JP2012178760A - High frequency coupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupler that has satisfactory contactless transmission characteristics over a wide band by using a coil and a polar plate formed on a substrate.SOLUTION: A high frequency coupler 10 includes a spiral-shaped coil section 30, a polar plate section 40 formed inside the coil shape, and a feed section 32. They are formed by integral patterning of a conductor on one surface (obverse surface) of a substrate 12. The other surface (reverse surface) of the substrate 12 is grounded.

Description

  The present invention relates to a high frequency coupler, and more particularly to a high frequency coupler that enables communication by high frequency coupling.

  UWB (Ultra Wide Band), one of ultra-short-distance communication technologies, has advantages such as high transmission speed and easy coexistence with other wireless systems. It is attracting attention as one of the leading technologies in various fields. And the technique which effectively performs the high frequency coupling between the information apparatuses which communicate using UWB is disclosed.

  As one of such techniques, a communication system that transmits a high-frequency signal by electric field coupling between a high-frequency coupler of a transmitter and a receiver has been proposed (see, for example, Patent Document 1). As shown in FIG. 6, this communication system includes a circuit unit that performs data processing, a transceiver including a high-frequency coupler that transmits a high-frequency signal as an electrostatic field or an induction electric field, and a high-frequency coupler of a transmitter and a receiver. The impedance matching unit for matching the impedance in The high frequency coupler is composed of an electrode plate. And if the pole plates which are the high frequency couplers of the transmitter and the receiver face each other and a capacitance is generated between the two pole plates, communication becomes possible. The impedance matching unit performs impedance matching between the electrode plates of the transmitter and the receiver, that is, at the coupling portion, and suppresses reflected waves. As a result, it is configured to operate as a bandpass filter that passes a desired high frequency band between the high frequency coupler of the transmitter and the receiver. In other words, it is an ultra-short-range communication system capable of high-speed data transmission that transmits UWB signals by electric field coupling between the high-frequency couplers of the transmitter and the receiver. Then, the communication operation is started by selecting the other party who wants to communicate intuitively without complicated settings. As a result, when there is no communication partner in the vicinity, no coupling relationship occurs, that is, no radio waves are radiated, so that other communication systems are not disturbed. In addition, even when radio waves arrive from a distance, the coupler does not receive radio waves, so that it is possible to avoid the interference from other communication systems.

JP 2008-271606 A

  By the way, in the capacitive coupling method (FIG. 6) using the electrode plate disclosed in Patent Document 1, there is a problem that it is difficult to provide broadband transmission characteristics at a low frequency. For example, when transmitting a signal in a band of several hundreds of MHz below 1 GHz at a frequency equal to or lower than UWB, it is necessary to enlarge the electrode plate size in order to increase transmission efficiency at a low frequency. In this case, in addition to the problem of the electrode plate size, the signal is attenuated at the high frequency part of the band, so it is difficult to maintain the wide band characteristics. On the contrary, in order to maintain the high frequency characteristics, when the electrode plate size is suppressed, there is a trade-off relationship that the low frequency part of the band is bad as it is. In any case, there is a problem that the deterioration of the transmission characteristics of either the low frequency part or the high frequency part in the band must be compromised.

  Furthermore, in order to adjust the frequency band to be transmitted, in addition to the electrode shape of the high-frequency coupling portion, it is essential to form an impedance matching portion including a chip component, and there is a problem that impedance adjustment is complicated and component costs are required.

  This invention is made | formed in view of such a condition, and it aims at providing the technique which solves said subject.

The high-frequency coupler of the present invention includes a spiral coil portion formed on a substrate and a capacitor portion formed on the substrate, and the coil portion and the capacitor portion function as a high-frequency coupling means. .
The coil part and the capacitor part may be formed on the same surface on the substrate.
The capacitor unit may be disposed inside the spiral shape of the coil unit.
The coil part and the capacitor part may be formed by patterning together.

  According to the present invention, it is possible to provide a coupler having good transmission characteristics over a wide band in a non-contact manner by using a coil and an electrode plate formed on a substrate.

It is a figure which shows the external appearance of the high frequency coupler which concerns on embodiment. It is a figure which shows the external appearance of the two high frequency couplers which perform communication based on embodiment. It is a figure which shows the coupling principle of the high frequency coupler based on embodiment. It is a figure which shows the simulation coil shape based on embodiment. It is a figure which shows the simulation result regarding a broadband characteristic based on embodiment. It is a figure which shows the coupling principle of the high frequency coupler based on a prior art.

  Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings. The outline of the present embodiment is as follows.

  FIG. 1 is a diagram illustrating a configuration of a high-frequency coupler 10 according to the present embodiment. FIG. 2 is a diagram showing a state where communication is performed by two high-frequency couplers 10, and FIG. 2A shows a state where two high-frequency couplers 10 are separated and communication is not possible, and FIG. b) shows the external appearance of a state where two high frequency couplers 10 are close to each other and can communicate with each other.

  As shown in FIG. 1, the high-frequency coupler 10 includes a spiral coil portion 30, an electrode plate portion 40 formed inside the coil shape, and a power feeding portion 32. They are formed by patterning conductors integrally on one surface (surface) of the substrate 12. The coil unit 30 and the electrode plate unit 40 function as the high-frequency coupling unit 20. The other surface (back surface) of the substrate 12 is grounded.

  The coil portion 30 has a spiral pattern. Specifically, the coil portion 30 starts from the outer periphery of the coil and is connected to the electrode plate portion 40 included in the center of the coil. Here, it is assumed that the spiral shape has at least approximately one turn. A power feeding unit 32 is connected to a winding start portion on the outer periphery of the coil. As described above, the back surface of the substrate 12 falls to the ground, but the coil portion 30 itself does not fall to the ground. That is, it is not a loop coil format. In the present embodiment, the spiral shape is an octagonal shape, but naturally it may be a circular shape, or a hexagonal shape or a quadrangular shape may be adopted.

  The electrode plate portion 40 is disposed so as to be included in the spiral central portion of the coil portion 30. Here, the electrode plate portion 40 has a square shape, but is not limited to this, and may be a circular shape, an octagonal polygon shape, or an arbitrary shape. Although details will be described later, the frequency characteristics in the configuration of only the coil unit 30 can be improved by providing the coil unit 30 with the electrode plate unit 40 added thereto. And the frequency characteristic which needs an improvement can be set and adjusted by selecting the shape and magnitude | size of the electrode plate part 40 suitably.

  The power feeding section 32 is designed with a 50Ω line by a grounded coplanar waveguide.

  In signal transmission using the high-frequency coupler 10, as shown in FIG. 2B, the substrate 12 on which the coil pattern such as the coil portion 30 and the electrode plate portion 40 is formed is brought close to each other. Signal transmission by contact.

  As described above, by using the coil unit 30 and the electrode plate unit 40 in the high-frequency coupler 10, the resonance of the magnetic field coupling of the coil unit 30 and the capacitive coupling of the electrode plate unit 40 causes a frequency from several hundred MHz to several. Broadband transmission with a frequency of GHz is possible. That is, as shown in the transmission principle of FIG. 3, the electrode plate part 40 arranged in the center of the coil part 30 and the electrode plate part 40 arranged in the center of the opposite coil part 30 facing each other are capacitively coupled. Further, signal transmission is performed by magnetic coupling with the surrounding coil unit 30.

  In general, it is difficult to perform broadband transmission including a low frequency range of several hundreds of MHz by using only the respective transmission methods of signal transmission based on resonance between magnetic field and electric field coupling between a coil and an electrode plate. At high frequencies in the UWB band, signals can be radiated easily in terms of frequency, and the electrode plate can be made smaller in wavelength. However, when signal transmission at GHz or lower, for example, 100 MHz to 200 MHz, is performed by capacitive coupling between the plates, there is a need to increase the size of the plates, the proximity between the plates, and the need for impedance matching parts. There is a difficulty.

  Therefore, transmission by magnetic field coupling using only a coil can be considered. In general, transmission using only a magnetic field coupling by a coil has better transmission characteristics around several hundred MHz than transmission by capacitive coupling, and signal attenuation with respect to distance is small. In addition, there is a feature that as the number of turns of the coil increases, the magnetic field coupling force increases and the low frequency transmission characteristics are improved. However, when the number of turns is increased, the frequency characteristics appear alternately as a good frequency and a bad frequency due to the effect of the self-resonant frequency of the coil along with the problem of an increase in size, and a flat characteristic cannot be obtained in a wide band. There is a problem. If the number of turns is reduced, the transmission characteristic itself is lowered and the target characteristic is not satisfied. Thus, it is difficult to satisfy the broadband transmission characteristic even with a single coil.

  Therefore, in the present embodiment, in the high-frequency coupling unit 20 (the coil unit 30 and the electrode plate unit 40), L (inductance) of magnetic field coupling of the coil unit 30 and C (capacitance) of capacitive coupling of the electrode plate unit 40 are used. This generates resonance and realizes good broadband transmission. In particular, this resonance effect contributes to improving the low frequency characteristics in the band.

  FIG. 4 shows simulation model shapes, and FIG. 5 shows simulation results regarding the broadband characteristics of these shapes. Four types of simulation model shapes are illustrated. As shown in the drawing, (a) a C-containing coil corresponding to the high-frequency coupler 10 of the present embodiment, (b) a single coil, (c) a single included C, and (d ) Same coil size C. FIG. 5 is a graph showing the S21 characteristic of the S parameter that is generally used for evaluating a high-frequency transmission circuit or the like, and shows transmission loss. The S21 characteristic is obtained by dividing the output power after transmission by the input power and taking 10 logs, and 0 dB indicates lossless transmission. That is, the closer to 0 dB, the better the transmission characteristics. This model does not include matching component elements such as L (inductance) and C (capacitance) in the signal input section, and the graph shows transmission characteristics with simple shape elements.

  The simulation was performed by arranging the high frequency couplers 10 to face each other as shown in FIG. The distance between terminals was fixed at 0.8 mm. First, the transmission characteristics of only the included coil will be described. Generally, there is a tendency that the signal suddenly attenuates as the distance between the electrode plates increases, but at the distance of 0.8 mm exemplified here, the attenuation is large and it is understood that the characteristics are worse than the characteristics of the single coil. Since the characteristic of the coil inclusion C alone is also greatly attenuated, it can be understood that efficient transmission using only C (capacitance) is difficult at this distance.

  Next, the characteristics of a single coil will be described. As shown, the characteristics around 100 MHz to 300 MHz are deteriorated. In order to improve this band, measures to increase the magnetic field coupling force by increasing the number of coil turns can be considered. However, signal attenuation due to coil length extension and frequency characteristics due to coil self-resonance occur, and flat transmission characteristics are maintained over a wide band. It ’s gone.

  It continues and demonstrates the C inclusion coil corresponding to the high frequency coupler 10 of this embodiment. In the C inclusion coil, the transmission characteristic of 100 MHz to 300 MHz is improved from the resonance characteristic of L (inductance) of the coil part 30 and the C (capacitance) of the electrode plate part 40 located in the center of the coil, and good transmission characteristics over a wide band. It is possible to keep. That is, in the frequency band other than the low frequency range, the transmission characteristic of only the coil unit 30 mainly contributes. In the low frequency range, the weak resonance generated by L (inductance) of the coil portion 30 and C (capacitance) of the electrode plate portion 40 disposed in the center is low, which is difficult to transmit only by L (inductance). Transmission in the frequency range is possible.

As described above, this embodiment can be summarized and the following effects can be obtained.
(1) Broadband transmission of several hundred MHz to several GHz can be realized with a small coupling portion by resonance by magnetic field coupling by the spiral coil portion 30 and electric field coupling of the electrode plate portion 40.
(2) Realization of the high-frequency coupler 10 having both of the good characteristics of several hundred MHz in the magnetic field coupling of the coil section 30 and the wide band characteristic of the capacitive coupling in the electric field by the electrode plate section 40. it can.
(3) In the prior art, an impedance matching unit for adjusting the impedance is required in addition to the high frequency coupling unit. Since the present invention includes elements of L (inductance) of the coil section 30 and C (capacitance) of the electrode plate section 40 in the coupling section, impedance matching is possible with the shape of the coil section 30. That is, the high-frequency coupler 10 that does not require a matching unit can be realized depending on the shape design of the pattern of the high-frequency coupling unit 20.
(4) Both analog and digital original signal transmission is enabled. Regarding digital pulse signal transmission, the capacitive coupling method using the electrode plate of the prior art does not have a broadband transmission characteristic and pulse transmission is difficult, so that it is necessary to perform modulation or the like, but this embodiment does not require such processing. .
(5) By expanding the size of the coil section 30, it is possible to have a broadband characteristic at a lower frequency, and it can be applied to a power supply coil in a non-contact manner.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to each of those components and combinations thereof, and such modifications are also within the scope of the present invention. For example, in the high frequency coupler 10, the position of the electrode plate portion 40 is disposed inside the coil portion 30, but may be provided in the outer peripheral portion of the coil portion 30 or in the middle of the spiral shape. Moreover, the electrode plate part 40 may be formed as a separate pattern. The frequency characteristics can be designed according to the desired band and the shape can be easily adjusted and changed.

  Note that the present invention relates to the results of research and development of the Japan Science and Technology Agency (JST) 2009 Consignment Development Adoption Project “Development of Contactless Connectors Using Electromagnetic Field Coupling”.

DESCRIPTION OF SYMBOLS 10 High frequency coupler 12 Board | substrate 20 High frequency coupling part 30 Coil part 40 Electrode board part

Claims (4)

A spiral coil formed on the substrate;
A capacitor portion formed on the substrate;
With
The coil unit and the capacitor unit function as high-frequency coupling means.   2. The high frequency coupler according to claim 1, wherein the coil part and the capacitor part are formed on the same surface on the substrate.   The high frequency coupler according to claim 1, wherein the capacitor unit is disposed inside a spiral shape of the coil unit.   The high frequency coupler according to any one of claims 1 to 3, wherein the coil part and the capacitor part are integrally patterned.

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