US3048801A - Non-reciprocal phase shifter and attenuator - Google Patents

Non-reciprocal phase shifter and attenuator Download PDF

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Publication number
US3048801A
US3048801A US818919A US81891959A US3048801A US 3048801 A US3048801 A US 3048801A US 818919 A US818919 A US 818919A US 81891959 A US81891959 A US 81891959A US 3048801 A US3048801 A US 3048801A
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United States
Prior art keywords
reciprocal
line
magnetic field
ferrite
mode
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Expired - Lifetime
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US818919A
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English (en)
Inventor
Robert L Fogel
Herbert T Suyematsu
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Raytheon Co
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Hughes Aircraft Co
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Publication date
Application filed by Hughes Aircraft Co filed Critical Hughes Aircraft Co
Priority to US818919A priority Critical patent/US3048801A/en
Priority to GB17278/60A priority patent/GB873672A/en
Priority to FR828614A priority patent/FR1258588A/fr
Priority to DEH39596A priority patent/DE1107303B/de
Application granted granted Critical
Publication of US3048801A publication Critical patent/US3048801A/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
    • H01P1/18—Phase-shifters
    • H01P1/19—Phase-shifters using a ferromagnetic device

Definitions

  • the present invention relates to non-reciprocal wave transmission and, more particularly, to a coaxial slowwave structure, partially disk-loaded, having selectively magnetized ferrite elements.
  • a number of non-reciprocal wave trans-mission devices have been developed for microwave frequencies.
  • the more recent, and most effective of these, utilize magnetized ferrite elements suitably mounted in a waveguiding structure to provide the required non-reciprocal characteristics.
  • the principle of operation upon which these devices are based is the action of the magnetized ferrite element to pass energy in one direction and attenuate or absorb the energy in the other direction.
  • the ferrite element be mounted within the waveguiding structure at a position Where is a net component of circularly polarized radio frequency magnetic field of the mode that is propagating.
  • the circularly polarized radio frequency magnetic field exists in the mode of the energy that propagates in the absence of the ferrite element.
  • the ferrite is placed in a position so that the resulting mode has its maximum component of circularly polarized magnetic field in the region of the magnetized ferrite.
  • the ferrite element is mounted within the waveguide to include a position located half way between the longitudinal center line and one side of the broad walls. While this structure is the more common, it is possible under certain conditions to obtain non-reciprocal wave transmission by placing the ferrite element in a position where the radio frequency magnetic field is linearly polarized.
  • Non-reciprocal devices as described in the foregoing paragraphs are suitable for operation at the higher microwave frequencies; however, when such devices are designed for operation at the lower microwave frequencies and at the ultra-high frequency region, they are extremely large. Since coaxial transmission lines are smaller, they are more suitable for the propagation of energy at such referenced lower frequencies and a new approach is required because the radio frequency magnetic field of the dominant TEM mode is linearly polarized. Second order non-reciprocal effects may be readily achieved but for the more eflicient first order non-reciprocal effects, one of several other approaches appear to be more feasible.
  • the frequency required is much higher than that of the TEM mode for the same line, or for a given frequency the size of the line required to support the TE mode is much larger.
  • the differences are such that the advantages of the coaxial line over the hollow waveguiding structures are lost.
  • energy progagated in this TE mode tends to be converted into the dominant TEM mode by mechanical and electrical asymmetries in the line, such as bends, junctions, etc.
  • the dominant mode for this modified type of coaxial line is a hybrid mode containing both the TE and TM modes, although in a few special cases, the dominant mode can be solely the TE or the TM mode.
  • This principle has been utilized with coaxial lines in which the line has been half filled with a material having a high value of dielectric constant. The boundary conditions imposed by this geometry require the existence of longitudinal components of the radio frequency magnetic field which in combination with the circular components of the radio frequency magnetic field provides the required circular polarization at the air-dielectric interface.
  • the velocity of propagation of the resulting distorted mode in the general case, a hybrid TE plus TM
  • the hybrid mode in the case under consideration, will have a component of circularly polarized radio frequency magnetic field. It is, therefore, readily apparent that as the ratio of velocities of propagation of the two media is increased, the amount of distortion of the original mode (and, thus in the present instance, the magnitude of the component of the circularly polarized radio frequency magnetic field) is also increased.
  • the non-reciprocal wave transmission device vof the present invention is a modified slow-wave-loaded 'waveguiding structure with suitably mounted elements of agnetized ferrite.
  • the slow-wave-loading is partial and is accomplished with conductive elements mounted in spaced-apart relation within the structure to extend across one-half thereof to provide an inhomogeneous cross section and thereby a circularly polarized component of the radio frequency magnetic field at the boundary of the loading elements.
  • the action of the ferrite as mounted at the referenced boundary then provides non-reciprocal operation of the device.
  • FIG. 1 is a perspective view, partly in section, of a modified slow-wave coaxial line having a non-reciprocal characteristic in accordance with the present invention
  • FIG. 2 is a characteristic curve showing the operation of the device of FIG. 1;
  • FIG. 3 is a modification of the device of FIG. 1.
  • a section of coaxial line 11 comprises an inner conductor 12 and an outer conductor 13.
  • a plurality of semi-circular conductive disks 14 are similarly and radially mounted in parallel and spaced-apart relation on the inner conductor 12 to extend transversely with respect thereto.
  • Such disks 14 are electrically connected to the inner conductor 12 and insulated, as by suitable spacing, from the outer conductor 13.
  • a modified slow-wave structure wherein energy propagates in a hybrid mode which is, in the general form, a combination of the TB and TM modes.
  • the inhomogeneity introduced by the partial disk-loading of the inner conductor requires that the resulting mode have a longitudinal component of the radio frequency magnetic field which is combination with the circular component provides a circularly polarized radio frequency magnetic field at or near the boundary between the loaded and unloaded regions of the line.
  • two substantially thin elongated strips 16 and 17 of ferrite material are mounted on the diametrical edges of the disks 14 to extend parallel to the inner conductor 12 with one on either side of such conductor.
  • the strips 16 and 17 are disposed at the boundary between the loaded and unloaded regions of the coaxial line structure where the circularly polarized radio frequency magnetic field of the hybrid mode of propagated energy is present.
  • An adjustable static magnetic field, H is established 4 in a conventional manner to extend diametrically through coaxial line 11 parallel to the broad faces of the strips 16 and 17.
  • the electron spins within the ferrite and the sense of rotation of the circularly polarized radio frequency magnetic field are properly related for only one direction of energy propagation and so provide a non-reciprocal differential phase shift and attenuation.
  • a 3 length of modified slow-wave coaxial line, as described in the foregoing, having a outside diameter and propagating energy at 3000 mc./s. operates as indicated in FIG. 2.
  • FIG. 2 is a plot of the differential phase shift in degrees obtained over a substantially low increment of applied static magnetic field of O to 400 gauss and a resulting curve 26 indicates a range of diiferential phase shift between zero and approximately 150 degrees.
  • Similar operation of a half-slow-wave caxial line 1.3" in length has provided a differential phase shift of +5 degrees with a loss of 0.3 db. with the foregoing structures a VSWR of 1.1 or less over a 12% band width has been obtained by providing matching transformer structure (not shown) at each end of the line.
  • the results described in the foregoing paragraph show the usefulness of the present invention as a differential phase shifter, which has many applications in the microwave art.
  • the ratio of the velocities of propagation for the loaded and unloaded regions is of the order of 10 to 1. From this it follows that to obtain the same ratio in a dielectrically-loaded waveguiding structure, a material having a dielectric constant of the order of would be required. The losses inherent in a material having such high dielectric constant would be prohibitive and are entirely avoided by the structure of the present invention.
  • the device is operable as an isolator with substantially high values of attenuation for one direction of propagation and substantially none in the opposite direction.
  • FIG. 3 there is illustrated a second non-reciprocal coaxial wave transmission line 31.
  • a plurality of conductive half disks 32 are radially mounted in spaced-apart and parallel relation in contact with the outer conductor 33 and extend toward, but not in contact with the inner conductor 34.
  • the resulting structure also constitutes a slow-wave-loaded coaxial line and operates in substantially the same manner as set forth for the structure of FIG. 1.
  • elongated ferrite strips 36 and 37 mounted on either side of and parallel to the inner conductor 34 on the diametric edges of the half disks 32 provide a non-reciprocal transmission characteristic when suitably magnetized.
  • a conventional adjustable static magnetic field structure (not shown) is mounted externally of the line and establishes a magnetic field, H, through the ferrite strips 36 and 37 parallel to the broad faces thereof as indicated by arrows 39.
  • the 50% loading factor provided by the semi-circular disks is not limiting.
  • Other geometric configurations providing an inhomogeneous cross section are within the scope of the invention set forth.
  • the waveguiding structure is not limited to circular coaxial lines as the same principles are applicable with respect to other structures in which the dominant mode of propagation is the TEM mode such as rectangular coaxial line, strip line, and slab line.
  • a non-reciprocal wave transmission device comprising: a coaxial type waveguide supporting radio frequency energy in the TEM mode, said Waveguide having an inner conductor and an outer conductor; slow-wave means disposed within said waveguide, said means including a plurality of spaced-apart conductive half-discs mounted on one of said conductors and spaced from the other conductor, said half-discs being similarly mounted in parallel relation to provide two regions in said waveguide having difierent velocities of propagation; a pair of elongated ferrite strips mounted on said half-discs parallel to said inner conductor along the boundary between said regions with one strip on either side of said inner conductor; said waveguide being operative in a transverse static magnetic field paralleling the broad surfaces of said ferrite strips.

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US818919A 1959-06-08 1959-06-08 Non-reciprocal phase shifter and attenuator Expired - Lifetime US3048801A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US818919A US3048801A (en) 1959-06-08 1959-06-08 Non-reciprocal phase shifter and attenuator
GB17278/60A GB873672A (en) 1959-06-08 1960-05-16 Non-reciprocal wave transmission device
FR828614A FR1258588A (fr) 1959-06-08 1960-05-30 Dispositif de transmission d'ondes non-réversible
DEH39596A DE1107303B (de) 1959-06-08 1960-06-02 Nichtreziproker Wellenuebertrager fuer Wellenleiter von im wesentlichen transversalem elektromagnetischem Typ

Applications Claiming Priority (1)

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US818919A US3048801A (en) 1959-06-08 1959-06-08 Non-reciprocal phase shifter and attenuator

Publications (1)

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US3048801A true US3048801A (en) 1962-08-07

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US (1) US3048801A (de)
DE (1) DE1107303B (de)
GB (1) GB873672A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3225318A (en) * 1962-11-21 1965-12-21 Sperry Rand Corp Heat transfer member for coaxial waveguide device
US3286207A (en) * 1962-11-23 1966-11-15 Wilcox Electric Company Inc Ferrite tuned coaxial cavity apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6765461B1 (en) * 2003-04-30 2004-07-20 Agilent Technologies, Inc. Asymmetric support for high frequency transmission lines

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2648000A (en) * 1943-10-02 1953-08-04 Us Navy Control of wave length in wave guides
FR1155022A (fr) * 1955-07-22 1958-04-21 Philips Nv Dispositif de transmission non réciproque
US2922126A (en) * 1954-06-24 1960-01-19 Bell Telephone Labor Inc Nonreciprocal wave guide component
US2946966A (en) * 1957-12-30 1960-07-26 Bell Telephone Labor Inc Nonreciprocal wave transmission
US2947906A (en) * 1954-08-05 1960-08-02 Litton Industries Inc Delay line
US3010086A (en) * 1958-11-17 1961-11-21 Bell Telephone Labor Inc Microwave isolator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2648000A (en) * 1943-10-02 1953-08-04 Us Navy Control of wave length in wave guides
US2922126A (en) * 1954-06-24 1960-01-19 Bell Telephone Labor Inc Nonreciprocal wave guide component
US2947906A (en) * 1954-08-05 1960-08-02 Litton Industries Inc Delay line
FR1155022A (fr) * 1955-07-22 1958-04-21 Philips Nv Dispositif de transmission non réciproque
US2946966A (en) * 1957-12-30 1960-07-26 Bell Telephone Labor Inc Nonreciprocal wave transmission
US3010086A (en) * 1958-11-17 1961-11-21 Bell Telephone Labor Inc Microwave isolator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3225318A (en) * 1962-11-21 1965-12-21 Sperry Rand Corp Heat transfer member for coaxial waveguide device
US3286207A (en) * 1962-11-23 1966-11-15 Wilcox Electric Company Inc Ferrite tuned coaxial cavity apparatus

Also Published As

Publication number Publication date
GB873672A (en) 1961-07-26
DE1107303B (de) 1961-05-25

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