US3146414A - Tapered waveguide transition section with dielectric sleeve positioned to reduce coupling between te circular modes - Google Patents

Tapered waveguide transition section with dielectric sleeve positioned to reduce coupling between te circular modes Download PDF

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Publication number
US3146414A
US3146414A US205326A US20532662A US3146414A US 3146414 A US3146414 A US 3146414A US 205326 A US205326 A US 205326A US 20532662 A US20532662 A US 20532662A US 3146414 A US3146414 A US 3146414A
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United States
Prior art keywords
mode
taper
sleeve
dielectric
modes
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Expired - Lifetime
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US205326A
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English (en)
Inventor
Enrique A J Marcatili
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to BE634088D priority Critical patent/BE634088A/
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US205326A priority patent/US3146414A/en
Priority to DEW34526A priority patent/DE1201432B/de
Priority to FR937850A priority patent/FR1358964A/fr
Priority to GB24564/63A priority patent/GB1036846A/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
    • H01P1/163—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion specifically adapted for selection or promotion of the TE01 circular-electric mode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/02—Coupling devices of the waveguide type with invariable factor of coupling
    • H01P5/022—Transitions between lines of the same kind and shape, but with different dimensions
    • H01P5/024—Transitions between lines of the same kind and shape, but with different dimensions between hollow waveguides

Definitions

  • mode conversionreconversion distortion in a circular electric mode transmission system can only be avoided by keeping the power in the higher order circular electric modes at an e tremely low level.
  • the tendency for mode conversion in multimode transition sections is materially reduced by the inclusion within the tapered sections of a low-loss dielectric element which is located in a region of high electric field intensity for one mode and in a region of low electric field intensity for another mode. While this technique can be used in connection with waveguides of various cross-sectional configurations and with all types of propagating modes, it is of particular interest in connection with circular waveguides propagating the circular electric mode. Hence, the invention Patented Aug. 25, 1964 will be described in more detail hereinbelow in that context.
  • the tendency for mode conversion from the TE to the TE circular electric mode is substantially reduced by the inclusion within a tapered transition section of a tapered sleeve of low-loss dielectric material.
  • the sleeve is placed in a region of high electric field intensity for the TE mode and low electric field intensity for the TE mode.
  • the sleeve conforms to the shape of the taper and, at any point along the taper, has an average radius b which is related to the taper radius a at that point by where k, and k are roots of the Bessel function of the first kind and order and are equal to 3.832 and 7.016 respectively.
  • the thickness of the sleeve t is a function of the taper radius a, the dielectric constant of the material and the frequency' A dielectric sleeve so proportioned has the effect of eliminating the degeneracy between the TE and TE modes that tends to occur for signals whose wavelengths are small compared to the radius of the waveguide. That is, the tendency for coupling between the TE mode and the TE mode is substantially reduced by the presence of the dielectric sleeve.
  • the improvement in operation realized in a tapered section containing a dielectric sleeve can be understood by recognizing that the coupling between the TE and TE modes can be likened to the coupling between separate transmission lines in that a large exchange of energy occurs if the phase constants for the two lines (or modes) are sufficiently similar. If, on the other hand, the phase constants are sufliciently different, little or no energy is coupled between the lines (or between modes).
  • a dielectric sleeve to increase the difference in the phase constants of these two modes, let us consider a wave having a wavelength of one millimeter propagating in a 2 inch diameter waveguide.
  • phase shift per unit wavelength in an unloaded waveguide is 0.0044 radian.
  • the added phase shift per unit wavelength in the same guide but including a dielectric sleeve having a thickness of one millimeter and a dielectric constant of 3, is 0.55 radian. This represents a change of over three orders of magmtude.
  • transition sections designed in accordance with the invention are reduced in length and operate over a far wider range of frequencies.
  • the thickness of the sleeve can be ad usted to produce related amounts of TE and TE mode wave energy or a second sleeve can be added to separately limit the TE mode level.
  • FIG. 1 shows, in cross-sectional view, a tapered transition section including a dielectric sleeve of varying thickness, in accordance with the invention
  • FIG. 2 included for purposes of illustration, shows the variation in the factor p as a function of B, the free space phase constant
  • FIG. 3 shows a section of a dielectric sleeve of uniform thickness.
  • FIG. 1 there is shown a preferred embodiment of the invention in which a pair of circular waveguides 10 and 11 of radii a and (1 respectively, are electrically and physically joined together by means of a tapered transition section 12.
  • section 12 can have y Shapes and y e either a solid wall taper or a helical taper of the type described in United States m Patent 3,126,517, which issued to S. E. Miller on March 24, 1964.
  • the taper is designed in accordance with the teachings of Unger and Tang cited hereinabove.
  • a low-loss dielectric sleeve 13 Located within section 12 is a low-loss dielectric sleeve 13 whose shape and thickness will be described in greater detail hereinbelow.
  • Sleeve 13 is supported within section 12 in any convenient manner. As shown in FIG. 1, a pair of dielectric rings 14 and 15, located one at each end, are used for this purpose.
  • the improvement in operation realized in a tapered section containing a dielectric sleeve can be understood by recognizing that the coupling between the TE and TE modes can be likened to the coupling between separate transmission lines in that a large exchange of energy occurs if the phase constants for the two lines (or modes) are sufficiently similar. If, on the other hand, the phase constants are sufiiciently different, little or no energy is coupled between the lines (or between modes).
  • p can be expressed as Z! 1 1 5]; (Bi-( 2W where Z is the total length of the taper.
  • the TE mode conversion is given by 2 2p 1-%-
  • the total length Z of the taper is obtained by integrating Equation 1 between the limits and p
  • Equation 6 From Equation 6 it is seen that the larger the difference between propagation constants (fi fi the smaller the taper length Z In accordance with the invention, the value 5 -5 is made and maintained large by the inclusion of the dielectric'sleeve 13.
  • the new length 2 is then Pl d o a-a where 8 and F are the phase constants of the TE and TE modes, respectively, in a taper having a sleeve.
  • the sleeve has a dielectric constant 6 and at each cross section it has an average radius b and a thickness t.
  • the local propagation constant 5, for the TE mode is given approximately by where [3,, is the propagation constant for the TE mode in an empty taper;
  • s is the dielectric constant of the empty taper (typically of air, for which GOEI).
  • J and J are Bessel functions of the first kind of zero and one, respectively.
  • Equation 5 For purposes of illustration, we select a sleeve 'whose thickness t varies as 1/ a in which case we can write From Equation 5 it is deduced that once the extreme radii a and a are given, the TE mode conversion depends exclusively on the value p as given by Equation 4. Let us therefore calculate p for an empty taper and F for the same taper with a dielectric sleeve. Substituting Equations 3 and 13 in 4 we obtain that ateire:
  • p and 71 are plotted as a function of the phase constant B for a fixed geometry of the metal taper and for different values of and It is seen from FIG. 2 that p decreases monotomically for increasing whereas F decreases to a minimum and then increases. It will be noted that :5 always has a minimum. This occurs at a phase constant 6 given by there is now no value for B for which Z p and consequently the taper with the sleeve can operate at any frequency with less TE mode conversion than the empty taper had at [3 From Equations 16 through 19 we deduce that and consequently from Equations 14, 15, and 20 we obtain, as the expression for the sleeve thickness t,
  • the sleeve thickness was assumed to vary inversely as the taper radius. This was done solely to simplify the mathematics. In practice the sleeve can be made of uniform thickness corresponding to the thickness at the small diameter end. A section of sleeve 13' of uniform thickness is shown in FIG. 3. In such a case the TE mode conversion is reduced still further than that given above.
  • both sleeves and the shape of the taper are derived following the technique used for a single sleeved taper as described hereinabove.
  • a tapered transition section for coupling said mode from a first circular waveguide having a first radius to a second circular waveguide having a second radius
  • k and k are roots of the Bessel function of first kind and order and are equal to 3.832 and 7.016, respectively.
  • e is the dielectric constant of the empty taper
  • k and k are roots of J J and I are Bessel functions of the first kind, of orders zero and one, respectively;
  • ⁇ 3 is the free space propagation constant in an empty taper for which the mode conversion has a specified maximum value.
  • k and k are roots of I and J and J are Bessel functions of the first kind, of order zero and one, respectively.
  • a tapered transition section for coupling said mode from a first circular waveguide having a first radius to a second circular waveguide having a second radius
  • a tapered transition section for coupling said preferred mode from a first Waveguide having first cross-sectional dimensions, to a second waveguide having second cross-sectional dimensions
  • At least one element of low-loss dielectric material disposed along a region of high electric field intensity for said preferred mode and low electric field intensity for said spurious mode.

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US205326A 1962-06-26 1962-06-26 Tapered waveguide transition section with dielectric sleeve positioned to reduce coupling between te circular modes Expired - Lifetime US3146414A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE634088D BE634088A (pl) 1962-06-26
US205326A US3146414A (en) 1962-06-26 1962-06-26 Tapered waveguide transition section with dielectric sleeve positioned to reduce coupling between te circular modes
DEW34526A DE1201432B (de) 1962-06-26 1963-05-18 Verjuengtes Hohlleiter-UEbergangsstueck mit dielektrischer Huelse
FR937850A FR1358964A (fr) 1962-06-26 1963-06-12 Section conique de transition de guides d'ondes à manchon diélectrique
GB24564/63A GB1036846A (en) 1962-06-26 1963-06-20 Improvements in or relating to electromagnetic wave transmission systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US205326A US3146414A (en) 1962-06-26 1962-06-26 Tapered waveguide transition section with dielectric sleeve positioned to reduce coupling between te circular modes

Publications (1)

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US3146414A true US3146414A (en) 1964-08-25

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US (1) US3146414A (pl)
BE (1) BE634088A (pl)
DE (1) DE1201432B (pl)
FR (1) FR1358964A (pl)
GB (1) GB1036846A (pl)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4598262A (en) * 1983-06-08 1986-07-01 Trw Inc. Quasi-optical waveguide filter
US4853656A (en) * 1987-08-03 1989-08-01 Aerospatiale Societe Nationale Industrielle Device for connecting together two ultra-high frequency structures which are coaxial and of different diameters
CN107666030A (zh) * 2016-07-28 2018-02-06 波音公司 多模波导

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104466320B (zh) * 2014-12-18 2017-05-10 西安电子工程研究所 应用截止波导的Ka波段宽带带通滤波器

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2197122A (en) * 1937-06-18 1940-04-16 Bell Telephone Labor Inc Guided wave transmission
US2632806A (en) * 1945-09-18 1953-03-24 William M Preston Mode filter
US2762982A (en) * 1951-05-17 1956-09-11 Bell Telephone Labor Inc Mode conversion in wave guides
US2940057A (en) * 1957-11-01 1960-06-07 Bell Telephone Labor Inc Selective mode filters
GB883439A (en) * 1957-09-16 1961-11-29 Western Electric Co Improvements in or relating to electromagnetic wave transmission systems
US3016502A (en) * 1959-12-23 1962-01-09 Bell Telephone Labor Inc Spurious mode suppressing wave guide
US3050701A (en) * 1961-03-22 1962-08-21 Bell Telephone Labor Inc Tapered waveguide transition section

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1081521B (de) * 1958-02-05 1960-05-12 Siemens Ag Querschnittsaenderungen aufweisender Hohlleiter

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2197122A (en) * 1937-06-18 1940-04-16 Bell Telephone Labor Inc Guided wave transmission
US2632806A (en) * 1945-09-18 1953-03-24 William M Preston Mode filter
US2762982A (en) * 1951-05-17 1956-09-11 Bell Telephone Labor Inc Mode conversion in wave guides
GB883439A (en) * 1957-09-16 1961-11-29 Western Electric Co Improvements in or relating to electromagnetic wave transmission systems
US2940057A (en) * 1957-11-01 1960-06-07 Bell Telephone Labor Inc Selective mode filters
US3016502A (en) * 1959-12-23 1962-01-09 Bell Telephone Labor Inc Spurious mode suppressing wave guide
US3050701A (en) * 1961-03-22 1962-08-21 Bell Telephone Labor Inc Tapered waveguide transition section

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4598262A (en) * 1983-06-08 1986-07-01 Trw Inc. Quasi-optical waveguide filter
US4853656A (en) * 1987-08-03 1989-08-01 Aerospatiale Societe Nationale Industrielle Device for connecting together two ultra-high frequency structures which are coaxial and of different diameters
CN107666030A (zh) * 2016-07-28 2018-02-06 波音公司 多模波导
US10027004B2 (en) * 2016-07-28 2018-07-17 The Boeing Company Apparatus including a dielectric material disposed in a waveguide, wherein the dielectric permittivity is lower in a mode combiner portion than in a mode transition portion
CN107666030B (zh) * 2016-07-28 2021-01-26 波音公司 包括执行模式转换的波导的设备和执行模式转换的方法

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Publication number Publication date
GB1036846A (en) 1966-07-20
BE634088A (pl)
FR1358964A (fr) 1964-04-17
DE1201432B (de) 1965-09-23

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