US3526856A - Electromagnetic coupling apparatus - Google Patents

Electromagnetic coupling apparatus Download PDF

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Publication number
US3526856A
US3526856A US762062A US3526856DA US3526856A US 3526856 A US3526856 A US 3526856A US 762062 A US762062 A US 762062A US 3526856D A US3526856D A US 3526856DA US 3526856 A US3526856 A US 3526856A
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Prior art keywords
wire
aperture
coupling
conductive
magnetic insulator
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Expired - Lifetime
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US762062A
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English (en)
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Edward F Heldt
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Hazeltine Research Inc
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Hazeltine Research Inc
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/08—Coupling devices of the waveguide type for linking dissimilar lines or devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H2/00—Networks using elements or techniques not provided for in groups H03H3/00 - H03H21/00

Definitions

  • the present invention relates generally to apparatus for coupling energy to or from magnetic insulator material and particularly to localized couplers for efficiently coupling electromagnetic energy to or from the magnetic insulator.
  • Objects of the present invention therefore are to provide new and improved simple localized coupling structures for coupling electromagnetic energy to or from magnetic insulator material.
  • a coupling structure for coupling electromagnetic energy having a predetermined range of frequencies to or from magnetic insulator material which comprises a piece of magnetic insulator material and a conductive member contiguous with one face of the magnetic insulator material and which has an aperture whose width is substantially less than the free space wavelength of the predetermined frequencies.
  • the invention further comprises a thin conductive wire a portion of which traverses the aperture transverse to its width in close proximity to the magnetic insulator material and which has one end connected to the conductive member for causing substantially all the return currents associated with the current flow in the wire to be shielded from the magnetic insulator material by the conductive member, whereby efficient localized coupling can be provided between the wire and the magnetic insulator material through the aperture.
  • FIG. 1 illustrates an electromagnetic coupling structure constructed in accordance with the present invention
  • FIG. 2 is an exploded view of a section of the FIG. 1 coupling structure
  • FIG. 3 is an exploded view of an alternative section corresponding to the section shown in FIG. 2;
  • FIGS. 4a and 4b illustrate a second electromagnetic coupling structure constructed in accordance with the present invention.
  • FIGS. 1-3 illustrate an electromagnetic coupling structure for coupling energy, such as electromagnetic energy, having a predetermined range of frequencies to or from the material 10 constructed in accordance with the present invention.
  • the apparatus consists of the stated piece of material 10 such as magnetic insulator material.
  • the most commonly used magnetic insulator is yttrium iron garnet (YIG).
  • YIG yttrium iron garnet
  • the material is either in the form of a slab in which the width W is substantially greater than the height H, or a bar in which the height and the width are in the same order of magnitude, or a cylindrical rod.
  • FIG. 1 illustrates the slab configuration.
  • the apparatus further comprises a conductive member 11 illustrated as a thin sheet of conductive material, such as copper foil, contiguous with the piece of magnetic insulator material 10.
  • a conductive member 11 illustrated as a thin sheet of conductive material, such as copper foil, contiguous with the piece of magnetic insulator material 10.
  • the sheet of conductive material should be placed as close to the YIG slab 10 as practical, preferably in direct contact with the YIG.
  • the conductive member 11 is shown as having a perpendicular base portion for purposes of mechanical support.
  • An alternative approach is to deposit the copper foil on the face of the magnetic insulator 10 by thick or thin film techniques.
  • the conductive member 11 has an aperture 12 whose width is substantially less than the free space wavelength of any of said predetermined frequencies.
  • the shape and relative size of the aperture are more clearly illustrated in FIG. 2 which is an expanded view of the section 13 and in FIG. 3 which is an alternative construction corresponding to FIG. 2.
  • FIG. 2 illustrates a conductive member 11 with a circular aperture 12 having a width 14.
  • FIG. 3 illustrates a conductive member 11' with an aperture 12" which is in the form of an elongated slot having a width 14' and a length 15';
  • the apparatus also includes a transmission line means illustrated as a portion of a strip-line 16 having a grounded conductor 17 and an ungrounded conductor 18 separated by dielectric material. At one end the transmission line is connected to an electrical circuit 19 by way of the strip-line connector 20 and coaxial cable 25. At the other end the grounded conductor 17 is connected to the sheet of conductive material 11 and the ungrounded conductor 18 is connected to a thin conductive wire 21 via the hole 22 in the grounded conductor 17.
  • the conductive wire 21 is positioned on the side of the copper foil 11 opposite the magnetic insulator so that wire 21 is electromagnetically shielded from the magnetic insulator 10 by the conductive member 11, except for the portion of the wire 21' which traverses the aperture 12. As more clearly illustrated in FIGS.
  • the wire 21 traverses the aperture 12 transverse to the width of the aperture and has one end connected to the conductive member 11 at junction 23.
  • Both the wire 21 and the grounded conductor 17 are connected to the side of the conductive member 11 opposite the magnetic insulator 10, thereby causing substantially all the return or ground currents associated with current flow in the wire 21. to flow on the same side of the copper foil 11 as the wire 21.
  • Conductive Wire 21 may be a length of conventional circular cross-sectional wire or a thin flat piece of conductive foil.
  • the portion 21 or 21" of wire 21 may be deposited directly on the end face of magnetic insulator 10 by vacuum deposition with an insulating film such as silicon monoxide isolating the two conductors.
  • the apparatus further includes means 24 for electrically insulating the conductive wire 21 from the conductive member 11 in the region of the aperture 12.
  • Means 24 may be a thin film of dielectric material such as Teflon. The sheet must be extremely thin in order to insure optimum coupling between the magnetic insulator 10 and the wire 21. The purpose of the dielectric sheet is to prevent the conductive member from coming in electrical contact with the conductive member on both sides of the aperture in order to avoid shorting the section 21' or 21 of the wire across the aperture 12.
  • the coupler of FIG. 1 is reciprocal in nature; that is to say, the same apparatus may be an input device coupling electromagnetic energy from the wire 21 to the magnetic insulator 10 or an output device coupling energy from the magnetic insulator 10 to the wire 21.
  • the electrical circuit 19 includes a signal generator and as an output device the electrical circuit includes a utilization load.
  • the de vice must efliciently couple energy between the wire radiator 21 and the magnetic insulator 10.
  • the other requirement is that the energy coupled to the magnetic insulator 10 be only the intended electromagnetic energy; i.e. that the source be localized.
  • An unshielded wire provides very eflicient coupling.
  • the additional coupling of spurious electromagnetic energy degrades the quality of such a coupler to the point where the location and nature of the source is not clearly defined.
  • the source is localized primarily due to the fact that the conductive member 11 confines the magnetic fields produced by the wire radiator 21 and substantially all the return current flow is limited to the wire side of the conductive member. If there were a substantial amount of concentrated current flow on the magnetic insulator side of the conductive member 11, corresponding electromagnetic waves would be produced which would be a source of spurious coupling.
  • By connecting both the Wire radiator 21 and the grounded conductor 17 of the transmission line to the same side of the conductive member 11, most of the return or ground current associated with current flow in the wire radiator flows 0n the wire side of the conductive member. Minimal current flow will occur on the magnetic insulator side of the conductive member. Therefore, the only substantial coupling to the YIG material results from the magnetic field produced by the portion of the wire 21' of the wire radiator 21 which traverses the aperture 12, thereby providing a very localized source.
  • the current supplied by source 19 consists of either a single frequency or predetermined frequency spectrum. In either case, the present practical range of signal frequencies is considered to be from about 350 mI-Iz. to 10 gHz. At present YIG material is generally used with signal frequencies between 1 gI-lz. and 2.5 gHz.
  • the wire 21 and the magnetic insulator 10 are positioned as close as possible to the opposite sides of the aperture 12.
  • the wire 21 was butted against a sheet of Teflon, .001 inch thick, which was affixed to a sheet of copper foil .002 inch thick.
  • a YIG slab was placed in physical contact with the copper foil on the.
  • Couplers provided excellent results. However, they are merely intended as representative examples of the present invention and the dimensions given are not critical. For a frequency range of 350 mHz. to gHz. the width 14 or 14' is less than one-eighth of an inch. The value chosen involves a compromise between the above mentioned conflicting requirements.
  • the larger aperture provides better coupling while the smaller aperture provides better isolation.
  • the width of the wire can be from one to ten mils, the finer wire being used for the smaller aperture. Generally speaking, the ratio of the width of the aperture to the width of the wire is in the order of 10:1.
  • the ratio of the shortest free space wavelength of the signal frequencies utilized in conjunction with the above mentioned couplers and the width of the aperture is almost 200: 1. That is to say that the width of the aperture is less than .006 times the free space wavelength. Although the compromise between efficient coupling and necessary isolation must be considered, it is preferred that for a particular coupler the width of the aperture be less than .03 times the free space wavelength.
  • the slot arrangement illustrated in FIG. 3 provides somewhat better coupling than a comparable width circular aperture with no appreciable degradation in localization. Since the width of the slot is the same as the width of the hole, the field in the horizontal direction is confined substantially the same amount. Therefore, in the horizontal direction the source is localized substantially to the same degree in both the circular aperture and slot configurations. On the other hand, in the slot configuration the source approximates a line source which provides superior coupling to the circular hole configuration which approximates a point source. Of the two above mentioned couplers successfully constructed and tested, the slot configuration had less than 5 db additional loss as compared to an unshielded wire radiator, while the circular aperture had less than 10 db additional loss. These losses must be evaluated in light of the fact that the insertion loss of YIG may be db or better.
  • FIGS. 4a and 4b illustrate another embodiment of an electromagnetic coupling structure for coupling electromagnetic energy having a predetermined range of frequencies to or from magnetic insulator material 10 constructed in accordance with the present invention.
  • the structure illustrated in FIG. 4a includes the stated piece of magnetic insulator material 10, such as a piece of single crystal YIG, a block of conductive material 27, and a section of strip-line 30, shown coupled via connector to electrical circuit 36.
  • FIG. 4a also illustrates a plastic channel 26 secured to the bottom of the block of conductive material 27 for holding the piece of YIG -10 in place against the block of conductive material 27.
  • FIG. 4b is a blown-up view of the FIG. 4a structure in which the YIG material 10 and the plastic holder 26 have been removed in order to more clearly illustrate the coupling structure.
  • the face 27a of the block of conductive material which is in contact with the YIG material 10 has a narrow groove 28 along the full height L of the face 27a. Groove 28 may be machined out by any conventional technique. The groove is substantially filled with dielectric material 29 such as Teflon.
  • the apparatus further comprises transmission line means 30 having a grounded conductor 31 connected to the block of conductive material 27 and an ungrounded conductor 32 coupled to a thin conductive wire 33.
  • the thin conductive wire 33 is positioned along the length L of the groove 28.
  • the conductive wire 33 is isolated from the block of conductive material along the length of the groove 28 by the dielectric material 29 which is positioned between the wire 33 and the block of conductive material 27.
  • the other end of the wire 33 is afiixed to the block of conductive material at junction 34 for causing substan tially all the return currents associated with current flow in the wire conductor 33 to be shielded from the YIG material 10 by the block of dielectric material 27.
  • the YIG material 10 in direct contact with the wire conductor 33. Therefore, it is preferable to have the wire 33 run along the front face 27a of the block of conductive material 27. This may be achieved by filling the groove 28 entirely with dielectric material 29 and then removing a small portion of the dielectric material 29 sufficient to accommodate the conductive wire 33 so that the wire 33 is fiush with the front face 27a of the conductor 27 and in direct contact With the YIG material 10.
  • the coupler of FIG. 4 operates in substantially the same manner as the previously described FIG. 1 coupler. Operating as an input device, high frequency current is coupled to the connector 35 from an external source 36 through the ungrounded conductor 32 of strip-line 30 to the thin conductor wire 33. The electromagnetic field produced by current flow in the wire couples to the YIG material 10.
  • the wire 33 is grounded at the junction point 34 so that substantially all the return current associated with current flow in the wire flows in the side walls of the groove 28 to the ground plane 31. Some of the current may flow on the front face 27a but it is widely dispersed so that it will not cause any significant coupling to the YIG material 10.
  • the parameters specified in conjunction with descriptions of the FIG. 1 embodiment are applicable to the FIG. 4 configuration.
  • the wire size generally will be in the range of one to ten mils and the width of the groove will be less than one-eighth of an inch.
  • the ratio of the 1width of the groove to the wire size is in the order of 10:
  • a coupler as illustrated in FIG. 4 was successfully constructed and tested.
  • the groove was filled with Teflon material and the wire was positioned within the Teflon so as to be in direct contact with the YIG material 10.
  • the wire was three mil wire and the width of the groove W was 30 mils.
  • the signal frequency was from 1.1 gHz. to 2.4 gHz.
  • the conductive member 27 was a small brass block. This coupler produced very efficie nt localized coupling.
  • the insertion loss was even less than either of the FIG. 1 couplers with no appreciable change in localization. It is expected that even better results can be achieved by using a more conductive material in place of the brass block or by plating the brass with a layer of good conductive material such as silver.
  • a COupling structure for coupling electromagnetic energy having a predetermined range of frequencies to or from magnetic insulator material comprising:
  • a conductive member contiguous with one face of said magnetic insulator material covering a substantial portion thereof, and having an aperture whose width is substantially less than the free space wavelength of said predetermined frequencies and whose crosssectional area is substantially less than the surface area of said face of the magnetic insulator material;
  • a thin conductive wire a portion of which traverses the aperture transverse to its width in close proximity to said magnetic insulator material and which has one end connected to said conductive member for causing substantially all the return currents associated with the current flow in said wire to be shielded from the magnetic insulator material by the conductive member;
  • a coupling structure as specified in claim 1 in which the width of the wire is substantially less than the width of the aperture in said conductive member.
  • a coupling structure as specified in claim 2 which additionally includes means for insulating the conductive wire from the conductive member in the region of said aperture.
  • a coupling structure as specified in claim 2 which additionally includes a thin sheet of dielectric material positioned between the conductive member and the conductive wire in the region of said aperture.
  • a coupling structure for coupling electromagnetic energy having a predetermined range of frequencies to or from yttrium iron garnet comprising:
  • YIG yttrium garnet
  • a thin sheet of conductive material positioned adjacent and parallel to one face of the YIG material covering a substantial portion thereof, and having an aperture whose width is less than .03 times the free space wavelength of said predetermined frequency and whose cross-sectional area is substantially less than the surface area of said face of the YIG material;
  • a transmission line means having a grounded conductor connected to the sheet of conductive material and an ungrounded conductor;
  • a coupling structure as specified in claim 5 in which the width of the conductive wire is betweenuOOl inches and .010 inch, the width of the aperture is less than oneeighth of an inch and the ratio of the Width of the aperture to the width of the wire is in the order of 10:1.
  • a coupling structure as specified in claim 6 in which the thickness of the sheet of dielectric material is in-the order of .001 inch and the thickness of the dielectric material is substantially the entire separation between the wire and the magnetic insulator material.
  • a coupling structure for coupling electromagnetic energy having a predetermined range of frequencies to or from yttrium iron garnet comprising:
  • YIG yttrium iron garnet
  • a block of conductive material having a substantially fiat face contiguous with one face of the YIG material and having a narrow groove along one dimension of said flat face;
  • transmission line means having a grounded conductor connected to the block of conductive material, and an ungrounded conductor;
  • a coupling structure as specified in claim 8 in which the conductive wire is isolated from the block of conductive material along the length of the groove by dielectric material positioned in the groove between the conductive wire and the block of conductive material.
  • a coupling structure as specified in claim 9 in which the width of the conductive wire is between .001 inches and .010 inch, the width of the groove is less than one-eighth of an inch, the ratio of the width of the groove to the width of the Wire is in the order of 10:1 i
  • the height of the groove is substantially equal to the height of the YIG material.
  • a coupling structure as specified in claim 10 in which the YIG material is in physical contact, with the wire conductor.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
US762062A 1968-09-24 1968-09-24 Electromagnetic coupling apparatus Expired - Lifetime US3526856A (en)

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US76206268A 1968-09-24 1968-09-24

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US (1) US3526856A (de)
JP (1) JPS4821766B1 (de)
DE (1) DE1948289A1 (de)
FR (1) FR2018729A1 (de)
GB (1) GB1233636A (de)
NL (1) NL6914525A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2116753A5 (de) * 1970-12-07 1972-07-21 Lignes Telegraph Telephon

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60166383U (ja) * 1984-04-13 1985-11-05 山本光学株式会社 スキ−用ストツクの石突構造

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3244993A (en) * 1962-02-06 1966-04-05 Raytheon Co Electronically adjustable spin-wave delay line and parametric amplifier
US3307120A (en) * 1962-09-26 1967-02-28 Bell Telephone Labor Inc Ultrasonic wave device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3244993A (en) * 1962-02-06 1966-04-05 Raytheon Co Electronically adjustable spin-wave delay line and parametric amplifier
US3307120A (en) * 1962-09-26 1967-02-28 Bell Telephone Labor Inc Ultrasonic wave device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2116753A5 (de) * 1970-12-07 1972-07-21 Lignes Telegraph Telephon

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NL6914525A (de) 1970-03-26
JPS4821766B1 (de) 1973-06-30
FR2018729A1 (de) 1970-06-26
GB1233636A (de) 1971-05-26
DE1948289A1 (de) 1970-04-02

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