EP0397755A4 - Magnetic field concentrator - Google Patents

Magnetic field concentrator

Info

Publication number
EP0397755A4
EP0397755A4 EP19890902008 EP89902008A EP0397755A4 EP 0397755 A4 EP0397755 A4 EP 0397755A4 EP 19890902008 EP19890902008 EP 19890902008 EP 89902008 A EP89902008 A EP 89902008A EP 0397755 A4 EP0397755 A4 EP 0397755A4
Authority
EP
European Patent Office
Prior art keywords
portion
concentrator
receiver means
adapted
substantially
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19890902008
Other versions
EP0397755A1 (en
Inventor
Graham Alexander Munro Murdoch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Western Australia
Magellan Tech Pty Ltd
Original Assignee
Magellan Tech Pty Ltd
Uniscan Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to AUPI658188 priority Critical
Priority to AU6581/88 priority
Application filed by Magellan Tech Pty Ltd, Uniscan Ltd filed Critical Magellan Tech Pty Ltd
Publication of EP0397755A1 publication Critical patent/EP0397755A1/en
Publication of EP0397755A4 publication Critical patent/EP0397755A4/en
Application status is Withdrawn legal-status Critical

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/52Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • H01Q1/526Electromagnetic shields
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
    • H01Q7/04Screened antennas

Abstract

A concentrator adapted to concentrate signals for reception by a receiver means, said concentrator comprising a conductive portion juxtaposed said receiver means, said concentrator being aligned so as to receive said signals and cause further signals to impinge on said receiver means, and thereby enhance reception of said signals by said receiver means. Also disclosed is a shield for substantially eliminating magnetic field radiation from within a predetermined area, the field being diverted from the area by means of conductive strip.

Description

MAGNETIC FIELD CONCENTRATOR FIELD OF INVENTION

The present invention relates to magnetic field concentration apparatus, particularly signal enhancement and/or apparatus for confining magnetic flux within an aperture, and/or to shield magnetic flux from components, and/or to means for improving signal reception. The present invention has a particular application to passive devices, such as tokens, transponders or smart cards. 10 PRIOR ART

It is well known that metal placed in the proximity of a magnetic field receiving coil will substantially reduce the amount of magnetic field received by the coil. For example, metal placed between a source of the magnetic field ις and the coil can operate to prevent any magnetic field from being picked up by the coil as shown in Figure 1. The metal sheet serves to absorb and deflect the flux radiated from the driver coil or magnetic field source.

Figure 2 shows another situation where a metal 20 sheet serves to reduce signal reception. The metal sheet is placed behind the coil. The metal sheet acts to reduce the amount of flux received by the coil by radiating an opposing flux field. The closer the metal sheet, to the coil, the larger the opposing flux field and the less signal flux is -r received by the coil. In effect the metal sheets serve to proportionately nullify the driver coil radiated flux.

U.S. Patent 4,373,163 discloses an electrostatic shield with an antenna loop therein (Figure 1). The antenna is surrounded by a metal shield. The specification does not ,n disclose a conductor plate proximate and in substantially the same plane as an antenna to enhance signal reception, in accordance with the present invention as will be described in more detail hereinafter.

U.S. Patent 4,486,731 discloses a signal , enhancement apparatus in the form of a coil having magnetically permeable material disposed in overlapping relationship with a coil. The coil is influenced by strips 23 and 24 when the coil is oriented parallel to the direction of impinging flux (column 2, lines 23 to 41). However, U.S. Patent 4,486,731 relates to the problem of coil reception when the coil is in the same plane as the impinging flux, whereas the present invention relates to ς increasing the reception of flux by a coil by providing a concentrator in juxtaposition to and in substantially the same plane as the coil.

U.S. Patent 4,754,284 discloses an automobile antenna system for use in receiving high frequency bands in - - excess of 50 MHz.

SUMMARY OF INVENTION

An object of the present invention is to provide a concentrator which can be associated or juxtaposed a coil without deleterious effect on the coil's ability to receive . f. signals or magnetic fields.

Another object of the present invention is to provide improved concentrator performance.

The present invention in one form provides a concentrator adapted to concentrate signals for reception by a receiver means, said concentrator comprising an

20 electrically conductive portion juxtaposed said receiver means, said concentrator being aligned so as to receive said signals and cause further signals to impinge on said receiver means, and thereby enhance reception of said signals by said receiver means..

25

The present invention further provides a magnetic field concentrator comprising an electrically conductive portion, said concentrator being orientated to receive a magnetic field and cause flux to be radiated from said portion, the concentrator being juxtaposed a receiver means,

30 adapted to also receive said field, such that said receiver means operates to receive said flux in addition to said field.

The electrically conductive portion is preferably made of metal, for example aluminium or copper.

35

The present invention also provides a magnetic field concentrator adapted to surround a receiver means, the concentrator comprising a loop having first and second interconnected portions, wherein : the first portion has first and second regions, the first portion being continuous between said first and second regions, the first region being juxtaposed and spaced from said second region, the first portion being adapted to c surround said receiver means, the second portion having third and fourth regions, the second portion being continuous between said third and fourth regions, the third region being juxtaposed and spaced from said fourth region, the second portion being adapted to 10 substantially encircle said first portion, first and second interconnection portions, the . first interconnection portion being adapted to couple said first region to said third region, the second interconnection portion being adapted to couple said second jc region and said fourth region, the loop being formed in a continuous manner and having a space provided between said first and second interconnection portions.

The concentrator described above may, upon being 2Q incident with a magnetic field, have substantially no magnetic field pass between said first and second portions, the field being diverted through said first portion and incident said receiver means.

The present invention also provides a magnetic 25 field concentrator adapted to enhance field reception by a receiver means, the concentrator being juxtaposed and adapted to influence said receiver means, wherein the concentrator comprises a metal portion adapted to substantially surround said receiver means in one plane, the 30 metal portion being further adapted to encircle the receiver means in the plane in a discontinuous manner, wherein, upon radiation by said field, the concentrator generates flux which is received by the receiver means in addition to said field. ,,. The present invention may provide a shield for alleviating radiation from magnetic fields within a predetermined area, the shield comprising a loop having first and second portions and third and fourth interconnecting portions, the first portion having first and second regions, the first portion being continuous between said first and second regions, the first region being substantially opposingly juxtaposed and spaced from said second region, the first portion substantially encircling said predetermined area, the second portion having third and fourth regions, being aligned with the first and second regions respectively, the second portion being continuous between said third and fourth regions, the third regaion beingy substantially opposingly juxtaposed and spaced from said' fourth region, the second portion being adapted to substantially encircle said first portion, the first interconnection portion being adapted to couple said first and fourth regions and the second interconnecting portion being adapted to couple said second and third regions, wherein said magnetic fields are substantially excluded from the area bounded by the first portion.

The portions of the shield and concentrators described above may in one form be substantially "C" shaped in configuration.

The present invention also provides a shield for substantially eliminating magnetic field radiation from within a predetermined area comprising a first conductive portion substantially encompassing said area and a second conductive portion substantially encompassing and being spaced from said first portion, end regions of said first and second portions being coupled in an overlapping arrangement so as to form one continuous strip, whereby, upon radiation by a magnetic field, the field is substantially diverted from said area.

The present invention may also provide a magnetic field concentrator which may be used to confine an alternating magnetic flux within an aperture and/or 5 concentrate a magnetic flux in a coil and/or shield components from the flux. The concentrator may be useful where a large coil for collecting flux is more expensive than a concentrator and smaller coil or where the coil size presents problems. The concentrator may preferably be made from a material with good electrical conductivity which thereby improves the concentrator's performance. The degree of conductivity may determine the amount of flux radiated from the concentrator. Non-magnetic or magnetic conductors may also be contemplated.

Preferred embodiment(s) of the present invention will now be described with reference to the accompanying drawings, wherein : 0

Figures 1 and 2 show prior art arrangements.

Figures 3 to 14 show various exemplary (only) forms of concentrator according to the present invention.

Throughout this document, the term "coil" should be construed in a non-limiting way. The term "coil" may 5 include, for example, any signal receiving apparatus or magnetic field receptor as the present invention has many applications. As can be appreciated, the shape of the metal herein described should not be limited to a particular configuration. The shape of metal is dependent on its 0 application or use.

Also, throughout this document, the terms "signal" or "signals" include within their scope any form of electromagnetic radiation. The signal may, for example, be a powering signal or a data or informational signal.

Although metal placed proximate a receiving coil is known to reduce the coil's receptive ability, a metal sheet placed in juxtaposition and/or in substantially the same plane as the coil as will be hereinafter detailed will not

„ have a negative effect on the coil's receptive ability. 0

Figure 3 shows a metal sheet placed in the same plane as the coil. The metal serves to increase the amount of flux, impinging the coil. The increase of flux on the coil due to the metal is inversely proportional to the spacing between the metal and the coil. 5

Figure 4 shows a coil surrounded in the coil's plane by metal. As can be seen, the additional fluxes produced by circulating currents, opposes and reduces the applied currents. Accordingly, no flux enhancement is produced for the coil the metal surrounds.

Figure 5 shows metal similar in shape to that previously mentioned, however, a slot or gap is provided in the metal so that the metal surrounds the coil in a discontinuous manner.

The gap in the metal surrounding the coil causes the eddy currents (produced in response to impinging flux) to produce a field that serves to increase the flux impinging the coil.

Figure 6 shows a concentrator similar to that -. hereinbefore described.

The concentrator may be preferably constructed in two formε :-

(i) A metal plate with a hole cut to allow the magnetic flux to pass through. A slot or slots are cut from the hole out to the perimeter to alleviate circulating currents, which causes a drastic reduction in flux, from encircling the hole. The slot(s) may overlap, as long as there is substantially no continuous conduction path around the central hole (Figures 5, 6 and 7). Co-pending Applications PI 7198 ANTENNA STRUCTURE AND METHOD OF MANUFACTURE and PJ 1693 INDUCTIVE ELEMENT FOR USE AS AN ANTENNA IN TRANSPONDERS filed in the name of Magellan Corporation (Australia) Pty. Limited disclose a method of simultaneously fabricating electrical coils and capacitors. Conveniently, the plates of capacitors so fabricated may take a substantially "C" shaped configuration and be disposed to surround the associated coils as hereinbefore described. This technique permits the area consumed by said capacitor plates to contribute towards the flux gathering ability of said coils.

(ii) A wire loop concentrator using high conductivity wire, for example bent to follow the perimeter of the metal plate shown in Figures 7, 9 and 10, may perform the same concentrating function provided the wire forms a continuous conducting path. The operation of both exemplary forms as shown in the drawings can be described thus :- c (i) Circulating currents induced on the surface of a metal plate prevent an alternating magnetic flux from penetrating below the skin depth. For lOOKHz on copper, this is about 0.18mm. Consequently, an alternating flux cannot penetrate thick metal ,Q plates and flows around the conducting obstacle.

With a hole cut in the metal plate, some of the" flux interrupted by the plate is diverted through the hole increasing the flux density in that area, while the balance goes around the outer edge of the 15 plate (Figure 8). Without the slot, the metal plate acts as a one turn short circuit. This may maintain an almost equal in magnitude, oppositely directed flux in the central hole cancelling most of the flux trying to pass through it. This may _0 have a negative effect for magnetic field concentration purposes, but may be used to substantially exclude flux from an area, (ii) The wire loop acts as a one turn short circuit. The back emf generated in the wire loop ensures _5 that the total flux passing through the space between the inner and outer loops is very small, only enough to account for ohmic losses. The flux intercepted by the loop configuration is concentrated in the inner loop in substantially the -,„ same manner as for the metal plate (Figure 9).

The wire loop concentrator may also be used to substantially exclude flux from an area. By crossing the wire connections between the inner and outer loops, without allowing them to touch, the flux passing through the inner 3C. loop is drastically reduced. Figure 10 shows an example of this configuration.

Figure 11 shows an example of a field concentrator acting as an electrostatic Faraday shield. The coil is - 8 - shown partially surrounded by a conventional Faraday shield. The Faraday shield is extended to form a field concentrator, or may be coupled to an existing concentrator.

Electrostatic shielding reduces the capacitive sensitivity of the coil to objects in the vicinity of the coil. The Faraday shield may extend only part way around the coil in order to adjust capacitive sensitivity.

Alternatively, field concentration and electrostatic shielding can be achieved using two field concentration plates. One placed in front of the coil, the other behind the coil as shown in Figure 12.

Figure 13 shows a cross-section of this arrangement. Connection between the front and back plates can be made anywhere along the plates, however, preferably this is done on the inside and/or the outside of the coil. See Figures 14A, B and C.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1. A concentrator adapted to concentrate signals for reception by a receiver means, said concentrator comprising an electrically conductive portion juxtaposed said receiver means, said concentrator being aligned so as to receive said signals and cause further signals to impinge on said receiver means, and thereby enhance reception of said signals by said receiver means.
2. A magnetic field concentrator comprising an electrically conductive portion, said concentrator being orientated to receive a magnetic field and cause flux to be radiated from said conductive portion, the concentrator being juxtaposed a receiver means, adapted to also receive said field, such that said receiver means operates to receive said flux in addition to said field.
3. A magnetic field concentrator adapted to surround a receiver means, the concentrator comprising a loop having first and second interconnected portions, wherein : the first portion has first and second regions, the first portion being continuous between said first and second regions, the first region being juxtaposed and spaced from said second region, the first portion being adapted to surround said receiver means, the second portion having third and fourth regions, the second portion being continuous between said third and fourth regions, the third region being juxtaposed and spaced from said fourth region, the second portion being adapted to substantially encircle said first portion, first and second interconnection portions, the first interconnection portion being adapted to couple said first region to said third region, the second interconnection portion being adapted to couple said second region and said fourth region, the loop being formed in a continuous manner and having a space provided between said first and second interconnection portions. 4. A concentrator as claimed in Claim 1, 2 or 3, wherein said conductive portion is made of metal.
5. A concentrator as claimed in Claim 3, wherein upon being incident with a magnetic field, the concentrator haε substantially no magnetic field pass between said first and second portions, the field being diverted through said first portion and incident said receiver means.
6. A magnetic field concentrator adapted to enhance field reception by a receiver means, the concentrator being juxtaposed and adapted to influence said receiver means, wherein the concentrator comprises a metal portion adapted to substantially surround said receiver means in one plane, the metal portion being further adapted to partially or completely surround the receiver means in the plane in a discontinuous manner, wherein, upon radiation by said field, the concentrator generates flux which is received by the receiver means in addition to said field.
7. A concentrator as claimed in Claim 1, 2 or 6, wherein said portion comprises at least one capacitor plate.
8. A concentrator as claimed in any one of the preceding claims further comprising an electrostatic Faraday shield acting on at least a portion of said receiver means.
9. A concentrator as claimed in any one of the preceding claims, wherein the portions are substantially "C" shaped.
10. A concentrator aε claimed in any one of Claims 1 to 6 or 9, εubεtantially as herein described with reference to the accompanying drawings.
11. A shield for alleviating radiation from magnetic fields within a predetermined area, the shield comprising a loop having first and second portions and third and fourth interconnecting portions, - li ¬ the first portion having first and second regions, the first portion being continuous between said first and second regions, the first region being substantially opposingly juxtaposed and spaced from said second region, the first portion substantially encircling said predetermined area, the second portion having third and fourth regions, being aligned with the first and second regions respectively, the second portion being continuous between said third and fourth regions, the third region being substantially opposingly juxtaposed and spaced from said, fourth region, the second portion being adapted to substantially encircle said first portion, the first interconnecting portion being adapted to couple said first and fourth regions and the second interconnecting portions being adapted to couple said second and third regions, wherein said magnetic fields are substantially excluded from the area bounded by the first portion.
12. A shield for substantially eliminating magnetic field radiation from within a predetermined area comprising a first conductive portion substantially encompassing said area and a second conductive portion substantially encompassing and being spaced from said first portion, end regions of said first and second portions being coupled in an overlapping arrangement so as to form one continuous strip, whereby, upon radiation by a magnetic field, the field is substantially diverted from said area.
13. A shield as claimed in Claim 12, wherein said conductive portion is made of metal.
14. A shield as claimed in Claim 6 or 10, substantially as herein described with reference to the accompanying drawings. 15. Apparatus such as a transponder, identification smart card, token card or actuator incorporating a concentrator or shield as claimed in any one of the preceding claims.
EP19890902008 1988-02-04 1989-02-03 Magnetic field concentrator Withdrawn EP0397755A4 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AUPI658188 1988-02-04
AU6581/88 1988-02-04

Publications (2)

Publication Number Publication Date
EP0397755A1 EP0397755A1 (en) 1990-11-22
EP0397755A4 true EP0397755A4 (en) 1992-11-04

Family

ID=3772776

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890902008 Withdrawn EP0397755A4 (en) 1988-02-04 1989-02-03 Magnetic field concentrator

Country Status (5)

Country Link
EP (1) EP0397755A4 (en)
JP (1) JPH03503467A (en)
CA (1) CA1334215C (en)
WO (1) WO1989007347A1 (en)
ZA (1) ZA8900872B (en)

Families Citing this family (53)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5130697A (en) * 1990-10-30 1992-07-14 Sensormatic Electronics Corporation Method and apparatus for shaping a magnetic field
GB9220409D0 (en) * 1992-09-28 1992-11-11 Texas Instruments Holland Shielded transponder
US5557279A (en) * 1993-09-28 1996-09-17 Texas Instruments Incorporated Unitarily-tuned transponder/shield assembly
US5694139A (en) * 1994-06-28 1997-12-02 Sony Corporation Short-distance communication antenna and methods of manufacturing and using the short-distance communication antenna
JP3526928B2 (en) * 1994-11-15 2004-05-17 株式会社ルネサスLsiデザイン Non-contact ic card system
JP4260917B2 (en) 1998-03-31 2009-04-30 株式会社東芝 Loop antenna
JP2001168618A (en) * 1999-12-08 2001-06-22 Smart Card Technologies:Kk Antenna device for reader/writer in non-contact type ic card system
DE10149126A1 (en) * 2001-10-05 2003-04-10 Flexchip Ag Production of a screen used for a transponder comprises applying ferromagnetic particles to a region of the substrate having the spatial expansion of the antenna structure of a transponder, aligning the ferromagnetic particles, etc.
US7339120B2 (en) 2003-06-26 2008-03-04 Matsushita Electric Industrial Co., Ltd. Electromagnetic wave shield
JP2005102101A (en) * 2003-09-01 2005-04-14 Matsushita Electric Ind Co Ltd Gate antenna device
WO2007030862A1 (en) * 2005-09-12 2007-03-22 Magellan Technology Pty Ltd An attenuation device for an antenna of an interrogator
US9064198B2 (en) 2006-04-26 2015-06-23 Murata Manufacturing Co., Ltd. Electromagnetic-coupling-module-attached article
WO2009011423A1 (en) 2007-07-18 2009-01-22 Murata Manufacturing Co., Ltd. Wireless ic device
CN103295056B (en) 2008-05-21 2016-12-28 株式会社村田制作所 Wireless IC device
EP2290586B1 (en) 2008-05-26 2014-06-25 Murata Manufacturing Co., Ltd. Wireless ic device system and method for authenticating wireless ic device
EP2320519B1 (en) 2008-08-19 2017-04-12 Murata Manufacturing Co., Ltd. Wireless ic device and method for manufacturing same
CN102187518B (en) 2008-11-17 2014-12-10 株式会社村田制作所 Ic antenna and wireless device
EP2385580B1 (en) 2009-01-30 2014-04-09 Murata Manufacturing Co., Ltd. Antenna and wireless ic device
JP5510450B2 (en) 2009-04-14 2014-06-04 株式会社村田製作所 Wireless IC device
JP4687832B2 (en) * 2009-04-21 2011-05-25 株式会社村田製作所 Antenna device
JP4788850B2 (en) 2009-07-03 2011-10-05 株式会社村田製作所 Antenna module
WO2011040393A1 (en) 2009-09-30 2011-04-07 株式会社村田製作所 Circuit substrate and method of manufacture thereof
JP5304580B2 (en) 2009-10-02 2013-10-02 株式会社村田製作所 Wireless IC device
CN102576939B (en) 2009-10-16 2015-11-25 株式会社村田制作所 Ic antenna and wireless device
CN102598413A (en) 2009-10-27 2012-07-18 株式会社村田制作所 Transmitting/receiving apparatus and wireless tag reader
JP5333601B2 (en) 2009-11-04 2013-11-06 株式会社村田製作所 Communication terminal and information processing system
WO2011055703A1 (en) 2009-11-04 2011-05-12 株式会社村田製作所 Communication terminal and information processing system
WO2011055702A1 (en) 2009-11-04 2011-05-12 株式会社村田製作所 Wireless ic tag, reader/writer, and information processing system
JP5652470B2 (en) 2010-03-03 2015-01-14 株式会社村田製作所 Wireless communication module and wireless communication device
JP5370581B2 (en) 2010-03-24 2013-12-18 株式会社村田製作所 RFID system
WO2011122163A1 (en) 2010-03-31 2011-10-06 株式会社村田製作所 Antenna and wireless communication device
JP5712506B2 (en) * 2010-05-24 2015-05-07 Tdk株式会社 Proximity antenna and wireless communication device
JP5435130B2 (en) * 2010-06-18 2014-03-05 株式会社村田製作所 Communication terminal device and antenna device
GB2495418B (en) 2010-07-28 2017-05-24 Murata Manufacturing Co Antenna apparatus and communication terminal instrument
WO2012020748A1 (en) 2010-08-10 2012-02-16 株式会社村田製作所 Printed wire board and wireless communication system
JP5062382B2 (en) 2010-09-07 2012-10-31 株式会社村田製作所 Antenna device
CN103038939B (en) 2010-09-30 2015-11-25 株式会社村田制作所 Wireless device ic
CN103053074B (en) 2010-10-12 2015-10-21 株式会社村田制作所 The antenna device and communication terminal apparatus
CN102971909B (en) 2010-10-21 2014-10-15 株式会社村田制作所 The communication terminal apparatus
WO2012093541A1 (en) 2011-01-05 2012-07-12 株式会社村田製作所 Wireless communication device
JP5304956B2 (en) 2011-01-14 2013-10-02 株式会社村田製作所 RFID chip package and RFID tag
KR101374302B1 (en) * 2011-02-15 2014-03-14 가부시키가이샤 무라타 세이사쿠쇼 Antenna device and communication terminal device
JP5370616B2 (en) 2011-02-28 2013-12-18 株式会社村田製作所 Wireless communication device
KR101317226B1 (en) 2011-04-05 2013-10-15 가부시키가이샤 무라타 세이사쿠쇼 Wireless communication device
WO2012157596A1 (en) 2011-05-16 2012-11-22 株式会社村田製作所 Wireless ic device
CN103370834B (en) 2011-07-14 2016-04-13 株式会社村田制作所 Wireless communication devices
WO2013035821A1 (en) 2011-09-09 2013-03-14 株式会社村田製作所 Antenna device and wireless device
JP5344108B1 (en) 2011-12-01 2013-11-20 株式会社村田製作所 Wireless IC device and manufacturing method thereof
WO2013125610A1 (en) 2012-02-24 2013-08-29 株式会社村田製作所 Antenna device and wireless communication device
JP5304975B1 (en) 2012-04-13 2013-10-02 株式会社村田製作所 RFID tag inspection method and inspection apparatus
TWI474953B (en) * 2012-05-23 2015-03-01 Taiwan Lamination Ind Inc Packaging bags with external stickers
JP5964155B2 (en) * 2012-06-28 2016-08-03 Necトーキン株式会社 Antenna device
US10476304B2 (en) * 2015-05-27 2019-11-12 Qualcomm Incorporated Wireless power receive coil for metal backed device

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2014796A (en) * 1978-02-17 1979-08-30 Lichtblau G J Antenna system for electronic security installation

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU113079B2 (en) * 1940-05-10 1941-05-22 Standa bd Telephones and Cables Pty. Limited Improvements in aerial systems for wireless communication
AU144473B2 (en) * 1948-01-22 1951-12-14 N. Y. Philips' Gloeilampenfabrieken Improvements in or relating to receiving or transmitting antennae
CA851281A (en) * 1967-10-24 1970-09-08 D. Boyd William Inductive loop signal system
JPS5226879B2 (en) * 1972-09-19 1977-07-16
US4331285A (en) * 1980-03-24 1982-05-25 Hewlett-Packard Company Method for fabricating a magnetic shielding enclosure
US4353064A (en) * 1981-01-14 1982-10-05 Honeywell Inc. Battery operated access control card
JPS5843604A (en) * 1981-09-09 1983-03-14 Japan Radio Co Ltd Antenna element
US4549186A (en) * 1982-04-14 1985-10-22 Sensormatic Electronics Corporation Coil assembly for substantially isotropic flux linkage in a given plane
US4486731A (en) * 1982-06-10 1984-12-04 Sensormatic Electronics Corporation Coil assembly with flux directing means
US4549794A (en) 1983-05-05 1985-10-29 Schering Corporation Hydrophilic bifocal contact lens
EP0225954A1 (en) * 1985-12-18 1987-06-24 Alcan International Limited Protection for control equipment
EP0242484A3 (en) * 1986-04-23 1988-05-25 Tektronix, Inc. Electrical assembly having shielded structural sub-parts
FR2602906B1 (en) * 1986-07-29 1991-10-31 Lesage Christian Material for producing protective devices against the magnetic environment of objects of medium magnetic inscriptions, and protective devices realized with such a material

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2014796A (en) * 1978-02-17 1979-08-30 Lichtblau G J Antenna system for electronic security installation

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION vol. 34, no. 1, January 1985, NEW YORK US pages 111 - 114; DONALD E. BARRICK: 'Miniloop Antenna Operation and Equivalent Circuit' *
See also references of WO8907347A1 *

Also Published As

Publication number Publication date
CA1334215C (en) 1995-01-31
EP0397755A1 (en) 1990-11-22
JPH03503467A (en) 1991-08-01
WO1989007347A1 (en) 1989-08-10
ZA8900872B (en) 1990-10-31

Similar Documents

Publication Publication Date Title
US6509879B2 (en) Antenna for a radio communications apparatus
JP4930658B2 (en) Antenna device and mobile communication terminal
EP1652270B1 (en) Slotted cylinder antenna
CN1098542C (en) Transmit and receive loop antenna
JP4013987B1 (en) Antenna device
CN102405557B (en) The antenna device
US7161542B2 (en) Antenna for RFID
EP1398847A1 (en) Antenna apparatus, printed wiring board, printed circuit board, communication adapter and portable electronic equipment
US4491843A (en) Portable receiver with housing serving as a dipole antenna
US5485166A (en) Efficient electrically small loop antenna with a planar base element
US5834992A (en) LC resonant part with a via hole inductor directly connected to the ground electrode
US6538607B2 (en) Adapter antenna
CN202839961U (en) Antenna apparatus and communication terminal
US5083134A (en) Antenna device for an automobile
US6861992B2 (en) Antenna
US4506267A (en) Frequency independent shielded loop antenna
US5097270A (en) Pane antenna having at least one wire-like antenna conductor combined with a set of heating wires
US4251808A (en) Shielded balanced loop antennas for electronic security systems
EP2515377A1 (en) Antenna device and communication terminal device
KR910006116B1 (en) Card-type radio receiver having slot antenna integrated with housing thereof
US9219310B2 (en) Communication terminal apparatus and antenna device
US3721989A (en) Cross loop antenna
US5406295A (en) Window antenna for a motor vehicle body
US6853338B2 (en) Wireless GPS apparatus with integral antenna device
EP0645840A1 (en) Antenna configuration of an electromagnetic detection system and an electromagnetic detection system comprising such antenna configuration

Legal Events

Date Code Title Description
17P Request for examination filed

Effective date: 19900726

AK Designated contracting states:

Kind code of ref document: A1

Designated state(s): AT BE CH DE FR GB IT LI LU NL SE

A4 Despatch of supplementary search report

Effective date: 19920911

AK Designated contracting states:

Kind code of ref document: A4

Designated state(s): AT BE CH DE FR GB IT LI LU NL SE

17Q First examination report

Effective date: 19940207

RAP1 Transfer of rights of an ep published application

Owner name: MAGELLAN TECHNOLOGY PTY. LIMITED

Owner name: THE UNIVERSITY OF WESTERN AUSTRALIA

18D Deemed to be withdrawn

Effective date: 19951109