,164, tiled January 26, 1953.
  • a piece of solder which is maintained soft by a ysoldering iron whereby the Wire is nudged from one position to another until an optimum reading is obtained whereupon the solder is permitted to freeze.
  • the filter When the proper location of the crosswise conductors is obtained, the filter may be reproduced with reasonable accuracy by photographic and printed circuit techniques. Such a filter when produced by these techniques may have the appearance shown in Figs. 3 and 4.
  • the line conductor 1a and the cross-conductors 4a through 7a are made integral. While the cross pieces 4a through 7a are shown to extend completely across the dielectric 3, it will be clear that they need not be so extended but may fall short of the Width of the dielectric similarly as illustrated in Fig. 1.
  • the use of small pieces of Wire may also be practiced on this form of printed filter as well as several other methods. As shown in Figs.
  • one such method comprises conductive posts 11 and 12 disposed in the dielectric 3 in the resonant cavity section of the line.
  • Another method of varying the length of line between adjacent cross pieces is that of compressing or stretching the width of the line conductor. This method is best employed by providing the line conductor with extended width with gradual curvature as indicated at 13. If this width provides in effect too long a section, that section may be shortened in effect by slicing away edge portions of the line conductor, thus compressing it as indicated between broken lines 14. This lengthening and shortening of the line has reference to line wavelength.
  • the cross pieces 4a through 7a shown in Fig. 3 may be open ⁇ or closed at their ends.
  • the cross pieces are shown to be open.
  • the cross pieces are shown to be closed with respect to the other line conductor 2a, the line conductor 4a for example being continued by a conductor for connection with conductor 2a.
  • the conductor 2a may comprise a planar conductor extending the full width of the dielectric 3 or it may be of substantially the same width as the line conductor 1a as indicated in Fig. 5.
  • the conductor 2a may also be provided with cross pieces the same as 4a through 7a.
  • Figs. 6 and 7 show another form of ilter arrangement comprising two ribbon-like conductors 16 and 17 of substantially equal width separated by a similar region of dielectric 18.
  • the susceptance obstacles of lumped impedance in this iilter comprise strips of conductive material 19, 20 and 21, 22 disposed on opposite sides of the line conductors.
  • the susceptance values of these obstacles may be adjusted by adjusting relative positions, one being offset with respect to the other.
  • the ends of these cross pieces may be either open as shown or may be closed similarly as indicated in Fig. 5.
  • a Smith admittance chart is shown onto which a circle has been applied corresponding to test data with respect to a susceptance obstacle illustrated at 24 in Fig. 8.
  • the line section ⁇ is of the same character illustrated in Fig. l and is provided with like reference characters.
  • the obstacle comprises a crosswise strip 25 which is shorted at its ends to conductor 2 as indicated at 26. It will be observed that the circle is large thereby indicating that the insertion loss of this type of obstacle is small. It also shows that the obstacle is substantially symmetrical.
  • a directly coupled lter comprising a line conductor 27 printed on a strip ⁇ of dielectric 3 which in turn is provided with a second conductor 2 on the opposite Vside thereof.
  • the line conductor 27 is provided with a series of susceptance obstacles of dilerent lengths, the obstacles 28, 29, 30,
  • the susceptance obstacles 32, 33, and 34 determine the susceptance of the resonant sections.
  • These crosswise obstacles may each be tuned by any one of the tuning or trimming means herein described but for purposes of illustration the tuning means is shown to be in the form of a capacitive post 35 which may be adjusted with respect to the opposite line conductor. It should also be observed that While the second conductor 2 is illustrated as a planar conductor that it may in fact correspond substantially to the shape of the line conductor 27 together with the obstacle susceptance projections thereof.
  • the iilter may follow various line configurations incorporating susceptance obstacles of lumped impedances.
  • the line conductor 36 is shown with obstacle projections along :one side thereof as indicated Iat 37, the projections being of a width less than ⁇ a quarter wavelength.
  • the printed configuration may also incorporate trimming projections ⁇ as indicated at 38 -and 39. These trimming projections correspond substantially to the small pieces of wire 9 and 10 illustrated in Fig. 1. Final trimming of the resonant sections and the susceptance obstacles may be accomplished by cutting away portions of these small projections 38 and 39 until the optimum lsusceptance is obtained. Should too much be removed, conductive material may be added by soldering.
  • Fig. 11 the line conductor 36 is shown with obstacle projections along :one side thereof as indicated Iat 37, the projections being of a width less than ⁇ a quarter wavelength.
  • the printed configuration may also incorporate trimming projections ⁇ as indicated at 38 -and 39. These trimming projections correspond substantially to the small pieces of wire 9 and 10
  • 12 obstacles may comprise cutouts such as indicated at 40 in the line conductor 41.
  • the susceptance values of these recesses in the line 41 are also in the nature of lumped impedances or reflection obstacles, since the width ⁇ of the slots are a small fraction of a quarter wavelength.
  • These recesses may be tuned by means of small pieces ⁇ of wire las indicated at 42 and 43. By adjusting the position of these wires optimum tuning may be had, the Wires being thereafter secured by soldering or other suitable fastening means.
  • a microwave filter comprising first and second ribbonlike conductors, means disposing said conductors in dielectrically spaced substantially parallel relation a small fraction of a quarter wavelength vapart to provide a waveguide, ⁇ said fir-st conductor being of a width equal to a fraction of a quarter wavelength, said second conductor being wider than said first conductor to present thereto a planar conducting surface for propagation ⁇ of microwave energy in a mode approximating the TEM mode, said irst conductor having laterally disposed projections extending in overlying parallel relation to the planar conducting surface of said second conductor, the width of said lateral projections being asmall fraction of a quarter wavelength to present reflecting lump impedances spaced apart longitudinally of said conductors to form a resonant section therebetween, and means for adjusting the susceptance value :of certain of said lateral projections, said means including a conductive screw carried by the projection for adjustment into the space between saidprojection and said planar conducting surface.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
US286763A 1952-05-08 1952-05-08 Microwave filters Expired - Lifetime US2819452A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US286763A US2819452A (en) 1952-05-08 1952-05-08 Microwave filters
GB12112/53A GB761763A (en) 1952-05-08 1953-05-01 Microwave filters
CH316535D CH316535A (fr) 1952-05-08 1953-05-07 Filtre pour ondes ultra-courtes
DEI7222A DE1139928B (de) 1952-05-08 1953-05-07 Mikrowellenfilter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US286763A US2819452A (en) 1952-05-08 1952-05-08 Microwave filters

Publications (1)

Publication Number Publication Date
US2819452A true US2819452A (en) 1958-01-07

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Application Number Title Priority Date Filing Date
US286763A Expired - Lifetime US2819452A (en) 1952-05-08 1952-05-08 Microwave filters

Country Status (4)

Country Link
US (1) US2819452A (fr)
CH (1) CH316535A (fr)
DE (1) DE1139928B (fr)
GB (1) GB761763A (fr)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2915716A (en) * 1956-10-10 1959-12-01 Gen Dynamics Corp Microstrip filters
US2919441A (en) * 1955-04-15 1959-12-29 Chu Lan Jen Radio-frequency-energy transmission line and antenna
US2962716A (en) * 1957-06-21 1960-11-29 Itt Antenna array
US2984802A (en) * 1954-11-17 1961-05-16 Cutler Hammer Inc Microwave circuits
US3327255A (en) * 1963-03-06 1967-06-20 Bolljahn Harriette Interdigital band-pass filters
US3345589A (en) * 1962-12-14 1967-10-03 Bell Telephone Labor Inc Transmission line type microwave filter
US3348173A (en) * 1964-05-20 1967-10-17 George L Matthaei Interdigital filters with capacitively loaded resonators
US3391356A (en) * 1964-06-30 1968-07-02 Bolljahn Harriette Strip-line filter
US3497835A (en) * 1965-12-10 1970-02-24 Hughes Aircraft Co Microwave filter
US3534301A (en) * 1967-06-12 1970-10-13 Bell Telephone Labor Inc Temperature compensated integrated circuit type narrowband stripline filter
US3670270A (en) * 1968-04-15 1972-06-13 Technitrol Inc Electrical component
US3749473A (en) * 1971-11-04 1973-07-31 T Stewart Landing gear lever knob
US3959749A (en) * 1973-10-29 1976-05-25 Matsushita Electric Industrial Co., Ltd. Filter of the distributed constants type
EP0028403A1 (fr) * 1979-11-05 1981-05-13 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Tronçon de ligne en dérivation pour l'adaptation de circuits à microbandes
EP0037421A1 (fr) * 1979-10-15 1981-10-14 Motorola Inc Structure a film mince pour substrats en ceramique.
FR2580118A1 (fr) * 1985-04-03 1986-10-10 Singer Co
US5734307A (en) * 1996-04-04 1998-03-31 Ericsson Inc. Distributed device for differential circuit
CN1050703C (zh) * 1992-09-24 2000-03-22 松下电器产业株式会社 带通滤波器
US6621382B2 (en) * 2000-12-11 2003-09-16 Sharp Kabushiki Kaisha Noise filter and high frequency transmitter using noise filter

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1160736B (it) * 1983-03-18 1987-03-11 Telettra Lab Telefon Circuito risuonatore per un sistema di estrazione dal flusso di dati dell'oscillazione alla frequenza di temporizzazione
EP1298757A1 (fr) * 2001-09-29 2003-04-02 Marconi Communications GmbH Filtre passe-bande à haute fréquence et son procédé d'accord

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2411555A (en) * 1941-10-15 1946-11-26 Standard Telephones Cables Ltd Electric wave filter
US2540488A (en) * 1948-04-30 1951-02-06 Bell Telephone Labor Inc Microwave filter
US2558748A (en) * 1945-12-14 1951-07-03 Andrew V Haeff Radio-frequency filter
US2721312A (en) * 1951-06-30 1955-10-18 Itt Microwave cable

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE456300A (fr) * 1943-06-16
US2585563A (en) * 1949-09-17 1952-02-12 Bell Telephone Labor Inc Wave filter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2411555A (en) * 1941-10-15 1946-11-26 Standard Telephones Cables Ltd Electric wave filter
US2558748A (en) * 1945-12-14 1951-07-03 Andrew V Haeff Radio-frequency filter
US2540488A (en) * 1948-04-30 1951-02-06 Bell Telephone Labor Inc Microwave filter
US2721312A (en) * 1951-06-30 1955-10-18 Itt Microwave cable

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2984802A (en) * 1954-11-17 1961-05-16 Cutler Hammer Inc Microwave circuits
US2919441A (en) * 1955-04-15 1959-12-29 Chu Lan Jen Radio-frequency-energy transmission line and antenna
US2915716A (en) * 1956-10-10 1959-12-01 Gen Dynamics Corp Microstrip filters
US2962716A (en) * 1957-06-21 1960-11-29 Itt Antenna array
US3345589A (en) * 1962-12-14 1967-10-03 Bell Telephone Labor Inc Transmission line type microwave filter
US3327255A (en) * 1963-03-06 1967-06-20 Bolljahn Harriette Interdigital band-pass filters
US3348173A (en) * 1964-05-20 1967-10-17 George L Matthaei Interdigital filters with capacitively loaded resonators
US3391356A (en) * 1964-06-30 1968-07-02 Bolljahn Harriette Strip-line filter
US3497835A (en) * 1965-12-10 1970-02-24 Hughes Aircraft Co Microwave filter
US3534301A (en) * 1967-06-12 1970-10-13 Bell Telephone Labor Inc Temperature compensated integrated circuit type narrowband stripline filter
US3670270A (en) * 1968-04-15 1972-06-13 Technitrol Inc Electrical component
US3749473A (en) * 1971-11-04 1973-07-31 T Stewart Landing gear lever knob
US3959749A (en) * 1973-10-29 1976-05-25 Matsushita Electric Industrial Co., Ltd. Filter of the distributed constants type
EP0037421A1 (fr) * 1979-10-15 1981-10-14 Motorola Inc Structure a film mince pour substrats en ceramique.
EP0037421A4 (fr) * 1979-10-15 1982-01-26 Motorola Inc Structure a film mince pour substrats en ceramique.
EP0028403A1 (fr) * 1979-11-05 1981-05-13 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Tronçon de ligne en dérivation pour l'adaptation de circuits à microbandes
FR2580118A1 (fr) * 1985-04-03 1986-10-10 Singer Co
US4654668A (en) * 1985-04-03 1987-03-31 The Singer Company Microstrip circuit temperature compensation with stub means
CN1050703C (zh) * 1992-09-24 2000-03-22 松下电器产业株式会社 带通滤波器
US5734307A (en) * 1996-04-04 1998-03-31 Ericsson Inc. Distributed device for differential circuit
US6621382B2 (en) * 2000-12-11 2003-09-16 Sharp Kabushiki Kaisha Noise filter and high frequency transmitter using noise filter

Also Published As

Publication number Publication date
DE1139928B (de) 1962-11-22
GB761763A (en) 1956-11-21
CH316535A (fr) 1956-10-15

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