US1837678A - Inductance coil particularly adapted for use with radio tuning devices - Google Patents

Inductance coil particularly adapted for use with radio tuning devices Download PDF

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Publication number
US1837678A
US1837678A US339939A US33993929A US1837678A US 1837678 A US1837678 A US 1837678A US 339939 A US339939 A US 339939A US 33993929 A US33993929 A US 33993929A US 1837678 A US1837678 A US 1837678A
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coil
coils
inductance
capacity
radio
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US339939A
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Ryder Samuel Charles
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F17/00—Fixed inductances of the signal type 
    • H01F17/0006—Printed inductances
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49117—Conductor or circuit manufacturing
    • Y10T29/49204—Contact or terminal manufacturing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T82/00—Turning
    • Y10T82/10—Process of turning

Definitions

  • 'A further object is to provide an induc- 1 tance coil of low self-capacity but having an extensive surface area to thus provide a lower resistance to radio-frequency or high-*frequency currents than is obtainable in inducglc wire of circular cross-section.
  • a further object of the invention is to pro- 4 vide an inductance coil of low self-capacity and high inductance whose magnetic field is, by virtue of the particular form and design of the coil, restricted to a comparatively small space, this feature being particularly desirable where two or more tuned circuits are incorporated in a radio-receiving set.
  • the improved coil construction is characterized-in that it is not wound, but has its coils formed by a thin conducting layer of spiral configuration applied by printing, 7 gold blocking, painting, metal spraying or electro-deposition or equivalent means to the 30 surface of a dielectric base, such as bakelite,
  • the coils may be self-sup-- porting and produced by any of the known methods of mould or die casting, mechanical cutting, stamping from sheet metal or the like.
  • the accompanying drawing illustrates a plan or face view of one preferred form of the improved inductance coil.
  • This coil comprises a base member 2 of di-electric material, such as ebonite or treated paper, having a thin conducting layer applied on its upper surface in such a manner as to form a coil 3 of spiral configuration.
  • This coil may be produced in various Ways.
  • a printing block is first made to print a spiral having the desired dimensions, and an impression from this block is made upon the di-electric base 2 in gold size or similar adhesive substance;
  • a sheet of metallic leaf such as gold leaf or silver leaf, is now placed over the impression thus formed and is caused to adhere to the portions of the base 2 treated with the gold size or adhesive.
  • the metallic leaf covering those port-ions of the base not coated with gold size or adhesive is now removed by rubbing lightly or similar procedure, thus leaving the spiral coil 3 reproduced on the base a stencil, or electro-depositin processes.
  • the coil has a central rt1on 4 and an extended end portion 5 hot adapted to receive terminals of any approved type or to make contact as with another circuit. If desired,
  • suitable taps may be provided in the length of the spiral coil 3 to enable the same to be used as a tapped inductance.
  • the spiral coil 3 of the improved inductance coil is characterized by having very thin edges of metal presented towards each other between the adjacent turns or coils. Consequently, the inherent or self-capacity of the coil is very low.
  • the extensive surface area of the turns of the spiral coil 3 enables two or more of said coils to be used very efiectively for close coupling radio circuits similarly to honeycomb, duo-lateral and like types of coils. In this form, the coils are fitted together fiatwise, and, if desired, means may be provided for'varying Other methods may be their proximity to thus vary the degree of capacitive'and inductive cou ling.
  • two or more 0 the improved coils may be connected in series, and means may be provided for varying their proximity to thus obtain a variometer eifect, or alternatively may be inductively coupled as in a vario-coupler or radio-frequency transformer, the degree of capacitive and inductive coupling being readily variable.
  • the number of turns in the spiral 3 and the surface area of the turns are variable as found desirable to provide any required inductance-capacity value ac cording to the particular circuit in which the coil is to be used.
  • the improved coil is of such character that it is eminently adaptable to mass production whereby it can be manufactured much more economically to a predetermined definite electrical standard than can coils of ordinary types produced by wire winding operations, thus ensuring a standard of interchangeability or duplication of circuits not hitherto possible.
  • the invention provides a form of coil which-particularly when two or more of the same are together usedby virtue of its special design and the thin edgeto-edge disposition of its turns, isolates its inherent or self-capacity from its natural inductance, and its said self-capacity and inductance may be said to have been thus sep arately lumped in a manner which renders them nevertheless arranged so to be each active and capable of being readily adapted for use with a tuned radio circuit whose tuning is effected by the sum product of, and ratio between, its capacity and inductance.
  • a coil according to the invention may function as a wavemeter coil where the essentials are an interchangeable coil of low self-capacity and non-variable inductance to facilitate standard calibration.
  • a coil according to the invention may function as a radio frequency choke Where low self-distributed capacity, a confined magnetic field and a low volt turns ratio are absolutely necessary. To effect this it is usual to wind a solenoid coil of small diameter in several sections or pies. It will be seen that the design of the improved coil lends itself readily to the construction Of a unit where these conditions obtain. A number of coils are connected in series and spaced to form the sections or pies. The connectionsfrom segment to segment or pie to pie may be made by a simple snap-in method, and thusthe inductance of the choke is governed by the number of pies. This flexibility is a desirable feature when changing from upper to lower wave bands.
  • a coil according to the invention may function as a wavetrap where a coil and condenser are imposed in the aerial circuit and tuned to the frequency of the unwanted signal by the variable capacity.
  • a number of coils according to the invention may together function as a radio frequency transformer where a primary winding is inductively and capacitivel coupled to a secondary winding. These win ings may be fixedly tuned by virtue of the degree of coupling and turn ratio, or alternatively the primary or secondary, or both, may be capacitively tuned to vary the frequency response.
  • a very flexible transformer results, the tuning being eiiectcd by the degree of coupling between primary and secondary and the amount of capacity introduced across the secondary; these factors being controlled by a variable position of the coils in respect to each other.
  • the secondary be composed of at least two sections to obtain variable capacity across same.
  • astatic and non-inductive coils may be made by superimposing one spiral upon another-such as for example by using a double-cut spiralthe inner ends being connected together and the outer ends being the beginning and end respectively of the cir cuit.
  • two coils may be con nected together so that their individual fields are opposed to each other.
  • the wavelength response of such a unit may be accurately checked and adjusted with a wavemeter and then sealed in wax, resin or similar insulator.
  • a number of popular wavelengths may be made up and incorporated in a receiving set where the selection of the wanted station is effected by the simple expedient of switching the suitable unit into circuit.
  • An inductance coil designed primarilyfor use with radio tuning devices, consisting of a dielectric base having a conducting layer of spiral configuration printed thereon in metallic ink.

Description

Dec. 22, 1931. s. c. RYDER 1,837,678
INDUCTANCE COIL PARTICULARLY ADAPTED FOR USE WITH RADIO TUNING DEVICES Filed Feb. 14, 1929 Jul/ma;-
fawn 44405! l azrjes 2 2 7 Patented 1931 i I UNITED STATES PATENT OFFICE m1. cmmas RYDER, or man, maw sourn WALES, ausraamn mnuc'rmca con. rnnrrcunmr anar'rma, ron. can wrrrr mm mum nnvrcns 1 Application am February 14, 1920, Serial No.
mum self-capacity between its adjacent turns or coils.
'A further object is to provide an induc- 1 tance coil of low self-capacity but having an extensive surface area to thus provide a lower resistance to radio-frequency or high-*frequency currents than is obtainable in inducglc wire of circular cross-section.
A further object of the invention is to pro- 4 vide an inductance coil of low self-capacity and high inductance whose magnetic field is, by virtue of the particular form and design of the coil, restricted to a comparatively small space, this feature being particularly desirable where two or more tuned circuits are incorporated in a radio-receiving set.
The improved coil construction is characterized-in that it is not wound, but has its coils formed by a thin conducting layer of spiral configuration applied by printing, 7 gold blocking, painting, metal spraying or electro-deposition or equivalent means to the 30 surface of a dielectric base, such as bakelite,
celluloid, mica, etc. 7.
'Alternatively, the coils may be self-sup-- porting and produced by any of the known methods of mould or die casting, mechanical cutting, stamping from sheet metal or the like. i
The accompanying drawing illustrates a plan or face view of one preferred form of the improved inductance coil. This coil comprises a base member 2 of di-electric material, such as ebonite or treated paper, having a thin conducting layer applied on its upper surface in such a manner as to form a coil 3 of spiral configuration. This coil may be produced in various Ways.
According to one method, a printing block is first made to print a spiral having the desired dimensions, and an impression from this block is made upon the di-electric base 2 in gold size or similar adhesive substance;
tance coils of present types wound from sin- 389,999, and in Australia September 19, 1928.
A sheet of metallic leaf, such as gold leaf or silver leaf, is now placed over the impression thus formed and is caused to adhere to the portions of the base 2 treated with the gold size or adhesive. The metallic leaf covering those port-ions of the base not coated with gold size or adhesive is now removed by rubbing lightly or similar procedure, thus leaving the spiral coil 3 reproduced on the base a stencil, or electro-depositin processes.
The coil has a central rt1on 4 and an extended end portion 5 hot adapted to receive terminals of any approved type or to make contact as with another circuit. If desired,
suitable taps may be provided in the length of the spiral coil 3 to enable the same to be used as a tapped inductance.
The spiral coil 3 of the improved inductance coil is characterized by having very thin edges of metal presented towards each other between the adjacent turns or coils. Consequently, the inherent or self-capacity of the coil is very low. By reason of the extensive surface area of the turns of the spiral coil 3, a very low resistance is offered to highfrequency currents and a much more confined magnetic field exists as compared with existing types of coils wound with wire of circular cross-section. These advantages are of considerable importance when the improved inductance coil is used in radio apparatus. The extensive surface area of the improved coil enables two or more of said coils to be used very efiectively for close coupling radio circuits similarly to honeycomb, duo-lateral and like types of coils. In this form, the coils are fitted together fiatwise, and, if desired, means may be provided for'varying Other methods may be their proximity to thus vary the degree of capacitive'and inductive cou ling.
Similarly, two or more 0 the improved coils may be connected in series, and means may be provided for varying their proximity to thus obtain a variometer eifect, or alternatively may be inductively coupled as in a vario-coupler or radio-frequency transformer, the degree of capacitive and inductive coupling being readily variable.
In the manufacture of the improved inductance coil, the number of turns in the spiral 3 and the surface area of the turns are variable as found desirable to provide any required inductance-capacity value ac cording to the particular circuit in which the coil is to be used.
The improved coil is of such character that it is eminently adaptable to mass production whereby it can be manufactured much more economically to a predetermined definite electrical standard than can coils of ordinary types produced by wire winding operations, thus ensuring a standard of interchangeability or duplication of circuits not hitherto possible.
It will be seen that the invention provides a form of coil which-particularly when two or more of the same are together usedby virtue of its special design and the thin edgeto-edge disposition of its turns, isolates its inherent or self-capacity from its natural inductance, and its said self-capacity and inductance may be said to have been thus sep arately lumped in a manner which renders them nevertheless arranged so to be each active and capable of being readily adapted for use with a tuned radio circuit whose tuning is effected by the sum product of, and ratio between, its capacity and inductance.
A few adaptations for the use of an improved coil or coils according to the invention, it is thought, may with advantage be mentioned herein and by virtue of the partlcular construction of a coil according to the invention and its particular characteristics as before-mentioned, many other special applications other than hereinafter dealt with will suggest themselves to those persons who are familiar with the art of designing radio and electrical components or circuits.
For example, a coil according to the invention may function as a wavemeter coil where the essentials are an interchangeable coil of low self-capacity and non-variable inductance to facilitate standard calibration.
Again, a coil according to the invention may function as a radio frequency choke Where low self-distributed capacity, a confined magnetic field and a low volt turns ratio are absolutely necessary. To effect this it is usual to wind a solenoid coil of small diameter in several sections or pies. It will be seen that the design of the improved coil lends itself readily to the construction Of a unit where these conditions obtain. A number of coils are connected in series and spaced to form the sections or pies. The connectionsfrom segment to segment or pie to pie may be made by a simple snap-in method, and thusthe inductance of the choke is governed by the number of pies. This flexibility is a desirable feature when changing from upper to lower wave bands.
Again, a coil according to the invention may function as a wavetrap where a coil and condenser are imposed in the aerial circuit and tuned to the frequency of the unwanted signal by the variable capacity.
In utilizing the improved coil, two or more are connected in series, the capacity across them varying as their proximity to each other varies. A suitable aerial tapping is taken from the intersection between coils.
Again, a number of coils according to the invention may together function as a radio frequency transformer where a primary winding is inductively and capacitivel coupled to a secondary winding. These win ings may be fixedly tuned by virtue of the degree of coupling and turn ratio, or alternatively the primary or secondary, or both, may be capacitively tuned to vary the frequency response. In applying the improved coils a very flexible transformer results, the tuning being eiiectcd by the degree of coupling between primary and secondary and the amount of capacity introduced across the secondary; these factors being controlled by a variable position of the coils in respect to each other.
It is of course essential that the secondary be composed of at least two sections to obtain variable capacity across same.
Again, astatic and non-inductive coils may be made by superimposing one spiral upon another-such as for example by using a double-cut spiralthe inner ends being connected together and the outer ends being the beginning and end respectively of the cir cuit. Alternatively, two coils may be con nected together so that their individual fields are opposed to each other.
Still again, where, as in fixedly tuned circuits, the best capacity and inductance ratio for a given wavelength are predeterm ned by the number of turns and effective surface area of two or more of the improved coils in respect to each other, the wavelength response of such a unit may be accurately checked and adjusted with a wavemeter and then sealed in wax, resin or similar insulator.
A number of popular wavelengths may be made up and incorporated in a receiving set where the selection of the wanted station is effected by the simple expedient of switching the suitable unit into circuit.
Again, where, as in balanced circuits, it is necessary to repeat a value of inductance and capacity, the method of manufacture and 17 ctiiistruction of the improved coil automatically repeats the physical and electrical properties of each coil. Further it is possible to readily find the exact electrical centre of an inductance by joining two coils in series and tapping at the intersection.
What I do claim is 1. An inductance coil designed primarilyfor use with radio tuning devices, consisting of a dielectric base having a conducting layer of spiral configuration printed thereon in metallic ink.
2. An inductance coil according to claim 1, in which the printed coil has a central portion and an extended end portion to make contact with another circuit or to receive terminals.
In testimony whereof I afiix my signature.
SAMUEL CHARLES RYDER.
US339939A 1928-09-12 1929-02-14 Inductance coil particularly adapted for use with radio tuning devices Expired - Lifetime US1837678A (en)

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Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2427144A (en) * 1936-11-23 1947-09-09 Jansen Franciscus Jo Wilhelmus Mechanical connection for electrical circuits
US2451725A (en) * 1945-03-24 1948-10-19 Jacob Poster Method of making a structural unit
US2474988A (en) * 1943-08-30 1949-07-05 Sargrove John Adolph Method of manufacturing electrical network circuits
US2542726A (en) * 1945-06-30 1951-02-20 Herbert W Sullivan Method of forming inductor coils
US2583854A (en) * 1948-10-01 1952-01-29 Siemens Ag Inductance coil with ceramic form for high frequency
US2599710A (en) * 1946-08-07 1952-06-10 Albert M Hathaway Method of making electrical wiring
US2601338A (en) * 1947-10-31 1952-06-24 Steatite Res Corp Varialbe parallel resonant circuit
US2611040A (en) * 1947-06-23 1952-09-16 Brunetti Cledo Nonplanar printed circuits and structural unit
US2622238A (en) * 1949-04-07 1952-12-16 Boltson Hannah Resonant tank circuit for diathermy apparatus or the like
US2649513A (en) * 1949-03-08 1953-08-18 Ibm Distributor and method for making the same
US2688649A (en) * 1951-12-14 1954-09-07 Bjorksten Res Lab For Electroc Printed battery and method for making
US2721152A (en) * 1948-11-12 1955-10-18 Ward Blenkinsop & Co Ltd Production of electrical elements
US2776235A (en) * 1952-09-18 1957-01-01 Sprague Electric Co Electric circuit printing
US2786187A (en) * 1950-04-06 1957-03-19 Chrysler Corp Electrical coil
US2850707A (en) * 1954-04-15 1958-09-02 Sylvania Electric Prod Electromagnetic coils
US2850709A (en) * 1954-04-28 1958-09-02 Int Standard Electric Corp High frequency electric transformers
US2851380A (en) * 1953-02-09 1958-09-09 Woodmont Products Inc Conductive ink and article coated therewith
US2886880A (en) * 1952-05-26 1959-05-19 Hermoplast Ltd Method of producing electric circuit components
DE972477C (en) * 1942-06-02 1959-07-30 Siemens Ag Circuit board made of insulating material with electrical connections made of conductive paint
US2913724A (en) * 1955-01-25 1959-11-17 Dynamics Corp America Antenna coupling device
US2913725A (en) * 1956-02-07 1959-11-17 Dynamics Corp America Antenna coupling apparatus
US2979615A (en) * 1956-11-06 1961-04-11 Liberty Mfg Corp Apparatus for tuning a radio frequency
US2981611A (en) * 1956-03-14 1961-04-25 Metropolitanvickers Electrical Manufacture of printed electrical circuits or components
US3046358A (en) * 1955-12-23 1962-07-24 Frank A Comerci Non-magnetic pickup loop for making absolute measurement of signal strength on magnetic recordings
US3068435A (en) * 1954-04-19 1962-12-11 Sylvania Electric Prod Electromagnetic coils
US3091734A (en) * 1960-11-07 1963-05-28 Electronic Devices Corp Transceiver construction
US3508457A (en) * 1967-09-27 1970-04-28 Us Navy Process for constructing thin film inductors
US3515979A (en) * 1957-11-04 1970-06-02 Perkin Elmer Corp Magnetic field control apparatus
US4114428A (en) * 1976-09-24 1978-09-19 Popenoe Charles H Radio-frequency tuned-circuit microdisplacement transducer
USRE30183E (en) * 1976-09-24 1980-01-08 Radio-frequency tuned-circuit microdisplacement transducer
US5963871A (en) * 1996-10-04 1999-10-05 Telefonaktiebolaget Lm Ericsson Retractable multi-band antennas
US6166694A (en) * 1998-07-09 2000-12-26 Telefonaktiebolaget Lm Ericsson (Publ) Printed twin spiral dual band antenna
US6329962B2 (en) 1998-08-04 2001-12-11 Telefonaktiebolaget Lm Ericsson (Publ) Multiple band, multiple branch antenna for mobile phone
US6343208B1 (en) 1998-12-16 2002-01-29 Telefonaktiebolaget Lm Ericsson (Publ) Printed multi-band patch antenna
US6353443B1 (en) 1998-07-09 2002-03-05 Telefonaktiebolaget Lm Ericsson (Publ) Miniature printed spiral antenna for mobile terminals
US20050198811A1 (en) * 2004-03-12 2005-09-15 A K Stamping Co. Inc. Manufacture of RFID tags and intermediate products therefor

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2427144A (en) * 1936-11-23 1947-09-09 Jansen Franciscus Jo Wilhelmus Mechanical connection for electrical circuits
DE972477C (en) * 1942-06-02 1959-07-30 Siemens Ag Circuit board made of insulating material with electrical connections made of conductive paint
US2474988A (en) * 1943-08-30 1949-07-05 Sargrove John Adolph Method of manufacturing electrical network circuits
US2451725A (en) * 1945-03-24 1948-10-19 Jacob Poster Method of making a structural unit
US2542726A (en) * 1945-06-30 1951-02-20 Herbert W Sullivan Method of forming inductor coils
US2599710A (en) * 1946-08-07 1952-06-10 Albert M Hathaway Method of making electrical wiring
US2611040A (en) * 1947-06-23 1952-09-16 Brunetti Cledo Nonplanar printed circuits and structural unit
US2601338A (en) * 1947-10-31 1952-06-24 Steatite Res Corp Varialbe parallel resonant circuit
US2583854A (en) * 1948-10-01 1952-01-29 Siemens Ag Inductance coil with ceramic form for high frequency
US2721152A (en) * 1948-11-12 1955-10-18 Ward Blenkinsop & Co Ltd Production of electrical elements
US2649513A (en) * 1949-03-08 1953-08-18 Ibm Distributor and method for making the same
US2622238A (en) * 1949-04-07 1952-12-16 Boltson Hannah Resonant tank circuit for diathermy apparatus or the like
US2786187A (en) * 1950-04-06 1957-03-19 Chrysler Corp Electrical coil
US2688649A (en) * 1951-12-14 1954-09-07 Bjorksten Res Lab For Electroc Printed battery and method for making
US2886880A (en) * 1952-05-26 1959-05-19 Hermoplast Ltd Method of producing electric circuit components
US2776235A (en) * 1952-09-18 1957-01-01 Sprague Electric Co Electric circuit printing
US2851380A (en) * 1953-02-09 1958-09-09 Woodmont Products Inc Conductive ink and article coated therewith
US2850707A (en) * 1954-04-15 1958-09-02 Sylvania Electric Prod Electromagnetic coils
US3068435A (en) * 1954-04-19 1962-12-11 Sylvania Electric Prod Electromagnetic coils
US2850709A (en) * 1954-04-28 1958-09-02 Int Standard Electric Corp High frequency electric transformers
US2913724A (en) * 1955-01-25 1959-11-17 Dynamics Corp America Antenna coupling device
US3046358A (en) * 1955-12-23 1962-07-24 Frank A Comerci Non-magnetic pickup loop for making absolute measurement of signal strength on magnetic recordings
US2913725A (en) * 1956-02-07 1959-11-17 Dynamics Corp America Antenna coupling apparatus
US2981611A (en) * 1956-03-14 1961-04-25 Metropolitanvickers Electrical Manufacture of printed electrical circuits or components
US2979615A (en) * 1956-11-06 1961-04-11 Liberty Mfg Corp Apparatus for tuning a radio frequency
US3515979A (en) * 1957-11-04 1970-06-02 Perkin Elmer Corp Magnetic field control apparatus
US3091734A (en) * 1960-11-07 1963-05-28 Electronic Devices Corp Transceiver construction
US3508457A (en) * 1967-09-27 1970-04-28 Us Navy Process for constructing thin film inductors
US4114428A (en) * 1976-09-24 1978-09-19 Popenoe Charles H Radio-frequency tuned-circuit microdisplacement transducer
USRE30183E (en) * 1976-09-24 1980-01-08 Radio-frequency tuned-circuit microdisplacement transducer
US5963871A (en) * 1996-10-04 1999-10-05 Telefonaktiebolaget Lm Ericsson Retractable multi-band antennas
US6166694A (en) * 1998-07-09 2000-12-26 Telefonaktiebolaget Lm Ericsson (Publ) Printed twin spiral dual band antenna
US6353443B1 (en) 1998-07-09 2002-03-05 Telefonaktiebolaget Lm Ericsson (Publ) Miniature printed spiral antenna for mobile terminals
US6329962B2 (en) 1998-08-04 2001-12-11 Telefonaktiebolaget Lm Ericsson (Publ) Multiple band, multiple branch antenna for mobile phone
US6343208B1 (en) 1998-12-16 2002-01-29 Telefonaktiebolaget Lm Ericsson (Publ) Printed multi-band patch antenna
US20050198811A1 (en) * 2004-03-12 2005-09-15 A K Stamping Co. Inc. Manufacture of RFID tags and intermediate products therefor
US7250868B2 (en) 2004-03-12 2007-07-31 A K Stamping Co. Inc. Manufacture of RFID tags and intermediate products therefor

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