JP4952439B2 - ANTENNA DEVICE AND WIRELESS COMMUNICATION SYSTEM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna apparatus and radio communication system capable of improving transmission power utilization efficiency by making uniform the distribution of magnetic field (Hx) in the lengthwise direction of an antenna coil and preventing a tag dead zone from being caused near the winding start and winding end of the coil. <P>SOLUTION: An antenna apparatus includes a magnetic plate member 9 including a magnetic substance in a shape having a plurality of side parts and a plurality of corner parts, and leading wires wound predetermined times to pass on neighboring two side parts forming one corner part of the relevant magnetic plate member 9. The leading wires are provided so as to be orthogonal to diagonal lines passing through the plurality of opposite corner parts, respectively, and cross each other on the magnetic plate member 9 to generate a magnetic field approximately uniformly almost over one surface of the magnetic plate member 9. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an antenna device for an RF-ID reader / writer device that communicates with a plurality of RF-ID tags using a frequency in the HF band (13.56 MHz band) and a wireless communication system using the antenna device.

  Conventionally, as an RF-ID antenna using a frequency in the HF band (13.56 MHz band), a single-turn or multiple-turn circular or rectangular loop antenna generally configured on the same plane has been practically used. ing.

  The loop antenna for the RF-ID reader / writer device has the highest magnetic field strength in the direction perpendicular to the opening surface S (the direction of the central axis). Therefore, the positional relationship between the loop antenna on the RF-ID tag side and the loop antenna for the RF-ID reader / writer device is generally arranged so that the opening surfaces S are parallel to each other.

  Further, even when communication with a plurality of RF-ID tags is performed, a plurality of RF-ID tags are arranged on the same plane so that the opening surfaces S do not overlap with each other, and the loop antenna for the RF-ID reader / writer device is arranged. The opening surfaces S are arranged in parallel.

  However, when the product is used for managing an extremely thin article such as a book management application or a CD / DVD management application, the book or CD / DVD case depends on the physical relationship between the size of the RF-ID tag and the thickness of the article. There has been a problem that the RF-ID tag cannot be pasted on the back cover of this. As a solution, a plurality of RF-ID tags are attached to the front cover surface or back cover surface of the managed article so that the center axes of the tag antennas coincide with each other at narrow intervals (article thickness + α). I had to.

  In the case of performing communication with a plurality of RF-ID tags arranged so as to overlap using a conventional one-turn or multiple-turn circular or rectangular loop antenna configured on the same common plane. If the number of read tags is extremely small due to interference between tags, deviation of the antenna resonance frequency due to interference between the tag and the antenna for the reader / writer device, or distance attenuation of the basic magnetic field strength, communication with all tags is impossible. There was a drawback to say.

  As a solution to this problem, there is a grounded multi-turn loop antenna described in (Patent Document 1). The grounded multi-turn loop antenna includes at least one RF-ID tag that does not coincide with the central axis of the opening surface of the multi-turn loop antenna and that is substantially parallel to the central axis that does not pass through the opening surface of the multi-turn loop antenna. The antenna apparatus is characterized in that a plurality of RF-ID tags are arranged close to each other on the outer peripheral top surface of the multi-loop antenna so that the central axis of the opening surface of the antenna is substantially coincident with the central axis of the antenna. .

  In addition, as a conventional technique of an antenna for an RF-ID tag in which a coil is wound around a plate-like or sheet-like magnetic material, it is described in (Patent Literature 2), (Patent Literature 3), and (Patent Literature 4). There is an antenna coil. These three conventional technologies relate to antennas for tags, but there are roughly two issues as electrical issues as antenna coils common to these three conventional technologies.

  The first problem is that, as shown in FIG. 13, the magnetic field distribution in the length direction of the coil (Hx in the figure) has a high magnetic field strength near the center with respect to the length direction of the coil. As it becomes, the magnetic field strength becomes weaker.

As a second problem, as shown in FIG. 13, the distribution of the magnetic field in the length direction of the coil (Hx in the figure) is around the start and end of winding of the coil (C, C1 and D, D1 in the figure). A null point (a portion where the Hx component is extremely weak) occurs.
JP 2007-164479 A JP 2002-252518 A JP 2007-041666 A Japanese Patent No. 3293554

  The prior art is shown in FIGS. 13A and 13B are diagrams showing a general antenna coil. FIG. 13A is a side view of the coil, FIG. 13B is a side view of the magnetic field strength distribution of the magnetic field Hx in the length direction, and FIG. FIG. 4 is a plan view of a magnetic field strength distribution of a magnetic field Hx in the length direction.

  FIG. 14 shows conventional techniques described in Patent Document 2, Patent Document 3, and Patent Document 4 in (a), (b), and (c), respectively. All of these three conventional techniques are proposals for an antenna coil for a tag. In any conventional technique, the antenna coil is wound around the magnetic plate at a uniform interval L multiple times. FIG. 12 shows the details. 12A shows the magnetic field strength distribution of the magnetic field Hx, and FIG. 12B shows a plan view. In FIG. 12B, the antenna coil is wound a plurality of times at a uniform interval L. The following problems are common in the case of such a structure.

  As shown in FIGS. 12 and 13, in the prior art, the magnetic field distribution in the length direction of the coil (Hx in FIGS. 12 and 13) shows that the magnetic field strength in the vicinity of the center is in the length direction of the coil. It can be seen that the magnetic field intensity gradually decreases as it approaches the ends of the coil, and there are null points (tag insensitive range) near the beginning and end of winding of the coil.

  Therefore, in the vicinity of the central portion of the antenna coil in the length direction, a sufficient transmission power is supplied to the RF-ID tag. On the contrary, the RF-ID tag operates near the both ends of the length of the antenna coil. There was a case where necessary transmission power was insufficient. In FIG. 12, the operating magnetic field strength of the tag is indicated by a broken line. When the magnetic field strength is higher than this value, the RF-ID tag can communicate with the reading / writing device. When the magnetic field strength is lower than this value, the RF-ID tag is connected to the reading / writing device with the RF-ID tag. Indicates that communication is not possible.

  Furthermore, in the vicinity of the null point (tag insensitive range) near the beginning and end of winding of the coil, there is a problem that there is a tag insensitive range where the RF-ID tag does not operate at all because the magnetic field strength is almost zero.

  Therefore, the present invention provides an RF that can improve the transmission power utilization efficiency by uniforming the magnetic field (Hx) distribution in the length direction of the antenna coil and preventing the occurrence of a tag insensitive range near the start and end of winding of the coil. An object of the present invention is to provide an antenna for an ID reader / writer device, an RF-ID reader / writer device using the antenna, and a wireless communication system.

  The antenna device according to the present invention passes through a magnetic plate member including a magnetic body having a shape having a plurality of sides and a plurality of corners, and two adjacent sides forming one corner of the magnetic plate member. A conductive wire wound a predetermined number of times, wherein the conductive wires are provided so as to be orthogonal to diagonal lines passing through the plurality of opposing corners, and on the magnetic plate member The magnetic plate members are configured to intersect with each other so as to generate a magnetic field substantially uniformly on one surface.

The spacing between conductors on the magnetic plate-unit was configured as gradually spread as away from the corner.

Furthermore, the angle of the two conductors intersecting at the magnetic plate-member on is configured to be substantially 90 degrees. Furthermore, the current flowing through the two conductors intersecting at the magnetic plate-member on is configured such that phase. Furthermore, the current flowing through the two conductors intersecting at the magnetic plate-member on is configured to be orthogonal phases.

  According to the present invention, in a multi-turn loop antenna, an axis that does not match the central axis of the opening surface of the antenna coil and that is substantially parallel to the central axis that does not pass through the opening surface of the antenna coil of the multi-turn loop antenna, and the antenna of the RF-ID tag In the antenna device in which a plurality of RF-ID tags are arranged close to each other on the outer peripheral top surface of the multi-loop antenna so that the central axis of the aperture surface of the multi-loop loop antenna substantially coincides, RF-, which has a uniform magnetic field (Hx) distribution and prevents the generation of a tag insensitive range near the beginning and end of winding of the coil, thereby improving the communication performance with the RF-ID tag and improving the transmission power utilization efficiency. An antenna for an ID reader / writer device, an RF-ID reader / writer device using the antenna, and a wireless communication system can be provided.

  An antenna device for an RF-ID reader / writer device according to the present invention includes a magnetic plate member including a magnetic body having a shape having a plurality of side portions and a plurality of corner portions, and an adjacent portion forming one corner portion of the magnetic plate member. A conductive wire wound a predetermined number of times so as to pass over the two side portions, wherein the conductive wires are provided so as to be orthogonal to diagonal lines passing through the plurality of opposing corner portions, respectively. In addition, the magnetic plate members are configured to intersect with each other so as to generate a magnetic field substantially uniformly on substantially one surface of the magnetic plate member. With this configuration, it is possible to improve the transmission power utilization efficiency by making the magnetic field distribution uniform.

  Embodiment 1 of the antenna device of the present invention will be described in detail below.

(Embodiment 1)
FIG. 1 is a perspective view showing a radio communication system according to Embodiment 1 of the present invention. In FIG. 1, 1 is the antenna device, 2 is an article, 3 is an RF-ID tag, and 4 is a coaxial cable. Further, 5 is a reading / writing device, 6 is a communication cable, and 7 is an input setting device (PC).

  FIG. 2A is a perspective view of the antenna element portion in a state where the housing lid 23 of the antenna device 1 of the present embodiment is removed. FIG. 2B is a cross-sectional perspective view including a housing. As shown in FIG. 2, the antenna element portion 1a of the antenna loop is an antenna for an RF-ID reader / writer device according to the present invention, and is housed in a resin casing 23. The antenna element unit 1 a is connected to the reader / writer device 5 through a resonance / matching / distribution / combination circuit board 25 on which a resonance / matching / distribution / combination circuit component 24 is arranged and the coaxial cable 4. The ground portion of the resonance / matching / distribution / combination circuit board 25 in which the antenna element portion 1 a and the resonance / matching / distribution / synthesis circuit component 24 are arranged is grounded to the ground conductor plate 8.

  The antenna device 1 connected to the reader / writer device (wireless communication device) 5 supplies power and transmission data to a plurality of RF-ID tags 3 having tag-side antennas (not shown) by electromagnetic induction. -Received data is acquired from the ID tag (wireless tag) 3 by load fluctuation.

  Further, as shown in FIG. 1, a plurality of RF-ID tags 3 are arranged in a plurality of rows at narrow intervals on a substantially vertical line on the outer peripheral top surface of the antenna device 1.

  With such an arrangement, communication with all the RF-ID tags 3 on the outer peripheral top surface of the antenna device 1 can be realized.

  And this invention can perform communication with several RF-ID tag 3 arrange | positioned at a narrow space | interval so that it may overlap by using this antenna device 1 for the antenna for RF-ID reader-writer apparatuses. .

  The embodiment of the antenna device of the present invention will be described in more detail.

  FIG. 3 is a detailed perspective view of the antenna element portion of the antenna device for the RF-ID reader / writer device according to Embodiment 1 of the present invention, FIG. 4 is a plan view thereof, and FIG. 5 is a detailed view of the winding method.

  3, 4, and 5, 1 a indicates an antenna element portion, and 9 indicates a magnetic plate member including a magnetic body having a plurality of side portions and a plurality of corner portions. Reference numerals 10 and 101 denote first antenna coils (1) and (11) made of a conductive wire made of a covered wire material such as UEW (polyurethane copper wire) or PEW (polyester copper wire), which constitutes the antenna coil. Yes. The first antenna coils 10 and 101 have a configuration in which the magnetic plate member 9 is wound a plurality of times from the winding start portion A to the winding end portion A1 perpendicular to the diagonal line.

  The second antenna coils 11 and 111 have the same configuration, but are magnetized a plurality of times from the winding start part B to the winding end part B1 perpendicular to the diagonal line (Hani) orthogonal to the diagonal line (Halo). It is the structure wound around the plate member 9.

  In this case, the first antenna coils 10 and 101 pass on two adjacent sides (In) and (I) forming one corner (A) of the magnetic plate member 9. Two adjacent antennas (Ro) that form one corner (Ro) of the multi-turn antenna coil (1) and the magnetic plate member 9 made of a conductive wire wound a predetermined number of times (Roney) It is composed of a multi-turn antenna coil (11) made of a conductive wire wound a predetermined number of times so as to pass above, and is wound in a direction substantially perpendicular to a diagonal line (iro).

  Further, the second antenna coils 11 and 111 pass on two adjacent side portions (high) and (halo) that form one corner (c) of the magnetic plate member 9. On the adjacent two sides (Nee) and (Nero) forming one corner (d) of the multi-turn antenna coil (2) and the magnetic plate member 9 made of a conductive wire wound a predetermined number of times And a multi-turn antenna coil (21) made of a conductive wire wound a predetermined number of times so as to pass through the wire and wound in a direction substantially perpendicular to the diagonal line (Hani).

  FIG. 5 shows details of how to wind the antenna coil. In the figure, L1, L2,... Ln indicate antenna coil pitches. Now, the pitch interval is gradually increased from the beginning of winding A toward L1 <L2 <L3... <Ln and the center point O, and the first antenna coil 10 has a relationship of Ln << Lo. Is configured. The first antenna coil 101 is wound symmetrically with respect to the point O and wound to the winding end A1. The intermediate points C and C1 are connected by Lc and Lc1 along the side.

  The second antenna coils 11 and 111 have the same configuration, but the magnetic plate is turned a plurality of times from the winding start part B to the winding end part B1 perpendicular to the diagonal line (Hani) orthogonal to the diagonal line (Halo). The structure is wound around the member 9. With this configuration, as shown in FIG. 11, the distribution of the magnetic field Hx in the horizontal direction can be made uniform, and null points (tag insensitive range) that have occurred near both ends of the antenna coil in the prior art are squared. By generating it only in a very narrow range only in the vicinity of the winding start portion A, it is possible to prevent the occurrence of a tag insensitive range that has occurred in the vicinity of both ends of the antenna coil in the prior art.

  FIG. 6 shows another embodiment. In this case, the magnetic plate member 9 has a rectangular shape, but the antenna coil is wound in the same manner as described above. It goes without saying that the communication range of the horizontal magnetic field Hx can be expanded horizontally by configuring in this way.

  FIG. 7 is a connection diagram inside and outside the antenna device according to the first embodiment. Reference numeral 1 denotes the antenna device, and reference numeral 1a denotes an antenna element portion. Now, the two winding start parts A and B of the antenna element part 1 a are connected to the resonance / matching circuit part 18 via the first signal line (1) 19.

In this case, the line segment AS = BS with respect to the connection point S, and a high-frequency signal having the same phase is supplied from the reading / writing device 5 to the terminal via the coaxial cable 4 and the resonance / matching circuit unit 18. The reading / writing device 5 is provided with a power supply unit 5a, which is connected to a commercial power supply (not shown), and receives power supply for driving the wireless communication system from the commercial power supply. ing. The two winding end portions A1 and B1 of the antenna element portion 1a are connected to the resonance / matching circuit portion 18 via the second signal line (2) 20. By adopting such a configuration, as shown in FIG. 8, _HA is generated in a direction perpendicular to the antenna loop by the current flowing from A to A1. Further, H _B is generated in a direction perpendicular to the antenna loop by the current flowing from B to B1. Since phase of the high-frequency current is supplied in this case A and B, these two magnetic fields H _A and H _B is synthesized as a horizontal magnetic field Hx of the vector-synthesized diagram 8 in space. With this magnetic field Hx, communication with the RF-ID tag 3 attached to the article 2 shown in FIG. 1 is possible over the entire antenna top surface.

(Embodiment 2)
Next, a second embodiment of the antenna device of the present invention will be described in detail.

  The antenna device of the second embodiment is connected to the reading / writing device 5 of the first embodiment, and the drawings are shared.

  FIG. 9 shows an antenna device for an RF-ID reader / writer device according to Embodiment 2 of the present invention. In FIG. 9, a connection diagram inside and outside the antenna device is shown. 1 denotes the antenna device, and 1a denotes an antenna element portion. Now, the winding start part A of the antenna element part 1a is connected to the resonance / matching circuit part 18 via the first signal line (1) 19, and further connected to the power distributor / combiner 22 via the phase shifter 21. And is further connected to the reading / writing device 5 via the coaxial cable 4. The reading / writing device 5 is provided with a power supply unit 5a, which is connected to a commercial power supply (not shown), and receives power supply for driving the wireless communication system from the commercial power supply. ing.

  The winding start part B of the antenna element part 1a is connected to the resonance / matching circuit part 18 via the third signal line (3) 191 and read via the power distributor / combiner 22 and the coaxial cable 4. / Connected to the writing device 5.

  The two winding end portions A1 and B1 of the antenna element portion 1a are connected to the resonance / matching circuit portion 18 via the second signal line (2) 20 and the fourth signal line (4) 201, respectively. .

  In this case, the high frequency signal emitted from the reading / writing device 5 is supplied to the power distributor / combiner 22 via the coaxial cable 4, and the power distributor / combiner 22 uses the two high frequency signals of equal amplitude / equal phase. It is divided into. One of the two high-frequency signals of equal amplitude / equal phase is connected to the resonance / matching circuit unit 18 via the 90 ° phase shifter 21 and starts winding the antenna coil via the first signal line (1) 19. Supplied to part A.

  The high-frequency signal emitted from the reading / writing device 5 is supplied to the power distributor / combiner 22 via the coaxial cable 4 and is converted into two high-frequency signals of equal amplitude / equal phase by the power distributor / synthesizer 22. Divided. The other one of the two high-frequency signals of equal amplitude / equal phase is directly connected to the resonance / matching circuit unit 18 without passing through the 90 ° phase shifter 21 and is connected to the antenna via the third signal line (3) 191. It is supplied to the winding start part B of the coil. By adopting this configuration, the phase of the high-frequency signal supplied to A and B at the start of winding of two orthogonally arranged antenna loops is a phase in which the phase of B is advanced by + 90 ° when the phase of A is 0 °. become.

With such a configuration, as shown in FIG. 10, _HA is generated in a direction perpendicular to the antenna loop by the current flowing from A to A1. Further, H _B is generated in a direction perpendicular to the antenna loop by the current flowing from B to B1. In this case, since a high-frequency current having an equal amplitude having a phase difference of 90 ° is supplied to _A and _B , these two magnetic fields H _A and H _B are combined in a vector in space and temporally and as shown in the figure. It is synthesized as a magnetic field H that spatially draws a circle. Communication with the RF-ID tag 3 affixed to the article 2 shown in FIG. 1 by the magnetic field H is possible over the entire antenna top surface, and the orientation of the RF-ID tag 3 is perpendicular to the antenna top surface. The RF-ID tag 3 and the reading / writing device 5 can communicate with each other over the entire top surface of the antenna.

  As described above, it is possible to control the current distribution of the high-frequency current flowing through each antenna loop by optimally selecting the separation distance (pitch) between the elements of each antenna loop, as shown in FIG. Thus, the magnetic field distribution of the magnetic field Hx in the length direction (X-axis direction) of the antenna can be made uniform. In addition, by winding the two antenna loops so as to be orthogonal to the diagonal line and rotated by 90 ° with respect to the center point, null points (tag insensitive range) that occurred near both ends of the antenna coil in the prior art ) Is generated only in a very narrow range only in the vicinity of the winding start portion A of each corner, thereby making it possible to remove the tag insensitive range. Therefore, communication between the RF-ID tag 3 affixed to the article 2 shown in FIG. 1 and the RF-ID reader / writer device is possible over the entire top surface of the antenna, further increasing the transmission power utilization efficiency supplied from the reader / writer device. Can be improved.

  The antenna device and the wireless communication system of the present invention are capable of reading a wide range of tags even for stacked tags that have been put into practical use in recent years and can be overlapped at an extremely narrow interval, and in the HF band (13.56 MHz band). The present invention can also be applied to an RF-ID reader / writer antenna that performs communication with a plurality of RF-ID tags using a frequency, an RF-ID reader / writer apparatus using the antenna, and an RF-ID system.

1 is a perspective view showing a wireless communication system according to Embodiment 1 of the present invention. The perspective view which shows the antenna element part in Embodiment 1 and 2 of this invention, and a cross-sectional perspective view which shows the antenna apparatus for RF-ID reader-writer apparatuses The detailed perspective view of the antenna element part of the antenna apparatus for RF-ID reader-writer apparatuses in Embodiment 1 and 2 of this invention Plan view of antenna element Detailed view of antenna coil winding method Other examples Connection diagram inside and outside the antenna device in the first embodiment Explanation of synthetic magnetic field in the first embodiment Connection diagram inside and outside the antenna device in the second embodiment Synthetic magnetic field explanatory drawing in Embodiment 2 Magnetic field distribution diagram and plan view of antenna element section of the present invention Conventional magnetic field distribution diagram and antenna element plan view Conventional magnetic field distribution diagram and antenna element side view Conventional technology diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 This antenna apparatus 1a Antenna element part 2 Goods 3 RF-ID tag 4 Coaxial cable 5 Reading / writing apparatus (reader-writer apparatus)
6 Communication cable 7 Input setting device (PC)
8 Conductor plate for grounding (ground conductor plate)
9 Magnetic plate member 10, 101 First antenna coil 11, 111 Second antenna coil 12 Diagonal wire (1)
13 Diagonal line (2)
14 Corner (I)
15 Corner (d)
16 corner (b)
17 Corner (C)
18 Resonance / matching circuit section 19 First signal line (1)
20 Second signal line (2)
DESCRIPTION OF SYMBOLS 21 Phaser 22 Power distribution / combining device 23 Case 24 Resonance / matching / distribution / combination circuit component 25 Resonance / matching / distribution / combination circuit board 191 Third signal line (3)
201 Fourth signal line (4)
A Winding start part A1 Winding end part B Winding start part B1 Winding end part L1-Ln, Lo Separation distance between antenna coils

Claims (12)

A magnetic plate member including a magnetic body having a shape having a plurality of side portions and a plurality of corner portions, and a predetermined number of turns so as to pass over two adjacent side portions forming one corner portion of the magnetic plate member. An antenna device comprising:
At least two of the conductive wires are provided so as to be orthogonal to diagonal lines passing through the plurality of opposing corner portions, respectively, and the magnetic plate is configured to generate a magnetic field substantially uniformly on substantially one surface on the magnetic plate member. An antenna device characterized by intersecting on a member. The magnetic properties plate member antenna device according to claim 1, characterized in that it comprises a plurality of sides having almost the same length. Spacing of the conductor on the magnetic plate-member is an antenna device according to claim 1, characterized in that gradually spread as away from the corner. The antenna device according to claim 1, wherein the angle of the two conductors intersecting at the magnetic plate-member on is approximately 90 degrees. An antenna unit that receives an electromagnetic field variation, a resonance matching circuit unit that converts the variation received from the antenna unit into a signal, and a reading / writing device that reads a signal converted by the resonance matching circuit unit. In a wireless communication system,
The antenna portion passes through a magnetic plate member including a magnetic body having a shape having a plurality of sides and a plurality of corners, and two adjacent sides forming one corner of the magnetic plate member. A conductive wire wound a predetermined number of times, and at least two of the conductive wires are provided so as to be orthogonal to diagonal lines passing through the plurality of opposing corners, respectively, and substantially one surface on the magnetic plate member Crossing on the magnetic plate member so as to generate a magnetic field almost uniformly,
Wireless communication system, wherein the current flowing through the two conductors intersecting at the magnetic plate-member is substantially in phase. Wireless communication system according to claim 5, characterized in that it comprises a plurality of sides having the magnetic properties plate member are approximately the same length. Wireless communication system according to claim 5, characterized in that gradually widened as spacing of the conductors on the magnetic plate-member is spaced apart from the corner portion. Wireless communication system according to claim 5, wherein the angle of the two conductors intersecting at the magnetic plate-member on is approximately 90 degrees. An antenna unit that receives electromagnetic field variation, a resonance matching circuit unit that converts the variation received from the antenna unit into a signal, a read / write device that reads a signal converted by the resonance matching circuit unit, and the antenna In a wireless communication system comprising: a phase shifter that changes a phase of electric power supplied to a lead wire
The antenna portion passes through a magnetic plate member including a magnetic body having a shape having a plurality of sides and a plurality of corners, and two adjacent sides forming one corner of the magnetic plate member. A conductive wire wound a predetermined number of times, and at least two of the conductive wires are provided so as to be orthogonal to diagonal lines passing through the plurality of opposing corners, respectively, and substantially one surface on the magnetic plate member Crossing on the magnetic plate member so as to generate a magnetic field almost uniformly,
The said phase shifter supplies the electric power of the phase different from the other to one of the said 2 conducting wire, The radio | wireless communications system characterized by the above-mentioned. Wireless communication system according to claim 9, wherein further comprising a plurality of sides having the magnetic properties plate member are approximately the same length. Wireless communication system according to claim 9, wherein that gradually widened as spacing of the conductors on the magnetic plate-member is spaced apart from the corner portion. Wireless communication system according to claim 9, wherein the angle of the two conductors intersecting at the magnetic plate-member on is approximately 90 degrees.

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