JP4822302B1 - Transmission / reception antenna and transmission / reception apparatus using the same - Google Patents

Abstract

An object of the present invention is to make it possible to widen the frequency characteristics without increasing the power consumption.
A magnetic body, an excitation loop antenna provided on the magnetic body, a transmission / reception loop antenna arranged close to the excitation loop antenna in a non-contact state, and the transmission / reception loop antenna. The magnetic body is composed of a pedestal portion 22 fixed to the substrate 21 and a columnar portion 23 protruding from the pedestal portion so that the central axis is substantially orthogonal to the substrate. The excitation loop antenna has a one-turn loop portion 12a, the transmission / reception loop antenna has a plurality of turns loop portion 13a, and the excitation loop antenna and the transmission / reception loop antenna are magnetic. It shall be provided in the aspect wound coaxially around the columnar part of the body.
[Selection] Figure 2

Description

  The present invention relates to a transmission / reception antenna that supplies power to a wireless communication medium such as an IC tag or a non-contact IC card and transmits / receives a signal to / from the wireless communication medium, and a transmission / reception apparatus using the transmission / reception antenna.

  In recent years, in logistics systems, transportation systems, merchandise management systems, book management systems, personal authentication systems, electronic money systems, etc., using wireless communication media such as IC tags and non-contact IC cards, etc., identification of articles and personal authentication Technology to do is widely spread. In such a system using a wireless communication medium, a transmission / reception device that supplies power to the wireless communication medium and transmits / receives a signal to / from the wireless communication medium is used. It is convenient that the communication with can be shared by a single transmission / reception device.

  However, if the type of system is different, the communication method of the wireless communication medium may be different. In this case, the bandwidth used for communication with the transmission / reception device may also be different. Broadband is desired. Therefore, in order to meet such a demand, a technique is known in which a plurality of resistors (resistance values) interposed in a transmission / reception path of a transmission / reception antenna are sequentially switched to widen a frequency characteristic (patent). Reference 1).

JP 2007-199871 A

  However, in the conventional technique, as a result of the resistor always being present in the transmission / reception path of the transmission / reception antenna, there is a problem that power loss is caused by the resistor and power consumption is increased.

  The present invention has been devised to solve such problems of the prior art, and the main purpose thereof is to increase the bandwidth of the frequency characteristics without increasing the power consumption. An object of the present invention is to provide a configured transmission / reception device.

  The transmission / reception antenna of the present invention includes a magnetic body, an excitation loop antenna provided on the magnetic body, a transmission / reception loop antenna disposed in close proximity to the excitation loop antenna, and the transmission / reception loop antenna. A resonance capacitor connected to both ends, and the magnetic body includes a pedestal portion fixed to the substrate, and a columnar portion protruding from the pedestal portion so that a central axis is substantially orthogonal to the substrate. The excitation loop antenna includes a one-turn loop portion, the transmission / reception loop antenna includes a plurality of turn loop portions, and the excitation loop antenna and the transmission / reception loop antenna include the magnetic body. It is set as the structure provided in the aspect wound around the columnar part of the same axis.

  Moreover, the transmission / reception apparatus of the present invention includes a transmission / reception antenna configured as described above, a transmission processing unit that outputs a transmission signal to the transmission / reception antenna, a reception processing unit that receives a reception signal from the transmission / reception antenna, A control unit that controls the transmission processing unit and the reception processing unit, the excitation loop antenna connected to the transmission processing unit, and the transmission / reception loop antenna connected to the reception processing unit; To do.

  According to the present invention, the frequency characteristics can be widened without increasing the power consumption, and communication with a wireless communication medium of another system having a different communication method can be handled by a single transmission / reception device. It becomes possible.

1 is an overall configuration diagram showing a transmission / reception system to which a transmission / reception apparatus according to an embodiment of the present invention is applied. The perspective view which shows the transmission / reception antenna 4 An exploded perspective view of the transmission / reception antenna 4 Perspective view of main part of substrate 21 The perspective view which shows the state of the electric current which arises in the loop antenna 12 for excitation and the loop antenna 13 for transmission / reception at the time of transmission The figure which shows the equivalent circuit which expressed the transmission / reception antenna 4 using the transformer circuit The figure which shows the equivalent circuit which expressed the transmission / reception antenna 4 using the coil The figure which shows the relationship between the coupling coefficient K between the loop antenna 12 for excitation, and the loop antenna 13 for transmission / reception, and the frequency characteristic of the primary side current I1 which flows into the loop antenna 12 for excitation. The figure which shows the relationship between the coupling coefficient K between the loop antenna 12 for excitation, and the loop antenna 13 for transmission / reception, and the frequency characteristic of the secondary side current I2 which flows into the loop antenna 13 for transmission / reception. The figure which shows the frequency characteristic of the transmission output and reception sensitivity according to the coupling coefficient K between the loop antenna 12 for excitation, and the loop antenna 13 for transmission / reception. The figure which shows the frequency characteristic in the case of the coupling coefficient K = 0.7, and the frequency characteristic by the prior art example which aimed at the broadband of the frequency characteristic using the resistance R The figure which shows the communication comprehensive evaluation regarding the coupling coefficient K between the loop antenna 12 for excitation, and the loop antenna 13 for transmission / reception. Schematic diagram of the main part of the transceiver 2 The perspective view which shows the example which applied the transmission / reception antenna 4 to the mobile telephone apparatus 51 Exploded perspective view of mobile phone device 51

  A first invention made to solve the above-described problems is a magnetic body, an excitation loop antenna provided on the magnetic body, and a transmission / reception loop antenna disposed in close proximity to the excitation loop antenna in a non-contact state. And a resonance capacitor connected to both ends of the transmission / reception loop antenna, and the magnetic body includes a pedestal portion fixed to the substrate, and a central axis extending substantially perpendicular to the substrate from the pedestal portion. And the excitation loop antenna has a one-turn loop portion, and the transmission / reception loop antenna has a plurality of turn loop portions. The loop antenna is provided in such a manner that it is coaxially wound around the columnar portion of the magnetic body.

  According to this, when a transmission signal is input to the excitation loop antenna, the transmission signal is transmitted from the excitation loop antenna to the transmission / reception loop antenna by magnetic induction. At this time, the transmission signal is amplified and transmitted from the transmission / reception loop antenna. Is output.

  By this configuration, the excitation loop antenna and the transmission / reception loop antenna are arranged close to each other, and the coupling coefficient between the excitation loop antenna and the transmission / reception loop antenna is set to be relatively large, thereby achieving a wider frequency characteristic. Can do. Further, since it is not necessary to interpose a resistor in the transmission / reception path of the transmission / reception antenna in order to widen the frequency characteristics, it is possible to avoid an increase in power consumption.

  In particular, since the currents flowing through the excitation loop antenna and the transmission / reception loop antenna are opposite to each other, the magnetic flux generated by the current flowing through the excitation loop antenna acts to weaken the magnetic flux generated by the current flowing through the transmission / reception loop antenna. However, the transmission / reception loop antenna is configured to have a plurality of loops, while the excitation loop antenna is configured to have a one-turn loop, thereby suppressing the flux of the transmission / reception loop antenna from being weakened. Thus, even if the transmission power of the excitation loop antenna is not increased, a sufficiently strong transmission signal is output from the transmission / reception loop antenna, so that power consumption can be kept low.

  In a second aspect based on the first aspect, the excitation loop antenna is disposed on the base side of the columnar portion adjacent to the pedestal portion, and the transmission / reception loop antenna is separated from the pedestal portion. It is set as the structure arrange | positioned at the front end side of the said columnar part.

  According to this, it is possible to efficiently transmit the signal by the transmission / reception loop antenna and receive the signal from the wireless communication medium.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the pedestal portion of the magnetic body is formed to have a larger diameter than the excitation loop antenna and the transmission / reception loop antenna.

  According to this, the magnetic influence by the components arranged on the substrate side, particularly on the side opposite to the transmitting / receiving antenna across the substrate can be suppressed.

According to a fourth invention, in the first to third inventions, a coupling coefficient K of electromagnetic coupling by mutual induction between the excitation loop antenna and the transmission / reception loop antenna is 0.5 to 0.7. The configuration is set so as to be within the range.

  According to this, it is possible to realize a high overall communication performance that balances transmission performance and reception performance.

A fifth invention is a transmission / reception antenna according to the first to fourth inventions, a transmission processing unit that outputs a transmission signal to the transmission / reception antenna, and a reception processing unit that receives a reception signal from the transmission / reception antenna. And a control unit that controls the transmission processing unit and the reception processing unit, wherein the excitation loop antenna is connected to the transmission processing unit, and the transmission / reception loop antenna is connected to the reception processing unit. The configuration.

  According to this, for the same reason as described above, the frequency characteristics can be widened without increasing the power consumption.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram showing a transmission / reception system to which a transmission / reception apparatus according to an embodiment of the present invention is applied. This transmission / reception system is utilized for a logistics system, a traffic system, a merchandise management system, a book management system, a personal authentication system, and the like, and supplies power to the wireless communication medium 1 and the wireless communication medium 1, It has a transmission / reception device 2 that transmits and receives signals to and from the wireless communication medium 1.

  The wireless communication medium 1 is a well-known one such as an IC tag affixed to a product or a book, a non-contact IC card used for personal authentication, and the like. It is comprised by the control IC (not shown) connected to it, For example, it communicates with the transmission / reception apparatus 2 using the frequency band of 13.56 MHz.

  The transmission / reception device 2 includes a transmission / reception antenna 4, a reader / writer device 5 connected to the transmission / reception antenna 4, and a control device 6 connected to the reader / writer device 5. The control device 6 is connected to a network line 7. Has been. The reader / writer device 5 controls the transmission processing unit 8 that outputs a transmission signal to the transmission / reception antenna 4, the reception processing unit 9 that receives the reception signal from the transmission / reception antenna 4, and the transmission processing unit 8 and the reception processing unit 9. The control unit 10 is connected to the control device 6.

  The transmission / reception antenna 4 includes a magnetic body 11, an excitation loop antenna 12 and a transmission / reception loop antenna 13 that are disposed in close proximity to the magnetic body 11 in a non-contact state, and a resonance connected to both ends of the transmission / reception loop antenna 13. For example, the capacitor 14 is provided.

  A transmission processing unit 8 of the reader / writer device 5 is connected to the excitation loop antenna 12 via a filter circuit 17, and a reception processing unit of the reader / writer device 5 is connected to the transmission / reception loop antenna 13 via a filter circuit 18. 9 is connected.

  In the transmission / reception apparatus 2, a coupling capacitor 19 is provided on a reception signal path that guides a signal received by the transmission / reception loop antenna 13 to the reception processing unit 9. In particular, here, a coupling capacitor 19 is provided between the filter circuit 18 and the reception processing unit 9.

  In this transmission / reception device 2, the transmission signal from the transmission processing unit 8 is input to the excitation loop antenna 12 via the filter circuit 17, and is transmitted by magnetic induction due to the current generated in the excitation loop antenna 12 in response thereto. A signal is transmitted from the excitation loop antenna 12 to the transmission / reception loop antenna 13, and a transmission signal is transmitted from the transmission / reception loop antenna 13 to the wireless communication medium 1. In the wireless communication medium 1, a transmission signal from the transmission / reception loop antenna 13 is received by the transmission / reception loop antenna 3, whereby reception and power supply are performed.

  On the other hand, a transmission signal from the wireless communication medium 1 is received by the transmission / reception loop antenna 13, and the reception signal is input to the reception processing unit 9 via the filter circuit 18 and the coupling capacitor 19.

  FIG. 2 is a perspective view showing the transmission / reception antenna 4. The magnetic body 11 constituting the transmission / reception antenna 4 includes a pedestal portion 22 that is fixed to the substrate 21 and a columnar portion 23 that protrudes from the pedestal portion 22 so that the central axis is substantially orthogonal to the substrate 21. The pedestal portion 22 is formed in a disc shape. The columnar part 23 is formed in a columnar shape.

  The excitation loop antenna 12 has a circular loop portion 12a that is wound once, and the transmission / reception loop antenna 13 has a circular loop portion 13a that is wound a plurality of times (here, four times). The loop antenna 12 and the transmission / reception loop antenna 13 are provided so as to be coaxially wound around the outer surface of the columnar portion 23 of the magnetic body 11.

  The excitation loop antenna 12 is disposed on the base side of the columnar portion 23 adjacent to the pedestal portion 22, and the transmission / reception loop antenna 13 is disposed on the distal end side of the columnar portion 23 separated from the pedestal portion 22. Thereby, signal transmission by the transmission / reception loop antenna 13 and signal reception from the wireless communication medium 1 can be efficiently performed.

  The pedestal portion 22 of the magnetic body 11 is formed to have a larger diameter than the excitation loop antenna 12 and the transmission / reception loop antenna 13. Thereby, the magnetic influence by the components arrange | positioned on the board | substrate 21 side, especially the side opposite to the transmission / reception antenna 4 on both sides of the board | substrate 21 can be suppressed.

  FIG. 3 is an exploded perspective view of the transmission / reception antenna 4. Grooves 31 and 32 are formed in the columnar portion 23 of the magnetic body 11 along positions where the loop portion 12a of the excitation loop antenna 12 and the loop portion 13a of the transmission / reception loop antenna 13 are respectively wound. Thereby, the loop part 12a of the excitation loop antenna 12 and the loop part 13a of the transmission / reception loop antenna 13 can be positioned reliably.

  The excitation loop antenna 12 and the transmission / reception loop antenna 13 are arranged so that the respective ends (connection terminals) 12b and 13b are drawn out to the outer peripheral side of the pedestal portion 22 through the back side of the pedestal portion 22 of the magnetic body 11. It has been. Specifically, the base portion 22 of the magnetic body 11 is formed with four holes 35 through which the extraction portion 12c of the excitation loop antenna 12 and the extraction portion 13c of the transmission / reception loop antenna 13 are respectively inserted. On the back surface side of the pedestal portion 22, four grooves 36 into which the extraction portion 12 c of the excitation loop antenna 12 and the extraction portion 13 c of the transmission / reception loop antenna 13 are fitted are formed in parallel to each other. Thereby, the lead-out part 12c of the excitation loop antenna 12 and the lead-out part 13c of the transmission / reception loop antenna 13 can be positioned reliably.

  The magnetic body 11 is fixed to the substrate 21 using an adhesive, a double-sided tape or the like after the excitation loop antenna 12 and the transmission / reception loop antenna 13 are wound (see FIG. 2).

  FIG. 4 is a perspective view of the main part of the substrate 21. On the substrate 21, four copper foil patterns 41 to 44 to which the end 12 b of the excitation loop antenna 12 and the end 13 b of the transmission / reception loop antenna 13 are respectively connected are formed. The two copper foil patterns 41, 42 to which the end 12 b of the excitation loop antenna 12 is connected are extended in a direction away from the pedestal portion 22 of the magnetic body 11, and the filter mounted on the substrate 21 here A circuit 17 (see FIG. 1) is connected.

  The resonance capacitor 14 is connected to the two copper foil patterns 43, 44 to which the end 13 b of the transmission / reception loop antenna 13 is connected, and one of the two copper foil patterns 43, 44 is a copper foil pattern 41. In order to avoid interference with the magnetic body 11, the magnetic body 11 is once extended in a direction close to the pedestal portion 22, then curved in a U shape and extended in a direction away from the pedestal portion 22 of the magnetic body 11. Here, the filter circuit 18 (see FIG. 1) mounted on the substrate 21 is connected.

  FIG. 5 is a perspective view showing a state of current generated in the excitation loop antenna 12 and the transmission / reception loop antenna 13 during transmission. During transmission, when a transmission signal is input to the end (connection terminal) 12b of the excitation loop antenna 12, a current I1 is generated in the excitation loop antenna 12 as indicated by a solid line arrow, and the transmission / reception loop antenna 13 is accordingly generated. , A magnetic current induces a current I2 opposite to the current I1 of the excitation loop antenna 12 as indicated by a broken line arrow, whereby the transmission signal is amplified and output from the transmission / reception loop antenna 13.

  Next, the characteristics of the transmission / reception antenna 4 will be described using an equivalent circuit. FIG. 6 is a diagram showing an equivalent circuit in which the transmission / reception antenna 4 is expressed using a transformer circuit. FIG. 7 is a diagram showing an equivalent circuit in which the transmission / reception antenna 4 is expressed using a coil.

A mutual induction M due to electromagnetic coupling exists between the inductance value L1 of the excitation loop antenna 12 and the inductance value L2 of the transmission / reception loop antenna 13. The following equation is established between the mutual induction M and the inductance value L1 and the inductance value L2.
M = K × √ (L1 × L2) (Formula 1)
Here, the coupling coefficient K is a value in the range of 0 ≦ K ≦ 1. As is clear from Equation 1, the value of the mutual induction M increases as the coupling coefficient K increases.

  Here, when the primary side current I1 flows through the excitation loop antenna 12, an induced voltage V2 is generated at the open end of the transmission / reception loop antenna 13 via the mutual induction M due to the magnetic flux generated by the primary side current I1. Since the resonance capacitor 14 (C1) is connected to the open end of the transmission / reception loop antenna 13, the secondary current I2 flows through a closed circuit including the inductance L2 and the capacitor C1.

  FIG. 8 is a diagram showing the relationship between the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13 and the frequency characteristics of the primary-side current I1 flowing through the excitation loop antenna 12. In FIG. FIG. 9 is a diagram illustrating the relationship between the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13 and the frequency characteristics of the secondary-side current I2 flowing through the transmission / reception loop antenna 13.

  As is clear from FIG. 8, the primary current I1 takes a peak value (minimum value) at the resonance frequency fo (here, 13.56 MHz), and the value of the coupling coefficient K is from 0.1 to 1.0. As the value increases, the peak value of the primary-side current I1 decreases, and accordingly, the value of the primary-side current I1 decreases in the entire band. In particular, the primary-side current I1 even at a frequency away from the resonance frequency fo. It can be seen that the value of is small and the frequency band is widened.

  Further, as apparent from FIG. 9, the secondary current I2 takes a peak value (maximum value) at the resonance frequency fo, and the peak value of the secondary current I2 and the secondary current at a frequency in the vicinity thereof. The value of I2 increases as the value of the coupling coefficient K increases in the range where the value of the coupling coefficient K ranges from 0.1 to 0.4, but when the value of the coupling coefficient K exceeds 0.4, Conversely, it becomes smaller. On the other hand, the value of the secondary current I2 in the frequency band away from the resonance frequency fo increases uniformly as the value of the coupling coefficient K increases from 0.1 to 1.0. It can be seen that the frequency band is widened.

Next, the magnetic flux (magnetic field strength) generated from the excitation loop antenna 12 and the transmission / reception loop antenna 13 will be described. Generally, the magnetic field intensity H generated by the current I flowing through the coil conductor and the inductance L of the coil conductor have the following relationship.
H∝L × I (Formula 2)
That is, the magnetic field strength H is proportional to the product of the inductance value L and the current I flowing through the coil conductor.

  Therefore, the magnetic field intensity H1 generated by the primary current I1 flowing through the excitation loop antenna 12 at the resonance frequency fo is proportional to the product of the inductance value L1 of the excitation loop antenna 12 and the primary current I1. Similarly, the magnetic field intensity H2 generated by the secondary current I2 flowing through the transmission / reception loop antenna 13 is proportional to the product of the inductance value L2 of the transmission / reception loop antenna 13 and the secondary current I2.

  Here, as shown in FIG. 5, the primary side current I1 flowing through the excitation loop antenna 12 and the secondary side current I2 flowing through the transmission / reception loop antenna 13 are in opposite directions. The direction of the magnetic flux generated in each of the loop antenna for transmission 12 and the loop antenna for transmission / reception 13 is also reversed, and a cancellation phenomenon occurs. The magnetic field strength H of the transmission / reception antenna 4 in consideration of this canceling phenomenon is a value obtained by subtracting the magnetic field strength H1 of the excitation loop antenna 12 from the magnetic field strength H2 of the transmission / reception loop antenna 13. In other words, the magnetic flux generated as a result of the current flowing through the excitation loop antenna 12 becomes weaker than the magnetic flux generated as a result of the current flowing through the transmitting / receiving loop antenna 13.

  Thus, in the first embodiment, the transmission / reception loop antenna 13 is configured to have a plurality of loop portions 13a, while the excitation loop antenna 12 is configured to have a one-turn loop portion 12a. The magnetic flux of the transmitting / receiving loop antenna 13 is prevented from being weakened. Thereby, even if the transmission power from the excitation loop antenna 12 is not increased, a sufficient magnetic flux is generated from the transmission / reception loop antenna 13, so that the power consumption can be kept low.

  In the first embodiment, the number of turns of the transmission / reception loop antenna 13 is four. However, the number of turns of the transmission / reception loop antenna 13 is not limited to this, and may be set as appropriate. The inductance value L1 of the loop antenna 12 for use and the inductance value L2 of the loop antenna for transmission / reception 13 may be set so as to satisfy the condition of L2 ≧ 10 × L1.

  FIG. 10 is a diagram illustrating frequency characteristics of transmission output and reception sensitivity according to the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13. Here, the transmission output and the reception sensitivity are substantially the same as a value obtained by multiplying the characteristic of the secondary-side current I2 shown in FIG. 9 by the inductance value L2 of the transmission / reception loop antenna 13. FIG. 11 is a diagram illustrating a frequency characteristic when the coupling coefficient K = 0.7 and a frequency characteristic according to a conventional example in which the frequency characteristic is widened using a resistor R.

  As shown in FIG. 11, when this embodiment (A line) is compared with the conventional example (B line), in this embodiment, the transmission power and the reception sensitivity are higher than those of the conventional example, and the frequency characteristics are wideband. I understand. As described above, in the present embodiment, by appropriately setting the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13, the frequency characteristics can be widened. Since no resistor is interposed in the transmission / reception path, power consumption can be kept low.

  Next, the optimum value of the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13 will be described. FIG. 12 is a diagram showing a comprehensive communication evaluation regarding the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13. Here, with the coupling coefficient K as a parameter, the transmission performance when transmitting a signal to the wireless communication medium 1 is A line, the reception performance when receiving a response signal from the wireless communication medium 1 is B line, and the transmission performance The total communication performance in consideration of both the reception performance and the reception performance is indicated by the C line.

  The transmission performance (A line) shows a good result in the range of the coupling coefficient K = 0.3 to 0.7, and the reception performance (B line) of the coupling coefficient K = 0.5 to 0.9. Good results in the range. Therefore, the total communication performance (C line) considering both transmission performance and reception performance is optimal in the range of the coupling coefficient K = 0.5 to 0.7. In the configuration of the first embodiment, as described above, the coupling coefficient K is approximately 0.7, so that good communication performance can be realized.

  As described above, according to the first embodiment, with the above configuration, the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13 is set to be relatively large, so that the frequency characteristics can be widened. can do. Moreover, the protrusion dimension from the board | substrate 21 can be made small by making the columnar part 23 of the magnetic body 11 in the transmission / reception antenna 4 into the flat shape which made height low. For this reason, for example, it becomes possible to mount it on a notebook personal computer, a portable information terminal, a mobile phone or the like.

  Next, the coupling capacitor 19 provided on the reception signal path will be described with reference to FIG. FIG. 13 is a schematic diagram of a main part of the transmission / reception device 2.

  In the transmission / reception antenna 4, the excitation loop antenna 12 and the transmission / reception loop antenna 13 are brought close to each other, and a transmission signal is transmitted from the excitation loop antenna 12 to the transmission / reception loop antenna 13 by magnetic induction to be amplified. For this reason, the transmission signal transmitted from the excitation loop antenna 12 to the transmission / reception loop antenna 13 wraps around the reception processing unit 9. On the other hand, the transmission / reception loop antenna 13 receives a signal transmitted from the wireless communication medium 1 and inputs the received signal to the reception processing unit 9. Therefore, although the transmission / reception loop antenna 13 itself is not powered, a large signal strength level difference occurs between the transmission signal and the reception signal.

  In particular, as described above, when the coupling coefficient K between the excitation loop antenna 12 and the transmission / reception loop antenna 13 is in the range of 0.5 to 0.7, the signal strength of the transmission signal that wraps around the reception processing unit 9 is the received signal. In this case, the transmission signal hinders the processing of the reception signal in the reception processing unit 9.

  Therefore, in the first embodiment, the transmission / reception loop antenna 13 and the reception processing unit 9 are connected via the coupling capacitor 19. Thereby, since the intensity of the transmission signal that wraps around the reception processing unit 9 is reduced, interference between the transmission signal and the reception signal can be suppressed, and the reception signal processing in the reception processing unit 9 can be performed normally. As the coupling capacitor 19, a capacitor having a required capacitance (for example, 3 pF) that provides high impedance with respect to the transmission signal based on characteristics such as the frequency of the transmission signal and the reception signal is used.

  The transmission / reception antenna 4 configured as described above can be applied to, for example, a mobile phone device. FIG. 14 is a perspective view showing an example in which the transmission / reception antenna 4 is applied to the mobile phone device 51. In FIG. 14, components housed inside through the casing 52 of the mobile phone device 51 are shown. FIG. 15 is an exploded perspective view of the mobile phone device 51.

  As shown in FIGS. 14 and 15, in the casing 52 of the mobile phone device 51, the substrate 21 to which the transmission / reception antenna 4 is attached, the battery pack 53, the magnetic sheet 54, the parasitic loop antenna 55, and the like. , And the opening of the housing 52 is covered with a lid 56.

  As shown in FIG. 15, the transmission / reception antenna 4 is arranged such that the columnar portion 23 of the magnetic body 11 has a central axis in the thickness direction of the housing 52. The parasitic loop antenna 55 is provided so that uniform sensitivity can be obtained throughout the casing 52, and a small loop 55 a that circulates around the transmission / reception antenna 4 and a side edge of the casing 52. And a large loop 55b that circulates along. The magnetic sheet 54 prevents the magnetic influence of the metal surface of the battery pack 53 from reaching the parasitic loop antenna 55, and is disposed between the battery pack 53 and the parasitic loop antenna 55.

  In the above example, as shown in FIG. 2, the columnar portion 23 is cylindrical, that is, the cross section is circular, and the excitation loop antenna 12 and the transmission / reception loop antenna 13 have circular loop portions. However, the present invention is not limited to this. For example, the columnar portion may have a prismatic shape, that is, the cross section may have a square shape, and the excitation loop antenna and the transmission / reception loop antenna may have a square loop portion. It is.

  In the above example, the columnar portion 23 has a circular constant cross section, and the excitation loop antenna 12 and the transmission / reception loop antenna 13 have the same diameter, but the present invention is not limited to this, The portion where the excitation loop antenna is disposed and the portion where the transmission / reception loop antenna is disposed may have different diameters.

  That is, in the columnar portion, the portion where the excitation loop antenna is disposed has a smaller cross section than the portion where the transmission / reception loop antenna is disposed, and the excitation loop antenna has a smaller diameter than the transmission / reception loop antenna. Good. Conversely, the portion where the excitation loop antenna is disposed has a larger cross section than the portion where the transmission / reception loop antenna is disposed, and the excitation loop antenna is larger in diameter than the transmission / reception loop antenna. It may be. In addition, the columnar portion can have various forms such as a form in which the diameter gradually increases toward the tip side.

  The transmission / reception antenna and the transmission / reception apparatus using the same according to the present invention have an effect that the frequency characteristics can be widened without increasing the power consumption, and a wireless communication medium such as an IC tag or a non-contact IC card. It is useful as a transmission / reception antenna for transmitting and receiving signals to / from the wireless communication medium and a transmission / reception device using the antenna.

DESCRIPTION OF SYMBOLS 1 Wireless communication medium 2 Transmission / reception apparatus 4 Transmission / reception antenna 8 Transmission processing part 9 Reception processing part 10 Control part 12 Excitation loop antenna, 12a Loop part 13 Transmission / reception loop antenna, 13a Loop part 14 Resonance capacitor 22 Base part 23 Columnar part

Claims (5)

A magnetic body, an excitation loop antenna provided on the magnetic body, a transmission / reception loop antenna disposed in close proximity to the excitation loop antenna, and a resonance antenna connected to both ends of the transmission / reception loop antenna A capacitor, and
The magnetic body includes a pedestal portion fixed to the substrate, and a columnar portion protruding from the pedestal portion so that a central axis is substantially orthogonal to the substrate,
The excitation loop antenna has a one-turn loop portion, the transmission / reception loop antenna has a plurality of turns loop portions, and the excitation loop antenna and the transmission / reception loop antenna are formed in a columnar shape of the magnetic body. A transmission / reception antenna provided in a manner wound coaxially around a portion.   The excitation loop antenna is disposed on a base side of the columnar portion adjacent to the pedestal portion, and the transmission / reception loop antenna is disposed on a distal end side of the columnar portion separated from the pedestal portion. The transmission / reception antenna according to claim 1.   3. The transmission / reception antenna according to claim 1, wherein the base portion of the magnetic body is formed to have a larger diameter than the excitation loop antenna and the transmission / reception loop antenna. The coupling coefficient K of electromagnetic coupling by mutual induction between the excitation loop antenna and the transmission / reception loop antenna is set to fall within a range of 0.5 to 0.7. The transmission / reception antenna according to claim 3 . A transmitting and receiving antenna according to any one of claims 1 to 4, a transmission processing unit that outputs a transmission signal to the transmitting and receiving antenna, a reception processing unit for receiving signals from the transmitting and receiving antennas is input, the transmission process And a control unit for controlling the reception processing unit,
The transmission / reception apparatus, wherein the excitation loop antenna is connected to the transmission processing unit, and the transmission / reception loop antenna is connected to the reception processing unit.

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