JP5727177B2 - ANTENNA DEVICE AND COMMUNICATION DEVICE - Google Patents

Description

  The present invention relates to an antenna device that performs information communication by electromagnetic field coupling between a pair of electrodes facing each other at a predetermined communication wavelength, and a communication device in which the antenna device is incorporated.

  In recent years, a system has been developed in which data such as music and images is transmitted wirelessly between electronic devices such as computers and small portable terminals without using cables or media. Some of such wireless transmission systems are capable of high-speed transfer of up to about 560 Mbps at a short distance of several centimeters. Among such transmission systems capable of high-speed transfer, TransferJet (registered trademark) is advantageous in that the communication distance is short but the possibility of eavesdropping is low and the transmission speed is high.

  TransferJet (registered trademark) can be achieved by electromagnetic field coupling of corresponding high frequency couplers at very short distances, and the signal quality depends on the performance of the high frequency coupler. For example, as shown in FIG. 9, a high frequency coupler described in Patent Document 1 has a printed circuit board 201 in which a ground 202 is formed on one surface and a microstrip structure formed on the other surface of the printed circuit board 201. The stub 203 includes a coupling electrode 208 and a metal wire 207 that connects the coupling electrode 208 and the stub 203. In the high frequency coupler described in Patent Document 1, a transmission / reception circuit 205 is also formed on the printed circuit board 201. Further, in Patent Document 1, as a modification example in which the transmission / reception circuit 205 is not formed on the printed circuit board 201, a printed circuit board 201 in which a ground 202 is formed on one surface as shown in FIG. A configuration including a microstrip structure stub 203 formed on the other surface, a coupling electrode 208, and a metal wire 207 connecting the coupling electrode 208 and the stub 203 is described.

JP 2008-31816 A

  However, as shown in FIG. 9, the high-frequency coupler described in Patent Document 1 needs to increase the area of the plate-like coupling electrode 208 in order to perform good communication. This is because a certain length depending on the communication wavelength is necessary, and in order to increase the coupling strength, the coupling electrode 208 must be enlarged. In addition, since the metal wire 207 needs to connect the coupling electrode 208 and the stub 203 at a predetermined position, there is a problem in process such that alignment accuracy is required at the time of manufacture.

  The present invention has been proposed in view of such circumstances, and an antenna device having a structure advantageous for downsizing of a coupling electrode while realizing both good communication characteristics and mechanical strength can be realized. The purpose is to provide. Another object of the present invention is to provide a communication device in which this antenna device is incorporated.

As a means for solving the above-described problems, an antenna device according to the present invention is an antenna device that performs information communication by electromagnetic coupling between a pair of electrodes facing each other at a predetermined communication wavelength. And a wiring formed two-dimensionally on a surface of the substrate opposite to the surface on which the ground layer is formed, and disposed at a position facing the antenna device. A coupling electrode that is electromagnetically coupled to an electrode of another antenna device to enable communication, and the coupling electrode includes a plurality of folded portions, and includes a wiring having a length that is approximately half the communication wavelength. Of these, one end is connected to a signal input / output end, and the other end is electrically connected to a ground layer formed on the substrate.

The communication device according to the present invention is a communication device that performs information communication by electromagnetic field coupling between electrodes of another communication device arranged at an opposite position by a predetermined communication wavelength, and one of the dielectrics And a wiring formed in a two-dimensional manner on a surface of the substrate opposite to the surface on which the ground layer is formed, and is disposed at a position facing the antenna device. A coupling electrode that is electromagnetically coupled to an electrode of an antenna device to enable communication, a ground layer, and one end portion of a wiring are electrically connected to each other, and a transmission / reception processing unit that performs signal transmission / reception processing is provided. The coupling electrode has a plurality of folded portions, and is composed of a wiring having a length approximately half of the communication wavelength, and of the wiring, a ground layer formed on the substrate with an end not connected to the transmission / reception processing unit, Having an electrically connected structure And wherein the door.

  In the present invention, the coupling electrode includes a wiring formed so as to have a plurality of folded portions on a surface opposite to the surface on which the ground layer is formed, and one end of the wiring is input / output of a signal. Since it is connected to the end and the other end is electrically connected to the ground layer, it is possible to realize good mechanical strength and downsizing of the entire antenna device. In the present invention, the length of the wiring is approximately half of the communication wavelength, one end is connected to the signal input / output end, and the other end is connected to the ground layer. The strength of the coupling between the coupling electrode and other coupling electrodes arranged at opposite positions by efficiently emitting a longitudinal wave of the electric field in the thickness direction of the substrate by having a high signal level at the center of the wiring Becomes stronger and good communication characteristics can be realized.

  As described above, according to the present invention, it is possible to reduce the size of the entire apparatus while realizing both good communication characteristics and mechanical strength.

It is a figure which shows the structure of the communication system with which the antenna device to which this invention was applied is integrated. It is a figure which shows the structure of the high frequency coupler which concerns on 1st Embodiment which is an antenna device to which this invention was applied. It is a perspective view which shows the communication state between high frequency couplers in the high frequency coupler which concerns on 1st Embodiment. It is an electric field distribution map which shows the electric field analysis result in the central section in the high frequency coupler concerning a 1st embodiment. It is an electric field distribution diagram which shows the electric field analysis result in 1 mm on the electrode surface of the high frequency coupler concerning a 1st embodiment. It is a frequency characteristic figure which shows the analysis result of the coupling strength between the high frequency coupler concerning a 1st embodiment, and a standard coupler. It is a figure which shows the structure of the high frequency coupler which concerns on the modification which is an antenna apparatus with which this invention was applied. It is a frequency characteristic figure which shows the analysis result of the coupling strength between the high frequency coupler which concerns on a modification, and a reference | standard coupler. It is a figure which shows the structure of the high frequency coupler which concerns on a prior art example. It is a figure which shows the structure of the high frequency coupler which concerns on a prior art example.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention.

<Communication system>
An antenna device to which the present invention is applied is a device that performs information communication by electromagnetic coupling between a pair of opposed electrodes, and is a communication system that enables high-speed transfer of about 560 Mbps, for example, as shown in FIG. 100 is used by being incorporated.

  The communication system 100 includes communication devices 101 and 105 that perform two data communications. Here, the communication apparatus 101 includes a high-frequency coupler 102 having a coupling electrode 103 and a transmission / reception circuit unit 104. In addition, the communication device 105 includes a high-frequency coupler 106 having a coupling electrode 107 and a transmission / reception circuit unit 108.

  As shown in FIG. 1, when the high-frequency couplers 102 and 106 provided in each of the communication devices 101 and 105 are arranged to face each other, the two coupling electrodes 103 and 107 operate as one capacitor, and the band-pass filter as a whole. By operating in this way, a high-frequency signal in the 4 to 5 GHz band for realizing high-speed transfer of, for example, about 560 Mbps can be efficiently transmitted between the two high-frequency couplers 102 and 106.

  Here, the transmitting and receiving coupling electrodes 103 and 107 included in the high-frequency couplers 102 and 106 are arranged to face each other with a distance of, for example, about 3 cm, and can be coupled to each other.

  In the communication system 100, for example, the transmission / reception circuit unit 104 connected to the high-frequency coupler 102 generates a high-frequency transmission signal based on the transmission data when a transmission request is generated from a higher-level application, and the coupling electrode 103 generates a coupling electrode. The signal is propagated to 107. Then, the transmission / reception circuit unit 108 connected to the reception-side high-frequency coupler 106 demodulates and decodes the received high-frequency signal, and passes the reproduced data to the higher-level application.

  The antenna device to which the present invention is applied is not limited to the above-described one that transmits a high frequency signal in the 4 to 5 GHz band, and can be applied to signal transmission in other frequency bands. A high frequency signal in the 4 to 5 GHz band will be described as a transmission target.

<High frequency coupler>
As an antenna device incorporated in such a communication system 100, a high-frequency coupler 1 as shown in FIG. 2 will be described.

  In FIG. 2, the dielectric substrate 11 is shown through to make the connection state of the wiring 15 easy to understand.

  As shown in FIG. 2, the high frequency coupler 1 has a wiring 15 functioning as a coupling electrode 18 on one surface 11a of a dielectric substrate 11, and a ground 12 formed on the other surface 11b opposite to the surface 11a. It has a structure.

  Further, in the coupling electrode 18, one end of the wiring 15 becomes a connection terminal portion 19 that becomes a connection portion with the transmission / reception circuit portion 104 described above, and the other end of the wiring 15 is connected to the ground 12 via the connection through hole 14. Connected. The coupling electrode 18 is formed of a so-called ninety-nine-fold or meander-shaped wiring 15 having a plurality of folded portions, and the wiring length of the wiring 15 is adjusted to be approximately half the communication wavelength. Yes.

  As is apparent from the following evaluation, the coupling electrode 18 having such a configuration has a high signal level at a position that is a quarter of the communication wavelength from the connection terminal portion 19, that is, at the central portion 15 a of the wiring 15. The electric charge in this portion and the mirror image charge on the opposite side via the ground 12 function as an electric dipole. Therefore, the coupling electrode 18 can efficiently emit a longitudinal wave of the electric field in the thickness direction of the substrate, and as a result, the coupling strength between the coupling electrodes disposed at the opposing positions is high. Thus, good communication characteristics can be realized.

  The high-frequency coupler 1 having such a configuration is manufactured by the following manufacturing process. First, out of a double-sided copper foil substrate in which a copper foil is pasted as a conductive member on both surfaces of the dielectric substrate 11, one surface 11b is used as a ground 12, and a part of the copper foil on the other surface 11a is etched. The coupling electrode 18 composed of the meander-shaped wiring 15 is formed by removing the processing.

  Subsequently, a hole is formed at one end of the wiring 15 by drilling or laser processing, and the connecting through hole 14 is completed by plating the hole or filling a conductive material such as a conductive paste. By this step, the wiring 15 constituting the coupling electrode 18 formed on the surface 11a of the dielectric substrate 11 and the ground 12 of the other surface 11b of the dielectric substrate 11 are electrically connected. Furthermore, the other end of the wiring 15 constituting the coupling electrode 18 that is not connected to the ground 12 becomes the connection terminal portion 19 and is processed into a shape suitable for the connection means with the transmission / reception circuit portion 104 described above. Thus, the high frequency coupler 1 is completed.

  By the above manufacturing process, the high-frequency coupler 1 can be manufactured by processing one double-sided copper foil substrate. Since the entire surface of one surface 11b is the ground 12, the wiring 15 and the ground 12 It is not necessary to align the patterns on both sides when connecting the wires, and the connection through holes 14 are provided in contact with one end of the wiring 15 so that they can be easily connected and can be manufactured by a simple process.

  As described above, the high-frequency coupler 1 includes the wiring 15 in which the coupling electrode 18 is formed in a meander shape on the surface 11a facing the surface 11b on which the ground 12 is formed. One end is connected to the transmission / reception circuit portion 104 via the connection terminal portion 19 which is a signal input / output end, and the other end is electrically connected to the ground 12, so that the mechanical strength is good. Therefore, it is possible to reduce the size of the entire high-frequency coupler.

  As described above, the mechanical strength is high on the dielectric substrate 11 without using the metal wire 207 that may be deformed by an external force as compared with the high frequency coupler according to the conventional example as shown in FIG. This is because the coupling electrode 18 is mounted. Moreover, the overall size of the high-frequency coupler can be reduced because the coupling strength can be increased by adjusting the length of the wiring 15 without necessarily increasing the area of the electrode.

  In the high-frequency coupler 1, as a material for the dielectric substrate 11, glass, a paper base material, or a glass fiber woven fabric is hardened with an epoxy resin, a phenol resin, or the like, for example, a glass epoxy, a glass composite substrate, Dielectric constant polyimide, liquid crystal polymer, polytetrafluoroethylene, polystyrene, polyethylene, polypropylene, or the like, or a material obtained by making them porous can be used. In particular, the dielectric substrate 11 is preferably made of a low dielectric constant material in terms of electrical characteristics.

  In the manufacturing process described above, in the high-frequency coupler 1, the wiring 15 is formed as the coupling electrode 18 by the etching process using the double-sided substrate on which the copper foil is pasted, but on the surfaces 11 a and 11 b of the dielectric substrate 11. It may be formed by patterning such as direct formation in a masked state by plating, vacuum deposition or the like, or etching after formation.

  In addition to copper, a good conductor such as aluminum, gold, or silver can be used as the material for the wiring 15 of the coupling electrode 18 and the ground 12. However, the material is not limited to these materials. Any of them can be used.

  Further, since the coupling electrode 18 has the wiring 15 formed in a meander shape, the space of the surface 11a of the dielectric substrate 11 can be used effectively, and the high-frequency coupler 1 itself can be miniaturized. it can.

  This is because, as described above, the length of the coupling electrode 18 is approximately ½ wavelength of the communication frequency. However, the formation space of the coupling electrode 18 can be reduced by forming these wirings so as to be dense and dense. This is because the high-frequency coupler can be miniaturized.

  As described above, the wiring pattern of the wiring 15 constituting the coupling electrode 18 may be formed by connecting a plurality of meander-shaped patterns having different shapes from the viewpoint of effectively utilizing the space of the dielectric substrate 11. An L-shaped, arc-shaped repeating pattern or the like may be used.

  Next, in order to investigate the performance of the high-frequency coupler 1, the coupling strength was analyzed using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft. Here, an analysis model of the high-frequency coupler 1 was used under the following conditions. Polytetrafluoroethylene was set as the material of the dielectric substrate 11, and copper was set as the material of the conductor of the coupling electrode 18. The size of the high-frequency coupler 1 was 6.5 mm × 6.5 mm on the surface 11 a on which the wiring pattern is formed, and the substrate thickness was 1.67 mm.

  The coupling strength is evaluated by the transmission characteristic S21 of the S parameter used for evaluating the high frequency transmission characteristic, and the connection port portion 19 serving as the signal input / output end of the high frequency coupler 1 and the ground 12 are used as an input port. The coupling strength S21 between the ports of the pair of high frequency couplers was calculated. FIG. 3 shows the relative arrangement between the high-frequency couplers used for the analysis of the coupling strength S21. Here, the coupling strength of the wiring 15 constituting the coupling electrode 18 of the high-frequency coupler 1 and the electrode 150a of the high-frequency coupler 150 are opposed to each other so that the central axes thereof coincide with each other and are spaced by 15 mm and 100 mm. The frequency characteristic of S21 was examined. In this example, one high frequency coupler 150 has a plate-like electrode 150a, and a reference high frequency coupler which is a reference machine for evaluation is used.

  Further, in order to evaluate the electric field generation state in the high frequency coupler 1, the electric field vector distribution in the vicinity of the high frequency coupler 1 was also examined.

  FIG. 4 shows an analysis of the electric field distribution at 4.5 GHz of the high-frequency coupler 1, and shows the electric field distribution in a cross section obtained by dividing the dotted line Y-Y ′ in FIG. 2 in the thickness direction. As is clear from FIG. 4, a strong electric field distribution is observed between the coupling electrode 18 and the ground 12, and an electric field is distributed on the arc from the central portion 15a of the wiring 15 constituting the coupling electrode 18 outward. ing.

  FIG. 5 shows the electric field distribution on the surface 1 mm away from the surface 11 a where the coupling electrode 18 is formed in the high-frequency coupler 1 in the vertically upward direction. As apparent from FIG. 5, the electric field is distributed substantially concentrically from the central portion 15 a of the wiring 15 constituting the coupling electrode 18.

  This is because the length of the wiring 15 constituting the coupling electrode 18 is approximately half of the communication wavelength, and one end of the wiring 15 is connected to the ground 12, which is a so-called short stub. This is because the electric field is maximized at the central portion 15a corresponding to the / 4 portion. Thus, in the high frequency coupler 1, it was confirmed by analysis that a strong electric field is generated around the central portion 15a of the coupling electrode 18.

  FIG. 6 shows an analysis result of the coupling strength S21 between the high-frequency coupler 1 and the reference high-frequency coupler 150, and the coupling strength of −22.5 dB is around 4.5 GHz at the communication distance of 15 mm facing distance. In addition, a wide band characteristic of 0.69 GHz was obtained in the -3 dB bandwidth, which is a frequency band that has a 3 dB attenuation from the maximum intensity. For example, TransferJet (registered trademark) requires a bandwidth of 560 MHz. Generally, the center frequency shifts due to variations in high frequency couplers and impedance matching with the circuit board. Since the bandwidth is sufficiently wide, good communication can be performed without being affected by these variations. In addition, a communication interruption of −48 dB or less is obtained at a non-communication distance of 100 mm facing distance.

  As described above, in the high-frequency coupler 1 according to the first embodiment, as is apparent from the above simulation, it is possible to realize good communication characteristics and further achieve coexistence with mechanical strength. The entire apparatus can be reduced in size.

<Modification>
Next, as an antenna device incorporated in the communication system 100, a high-frequency coupler 2 according to a modification as shown in FIG. 7 will be described.

  FIG. 7 shows the dielectric substrate 21 in a transparent state for easy understanding of the connection state of the wiring 25.

  As shown in FIG. 7, in the high frequency coupler 2, a wiring 25 functioning as a coupling electrode 28 and a stub 27 connected to the wiring 25 are formed on one surface 21a of the dielectric substrate 21, and the surface 21a. The ground 22 is formed on the other surface 21b facing the surface.

  In the coupling electrode 28, one end of the wiring 25 serves as a connection terminal portion 29 to be a connection portion with the transmission / reception circuit portion 104, and the other end of the wiring 25 is connected to the ground 22 through the connection through hole 24a. Is done. The coupling electrode 28 is formed by a wiring 25 having a plurality of folded portions, a ninety-nine fold shape, or a meander shape, and the wiring length of the wiring 25 is adjusted to be approximately half the communication wavelength. .

  In the coupling electrode 28 having such a configuration, as is apparent from the following evaluation, the signal level is high at a position away from the connection terminal portion 29 by a quarter of the communication wavelength, that is, at the central portion 25a of the wiring 25. The electric charge in this portion and the mirror image charge on the opposite side via the ground 22 function as an electric dipole. Therefore, the coupling electrode 28 can efficiently emit a longitudinal wave of the electric field in the thickness direction of the substrate, and as a result, the coupling strength between the coupling electrode disposed at the opposite position is high. Thus, good communication characteristics can be realized.

  One end of the stub 27 is connected to the coupling electrode 28 at the connection terminal portion 29, and the other end is connected to the ground 22 through the connection through hole 24b. Further, by using a stub 27 whose length is adjusted, when the coupling electrode 28 is electromagnetically coupled to another electrode, the coupling strength and the bandwidth can satisfy desired conditions. it can.

  The high-frequency coupler 1 having such a configuration is manufactured by the following manufacturing process. First, out of a double-sided copper foil substrate in which, for example, a copper foil is pasted as a conductive member on both surfaces of the dielectric substrate 21, one surface 21b is used as a ground 22 and a part of the copper foil on the other surface 21a is etched. The coupling electrode 28 composed of the meander-shaped wiring 25 and the stub 27 are formed by removing the processing.

  Subsequently, holes are formed in one end of the wiring 25 and one end of the stub 27 by drilling or laser processing, and each hole is plated or filled with a conductive material such as a conductive paste to connect through holes. The holes 24a and 24b are completed. By this step, the wiring 25 constituting the coupling electrode 28 formed on the surface 21a of the dielectric substrate 21 and the ground 22 of the other surface 21b of the dielectric substrate 21 are electrically connected. Similarly, the stub 27 and the ground 12 are electrically connected. Further, the other end of the wiring 25 constituting the coupling electrode 28 that is not connected to the ground 22 becomes a connection terminal portion 29 connected to the stub 27, which is suitable for the connection means with the transmission / reception circuit portion 104 described above. The high frequency coupler is completed by processing into the shape to be performed.

  As shown in FIG. 7, when the pattern shape is such that the two connection through holes 24a and 24b are close to each other, the position of the end of the wiring 25 or the stub 27 constituting the coupling electrode 28 is adjusted. Thus, it is also possible to connect to the ground 22 by using one connection through hole.

  As described above, the high-frequency coupler 2 can be manufactured by processing the single-sided double-sided copper foil substrate with the coupling electrode 28, and the entire surface of the one surface 21 b serves as the ground 22. When connecting the ground 22 to the ground 22, it is not necessary to align the patterns on both sides, and contact one end of the wiring constituting the coupling electrode 28 and one end of the stub 27. By providing 24b, it can connect easily and can be produced by a simple process.

  Next, in order to investigate the performance of the high-frequency coupler 2, the coupling strength was analyzed using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft. Here, an analysis model of the high frequency coupler 2 was used under the following conditions. Polytetrafluoroethylene was set as the material of the dielectric substrate 21, and copper was set as the material of the conductor used as the coupling electrode 28 and the stub 27. The size of the high-frequency coupler 2 is such that the surface 21a on which the wiring pattern is formed is 6.5 mm × 6.5 mm, the substrate thickness is 1.67 mm, and the length of the stub 27 is 5.2 mm. .

  The coupling strength is evaluated by the transmission characteristic S21 of the S parameter used for evaluating the high-frequency transmission characteristic, and the connection port portion 29 serving as the signal input / output terminal of the high-frequency coupler 2 and the ground 22 are used as an input port. The coupling strength S21 between the ports of the pair of high frequency couplers was calculated. The relative arrangement between the high-frequency couplers used in the analysis is the same as the condition shown in FIG.

  FIG. 8 shows the analysis result of the frequency characteristics of the coupling strength S21 when the facing distance between the high frequency couplers is 15 mm. For comparison, the coupling strength when the facing distance is 15 mm shown in FIG. 6, which is a characteristic of the high-frequency coupler 1 having no stub 27, is also shown.

  In this example, the reference high frequency coupler 150 which is a reference machine for evaluation is used as one high frequency coupler.

  As can be seen from FIG. 8, in the high frequency coupler 2 having the stub 27, the coupling strength can be increased, but the frequency band in which strong coupling strength is obtained is narrow. In general, the strength of the coupling strength and the -3 dB bandwidth are in a trade-off relationship. Therefore, when these balances are insufficient with respect to the required specifications, a stub 27 is provided as in the high frequency coupler 2, and By changing the length, the balance between the two can be adjusted.

  1, 2, 102, 106, 150 High frequency coupler, 11, 21 Dielectric substrate, 11a, 11b, 21a, 21b surface, 12, 22, 202 Ground, 14, 24a, 24b Connection through hole, 15, 25 Wiring 15a central part, 18, 28, 103, 107, 208 coupling electrode, 19, 29 connection terminal part, 27, 203 stub, 100 communication system, 101, 105 communication device, 104, 108 transmission / reception circuit part, 150a electrode, 201 Printed circuit board, 205 Transmission / reception circuit, 207 Metal wire

Claims (3)

In an antenna device that performs information communication by electromagnetic field coupling between a pair of opposed electrodes at a predetermined communication wavelength,
A substrate having a ground layer formed on one surface of the dielectric;
The wiring is formed two-dimensionally on the surface of the substrate opposite to the surface on which the ground layer is formed, and is electromagnetically coupled to electrodes of other antenna devices disposed at positions facing the antenna device. It has a coupling electrode that can communicate,
The coupling electrode has a plurality of folded portions, and is composed of a wiring having a length approximately half of the communication wavelength. Among the wirings, a signal input / output end is formed at one end, and the other end The antenna device has a structure in which is electrically connected to a ground layer formed on the substrate.   2. The antenna apparatus according to claim 1, wherein a stub having a predetermined length branched from an input / output end formed in the wiring is connected to the coupling electrode. In a communication device that performs information communication by electromagnetic coupling between electrodes of other communication devices arranged at opposing positions by a predetermined communication wavelength,
A substrate having a ground layer formed on one surface of the dielectric;
The wiring is formed two-dimensionally on the surface of the substrate opposite to the surface on which the ground layer is formed, and is electromagnetically coupled to electrodes of other antenna devices disposed at positions facing the antenna device. A coupling electrode capable of communication;
The ground layer, one end of the wiring, and a transmission / reception processing unit that is electrically connected and performs signal transmission / reception processing,
The coupling electrode has a plurality of folded portions, and is composed of a wiring having a length approximately half of the communication wavelength, and an end of the wiring that is not connected to the transmission / reception processing unit is formed on the substrate. A communication device having a structure electrically connected to a ground layer.

Images