US3516032A - Apparatus for filtering and dissipating microwave energy possessing undesired wave modes - Google Patents

Apparatus for filtering and dissipating microwave energy possessing undesired wave modes Download PDF

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Publication number
US3516032A
US3516032A US706552A US3516032DA US3516032A US 3516032 A US3516032 A US 3516032A US 706552 A US706552 A US 706552A US 3516032D A US3516032D A US 3516032DA US 3516032 A US3516032 A US 3516032A
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United States
Prior art keywords
filtering
slit
waveguide
wave
microwave energy
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Expired - Lifetime
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US706552A
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English (en)
Inventor
Hans Wernli
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Siemens Schweiz AG
Albiswerk Zuerich AG
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Siemens Albis AG
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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/24—Terminating devices
    • H01P1/26—Dissipative terminations
    • H01P1/264—Waveguide terminations

Definitions

  • the present invention relates to an improved apparatus for both filtering and dissipating microwave energy possessing undesired polarization direction in a predetermined frequency range.
  • the present invention comprises a waveguide in which at least one filtering slit is provided in a wall extending parallel to the longitudinal axis of the waveguide.
  • the direction of the electric field or E-field of an infed linear polarized wave is generally not fixed by the crosssectional form of a waveguide having a circular-shaped cross-sectional dimension.
  • Polarization changes of the infed Wave occur during transmission because of small deviations in the cross-sectional waveguide configuration from that of a perfect circle.
  • a linear polarized wave infed to a waveguide of circular cross-section might appear elliptically polarized after transmission.
  • Microwave technology accordingly, is greatly concerned with the problem of eliminating these undesired changes in wave polarization.
  • One solution for suppressing such elliptic polarized waves produced within a waveguide resides in filtering out and dissipating the undesired components of the wave.
  • an elliptic polarized wave can be construed as the resultant of two linear polarized waves, the E-fields of which are disposed perpendicular to one another and which exhibit a difference in phase. Accordingly, a filtering apparatus can be applied in such a manner that the component of the wave whose E-field is disposed perpendicular to that of the desired wave component is filtered out.
  • One such filtering apparatus comprises a waveguide with a circular-shaped cross-section in which another waveguide of rectangular cross-section is inserted in the plane of the magnetic field of the undesired wave component which is to be filtered.
  • the rectangular waveguide is reflectionless terminated.
  • this apparatus is not wholly satisfactory since, without expensive matching devices, it can only be used for a very narrow frequency range.
  • the inventive filtering apparatus is characterized by the features that a filtering slit is provided in a wall of the waveguide and is sealed at the outside of the waveguide by a cover plate formed of a microwave absorbing material.
  • the cover plate possesses a groove of rectangular cross-section, the longitudinal sides of which are disposed in form-locking fashion or fiush with the filtering .slit.
  • the length and penetration depth of the groove are selected in such a manner that the major por tion of the waves in a predetermined frequency range having the undesired polarization direction are absorbed by the apparatus.
  • FIG. 1 schematically illustrates a cross-sectional view of said filtering slit and in alignment therewith
  • FIG. 2 is a longitudinal sectional view taken through the longitudinal axis of the inventive apparatus depicted in FIG. 1 substantially along the line 11-11 thereof;
  • FIG. 3 is a top plan view of the waveguide essentially as viewed along the line IIIIII of FIG. 1.
  • the illustrated exemplary embodiment of the inventive apparatus is composed of a waveguide 1 with a circularshaped cross-section and a cover plate 3 formed of microwave-absorbing material.
  • reference character EN represents the main direction of the E-field of the microwave component in the desired or useful mode. Extending perpendicular to this E-field of the desired wave component is the E-field Est of the undesired, dis turbing or interference wave component.
  • the wall 7 of the waveguide 1 is provided with a filtering slit or slot 2 arranged such that the undesired wave component having the E-field direction Est is filtered out.
  • the filtering slit :or slot 2 constitutes a reflecting field disturbance location for both the desired or useful wave and for the undesired wave.
  • the filtering slit 2 is extended at both ends by a narrower matching slit 5.
  • the length and the width of the matching slits 5 are chosen such that the reflected wave components from the matching slits 5 and from the wider filtering slit 2 mutually cancel or nullify one another.
  • the total length of the filtering slits provided depends upon the required frequency range since the longer the filter slit, the greater is the useful frequency range.
  • the slit 2 is sealed with a cover plate 3 formed of microwave-absorbing material such as a material commercially available on the market under the trademark Eccosorb CR.
  • the cover plate 3 possesses a gro ve 4 as an extension of the slit 2, the longitudinal sides of the groove 4 being disposed in form-locking fashion or flush with the filtering slit 2.
  • the length and the penetration depth of the groove 4 is selected in a manner ergy is actually absorbed.
  • the filtered energy should be completely absorbed, that is to say, the cover plate or apparatus should be matched to the waveguide 1 such that the major portion of the filtered microwave ening slit 2 and matching slits 5, the outermost ends of the matching slits 5 are sealed by a plate 6 of microwaveabsorbing material.
  • the major portion of the wave energy appearing at both of the plates 6 is reflected rather than absorbed.
  • the magnitude of these reflected waves is a function of the surface or area of both plates 6, this plate area itself being a function of the length of the groove 4.
  • these reflected wave components can be coordinated in such a manner that the reflected wave components from the plate 6 and from the filtering slit 2 mutually cancel or eliminate one another.
  • This point of coordination or matching is realized when the reflections monitored by the known measuring technique as discussed above reach a minimum.
  • the penetration depth of the groove 4 is also varied during such adaptation or matching procedure-as a parameter for the wave phase.
  • Optimum matching of the apparatus for the disturbance or undesired wave component can also be obtained if the length of the groove 4 is equal to the total length of the filtering slit 2 and matching slits 5.
  • the plate 6 formed by a portion of the cover plate 3 is replaced by a conducting web or arm to partially seal the matching slit 5 with respect to the groove 4.
  • the filtered and therefore the reflected desirable or useful wave component energy at the plates 6 is relatively small. Accordingly, the groove length has no appreciable influence upon the matching conditions of the desirable or useful wave component.
  • An apparatus for filtering and dissipating microwave energy in a predetermined frequency range having undesired polarization direction comprising:
  • a waveguide having a filtering slit in a wall parallel to its longitudinal axis
  • cover plate means for sealing said filtering slit at the outside of said waveguide, said cover plate means being formed of a microwave-absorbing material;
  • groove means provided in said cover plate means, said groove means having a rectangular cross-section, the longitudinal sides of which are form-locking with said filtering slit and the length and penetration depth of which are such that the predominant portion of said microwave energy in said predetermined frequency range having said undesired polarization direction is absorbed.
  • said filtering slit has a predetermined width and is elongated at both ends thereof by a matching slit narrower than said predetermined width.
  • An apparatu? Ior filtering and dissipating micro- Wave energy in a predetermined frequency range having undesired polarization direction comprising:
  • a waveguide having walls and a longitudinal axis
  • a filtering slit provided in at least one waveguide wall parallel to said longitudinal axis
  • cover plate means for sealing said filtering slit from the outside of said waveguide, said cover plate means being formed of microwave-absorbing material and exhibiting an internal groove aligned with said filtering slit.
  • said filtering slit has a predetermined width and length, and further including a matching slit provided at each end of said filtering slit and in alignment therewith, said matching slits being narrower than said filtering slit and providing with said filtering slit an elongated slot.

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  • Control Of Motors That Do Not Use Commutators (AREA)
  • Waveguide Aerials (AREA)
  • Waveguide Switches, Polarizers, And Phase Shifters (AREA)
US706552A 1967-04-14 1968-02-19 Apparatus for filtering and dissipating microwave energy possessing undesired wave modes Expired - Lifetime US3516032A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH534667A CH455892A (de) 1967-04-14 1967-04-14 Vorrichtung zum Auskoppeln und Vernichten von Mikrowellenenergie mit unerwünschter Polarisationsrichtung

Publications (1)

Publication Number Publication Date
US3516032A true US3516032A (en) 1970-06-02

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US706552A Expired - Lifetime US3516032A (en) 1967-04-14 1968-02-19 Apparatus for filtering and dissipating microwave energy possessing undesired wave modes

Country Status (12)

Country Link
US (1) US3516032A (de)
AT (1) AT278100B (de)
CH (1) CH455892A (de)
DE (1) DE1616232A1 (de)
DK (1) DK116800B (de)
ES (1) ES352704A1 (de)
FI (1) FI48789C (de)
FR (1) FR1561593A (de)
GB (1) GB1199114A (de)
NL (1) NL6801291A (de)
NO (1) NO126503B (de)
SE (1) SE336615B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4356459A (en) * 1981-03-23 1982-10-26 Ford Aerospace & Communications Corp. Flat phase response septum polarizer
US4549310A (en) * 1984-03-29 1985-10-22 Rca Corporation Cross-polarization corrector for circular waveguide
US4599744A (en) * 1983-11-10 1986-07-08 Micro Communications, Inc. UHF broadcast antenna on a tower with circular waveguide carrying RF energy up the tower to the antenna with polarization adjustments and exclusions
US6499346B1 (en) * 1998-03-28 2002-12-31 Endress + Hauser Gmbh + Co. Filling level measuring device operating with microwaves

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2512468A (en) * 1943-05-12 1950-06-20 Emi Ltd Wave guide with mode suppression means
GB720153A (en) * 1952-06-19 1954-12-15 Gen Electric Co Ltd Improvements in or relating to devices for converting plane-polarised electromagnetic energy into elliptically-polarised electromagnetic energy
US2869085A (en) * 1954-01-19 1959-01-13 Raytheon Mfg Co Selective absorbers
US2877434A (en) * 1945-11-19 1959-03-10 Harold K Farr Mode filter
US3184695A (en) * 1960-11-01 1965-05-18 Bell Telephone Labor Inc Circular electric mode filter
US3321720A (en) * 1961-11-09 1967-05-23 Shimada Sadakuni Circular waveguide teon mode filter

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2512468A (en) * 1943-05-12 1950-06-20 Emi Ltd Wave guide with mode suppression means
US2877434A (en) * 1945-11-19 1959-03-10 Harold K Farr Mode filter
GB720153A (en) * 1952-06-19 1954-12-15 Gen Electric Co Ltd Improvements in or relating to devices for converting plane-polarised electromagnetic energy into elliptically-polarised electromagnetic energy
US2869085A (en) * 1954-01-19 1959-01-13 Raytheon Mfg Co Selective absorbers
US3184695A (en) * 1960-11-01 1965-05-18 Bell Telephone Labor Inc Circular electric mode filter
US3321720A (en) * 1961-11-09 1967-05-23 Shimada Sadakuni Circular waveguide teon mode filter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4356459A (en) * 1981-03-23 1982-10-26 Ford Aerospace & Communications Corp. Flat phase response septum polarizer
US4599744A (en) * 1983-11-10 1986-07-08 Micro Communications, Inc. UHF broadcast antenna on a tower with circular waveguide carrying RF energy up the tower to the antenna with polarization adjustments and exclusions
US4549310A (en) * 1984-03-29 1985-10-22 Rca Corporation Cross-polarization corrector for circular waveguide
US6499346B1 (en) * 1998-03-28 2002-12-31 Endress + Hauser Gmbh + Co. Filling level measuring device operating with microwaves

Also Published As

Publication number Publication date
FI48789B (de) 1974-09-02
DK116800B (da) 1970-02-16
NL6801291A (de) 1968-10-15
AT278100B (de) 1970-01-26
DE1616232A1 (de) 1971-03-18
SE336615B (de) 1971-07-12
CH455892A (de) 1968-05-15
FR1561593A (de) 1969-03-28
NO126503B (de) 1973-02-12
GB1199114A (en) 1970-07-15
FI48789C (fi) 1974-12-10
ES352704A1 (es) 1969-09-16

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