199results about "Screened loop antennas" patented technology

An apparatus and method is provided to shield contactless portable electronic consumer devices such as radio frequency identification devices (RFID), tokens, mini-cards, key fobs, cellular phones, smartcards, etc. from wireless interrogation. In one embodiment, a contactless portable consumer device which includes a first antenna is shielded from unauthorized wireless interrogation with a radio frequency (RF) shield. The RF shield includes electrically conductive, non-ferromagnetic material and is configured to prevent unauthorized data transfer between a second antenna external to the portable consumer device and the first antenna.

An artificial magnetic conductor is resonant at multiple resonance frequencies. The artificial magnetic conductor is characterized by an effective media model which includes a first layer and a second layer. Each layer has a layer tensor permittivity and a layer tensor permeability having non-zero elements on the main tensor diagonal only.

A RFID tag having a loop antenna comprises: a flat plate shaped dielectric member 51; first and second loop antenna patterns 52, 53 that are formed on a first and second surface of the dielectric member 51 so that they are separated from each other by a specified space, and so that each is continuous from the first surface to the second surface of the dielectric member 51; and an IC chip 54 that electrically connects the first and second loop antenna patterns 52, 53 on one of the surfaces.

An antenna apparatus (60) is provided which is used in a recorder and / or player to write and read data to and from a contactless IC card (1). The antenna apparatus (60) includes a loop coil (61) to radiate an electromagnetic field for magnetic coupling with a loop coil (4) at the IC card (1) to send and receive data to and from the IC card (1), and a magnetic sheet (62) disposed to face the main side of the loop coil (61), opposite to the main side facing the IC card (1). The magnetic sheet (62) has the specific permeability μ′ and product Ms.t of saturation magnetization Ms and thickness t thereof set in accordance with a necessary range of communications with the contactless IC card (1).

In an electronic article surveillance system, quadrature transmitting and receiving antennas are used to improve field distribution. A transmitting antenna arrangement includes first and second adjacent co-planar antenna loops and excitation circuitry for generating respective alternating currents in the first and second loops such that the respective alternating currents are 90 DEG out of phase. In a receiving arrangement, respective signals received from two adjacent co-planar antenna loops are respectively phase-shifted by +45 DEG and -45 DEG , and the resulting phase-shifted signals are summed. A far-field cancelling transmitting antenna arrangement includes four loops operated at phases of 0 DEG , 90 DEG , 180 DEG and 270 DEG respectively. All four loops may be co-planar, with any bucking vertical segments being horizontally displaced from each other. Alternatively, the 0 DEG and 180 DEG loops may also be arranged in a common plane that is close to and parallel with another plane in which the 90 DEG and 270 DEG loops are arranged.

An arrangement for providing protection to wireless portable transponders (including resonant tags such as RFID tags) from unauthorized interrogation by employing a mechanical means for disabling reception by or from the antenna of the transponder. The tags can be protected from receiving or providing unauthorized or unwanted information. Contemplated are mechanical means that permit the owner to decide when reception / interrogation of personal or other information is not desired by employing the provided mechanical disable control means. Also broadly contemplated herein is the altering interrogation characteristics of RFID tags to such an extent that they may still be read at a close range instead of the original range, and this result of this altering is visible to the user.

An EAS or RFID system including first and second core antenna systems. The first and second antenna systems establish magnetic fields having opposite directions and are positioned so that the fields at least partially cancel outside of an interrogation zone for detecting an EAS or RFID tag. There is also provided an EAS or RFID wherein the magnetic field direction established by a core antenna is varied at certain time intervals to minimize the effects of null zones in the interrogation zone.

In an electronic article surveillance system, quadrature transmitting and receiving antennas are used to improve field distribution. A transmitting antenna arrangement includes first and second adjacent co-planar antenna loops and excitation circuitry for generating respective alternating currents in the first and second loops such that the respective alternating currents are 90 DEG out of phase. In a receiving arrangement, respective signals received from two adjacent co-planar antenna loops are respectively phase-shifted by +45 DEG and -45 DEG , and the resulting phase-shifted signals are summed. A far-field cancelling transmitting antenna arrangement includes four loops operated at phases of 0 DEG , 90 DEG , 180 DEG and 270 DEG respectively. All four loops may be co-planar, with any bucking vertical segments being horizontally displaced from each other. Alternatively, the 0 DEG and 180 DEG loops may also be arranged in a common plane that is close to and parallel with another plane in which the 90 DEG and 270 DEG loops are arranged.

An antenna (100), which is designed for exciting and / or detecting a magnetic resonance in an object (1) under investigation, comprises a conductor loop (10) with an inner conductor (11) and a primary shield conductor (12), which form at least one waveguide, wherein the primary shield conductor (12) is interrupted by a gap (13), and wherein a secondary shield conductor (14) is provided which surrounds the primary shield conductor (12), wherein a dielectric (15) is arranged between the primary shield conductor (12) and the secondary shield conductor (14) and at least the gap is covered by the secondary shield conductor (14). An antenna arrangement which comprises a plurality of such antennas, a magnetic resonance device, and a method for magnetic resonance imaging or magnetic resonance spectroscopy are also described.

The antenna includes a Litz wire loop having a plurality of individually insulated wires braided together and a plurality of splices therein to define distributed capacitors. A magnetically coupled feed loop is provided within the electrically conductive loop, and a feed structure, such as a coaxial feed line, feeds the magnetically coupled feed loop.

The invention provides protection to wireless portable transponders from unauthorized interrogation by employing a mechanism for disabling reception by or from the antenna of the transponder. Transponders include RFID tags that are attached to items that a persons may purchase or carry. Such transponders generally have an ability for receiving and storing electronic and other information, commonly in binary form using memories as in electronic circuits, etc. The invention is designed to provide privacy of electronic information. The tags can be protected from receiving or providing unauthorized or unwanted information. The invention provides the mechanism that permit the owner to decide when reception / interrogation of personal or other information is not desired by employing the provided mechanical disable control.

In antenna device, a coil conductor of an antenna coil module and a conductor layer at least partially overlap. A current flows in the conductor layer and blocks a magnetic field generated by a current flowing in the coil conductor. A current, which flows around the periphery of an opening of the conductor layer, flows along the periphery of a slit and around the periphery of the conductor layer due to a cut-edge effect. Since magnetic flux does not pass through the conductor layer, magnetic flux attempts to bypass the conductor layer along a path in which the conductor opening of the conductor layer is on the inside and the outer edge of the conductor layer is on the outside. Accordingly, the magnetic flux generates relatively large loops linking the inside and the outside of a coil conductor of an antenna on a reader / writer side.

A portable type information processing terminal device is provided which includes a substrate carrying a substantially annular antenna coil thereon, a signal processing integrated circuit element arranged inside the antenna coil, a magnetic plate arranged under the substrate and a metal plate arranged under the magnetic plate, which are integrally formed and arranged on one or more than one metal parts including a battery pack. The metal plate is used to substantially regulate the resonance frequency of the antenna coil so that it is allowed to be arranged in a cabinet of the portable device.

A communication-capable electronic device is provided which includes a metallic housing (122) to accommodate electronic parts of the device, and a communication terminal (90) that makes communications with a communication-cable IC card (110) incorporating an antenna (115). The communication antenna (90) is located such that when the IC card is placed near the housing (122), the antenna (115) built in the IC card (110) faces, at a part thereof, a part of the communication terminal (90) while the rest of the antenna (115) of the IC Card (110) does not face the housing (122). Thus, it is possible to prevent the inductance in the antenna (115) of the IC card (110) from being reduced.

An antenna includes: a case body having a bottom plate portion, side plate portions extending from the bottom plate portion, and an opening portion surrounded by the side plate portions; a magnetic resonance antenna portion placed in the case body; and a magnetic shield body disposed on a side closer to the opening portion than the magnetic resonance antenna portion.

Apparatus and methods for providing a substantially surface independent tagging system are disclosed. A resonant dielectric cavity is defined between upper and lower conducting layers, and closed at one end by a conducting base portion. Incident radiation couples into the cavity and is resonantly enhanced. An electronic device or tag paced at the edge of the cavity experiences a high electric field strength on account of this enhancement and is driven into operation.

To provide a cell phone equipped with a broadcast receiver that delivers a high receiving sensitivity and antenna performance in various usage states.A loop element 12 as an antenna for receiving television broadcast is arranged in a range (c) of an upper end portion of an upper housing 1. An end part of an upper circuit board is matched with a portion shown by (a) so that a conductor other than the antenna element does not exist in the range (c). A monopole element 19 for cell phone communication is arranged at a lower end portion of a lower housing 2.

In a communication device, electric circuits other than an antenna are enclosed in a shielding member made of a material that shuts off radio waves, and the antenna is enclosed by disposing in front thereof a radio wave absorbing member that attenuates radio waves in a predetermined frequency band. Thus, unnecessary electromagnetic emission is alleviated while satisfactory communication quality is secured.

A cover (100) for an electronic device may include a metal plate (101) having a first metal region (110) formed of a metal; a through-hole (150) formed in a portion of the first metal region (110) of the metal plate (101); and an electrical open path (180) extending from the through-hole (150) to an end portion on one side of the first metal region (110) through metal oxidation. The cover of the electronic device can be used as an antenna and the oxidation process electrically separates the metal plate such that eddy currents are reduced and the antenna recognition distance is increased.

Antennas with steerable antenna patterns and techniques for using such antennas are described. In accordance with the invention, antenna patterns with one or more NULLs are used. Through the use of digital control signals the antenna pattern is steered so that a source of signal interference, e.g., a multipath signal, will be located in a NULL. In this manner the received signal's S / N ratio can be maximized thereby facilitating demodulation. The techniques of the invention can be applied to television, computer devices, mobile devices and a wide range of other systems. Digital commands to control an antenna may include multiple information fields, e.g., a direction field, a channel field, a gain field and a polarity field. Antennas incapable of supporting the specified fields disregard information in fields which are not supported. Information in each supported field is decoded and used to adjust the corresponding antenna characteristic.

In an antenna apparatus, on an undersurface of a metal cover, a feeding coil module is disposed. In a casing, a printed circuit board is included. A ground conductor, a feeding pin, and a ground connection conductor are disposed on the printed circuit board. When the metal cover is mounted on the casing, the feeding pin is in contact with a connection portion of the feeding coil module and is electrically connected thereto. The ground connection conductor is in contact with the metal cover and connects the metal cover to the ground conductor. The ground connection conductor is disposed at either side of a slit outside an area in which the current density of an induced current flowing through the metal cover is in a range from a maximum value to approximately 80% of the maximum value or one side of the slit in the area.

Systems and methods for disabling transponders used in electronic toll collection or other RFID systems, wherein the transponders include an antenna and RFID circuitry. The transponders can be selectively disabled by releasably securing a disabling device having a metallic portion at an operative position over the antenna of the RFID system, whereupon the metallic portion is coupled to the antenna in such a manner as to disable the RFID circuitry so long as the disabling device is at the operative position. The RFID circuitry is arranged to be automatically enabled upon removal of the disabling device from the operative position.

A portable electronic device having an RFID function has an RFID antenna having a planar coil formed by winding a conductor. The RFID antenna is a loop antenna having a loop diameter corresponding to RFID with a strong electromagnetic field characteristic, and has an antenna pattern where a part of its coil turn which is other than an innermost coil turn is placed inward of the innermost coil turn. The antenna pattern can be provided by bending or branching a part of a coil turn of the conductor which is other than the innermost coil turn in such a way that the part of the coil turn is laced inward of the innermost coil turn, thereby ensuring compensation for the magnetic field strength at the center portion of the antenna and achieving excellent communications without a non-communicatable area even with the RFID having a slight electromagnetic field characteristic.

Methods, systems, and apparatuses for a radio frequency identification (RFID) tag tester / programmer and marker are described. A surface is in contact with a web of RFID tags. The surface has a first portion and a second portion. The first portion of the surface is grounded to ground tags of the web that are in contact with the first portion. A radio frequency (RF) source transmits a RF signal to interact with a tag adjacent to the second portion of the surface. The RF signal may be a signal for testing the tag and / or a signal for programming the tag.

A system is disclosed for minimizing coupling nulls between an electromagnetic field derived from one or more sources and a plurality of randomly oriented RFID tags, wherein the electromagnetic field is rotated relative to the tags such that no tag is persistently located in a coupling null relative to the field. The source of the electromagnetic field may include a passive antenna or loop that changes its orientation relative to a direction of movement of the tags. The source of the electromagnetic field may further include an active antenna or loop that is electromagnetically coupled to the passive antenna or loop. A method for minimizing coupling nulls between the electromagnetic field and the randomly oriented tags is also disclosed.

An arrangement for providing protection to wireless portable transponders (including resonant tags such as RFID tags) from unauthorized interrogation by employing a mechanical arrangement for disabling reception by or from the antenna of the transponder. The tags can be protected from receiving or providing unauthorized or unwanted information. Contemplated are mechanical arrangements that permit the owner to decide when reception / interrogation of personal or other information is not desired by employing the provided mechanical disable control arrangement. Also broadly contemplated herein is the altering interrogation characteristics of RFID tags to such an extent that they may still be read at a close range instead of the original range, and this result of this altering is visible to the user.