US3187277A - Waveguide harmonic suppressor employing subsidiary waveguides, cut off for fundamental, for coupling main waveguide harmonics to absorber - Google Patents

Waveguide harmonic suppressor employing subsidiary waveguides, cut off for fundamental, for coupling main waveguide harmonics to absorber Download PDF

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Publication number
US3187277A
US3187277A US194282A US19428262A US3187277A US 3187277 A US3187277 A US 3187277A US 194282 A US194282 A US 194282A US 19428262 A US19428262 A US 19428262A US 3187277 A US3187277 A US 3187277A
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Prior art keywords
waveguide
harmonic
passageways
main
microwave
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Expired - Lifetime
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US194282A
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English (en)
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Wantuch Ernest
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Airtron Inc
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Airtron Inc
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Priority to US194282A priority Critical patent/US3187277A/en
Priority to FR924853A priority patent/FR1348151A/fr
Priority to DEL44587A priority patent/DE1266892B/de
Priority to GB18112/63A priority patent/GB1037667A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
    • H01P1/162—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion absorbing spurious or unwanted modes of propagation

Definitions

  • a waveguide normally operates at a fundamental frequency and mode; however, higher harmonics may be applied to the waveguide in various modes by transmitters such as magnetrons or high power klystrons. For many known reasons, it is often desirable to eliminate these higher harmonics.
  • the usual arrangements for suppressing harmonic include a series of apertures along one side wall of the waveguide and dissipation material located near the apertures for dissipating microwave energy coupled through the apertures.
  • the prior art harmonics Suppressors frequently do not provide sufficient attenuation for the harmonics and introduce unnecessary loss into the main waveguide channel.
  • the Suppressors have exhibited undesirably high reflection for the higher harmonics, and in other cases, some of the many modes in which the harmonic energy is present may not be attenuated to any significant extent.
  • a principal object of the present invention is to increase the attenuation of harmonics and reduce the attenuation of the dominant or fundamental waveguide mode, in waveguide harmonic Suppressors.
  • Another object of the invention is to minimize the size of harmonic Suppressors having these properties. Additional objects include reduction of reflections in the harmonic or stop band of frequencies, and increasing the attenuation for all the modes in which harmonic energy may propagate.
  • a main waveguide channel is provided with a series of apertures on all four sides, and each aperture is provided with an associated short waveguiding passageway.
  • Subordinate microwave chambers containing lossy material may extend parallel to the main waveguide, and many of the small waveguiding passageways may be coupled to a single one of these subordinate lossy chambers.
  • Dielectric rods may extend through the passageways to more strongly couple harmonics from the main waveguide to the subordinate waveguide chambers where the harmonic energy is dissipated. By extending the rods physically into the main waveguide, or the lossy subordinate chambers, or both, much greater attenuation of the harmonic energy is achieved than has been possible heretofore.
  • the dielectric rods are preferably made of a material having a very low loss such as quartz so that the material extending into the main waveguide channel does not significantly increase the attenuation of the fundamental mode.
  • the use of dielectric material in the passageways has the collateral advantage of permitting the diversion of harmonic waves through waveguide passageways of relatively small cross-section. Accordingly, a great many of the branch passageways may be packed along a relatively short length of the main waveguide. High attenu- Awhich microwave energy lmay propagate.
  • the second harmonic of the fundamental was reduced by 40 decibels, or 99.99%.
  • the attenuation for the fundamental frequency in the case of this representative harmonic suppressor was less than one-quarter of one decibel.
  • a rectangular waveguide is provided with four spaced subordinate lossy waveguiding chambers, and a set of dielectric-filled conductively bounded passageways interconnects each of the four walls of the main waveguide with the subordinate channels.
  • a harmonic suppressor is provided with a main waveguiding passageway and a subordinate lossy chamber, and dielectric elements extending into the main waveguide to couple microwave energy to the lossy chamber.
  • FIG. l is an isometric view of a harmonic suppressor illustrating the principles of the present invention.
  • FIG. 2 is a cross-sectional view of a modified version of the invention.
  • FIG. 1 shows a harmonic suppressor having a principal waveguide channel 12.
  • the principal channel 12 is provided with coupling flanges 14 and 16 at its two ends to facilitate connection to the other components ofV a microwave system.
  • harmonic suppression structures 18, 2l), 22 and 24 are provided on each of the four sides of the waveguide channel 12. As these four structures are generally similar, only the structure 22 associated with the upper broad wall of waveguide 12 will be considered in detail.
  • the structure 22 includes an outer conductive Wall 26, shown cut away in FIG. 1 to reveal the operative inner components.
  • the operative harmonic suppression components within the conductive wall 26 includes a strip of corrugated lossy material 28 mounted against the upper surface of the harmonic suppressor structure 22.
  • Immediately below the lossy dielectric strip 2S is an open space through This space, together with material 28, provides a subordinate lossy microwave channel or chamber which extends generally 12 to the lossy chamber near the top of the structure 22.
  • these microwave passageways are implemented by openings in the upper wall 30 of the waveguide I2 and by a series of hollow conductive tubes 32. ⁇
  • the conductive passageways may be implemented by using a single thicker member of conductive material with holes drilled through it.
  • Dielectric rods 34 extend through the conductive passageways from the waveguide 12 to the space below the lossy strip 2S. It has been found that coupling to the harmonics which are present in the main guide 12 is greatly enhanced by extension of the dielectric rods 34 into the main waveguide channel. Thus, for example decibel more coupling of the harmonic energy is obtained waveguide, as contrasted with an arrangement in which the dielectric rods were flush with the inner wall of thek waveguide.
  • the openings may be staggered, with two holes present in the first row and three holes being provided in the second row. This arrangement of alternate and staggered holes is continued along the length of the upper surface of the waveguide.
  • a similar arrangement of closely-packed passageways is provided on the lower surface of waveguide 12.
  • the tubes 36 are arranged at aV considerable angle and successive pairs of tubes are mounted to form closely-packed arrays along each of the narrow sidewalls of waveguide 12.
  • the lossy material 58 and 40 associated with the harmonic suppression structures and 24 may also be seen in FIG. 1.
  • FIG. 2 is a cross-sectional view through a slightly modified version of the device shown in FIG. 1.
  • y Primed reference numerals in FIG. Z correspond to ⁇ unprimed numerals in FIG. l. central waveguide channel 12 and the four associated waveguide suppression structures 18', 20', 22 and 24.
  • the structure FIG. 2 also includes lossy material 28' associated with suppression structure 22, and additional lossy material 38 and 4G associated with waveguide suppression structures 20 and 24.
  • the quartz rods 24' of FIG. 2 serve to couple harmonic microwave energy from the main guiding passageway 12 to thesubordinate lossy microwave chamber above rods 34'.
  • One difference between the embodiments of FIGS. 1 and 2 involvesV the use of a solid strip of material such as strip 44 having a series of holes drilled through -it to accommodate the quartz rods 34, on each side of the main waveguide.
  • FIG. 2 This is in contrast to the arrangement of FIG. 1 in which a number of conducting tubes 32 are employed to provide the conductive passageways.
  • the section is taken tok include quartz rod 46, and an adjacent quartz rod 48 is shown slightly behind the quartz rod 46 to indicate Vthe offsetting which is present in the coupling apertures in the narrow side walls of the waveguide 12'.
  • the main channel 12 for C-band has dimensions of 1.872 inches for :the broader side walls,V
  • the recommended frequency range for C-band waveguides is 3.95 to 5.85 kilomegacycles, in accordance with Table II which appears at page 6-6 in the ⁇ Radio Engineering Handbook, Fifth Edition, 1959, by Keith Henney, Editorin-Chief, McGraw-Hill Company, Inc., New York.
  • a frequency band of from l4.4 to 5.0 kilomegacycles was primarily of interest.
  • Sys- The device of FIG. 2 includes the tem requirements necessitated suppression of second and higher harmonics present in the microwave signals.
  • the branch waveguide channels must not transmit signals below 5.85 kilornegacycles to any substantial extent, but they must readily transmit harmonic signals which would have a frequency of at least twice the lowest frequency in the band.
  • the branch passageways must readily couple energy of frequencies higher than twice the 3.95 kilomegacycles lower frequency which is recommended for C-band waveguides. Multiplying 3.95 2 gives a desired maximum cutoff frequency of 7.9 kilomegacycles.
  • the branch waveguide passageways therefore must have a cutoff frequency below this 7.9 kilomegacycle frequency and above the maximum frequency of 5.85 kilomegacycles which is recommended for C-band waveguides.
  • the cutoff wave length for circular waveguides is given by the following formula:
  • Lc is the cutoff wave length
  • D is the diameter of the waveguide passageway
  • e is the dielectric ⁇ constant of the material in the waveguide.
  • quartz rods having a diameter of one-half inch werey employed. Quartz has a dielectric constant of 4. Substituting in Equation l the cutoff wave length is determined to be 4.25 centimeters.Y To compute the cutoff frequency, the following formula may be used:
  • L is equal to the Wave length
  • f is the frequency
  • 3 1O10 cms/sec. is the speed of light and of microwave energy propagation in free space.
  • the cutoff frequency may be readily calculated to be about 7 kilomegacycles.
  • the branch passageways will transmit signals of about 7 kilomegacycles and higher frequencies, but will not transmit lower microwave signals.
  • a harmonic suppressor in which the suppression structures 1S, 20, 22 and 24 were fifteen inches long exhibited 40 decibels suppression for the second harmonic, corresponding to the elimination of 99.99 percent of this undesired higher frequency energy.
  • this structure only introduced one-quarter of one decibel of loss for signals in the fundamental mode in the waveguide y12.
  • the dielectric constant for quartz is four, as contrasted with the dielectric constant of one, for air. If the tubes 32 of FIG. 1 were not filled with quartz, the cutoff frequency of the one-half inch tubes would be raised from 7 kilomegacycles to 14 kilomegacycles. Under these circumstances, of course, no suppression of the second harmonic signals would occur. In order to provide harmonic suppression, much larger diameter airfilled passageways would have to be provided. Accordingly, through the use of quartz rods, the diameter may be reduced and the packing density of the passageways may be greatly increased.
  • surfaces may be ⁇ of copper, aluminum, or of any of a tures, they may be formed of any known microwave loss material.
  • One typical material which may be employed is carbon-loaded epoxy.
  • quartz is preferred for the dielectric material in the branch passageways; however, other dielectric material such as alumina, and more common dielectric substances, may also be employed.
  • a balanced microwave harmonic suppressor comprising:
  • microwave loss material for dissipating harmonic energy
  • dielectric material mounted in said passageways and protruding into said main waveguide.
  • a balanced microwave harmonic suppressor comprising:
  • microwave loss material for dissipat- Iing harmonic energy
  • subsidiary waveguides having a significantly ysmaller cross-section than said main waveguide coupling harmonic energy from said apertures to said d-issipating means, the length of said subsidiary waveguides being greater than their width, whereby they ⁇ are beyond cut-off for the principal mode in said main waveguide.
  • a main section of conductive waveguide means including a plurality of conductively bounded passageways of reduced cross-section connected to said waveguide for eliminating harmonic energy from said waveguide, and means consisting solely of substantially lossless dielectric material located in said pa'ssageways and protruding into said main waveguide for coupling the harmonics from said main waveguide into said passageways without disturbing the principal mode in said m-ain waveguide.
  • a microwave harmonic suppressor comprising:
  • microwave loss material for dissipatling harmonic energy, a plurality of apertures in each of the four walls of the main waveguide, and
  • subordinate waveguides having a sig niiicantly smaller cross-section than said main waveguide for coupling harmonic energy from said apertures topsaid dissipating means, the length of said Iwaveguides being greater than their width, whereby they are beyond cut-ott for the principal mode in said main waveguide.
  • a microwave harmonic suppressor a main sect-ion of conductive waveguide, a lossy waveguide space adjaject said waveguide, a plurality of conductively bounded passageways extending between said waveguide and said lossy space, and dielectric material located in said passageways and extending into said main waveguide.
  • a microwave harmonic suppressor comprising:
  • microwave loss material for dissi- -pating harmonic energy
  • a microwave harmonic suppressor a main section of conductive waveguide, a lossy waveguide space adjacent said waveguide, a plurality of conductively bounded passageways extending between said waveguide tand said lossy space, said passageways having a length which is greater than their width, and quartz rods 1ocated in said passageways.
  • a microwave harmonic suppressor In a microwave harmonic suppressor, a main section of conductive waveguide, a subordinate waveguide space adjacent said main waveguide, a plurality of conductively bounded passageways extending between said main waveguide and said subordinate waveguide space, dielectric rods extending through said p-assageways into said lsubordinate waveguide space, and lossy material substantially iilling said space and surrounding the ends of said dielectric rods.
  • a balanced microwave harmonic suppressor comprising:
  • quartz rods extending through said passageways from said subordin-ate channels and protruding slightly into lsaid main rectangular waveguide.

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US194282A 1962-05-14 1962-05-14 Waveguide harmonic suppressor employing subsidiary waveguides, cut off for fundamental, for coupling main waveguide harmonics to absorber Expired - Lifetime US3187277A (en)

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Application Number Priority Date Filing Date Title
US194282A US3187277A (en) 1962-05-14 1962-05-14 Waveguide harmonic suppressor employing subsidiary waveguides, cut off for fundamental, for coupling main waveguide harmonics to absorber
FR924853A FR1348151A (fr) 1962-05-14 1963-02-14 Suppresseur d'harmoniques pour guide d'ondes
DEL44587A DE1266892B (de) 1962-05-14 1963-04-09 Oberwellensperrfilter in Form eines Hohlleiterabschnitts mit mehreren Stichleitungen
GB18112/63A GB1037667A (en) 1962-05-14 1963-05-08 Improvements in or relating to electromagnetic waveguides

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451014A (en) * 1964-12-23 1969-06-17 Microwave Dev Lab Inc Waveguide filter having branch means to absorb or attenuate frequencies above pass-band
US3464035A (en) * 1966-07-25 1969-08-26 Gerald W Van Kol Filter coupled to microwave guide
US3511958A (en) * 1968-12-31 1970-05-12 Gen Electric Electronic oven including microwave coupling structure and folded cavity filters therefor
US3536878A (en) * 1968-12-31 1970-10-27 Gen Electric Electronic heating apparatus including microwave coupling structure and filters therefor
US3537040A (en) * 1968-01-11 1970-10-27 Us Air Force Low-pass waveguide filter
US3916352A (en) * 1973-08-11 1975-10-28 Marconi Co Ltd Waveguide filters
US3952270A (en) * 1974-01-25 1976-04-20 Compagnie Industrielle Des Telecommunications Cit-Alcatel Hyperfrequency band-cut filter
US4060778A (en) * 1976-07-12 1977-11-29 Microwave Research Corporation Microwave harmonic absorption filter
US4096457A (en) * 1976-10-29 1978-06-20 Harvard Industries, Inc. Low pass harmonic absorber
US4559490A (en) * 1983-12-30 1985-12-17 Motorola, Inc. Method for maintaining constant bandwidth over a frequency spectrum in a dielectric resonator filter
US4568894A (en) * 1983-12-30 1986-02-04 Motorola, Inc. Dielectric resonator filter to achieve a desired bandwidth characteristic
US4575701A (en) * 1983-05-27 1986-03-11 The Marconi Company Ltd. Microwave switch
US4578657A (en) * 1984-05-30 1986-03-25 Alcatel Thomson Faisceaux Hertziens Filter of the type consisting of a primary waveguide having lateral secondary guides
US4593460A (en) * 1983-12-30 1986-06-10 Motorola, Inc. Method to achieve a desired bandwidth at a given frequency in a dielectric resonator filter
CN104868209A (zh) * 2015-06-10 2015-08-26 成都赛纳赛德科技有限公司 多通道微波器件
CN106374174A (zh) * 2016-08-29 2017-02-01 成都赛纳微波科技有限公司 具有金属体的大功率微波器件
WO2023186621A1 (en) * 2022-03-28 2023-10-05 Sweden Quantum Ab A filter arrangement for quantum processors

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US2197123A (en) * 1937-06-18 1940-04-16 Bell Telephone Labor Inc Guided wave transmission
US2425345A (en) * 1942-12-23 1947-08-12 Bell Telephone Labor Inc Microwave transmission system
US2749520A (en) * 1952-11-04 1956-06-05 Burt J Bittner Directional coupling means for transmission lines
US2810908A (en) * 1951-10-10 1957-10-22 Rca Corp Microwave phase compensation system
US2877434A (en) * 1945-11-19 1959-03-10 Harold K Farr Mode filter
US2907961A (en) * 1954-09-14 1959-10-06 Sperry Rand Corp Adjustable attenuators for microwave radio energy
US2909735A (en) * 1955-12-08 1959-10-20 Itt Twin probe waveguide transition
US2945193A (en) * 1954-02-02 1960-07-12 Texas Instruments Inc Rotary waveguide joint and switching structure

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US2106768A (en) * 1934-09-25 1938-02-01 American Telephone & Telegraph Filter system for high frequency electric waves
GB659812A (en) * 1947-06-30 1951-10-31 Gen Electric Co Ltd Improvements in and relating to electric filter circuits

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2197123A (en) * 1937-06-18 1940-04-16 Bell Telephone Labor Inc Guided wave transmission
US2425345A (en) * 1942-12-23 1947-08-12 Bell Telephone Labor Inc Microwave transmission system
US2877434A (en) * 1945-11-19 1959-03-10 Harold K Farr Mode filter
US2810908A (en) * 1951-10-10 1957-10-22 Rca Corp Microwave phase compensation system
US2749520A (en) * 1952-11-04 1956-06-05 Burt J Bittner Directional coupling means for transmission lines
US2945193A (en) * 1954-02-02 1960-07-12 Texas Instruments Inc Rotary waveguide joint and switching structure
US2907961A (en) * 1954-09-14 1959-10-06 Sperry Rand Corp Adjustable attenuators for microwave radio energy
US2909735A (en) * 1955-12-08 1959-10-20 Itt Twin probe waveguide transition

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451014A (en) * 1964-12-23 1969-06-17 Microwave Dev Lab Inc Waveguide filter having branch means to absorb or attenuate frequencies above pass-band
US3464035A (en) * 1966-07-25 1969-08-26 Gerald W Van Kol Filter coupled to microwave guide
US3537040A (en) * 1968-01-11 1970-10-27 Us Air Force Low-pass waveguide filter
US3511958A (en) * 1968-12-31 1970-05-12 Gen Electric Electronic oven including microwave coupling structure and folded cavity filters therefor
US3536878A (en) * 1968-12-31 1970-10-27 Gen Electric Electronic heating apparatus including microwave coupling structure and filters therefor
US3916352A (en) * 1973-08-11 1975-10-28 Marconi Co Ltd Waveguide filters
US3952270A (en) * 1974-01-25 1976-04-20 Compagnie Industrielle Des Telecommunications Cit-Alcatel Hyperfrequency band-cut filter
US4060778A (en) * 1976-07-12 1977-11-29 Microwave Research Corporation Microwave harmonic absorption filter
US4096457A (en) * 1976-10-29 1978-06-20 Harvard Industries, Inc. Low pass harmonic absorber
US4575701A (en) * 1983-05-27 1986-03-11 The Marconi Company Ltd. Microwave switch
US4559490A (en) * 1983-12-30 1985-12-17 Motorola, Inc. Method for maintaining constant bandwidth over a frequency spectrum in a dielectric resonator filter
US4568894A (en) * 1983-12-30 1986-02-04 Motorola, Inc. Dielectric resonator filter to achieve a desired bandwidth characteristic
US4593460A (en) * 1983-12-30 1986-06-10 Motorola, Inc. Method to achieve a desired bandwidth at a given frequency in a dielectric resonator filter
US4578657A (en) * 1984-05-30 1986-03-25 Alcatel Thomson Faisceaux Hertziens Filter of the type consisting of a primary waveguide having lateral secondary guides
CN104868209A (zh) * 2015-06-10 2015-08-26 成都赛纳赛德科技有限公司 多通道微波器件
CN106374174A (zh) * 2016-08-29 2017-02-01 成都赛纳微波科技有限公司 具有金属体的大功率微波器件
WO2023186621A1 (en) * 2022-03-28 2023-10-05 Sweden Quantum Ab A filter arrangement for quantum processors

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DE1266892B (de) 1968-04-25
GB1037667A (en) 1966-08-03
FR1348151A (fr) 1964-01-04

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