JP2012015848A - Antenna device and communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device having a structure advantageous for miniaturization while sufficient communication characteristic and mechanical strength are realized.SOLUTION: The antenna device includes: a printed board 11 where a ground layer 12 is formed on a board face 11a; a coil board 16 installed on a board face 11b of the printed board 11; and a coupling electrode 103 which consists of coils 162 to which coil wires are wound to form a figure eight via through holes 13 on upper and lower faces of the coil board 16 and is electromagnetically coupled to an electrode of another antenna device to be communicable. The coupling electrode 103 has a structure where one end of the wound coils 162 is connected to an input/output end 18c of a signal, and the other end is electrically connected to the ground layer 12 formed on the printed board 11. The whole length of the coils 162 is almost half of a communication wavelength.

Description

  The present invention relates to an antenna device that performs information communication by electromagnetic field coupling between a pair of opposed electrodes, 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, the 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 as shown in FIG. 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 modified 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

  In the high-frequency coupler described in Patent Document 1, the coupling strength includes the capacitance between the coupling electrodes 208 in a coupled state in which a pair of high-frequency couplers are arranged to face each other, and the coupling electrode 208 and the stub 203. Greatly depends on the inductance of the metal wire 207 connecting the two. In the high-frequency coupler shown in FIGS. 30 and 31, the coupling electrode 208 is supported by a metal wire 207. However, considering the mechanical strength and handling during movement, the coupling electrode 208 and It is preferable that the metal wire 207 is mechanically held by bonding the metal wire 207 to a substrate or the like. However, in this case, since the substrate holding the coupling electrode 208 and the metal wire 207 is generally a dielectric substrate having a dielectric constant, the capacitance component between the coupling electrodes 208 changes greatly. The resonance frequency changes, and adjustment for adjusting to a predetermined frequency is complicated, such as adjusting the inductance by changing the length and thickness of the metal wire 207 in order to match this frequency. Further, when a substrate having a high dielectric constant is used, the coupling efficiency is greatly reduced.

  The present invention has been proposed in view of such circumstances, and as described above, an antenna device having a structure advantageous for downsizing while realizing both good communication characteristics and mechanical strength. 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 configured such that a ground layer is formed on one surface of a dielectric in an antenna device that performs information communication by electromagnetic field coupling between a pair of opposed electrodes. A first substrate formed on the first substrate, a second substrate made of a dielectric disposed opposite to a surface different from the surface on which the ground layer is formed, and the second substrate. It consists of a coil wound with a coil wire so that the winding shape is 8-shaped on the upper and lower surfaces through through holes, and is electromagnetically coupled to the electrodes of other antenna devices arranged at opposing positions. And the coupling electrode is configured such that one end of the wound coil is connected to a signal input / output end and the other end is the first electrode. Electrically connected to the ground layer formed on the substrate Has a concrete, characterized in that the total length of the coil is a length of approximately half of the communication wavelength.

  In the communication device according to the present invention, a ground layer is formed on one surface of a dielectric in a communication device that performs information communication by electromagnetic coupling between electrodes of another communication device disposed at an opposite position. A first substrate, a second substrate made of a dielectric disposed opposite to a surface different from the surface on which the ground layer is formed, and through holes on the upper and lower surfaces of the second substrate, A coupling electrode that is composed of a coil in which a coil wire is wound so that the winding shape is a figure 8, and is electromagnetically coupled to an electrode of another antenna device arranged at an opposing position to enable communication A transmission / reception processing unit for performing signal transmission / reception processing, wherein the coupling electrode has one end connected to the transmission / reception processing unit and the other end connected to the first of the wound coils. Electrically connected to the ground layer formed on the substrate It has a structure, wherein the total length of the coil is a length of approximately half of the communication wavelength.

  According to the present invention, since the coupling electrode is formed of a coil wound on the upper and lower surfaces of the second substrate through a through hole, it is possible to realize a good degree of mechanical strength. In addition, the present invention is that the entire length of the coil is approximately half the length of the communication wavelength, and one end of the coil is electrically connected to the ground layer, so that the signal level at the center of the coil is increased, The coupling strength between the other coupling electrodes arranged at the opposing positions is increased, and good communication characteristics can be realized. Furthermore, in the present invention, since the coupling electrode is a coil wound so that the winding shape viewed from one cross-sectional direction in the second substrate is a figure 8, the total length of the coil is as described above. However, even if the length is approximately half the communication wavelength, the entire coil can be made small, and the entire antenna device can be downsized.

  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 figure for demonstrating the winding shape of the coil wound by the coil board | substrate, and the magnetic field which a coil generate | occur | produces. It is the top view which shows the coordinate of the analysis model of the high frequency coupler which concerns on 1st Embodiment, and is the figure which looked at the surface side of the coil board | substrate. It is a figure which shows magnetic field vector distribution which a coil generate | occur | produces in the high frequency coupler which concerns on 1st Embodiment. In the high-frequency coupler according to the first embodiment, FIG. 6A is a diagram illustrating the electric field strength distribution on the XZ plane, and FIG. 6B is a diagram illustrating the electric field strength distribution on the YZ plane. It is a perspective view which shows the communication state between high frequency couplers in the high frequency coupler which concerns on 1st Embodiment. In the high frequency coupler which concerns on 1st Embodiment, it is a figure for demonstrating the frequency characteristic of coupling intensity | strength S21 when the opposing distance between high frequency couplers is 15 [mm] and 100 [mm]. The frequency characteristic of the coupling strength S21 when the facing distance between the high frequency couplers is 15 [mm] and 100 [mm] using a high frequency coupler in which the resonance line 18a and the through hole 15b are not provided will be described. FIG. It is a figure which shows the structure of the high frequency coupler which concerns on the modification 1 of 1st Embodiment. It is the top view which shows the coordinate of the analysis model of the high frequency coupler which concerns on the modification 1 of 1st Embodiment, and is the figure which looked at the surface side of the coil board | substrate. It is a figure which shows magnetic field vector distribution which a coil generate | occur | produces in the high frequency coupler which concerns on the modification 1 of 1st Embodiment. In the high-frequency coupler according to Modification 1 of the first embodiment, FIG. 13A is a diagram showing the electric field strength distribution on the XY plane that is 1 mm away from the upper surface of the coil substrate 16, and FIG. FIG. 4 is a diagram showing an electric field strength distribution on an XY plane that is 5 mm away from the upper surface of the coil substrate 16. The figure for demonstrating the frequency characteristic of coupling intensity | strength S21 when the opposing distance between high frequency couplers is 15 [mm] and 100 [mm] in the high frequency coupler which concerns on the modification 1 of 1st Embodiment. It is. It is a figure which shows the structure of the high frequency coupler which concerns on the modification 2 of 1st Embodiment. It is the top view which shows the coordinate of the analysis model of the high frequency coupler which concerns on the modification 2 of 1st Embodiment, and is the figure which looked at the surface side of the coil board | substrate. It is a figure which shows magnetic field vector distribution which a coil generate | occur | produces in the high frequency coupler which concerns on the modification 2 of 1st Embodiment. In the high-frequency coupler according to Modification 2 of the first embodiment, FIG. 18A is a diagram showing the electric field strength distribution on the XY plane that is 1 mm away from the upper surface of the coil substrate 16, and FIG. FIG. 4 is a diagram showing an electric field strength distribution on an XY plane that is 5 mm away from the upper surface of the coil substrate 16. FIG. 10 is a diagram for explaining a change in frequency characteristics of the coupling strength S21 according to the depth of the cavity 19 in the analysis model of the high-frequency coupler according to Modification 2 of the first embodiment. It is a figure which shows the structure of the high frequency coupler which concerns on 2nd Embodiment. It is a figure for demonstrating the winding shape of the coil wound by the coil board | substrate, and the magnetic field which a coil generate | occur | produces. It is the top view which shows the coordinate of the analysis model of the high frequency coupler which concerns on 2nd Embodiment, and is the figure which looked at the surface side of the coil board | substrate. It is a figure which shows magnetic field vector distribution which a coil generate | occur | produces in the high frequency coupler which concerns on 2nd Embodiment. In the high frequency coupler which concerns on 2nd Embodiment, it is a figure which shows the electric field strength distribution of XY surface 1 mm away from the upper surface of the coil board | substrate. It is a perspective view which shows the communication state between high frequency couplers in the high frequency coupler which concerns on 2nd Embodiment. In the high frequency coupler which concerns on 2nd Embodiment, it is a figure for demonstrating the frequency characteristic of coupling strength S21 when the opposing distance between high frequency couplers is 15 [mm] and 100 [mm]. The frequency characteristic of the coupling strength S21 when the opposing distance between the high frequency couplers is 15 [mm] and 100 [mm] using a high frequency coupler in which the resonance line 28a and the through hole 25b are not provided will be described. FIG. It is a figure which shows the structure of the high frequency coupler which concerns on the modification of 2nd Embodiment. FIG. 10 is a diagram for explaining a change in frequency characteristics of the coupling strength S21 according to the depth of a cavity 29 in an analysis model of a high-frequency coupler according to a modification of the second embodiment. It is a figure which shows the structure which concerns on the high frequency coupler which concerns on a prior art example. It is a figure which shows the structure which concerns on 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.

<First Embodiment>
As an antenna device incorporated in such a communication system 100, a high-frequency coupler 1 according to the first embodiment as shown in FIG. 2 will be described.

  That is, as shown in FIG. 2, the high-frequency coupler 1 according to the first embodiment includes a printed circuit board 11 corresponding to the first substrate according to the present invention and a coil corresponding to the second substrate according to the present invention. A substrate 16.

  The printed circuit board 11 has a base material 14 made of a dielectric, and a ground layer 12 formed on one surface of the base material 14.

  The coil substrate 16 is a substrate that is installed on the printed circuit board 11 on a substrate surface 11b that faces the substrate surface 11a on which the ground layer 12 is formed. The coil substrate 16 has an upper substrate 161 made of a dielectric, and the upper substrate 161 is formed with a coil 162 that functions as the coupling electrodes 103 and 107 described above.

  Here, for the coil substrate 16, the direction parallel to the wiring 18 b described later is the X direction, the direction perpendicular to the wiring 18 b in the plane of the upper substrate 161 is the Y direction, and the thickness direction of the high frequency coupler 1 is the Z axis. The three-dimensional orthogonal coordinate system is defined and described.

  As shown in FIGS. 3A and 3B, the coil 162 has a winding shape viewed from one cross-sectional direction in the coil substrate 16 through a plurality of through holes 13 on the upper and lower surfaces of the upper substrate 161. It is formed by winding a coil wire so as to be substantially “8”. Specifically, the coil 162 is formed by forming a wiring for forming a coil on the upper and lower surfaces of the upper substrate 161 by a patterning technique, and the formed upper and lower coil pattern ends are opened by a drill or the like, and conductive plating treatment is performed. Alternatively, it is formed by electrically connecting through a through hole 13 in which a conductive paste is embedded.

  In the present embodiment, the coil 162 has a substantially “8-shaped” winding shape as viewed from the YZ plane in the coil substrate 16, but is not limited to this, and from any cross section in the coil substrate. What is necessary is just to be formed in the coil board | substrate so that the winding shape which looked may become substantially "8 shape".

  In addition, the coil 162 has the winding directions T shown in FIGS. 3A and 3B opposite to each other, and the coils 162a and 162b having the same number of turns are connected to each other by the winding direction reversing unit 17. Is. That is, a portion corresponding to approximately half the total length of the coil 162 is a winding direction reversing portion 17. The overall length of the coil 162 is adjusted to be approximately half the communication frequency.

  Here, the winding direction is a direction in which a substantially “eight-letter shape” that is a winding shape is drawn when viewed from an arbitrary cross section of the coil substrate. In the present embodiment, the winding direction T is a direction in which substantially “8” is drawn when viewed in the −X direction of the YZ plane of the coil substrate 16. Specifically, the coil 162a corresponds to a winding shape and a winding direction T as shown in FIG. 3A, and the coil 162b has a winding shape and a winding direction T as shown in FIG. It corresponds. 3A and 3B also show a magnetic field B generated when a current flows in the winding direction T and the forward direction.

  Further, one end of the coil 162 is electrically connected to the ground layer 12 formed on the substrate surface 11a of the printed circuit board 11 through the through hole 15a, and the resonance line 18a and the wiring 18b are connected to the other end. Is done. A signal input / output end 18c is formed at the other end of the wiring 18b. As described above, one end of the resonance line 18a is connected to the coil 162, and the other end is printed via the through hole 15b. The substrate 11 is electrically connected to the ground layer 12 formed on the substrate surface 11a.

  Here, the resonance line 18a is for adjusting the steepness of the resonance characteristic of the high frequency coupler 1, and the steepness of the resonance characteristic can be adjusted by changing the length of the resonance line 18a. The through holes 15a and 15b are paths through which the base material 14 of the printed circuit board 11 is electrically connected, and, like the through holes 13 described above, are subjected to a conductive plating process or a conductive paste filling process. It is formed with.

  Examples of the material of the base material 14 of the printed circuit board 11 and the upper substrate 161 of the coil substrate 16 include plasticity such as glass epoxy (FR4), glass composite (CEM3), paper epoxy (FR3), and paper phenol (XPC). Although a member is used, a low dielectric material such as flexible polyimide, liquid crystal polymer, or Teflon may be used. In particular, when the input / output end 18c is provided by projecting the wiring 18b of the coil substrate 16 with respect to the printed circuit board 11, the substrate 161 is a flexible substrate made flexible by using a thin polyimide or the like. It is preferable. This is because the input / output end 18 c protruding from the printed circuit board 11 can be flexibly bent and the degree of freedom in attaching the transmission / reception circuit unit 104 and the high-frequency coupler 1 is improved. Because you can.

  Next, in order to investigate the performance of the high-frequency coupler 1 having the above-described configuration, analysis using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft Corporation was performed. The analysis model has the configuration shown in FIG. 2, and polyimide is used for the base material 14 and the upper substrate 161. The dimensions of the printed circuit board 11 and the coil substrate 16 are 8 × 8 × 1 in length × width × thickness, respectively. .6 mm and 8 × 8 × 0.4 mm.

  FIG. 4 is a plan view showing the coordinates of this analysis model, and is a view of the surface side of the coil substrate 16. In FIG. 4, the upper substrate 161 is transmitted so that the winding state of the coil 162 can be seen. As described above, the direction parallel to the wiring 18 b is the X direction, and the wiring is performed within the plane of the upper substrate 161. The direction perpendicular to 18b is the Y direction, and the thickness direction of the high frequency coupler 1 is the Z axis.

  FIG. 5 is an analysis of the magnetic field vector distribution of the coil 162, and represents the magnetic field vector of the resonance frequency on the XY plane 200 μm below the upper surface of the coil substrate 16 in the thickness direction Z. From FIG. 5, in the coil 162, the magnetic field vector is directed to the X direction minus side on the Y direction plus side, and the magnetic field vector is directed to the X direction plus side on the Y direction minus side. For this reason, the flow of the magnetic field is generated so as to circulate around the winding direction inversion portion 17, that is, in a closed loop on the XY plane.

  Specifically, the magnetic field flow will be described below. As shown in FIGS. 3 (A) and 3 (B), the coil 162a and the coil 162b constituting the coil 162 are wound. The reason why the turning directions are opposite to each other is because the polarities of the currents in the coils 162a and 162b are opposite.

  First, paying attention to the individual coils 162a and 162b, the winding shape is a figure-eight shape. When a current is passed through the coil having such a shape, as shown in FIG. It has the property that the direction of the magnetic field that penetrates the two rings that constitutes is reversed. Therefore, when such eight-shaped coils are continuously stacked, that is, when they are wound, the direction of the magnetic field is the same in each of the overlapping rings, so that two solenoid coils with different winding directions result. It can be considered that they are arranged side by side, and a closed loop of a magnetic field is created between adjacent solenoid coils, so that the inductance of the coil can be increased. However, in the case of a high-frequency current, the polarity of the current changes at a half wavelength due to the phase relationship. Therefore, if the winding direction is the same over the entire length of the coil 162, the currents with locally different polarities For this reason, a phenomenon occurs in which the magnetic fields cancel each other.

  Further, in the high frequency coupler 1, since one end of the coil 162 is short-circuited to the ground layer 12 through the through hole 15b, the current is maximized at that portion, and the entire length of the coil 162 is reduced to a half wavelength. Therefore, the current is also maximized at the other end of the coil 162. Here, the currents at both ends of the coil 162 are opposite in polarity because the phases are different by 180 degrees. As described above, if the coil 162 is formed by overlapping the same 8-shaped coil in the winding direction, the generated magnetic field Will cancel each other out, and it will not be a closed loop as described above.

  On the other hand, in the high frequency coupler 1, the coil 162 is configured by combining the eight-shaped coils 162 a and 162 b having different winding directions with the winding direction inversion portion 17 as a boundary. The magnetic field flow can be closed loop.

  In this way, in the high frequency coupler 1, by making the flow of the magnetic field a closed loop as described above, the inductance of the coil 162 can be increased and the Q value as the antenna can be increased. The coupling efficiency can be increased. For example, in an application using a longitudinal wave of an electric field such as TransferJet (registered trademark), the electric field is applied in the Z-axis direction from the periphery of the winding direction inversion unit 17 at the center of the coil 162 where the voltage level of the signal is highest. Since longitudinal waves are efficiently emitted, the degree of coupling can be increased. The voltage level is highest around the winding direction inversion portion 17 because the coil 162 is approximately half the length of the communication wavelength, and one end of the coil is electrically connected to the ground layer 12 where the voltage level is zero. This is because they are connected.

  6A and 6B show the electric field intensity distributions on the XZ plane and the YZ plane, respectively, and the intensity is expressed by contour lines with the central portion of the coil 162 as a reference. In the figure, contour lines are indicated by dotted lines. Here, the electric field strength distribution is a symmetric distribution with the winding direction reversing portion 17 installed substantially at the center of the high frequency coupler 1 as the center, and communication is performed with the two high frequency couplers facing each other. The point at which the maximum coupling strength can be obtained when performing is easy to understand and is preferable from the viewpoint of easy antenna arrangement.

  Next, in order to examine the communication status of the high frequency coupler 1, the high frequency coupler 150 including the plate-like coupling electrode 150a is used as a reference machine for evaluation as shown in FIG. , 150 was analyzed with respect to the coupling strength when communicating with each other. The coupling strength is evaluated by the transmission characteristic S21 of the S parameter used for evaluating the high frequency transmission characteristic, and the input / output terminal 18c of the wiring 18b serving as the signal input / output terminal of the high frequency coupler 1 is used as the power input port. Similarly, the transmission characteristic S21 is analyzed using the input / output terminal of the high-frequency coupler 150 as an output port.

  FIG. 7 shows a relative arrangement between the high-frequency couplers 1 and 150 using the coupling strength S21 for analysis. As shown in FIG. 7, the frequency characteristics of the coupling strength S21 are examined in a state where the high-frequency couplers 1 and 150 face each other so that their central axes coincide with each other and are spaced apart from each other.

  FIG. 8 is an analysis of the frequency characteristics of the coupling strength S21 when the facing distance between the high frequency couplers 1 and 150 is 15 [mm] and 100 [mm]. In the case of the opposing distance 15 [mm] and the opposing distance 100 [mm], the coupling strength S21 is −23 dB and −48 dB, respectively, near the communication frequency of 4.5 GHz. As is clear from this result, the coupling strength S21 is large when the communication distance is a short distance, that is, about 15 [mm], and is far away as a non-communication distance, that is, when the distance is about 100 [mm]. However, since it is small, it has good communication characteristics when short-range communication is used.

  As described above, in the high-frequency coupler 1 according to the first embodiment, since the coupling electrode includes the coil 162 wound around the upper and lower surfaces of the coil substrate 16 through the through hole 13, for example, FIG. As shown in FIG. 31 and FIG. 31, the coupling electrode can realize a better mechanical strength than the high-frequency coupler according to the conventional example in which the coupling electrode 208 is supported by the metal wire 207. This is because the coupling electrode of the high-frequency coupler 1 according to the first embodiment is formed in the coil substrate 16, and compared with the case where the coupling electrode 208 is supported by the metal wire 207. This is because damage to the coupling electrode can be prevented even if such is added.

  Further, the high-frequency coupler 1 has a coil 162 that is approximately the half of the communication wavelength, and one end of the coil 162 is electrically connected to the ground layer 12. By increasing the signal level at the direction inversion unit 17, the coupling strength with other coupling electrodes arranged at opposing positions is increased, and good communication characteristics can be realized.

  Furthermore, the high-frequency coupler 1 is a coil in which the coupling electrode is wound so that the winding shape in the cross-sectional direction of the coil substrate 16 is a figure 8, so that the total length of the coil 162 is approximately half the communication wavelength. The entire coil 162 can be made small and the entire antenna device can be miniaturized even if the length is.

  As is apparent from this point, the high-frequency coupler 1 can achieve a reduction in size of the entire high-frequency coupler 1 while realizing both good communication characteristics and mechanical strength.

  In the high-frequency coupler 1, the coil substrate 16 does not necessarily have the resonance line 18a and the through hole 15b that electrically connects the resonance line 18a and the ground layer, but the resonance line 18a is provided. This is particularly preferable in that the coupling strength and the resonance frequency can be adjusted.

  For example, when the resonance line 18a and the through hole 15b are not provided, the frequency characteristic of the coupling strength S21 with the facing distance between the high frequency coupler being 15 [mm] and 100 [mm] is as shown in FIG. become. Here, when the opposing distance is 15 [mm], the coupling strength S21 is −25.2 dB in FIG. 9 while it is −22.9 dB in FIG. From this result, for example, the presence of the resonance line 18a can be adjusted to increase the coupling strength. When the facing distance is 15 [mm], the bandwidth from the peak to −3 dB down is −3 dB in FIG. 9, whereas that in FIG. 8 is 0.43 GHz. From this result, the resonance line 18a can be adjusted so that, for example, the bandwidth is narrowed.

  In general, since the strength of the coupling strength and the bandwidth are in a trade-off relationship, when these balances are insufficient with respect to the required specifications, the resonance line 18a and the through hole 15b are used as in the high-frequency coupler 1. By mainly changing the length of the resonance line 18a, the characteristics of the strength of the coupling strength and the bandwidth can be adjusted.

<Modification 1>
Next, a configuration of a high-frequency coupler 1a as shown in FIG. 10 will be described as a first modification according to the first embodiment.

  As shown in FIG. 10, the high-frequency coupler 1 a includes a printed board 11 and a coil board 16, as in the above-described high-frequency coupler 1, and a plurality of through holes are formed on the upper and lower surfaces of the upper board 161 of the coil board 16. 13, a coil 162 having a winding shape of “eight” is formed. In addition, the high frequency coupler 1a attaches | subjects the same code | symbol about the structure similar to the high frequency coupler 1 mentioned above, and shall omit the description.

  Specifically, the high-frequency coupler 1a differs from the high-frequency coupler 1 described above in the configuration of the coil 162 mounted on the coil substrate 16.

  That is, the coil 162 is obtained by connecting coils 162a and 162b having approximately the same number of turns in the winding direction to each other by the winding direction reversing portion 17a. Here, unlike the high-frequency coupler 1, the winding direction reversing unit 17a according to the high-frequency coupler 1a has a coil pitch d of each of the coils 162a and 162b, that is, the winding of the coil wire in the coils 162a and 162b. It is wider than the interval. This is to make the field radiation distribution of the high-frequency coupler 1a symmetrical in the plane, as will be apparent from the performance evaluation described later. The area of the winding direction inversion portion 17a is preferably adjusted according to the overall size of the coil 162. Furthermore, in the winding direction inversion portion 17a, the coupling strength can be further increased as will be described later by increasing the line width of the coil wire in the vicinity thereof. For example, in the winding direction reversing part 17a, the line width of the coil wire at the part can be expanded as compared with other parts by forming a circular shape as shown in FIG.

  Next, in order to investigate the performance of the high-frequency coupler 1a configured as described above, an analysis was performed using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft. The analysis model has the configuration shown in FIG. 10, and polyimide is used for the base material 14 and the upper substrate 161. The dimensions of the printed circuit board 11 and the coil substrate 16 are 8 × 8 × 1 in length × width × thickness, respectively. .6 mm and 8 × 8 × 0.4 mm.

  FIG. 11 is a plan view showing the coordinates of this analysis model, and is a view of the surface side of the coil substrate 16. In FIG. 11, the upper substrate 161 is transmitted so that the winding state of the coil 162 can be seen. As described above, the direction parallel to the wiring 18b is the X direction, and the wiring is performed within the plane of the upper substrate 161. The direction perpendicular to 18b is the Y direction, and the thickness direction of the high frequency coupler 1a is the Z axis.

  FIG. 12 is an analysis of the magnetic field vector distribution of the coil 162, and represents the magnetic field vector corresponding to the resonance frequency on the XY plane 200 μm below the upper surface of the coil substrate 16 in the thickness direction Z. Here, in the coil 162, the magnetic field vector is directed to the X direction minus side on the Y direction plus side, and the magnetic field vector is directed to the X direction plus side on the Y direction minus side. For this reason, the flow of the magnetic field is generated so as to circulate around the winding direction inversion portion 17a, that is, in a closed loop on the XY plane.

  In this way, in the high frequency coupler 1a, as with the high frequency coupler 1, by making the flow of the magnetic field a closed loop, the inductance of the coil 162 can be increased and the Q value as an antenna can be increased. The coupling efficiency of the high frequency coupler can be increased. For example, in an application using a longitudinal wave of an electric field such as TransferJet (registered trademark), the electric field is applied in the Z-axis direction from the periphery of the winding direction inversion portion 17a at the center of the coil 162 where the voltage level of the signal is highest. Since longitudinal waves are efficiently emitted, the degree of coupling can be increased.

  FIGS. 13A and 13B each analyze the electric field strength distribution on the XY plane 1 mm and 5 mm away from the upper surface of the coil substrate 16, and the strength is based on the center of the coil 162. Is represented by contour lines. In the figure, contour lines are indicated by dotted lines. Here, the electric field strength distribution is a symmetric distribution with the winding direction reversing portion 17a installed at substantially the center of the high-frequency coupler 1a substantially at the center. Therefore, the high frequency coupler 1a is preferable from the viewpoint of easily arranging the antenna because it is easy to understand the point at which the maximum coupling strength can be obtained when communicating with another high frequency coupler.

  In particular, the high-frequency coupler 1a is isotropic and stable compared to the above-described high-frequency coupler 1 even when a positional shift in the XY in-plane direction occurs between the high-frequency couplers disposed at the opposite positions. Communication is possible. This is because the electric field intensity analyzed by the high frequency coupler 1 as shown in FIG. 6 spreads in the Y direction compared to the X direction, whereas the high frequency coupler 1a according to the modification shown in FIG. This is because the electric field intensity of both extends substantially uniformly in both the X and Y directions.

  Next, in order to investigate the communication status of the high-frequency coupler 1a, the coupling strength when the high-frequency couplers 1a and 150 communicate with each other in the same manner as in FIG. 7 was analyzed. The coupling strength is evaluated by the transmission characteristic S21 of the S parameter used for evaluating the high frequency transmission characteristic, and the input / output terminal 18c of the wiring 18b serving as the signal input / output terminal of the high frequency coupler 1a is used as the power input port. The transmission characteristic S21 is analyzed using the input / output end of the high-frequency coupler 150 as an output port.

  The frequency characteristics of the coupling strength S21 are examined in a state where the high-frequency couplers 1a and 150 face each other so that their central axes coincide with each other and are spaced apart from each other. In this example, for one high frequency coupler 150, a reference high frequency coupler including a plate-like coupling electrode 150a was used as a reference machine for evaluation.

  FIG. 14 is an analysis of the frequency characteristics of the coupling strength S21 when the facing distance between the high frequency couplers 1a and 150 is 15 [mm] and 100 [mm]. In the case of the opposing distance 15 [mm] and the opposing distance 100 [mm], the coupling strength S21 is −23 dB and −48 dB, respectively, near the communication frequency of 4.5 GHz. As is clear from this result, the coupling strength S21 is large when the communication distance is a short distance, that is, about 15 [mm], and is far away as a non-communication distance, that is, when the distance is about 100 [mm]. However, since it is small, it has good communication characteristics when short-range communication is used.

  As described above, the high-frequency coupler 1a according to the modified example, as with the high-frequency coupler 1 described above, can achieve both good communication characteristics and mechanical strength, and can be small in size. Can be achieved. Furthermore, the high-frequency coupler 1a can perform isotropic and stable communication even when a positional shift occurs in the XY in-plane direction with a high-frequency coupler disposed at an opposing position.

<Modification 2>
Next, as a second modified example according to the first embodiment, a configuration of a high-frequency coupler 1b as shown in FIG. 15 will be described.

  As shown in FIG. 15, the high-frequency coupler 1 b includes a printed circuit board 11 and a coil substrate 16, as in the above-described high-frequency coupler 1, and a plurality of through holes are formed on the upper and lower surfaces of the upper substrate 161 of the coil substrate 16. 13, a coil 162 having a winding shape of “eight” is formed. In addition, the high frequency coupler 1b attaches | subjects the same code | symbol about the structure similar to the high frequency coupler 1 mentioned above, and shall omit the description.

  Specifically, the high-frequency coupler 1b differs from the high-frequency coupler 1 described above in the configuration of the coil 162 mounted on the coil substrate 16 and the printed board 11.

  That is, the coil 162 is obtained by connecting coils 162a and 162b having approximately the same number of turns in the winding direction to each other by the winding direction reversing portion 17a. Here, unlike the high-frequency coupler 1, the winding direction reversing unit 17a according to the high-frequency coupler 1b has a wider area than the coil pitch d of the coils 162a and 162b. This is to make the field radiation distribution of the high-frequency coupler 1b symmetrical in the plane. The area of the winding direction inversion portion 17a is preferably adjusted according to the overall size of the coil 162. Further, in the winding direction inversion portion 17a, in order to increase the line width of the coil wire in the vicinity, the shape of the coil wire in the part is expanded as compared with other parts as shown in a circular shape as shown in FIG. Has been.

  Further, in the high-frequency coupler 1b according to the modified example 2, a hollow portion 19 is formed in a part of the printed circuit board 11 from the viewpoint of improving communication characteristics. Specifically, the cavity portion 19 is formed at a position facing the winding direction reversing portion 17 a formed on the coil substrate 16 disposed on one surface of the printed circuit board 11. Thus, the cavity portion 19 is formed at a position facing the coil winding direction reversing portion 17a where the electric field is strong, that is, immediately below the thickness direction of the substrate. In particular, the deeper the shape of the cavity portion 19 is in the thickness direction. The effect of improving communication characteristics is high. This effect will be specifically described in the analysis results described later.

  The cavity 19 is formed by cutting the printed board 11. In addition to this, for example, the printed circuit board 11 in which the cavity portion 19 is formed may be completed by bonding a substrate provided with a through hole to a substrate that is not cut.

  Next, in order to investigate the performance of the high-frequency coupler 1b having the above-described configuration, analysis using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft Corporation was performed. The analysis model has the configuration shown in FIG. 15, and polyimide is used for the base material 14 and the upper substrate 161. The dimensions of the printed circuit board 11 and the coil substrate 16 are 8 × 8 × 1 in length × width × thickness, respectively. .6 mm and 8 × 8 × 0.4 mm.

  FIG. 16 is a plan view showing the coordinates of this analysis model, and is a view of the surface side of the coil substrate 16. In FIG. 16, the upper substrate 161 is transmitted so that the winding state of the coil 162 can be seen. As described above, the direction parallel to the wiring 18b is the X direction, and the wiring is performed within the plane of the upper substrate 161. The direction perpendicular to 18b is the Y direction, and the thickness direction of the high frequency coupler 1b is the Z axis.

  FIG. 17 is an analysis of the magnetic field vector distribution of the coil 162, and represents the magnetic field vector corresponding to the resonance frequency in the XY plane 200 [μm] below the upper surface of the coil substrate 16 in the thickness direction Z. Here, in the coil 162, the magnetic field vector is directed to the X direction minus side on the Y direction plus side, and the magnetic field vector is directed to the X direction plus side on the Y direction minus side. For this reason, the flow of the magnetic field is generated so as to circulate around the winding direction inversion portion 17a, that is, in a closed loop on the XY plane.

  In this way, in the high frequency coupler 1b, as with the high frequency coupler 1, by making the flow of the magnetic field a closed loop, the inductance of the coil 162 can be increased and the Q value as an antenna can be increased. The coupling efficiency of the high frequency coupler can be increased. For example, in an application using a longitudinal wave of an electric field such as TransferJet (registered trademark), the electric field is applied in the Z-axis direction from the periphery of the winding direction inversion portion 17a at the center of the coil 162 where the voltage level of the signal is highest. Since longitudinal waves are efficiently emitted, the degree of coupling can be increased.

  18A and 18B, respectively, analyze the electric field intensity distribution on the XY plane 1 mm and 5 mm away from the upper surface of the coil substrate 16, and the intensity is based on the central portion of the coil 162. Is represented by contour lines. In the figure, contour lines are indicated by dotted lines. The electric field strength distribution is a symmetric distribution with the winding direction reversing portion 17a installed substantially at the center of the high-frequency coupler 1b substantially at the center. Therefore, the high-frequency coupler 1b is preferable from the viewpoint of easily arranging the antenna because it is easy to understand the point at which the maximum coupling strength can be obtained when communicating with another high-frequency coupler.

  That is, the high-frequency coupler 1b is connected to the high-frequency coupler 1 even if a positional shift in the XY in-plane direction occurs between the high-frequency coupler 1a and the high-frequency coupler disposed at the opposite position. Compared to isotropic and stable communication.

  Next, in order to investigate the communication status of the high-frequency coupler 1b, the coupling strength when the high-frequency couplers 1b and 150 face each other and perform communication was analyzed. The coupling strength is evaluated by the transmission characteristic S21 of the S parameter used for evaluating the high frequency transmission characteristic. The input / output terminal 18c of the high frequency coupler 1b is used as the power input port, and the input / output terminal of the high frequency coupler 150 is used. Is used as an output port to analyze the transmission characteristic S21.

  The frequency characteristics of the coupling strength S21 are examined in a state where the high-frequency couplers 1b and 150 face each other so that their central axes coincide with each other and are spaced apart from each other. In this example, for one high frequency coupler 150, a reference high frequency coupler including a plate-like coupling electrode 150a was used as a reference machine for evaluation.

  FIG. 19 shows an analysis model of the high-frequency coupler 1b, in which the cavity 19 having an XY plane dimension of 3.5 mm × 4 mm is aligned with its center axis at the center of the winding direction inversion part 17a, and its short axis is in the X direction. The bond strength S21 is examined when the depth defined in the Z-axis direction of the cavity 19 is 0.4 mm, 0.7 mm, and 1.2 mm. Here, simply changing the depth of the cavity 19 shifts the resonance frequency, making comparison difficult. Therefore, in each result of FIG. 19, the resonance frequency is almost the same with the length of the coil 162. It is adjusting. Moreover, in FIG. 19, the thing without the cavity part 19 was analyzed as a comparison object.

  As is apparent from the analysis result shown in FIG. 19, the high-frequency coupler 1 b is improved in coupling strength by providing the cavity portion 19, and in particular, as the depth of the cavity portion 19 increases, the coupling becomes better. Strength can be realized.

<Second Embodiment>
Next, with reference to FIG. 20, the high frequency coupler 2 which concerns on 2nd Embodiment is demonstrated.

  As shown in FIG. 20, the high-frequency coupler 1 according to the second embodiment includes a printed board 21 corresponding to the first board according to the present invention and a coil board 26 corresponding to the second board according to the present invention. With.

  The printed circuit board 21 has a base material 24 made of a dielectric, and a ground layer 22 formed on one surface of the base material 24.

  The coil substrate 26 is a substrate placed on the printed circuit board 21 so as to face a substrate surface 21b different from the substrate surface 21a on which the ground layer 22 is formed. The coil substrate 26 includes an upper substrate 261 made of a dielectric, and the coil 262 that functions as the above-described coupling electrodes 103 and 107 is formed on the upper substrate 261.

  Here, for the coil substrate 26, the direction parallel to the wiring 28b described later is the X direction, the direction perpendicular to the wiring 28b in the plane of the upper substrate 261 is the Y direction, and the thickness direction of the high frequency coupler 2 is the Z axis. The three-dimensional orthogonal coordinate system is defined and described.

  The coil 262 is wound with a coil wire on the upper and lower surfaces of the upper substrate 261 through a plurality of through holes 23 so that the winding shape is substantially “eight” as shown in FIG. Is formed. Specifically, the coil 262 is formed by forming a wiring for forming a coil on the upper and lower surfaces of the upper substrate 261 by a patterning technique, and opening the formed upper and lower coil pattern ends with a drill or the like to conduct a conductive plating process. Alternatively, it is formed by electrically connecting through a through hole 23 in which a conductive paste is embedded.

  In the present embodiment, the coil 262 has a substantially “8-shaped” winding shape when viewed from the YZ plane in the coil substrate 26, but is not limited to this, and any cross-section in the coil substrate 26. As long as it is formed on the coil substrate 26, the winding shape as viewed from FIG.

  The coil 262 is formed by connecting the coils 262a and 262b having the same winding direction T shown in FIG. Therefore, a portion corresponding to approximately half the total length of the coil 262 is a line width extending portion 27. The total length of the coil 262 is adjusted to be approximately half the frequency of communication.

  Here, the winding direction is a direction in which a substantially “eight-letter shape” that is a winding shape is drawn when viewed from an arbitrary cross section of the coil substrate. In the present embodiment, the winding direction T is a direction in which substantially “8-shaped” is drawn when viewed in the −X direction of the YZ plane of the coil substrate 26. Specifically, the coils 262a and 262b both correspond to the winding shape and the winding direction T as shown in FIG. FIG. 21 also shows a magnetic field B generated when a current flows in the winding direction T and the forward direction.

  Further, one end of the coil 262 is electrically connected to the ground layer 22 formed on one side of the printed board 21 through the through hole 25a, and the resonance line 28a and the wiring 28b are connected to the other end. . The other end of the wiring 28b is formed with an input / output end 28c serving as a signal input / output end. As described above, one end of the resonance line 28a is connected to the coil 162, and the other end is a through hole. It is electrically connected to the ground layer 22 formed on one side of the printed circuit board 21 through 25b.

  Here, the resonance line 28a is for adjusting the steepness of the resonance characteristic of the high-frequency coupler 2, and the steepness of the resonance characteristic can be adjusted by changing the length of the resonance line 28a. The through holes 25a and 25b are paths through which the base material 24 of the printed circuit board 21 is electrically connected, and, like the through holes 23 described above, are subjected to a conductive plating process or a conductive paste filling process. It is formed with.

  Examples of materials for the base material 24 of the printed circuit board 21 and the upper substrate 261 of the coil substrate 26 include plasticity such as glass epoxy (FR4), glass composite (CEM3), paper epoxy (FR3), and paper phenol (XPC). Although a member is used, a low dielectric material such as flexible polyimide, liquid crystal polymer, or Teflon may be used. In particular, when the input / output end 28c is provided by protruding the wiring 28b of the coil substrate 26 with respect to the printed circuit board 21, the substrate 261 is a flexible substrate made of a flexible material using thin polyimide or the like. It is preferable. This is because the input / output end 28c protruded from the printed circuit board 21 can be flexibly bent and the degree of freedom in attaching the transmission / reception circuit unit 104 and the high-frequency coupler 2 is improved. Because you can.

  Next, in order to investigate the performance of the high-frequency coupler 2 having the above-described configuration, analysis using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft Corporation was performed. The analysis model has the configuration shown in FIG. 20, and polyimide is used for the base material 24 and the upper substrate 261. The dimensions of the printed circuit board 21 and the coil substrate 26 are 8 × 8 × 1 in length × width × thickness, respectively. .6 mm and 8 × 8 × 0.4 mm.

  FIG. 22 is a plan view showing the coordinates of this analysis model, and is a view of the surface side of the coil substrate 26. In FIG. 22, the upper substrate 261 is transmitted so that the winding state of the coil 262 can be seen, the direction parallel to the wiring 28 b is the X direction, and the direction perpendicular to the wiring 28 b is within the plane of the upper substrate 261. The Y direction is set, and the thickness direction of the high frequency coupler 2 is set as the Z axis.

  FIG. 23 is an analysis of the magnetic field vector distribution of the coil 262, and represents the magnetic field vector corresponding to the resonance frequency on the XY plane 200 μm below the upper surface of the coil substrate 26 in the thickness direction Z. Here, in the coil 262, the X direction plus side forms a closed loop in which the magnetic field vector faces counterclockwise on the XY plane, and on the X direction minus side, the magnetic field vector turns clockwise on the XY plane. Constructs a closed loop.

  The reason why the magnetic field flows in this manner will be described in detail below. As shown in FIG. 21, the winding directions of the coils 262a and 262b constituting the coil 262 are the same. This is because the polarity of the current is reversed between the coil 262a and the coil 262b.

  First, paying attention to the individual coils 262a and 262b, the winding shape is a figure-eight shape. When a current is passed through the coil having such a shape, as shown in FIG. It has the property that the direction of the magnetic field that penetrates the two rings that constitutes is reversed. Therefore, when the eight-shaped coils are continuously overlapped, that is, wound, the direction of the magnetic field is the same in each of the overlapping rings. As a result, two solenoid coils having different winding directions are adjacent to each other. It can be considered that they are arranged side by side, and a magnetic field closed loop is formed between adjacent solenoid coils, so that the inductance of the coil can be increased. However, in the case of a high-frequency current, the polarity of the current changes at a half wavelength due to the phase relationship, so that a phenomenon occurs in which magnetic fields cancel each other because the current has a locally different polarity.

  In the high frequency coupler 2, since one end of the coil 262 is short-circuited to the ground layer 22 through the through hole 25b, the current is maximized at that portion, and the entire length of the coil 262 is reduced to a half wavelength. Therefore, the current is also maximized at the other end of the coil 262.

  Here, the currents at both ends of the coil 262 are opposite in polarity because the phases are different by 180 degrees. If the same 8-shaped coils in the winding direction are simply stacked, the generated magnetic fields cancel each other and the closed loop is However, in the high-frequency coupler 2, the magnetic field flow can be made to be two closed loops inside the coil 262 for the following reason.

  That is, in the high-frequency coupler 2, in the line width extending portion 27, which is an intermediate portion of the coil 262, the coil pitch d of 262 a, 262 b, that is, wider than the winding interval of the coil wire in the coils 262 a, 262 b, Since the distance between the positive and negative solenoids is wide, there is little interference between the coils 262a and 262b, and two closed loops are formed on the positive and negative sides in the X direction as shown in the analysis results of FIG. The inductance of the coil 262 can be increased.

  Therefore, in the high frequency coupler 2, since the inductance of the coil 262 can be increased and the Q value as the antenna can be increased, the coupling efficiency of the high frequency coupler can be increased. For example, in an application that uses a longitudinal wave of an electric field such as TransferJet (registered trademark), the vertical direction of the electric field extends in the Z-axis direction from the periphery of the line width extension portion 27 at the center of the coil 262 where the voltage level of the signal is highest. Since waves are emitted efficiently, the degree of coupling can be increased. The voltage level is highest around the line width extension portion 27 because the entire length of the coil 262 is approximately half the communication wavelength, and one end of the coil is electrically connected to the ground layer 22 where the voltage level is zero. Because it is.

  FIG. 24 shows the electric field intensity distribution on the XY plane that is 1 mm away from the upper surface of the coil substrate 26, and the intensity is represented by contour lines with the central portion of the coil 262 as a reference. In the figure, contour lines are indicated by dotted lines. Here, the electric field strength distribution has a substantially circular diameter with the line width extending portion 27 installed substantially at the center of the high-frequency coupler 2 being substantially at the center. For this reason, the high frequency coupler 2 is preferable from the viewpoint of facilitating antenna arrangement in that it is easy to understand the point at which the maximum coupling strength can be obtained when communicating with another high frequency coupler.

  That is, the high-frequency coupler 2 can perform isotropic and stable communication even when a positional shift occurs in the XY in-plane direction with the high-frequency coupler disposed at the opposite position.

  Next, in order to investigate the communication status of the high frequency coupler 2, a high frequency coupler 250 including a plate-like coupling electrode 250a is used as a reference machine for evaluation as shown in FIG. The bond strength when communication was performed with 250 facing each other was analyzed. The coupling strength is evaluated by the transmission characteristic S21 of the S parameter used for evaluating the high frequency transmission characteristic, and the input / output terminal 28c of the wiring 28b serving as the signal input / output terminal of the high frequency coupler 2 is used as the power input port. The transmission characteristic S21 is analyzed using the input / output end of the high-frequency coupler 250 as an output port.

  FIG. 25 shows a relative arrangement between the high-frequency couplers 2 and 250 using the coupling strength S21 for analysis. As shown in FIG. 25, the frequency characteristics of the coupling strength S21 are examined with the high-frequency couplers 2 and 250 facing each other so that the central axes thereof coincide with each other and spaced by 15 mm and 100 mm.

  FIG. 26 shows an analysis of the frequency characteristics of the coupling strength S21 when the facing distance between the high-frequency couplers 2 and 250 is 15 [mm] and 100 [mm]. In the case of the facing distance of 15 mm and the facing distance of 100 [mm], the coupling strength S21 is −23 dB and −45 dB, respectively, near the communication frequency of 4.5 GHz. As is clear from this result, the coupling strength S21 is large when the communication distance is a short distance, that is, about 15 [mm], and is far away as a non-communication distance, that is, when the distance is about 100 [mm]. However, since it is small, it has good communication characteristics when short-range communication is used.

  As described above, in the high-frequency coupler 2 according to the second embodiment, the coupling electrode includes the coil 262 wound around the upper and lower surfaces of the coil substrate 26 through the through hole 23. For example, FIG. As compared with the high frequency coupler in which the coupling electrode 208 is supported by the metal wire 207 as shown in FIG. 31, the coupling electrode can realize a better degree of mechanical strength. This is because the coupling electrode of the high frequency coupler 2 according to the second embodiment is formed in the coil substrate 26, so that the coupling electrode 208 as shown in FIGS. 30 and 31 is a metal. This is because damage to the coupling electrode can be prevented even when an impact or the like is applied, as compared with the case where it is supported by the wire 207.

  In the high-frequency coupler 2, the entire length of the coil 262 is approximately half the communication wavelength, and one end of the coil 262 is electrically connected to the ground layer 22. By increasing the signal level at the extended portion 27, the strength of coupling with other coupling electrodes arranged at opposing positions is increased, and good communication characteristics can be realized.

  Furthermore, the high-frequency coupler 2 is a coil in which the coupling electrode is wound so that the winding shape in the cross-sectional direction of the coil substrate 26 is a figure 8, so that the total length of the coil 262 is approximately half the communication wavelength. Even if the length of the antenna device is, the entire coil 262 can be reduced, and the entire antenna device can be reduced in size.

  As is clear from this point, the high-frequency coupler 2 can achieve downsizing of the entire high-frequency coupler 2 while realizing both good communication characteristics and mechanical strength.

  Further, as shown in FIG. 25, the high-frequency coupler 2 is isotropically and stably communicates even if a positional shift occurs in the XY plane direction with respect to the high-frequency couplers disposed at the opposing positions. It can be performed.

  In the high frequency coupler 2, the coil substrate 26 does not necessarily have the resonance line 28a and the through hole 25b that electrically connects the resonance line 28a and the ground layer, but the resonance line 28a is provided. This is particularly preferable in that the coupling strength and the resonance frequency can be adjusted.

  For example, when the resonance line 28a and the through hole 25b are not provided, the frequency characteristic of the coupling strength S21 with the facing distance between the high frequency coupler being 15 [mm] and 100 [mm] is as shown in FIG. become. Here, when the facing distance is 15 [mm], the coupling strength S21 is −25.4 dB in FIG. 27, whereas FIG. 26 is −22.8 dB. From this result, for example, the presence of the resonance line 28a can be adjusted to increase the coupling strength. Further, when the facing distance is 15 [mm], the bandwidth from the peak to −3 dB down is −955 GHz in FIG. 27 and 0.45 GHz in FIG. 26. From this result, the resonance line 18a can be adjusted so that, for example, the bandwidth is narrowed.

  In general, since the strength of the coupling strength and the bandwidth are in a trade-off relationship, when these balances are insufficient with respect to the required specifications, the resonance line 28a and the through hole 25b are used like the high frequency coupler 2. By mainly changing the length of the resonance line 28a, the characteristics of the strength of the coupling strength and the bandwidth can be adjusted.

<Modification>
Next, as a modification of the second embodiment, the configuration of a high-frequency coupler 2a as shown in FIG. 28 will be described.

  As shown in FIG. 28, the high-frequency coupler 2a includes a printed circuit board 21 and a coil substrate 26, as in the above-described high-frequency coupler 2a. A plurality of through holes are formed on the upper and lower surfaces of the upper substrate 261 of the coil substrate 26. 23, a coil 262 having a winding shape of “eight” is formed. In addition, the high frequency coupler 2a attaches | subjects the same code | symbol about the structure similar to the high frequency coupler 2 mentioned above, and shall omit the description.

  Specifically, unlike the high frequency coupler 2 described above, the high frequency coupler 2a has a cavity 29 formed in a part of the printed circuit board 21 from the viewpoint of improving communication characteristics. Specifically, the hollow portion 29 is formed at a position facing the line width extending portion 27 formed on the coil substrate 26 disposed on one surface of the printed circuit board 21. In this way, the cavity 29 is formed at a position facing the line width extension 27 where the electric field is strong, that is, directly below the thickness direction of the substrate. In particular, the communication characteristics increase as the shape of the cavity 29 increases in the thickness direction. Improvement effect goes up. This effect will be specifically described in the analysis results described later.

  The cavity 29 is formed by cutting the printed board 21. In addition to this, for example, the printed board 21 in which the cavity 29 is formed may be completed by bonding a board provided with a through hole to a board that has not been cut.

  Next, in order to investigate the performance of the high-frequency coupler 2a configured as described above, an analysis was performed using a three-dimensional electromagnetic field simulator HFSS manufactured by Ansoft. The analysis model has the configuration shown in FIG. 28, and polyimide is used for the base material 24 and the upper substrate 261. The dimensions of the printed circuit board 21 and the coil substrate 26 are 8 × 8 × 1 in length × width × thickness, respectively. .6 mm and 8 × 8 × 0.4 mm.

  FIG. 29 shows an analysis model of the high-frequency coupler 2a, in which the cavity 29 having an XY plane dimension of 3.5 × 4 mm is aligned with its center axis at the center of the line width extension 27, and its minor axis is directed in the X direction. The coupling strength S21 when the depth defined in the Z-axis direction of the cavity 29 is 0.4, 1, and 1.6 mm is examined. Here, simply changing the depth of the cavity 29 shifts the resonance frequency, making comparison difficult. Therefore, in each result of FIG. 29, the resonance frequency is almost the same as the length of the coil 262. It is adjusted. Further, in FIG. 29, a comparative example without the hollow portion 29 was also analyzed.

  As is clear from the analysis result shown in FIG. 29, the high-frequency coupler 2a is improved in coupling strength by providing the cavity 29, and in particular, the coupling becomes better as the depth of the cavity 29 increases. Strength can be realized.

1, 1a, 1b, 2a, 102, 106, 150, 250 High frequency coupler, 11, 21, 201 Printed circuit board, 11a, 11b, 21a, 21b Board surface, 12, 22 Ground layer, 13, 15a, 15b, 23 25a, 25b Through hole, 14, 24 Base material, 16, 26 Coil substrate, 161, 261 Upper substrate, 162, 162a, 162b, 262, 262a, 262b Coil, 17, 17a, Winding direction reversing portion, 18a, 28a Resonant line, 18b, 28b Wiring, 18c, 28c Input / output end, 19, 29 Cavity, 27 Line width extension, 100 Communication system, 101, 105 Communication device, 103, 107, 150a, 208, 250a Coupling electrode 104, 108 Transmission / reception circuit section, 202 Ground, 203 Stub, 2 5 transceiver circuit, 207 a metal wire,

Claims (7)

In an antenna device that performs information communication by electromagnetic field coupling between a pair of opposed electrodes,
A first substrate having a ground layer formed on one surface of the dielectric;
A second substrate made of a dielectric disposed on the first substrate so as to face a surface different from the surface on which the ground layer is formed;
Another antenna device is formed of a coil in which a coil wire is wound so that a winding shape becomes a figure 8 through a through hole on the upper and lower surfaces of the second substrate, and is arranged at an opposing position. A coupling electrode that is electromagnetically coupled to the electrode to enable communication;
The coupling electrode has one end of the wound coil connected to a signal input / output end and the other end electrically connected to a ground layer formed on the first substrate. An antenna device characterized in that the overall length of the coil is approximately half the length of the communication wavelength.   The antenna device according to claim 1, wherein the coil is wound so that a winding direction is reversed at a central portion that is substantially half of the entire length of the coil.   3. The antenna device according to claim 2, wherein a winding interval of the coil wire is widened and a line width of the coil wire is widened at a central portion of the coil.   4. The antenna device according to claim 3, wherein a hollow portion is formed in the first substrate at a position facing a central portion of the coil formed by being wound around the second substrate. . The coil is wound in the same direction over the entire length of the coil,
2. The antenna device according to claim 1, wherein a winding interval of the coil wire is widened and a line width of the coil wire is widened at a central portion of the coil.   6. The antenna device according to claim 5, wherein a hollow portion is formed in the first substrate at a position facing a central portion of the coil formed by being wound around the second substrate. . In a communication device that performs information communication by electromagnetic field coupling between electrodes of other communication devices arranged at opposing positions,
A first substrate having a ground layer formed on one surface of the dielectric;
A second substrate made of a dielectric disposed opposite to a surface different from the surface on which the ground layer is formed;
Another antenna device is formed of a coil in which a coil wire is wound so that a winding shape becomes a figure 8 through a through hole on the upper and lower surfaces of the second substrate, and is arranged at an opposing position. A coupling electrode that is electromagnetically coupled to the electrode to enable communication;
A transmission / reception processing unit for performing transmission / reception processing of signals,
The coupling electrode has one end of the wound coil connected to the transmission / reception processing unit and the other end electrically connected to a ground layer formed on the first substrate. A communication device characterized in that the overall length of the coil is approximately half the length of the communication wavelength.

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