JP2013093643A - Antenna device and radio communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an antenna device equipped with a frequency variable function which can further be reduced in size, and a radio communication apparatus incorporating the antenna device.SOLUTION: There is provided an antenna device comprising: an inverted L-shaped element conductor which is formed on one face of a dielectric substrate; an annular first conductor having an opening which is formed on one face of the dielectric substrate; an annular second conductor, formed on the other face of the dielectric substrate, which has an opening facing the opposite direction to the direction which the opening of the first conductor faces and is opposed to the first conductor across the dielectric substrate; a ground conductor which is formed in a region on the other face of the dielectric substrate corresponding to a region opposed to the element conductor across the first conductor on the one face of the dielectric substrate; a capacitance element which is formed so as to close up the opening in the first or the second conductor; and a variable capacitance element which is formed so as to close up the opening in the first or the second conductor whichever does not have the capacitance element in the opening thereof.

Description

  The present invention relates to an antenna device and a radio communication device, and more particularly to an antenna device and a radio communication device applicable to a mobile communication terminal.

  In recent years, wireless communication devices have been required to support a plurality of wireless communication systems. Therefore, an antenna device mounted on such a wireless communication device is required to have a function of operating in a plurality of frequency bands or a wide band in addition to downsizing. As an antenna apparatus that operates in a plurality of frequency bands, for example, there is a tunable antenna that can change the frequency band. In addition, there is an antenna device in which an adjustment circuit combining a plurality of conductor lines having different lengths is provided in a feeding portion of a monopole antenna to vary the frequency band (for example, see Patent Document 1 below) . Furthermore, there is an antenna device that changes a frequency band by switching a selection circuit connected to a parasitic element of the antenna device (see, for example, Patent Document 2 below).

International Publication No. 07/042615 Pamphlet Special table 2009-510900

  However, since the antenna device described in Patent Document 1 has a mechanism for changing a frequency band by switching a plurality of conductor lines having different lengths with a switch, a conductor line corresponding to the number of variable frequency bands is required. Become. Therefore, when the number of variable frequency bands increases, the number of necessary conductor lines increases, and it becomes difficult to reduce the size of the antenna device. In addition, the antenna device described in Patent Document 2 has a mechanism in which a selection circuit is connected to a parasitic element and a frequency band is changed by switching a switch. Therefore, when the number of variable frequency bands increases, it is necessary to increase the number of parasitic elements, and it is difficult to reduce the size of the antenna device.

  In view of these problems, the present inventor has devised an antenna device in which the resonance frequency is made variable by switching between short-circuiting / opening of a switch provided on the SRR conductor (see JP 2011-103630 A). This antenna device has a configuration in which an SRR conductor is disposed between an inverted L-shaped element conductor and a ground conductor, and a resonance frequency is varied by controlling short-circuiting / opening of a plurality of switches provided on the SRR conductor. Have. By applying this configuration, an antenna device (conventional example) can be realized that can be reduced in size and easily change the resonance frequency to a desired frequency band as compared with the antenna devices described in Patent Documents 1 and 2 above. can do.

  However, also in the antenna device according to the above-described conventional example, a plurality of switches must be provided on the SRR conductor according to the variable range of the resonance frequency. If the variable range is widened, an increase in the number of components is inevitable. Furthermore, the control of the switch becomes complicated by increasing the number of switches. Accordingly, the present invention has been devised in view of such problems, and an object of the present invention is to mount an antenna device having a frequency variable function capable of further miniaturization and the antenna device. It is to realize a wireless communication apparatus.

  In order to solve the above problems, according to one aspect of the present invention, an inverted L-shaped element conductor having a feeding point and formed on one surface of a dielectric substrate, and one surface of the dielectric substrate is provided. An annular first conductor having an opening formed on the other surface of the dielectric substrate and having an opening in a direction opposite to a direction in which the opening of the first conductor faces; An annular second conductor facing the first conductor across the body substrate, and the dielectric substrate corresponding to a region facing the element conductor across the first conductor on one surface of the dielectric substrate Of the ground conductor formed in the region on the surface, the capacitive element formed so as to close the opening of the first or second conductor, and the capacitive element is formed in the opening of the first or second conductor. Variable capacitance element formed so as to close the opening of the non-conductive conductor It comprises, when the antenna device is provided.

  With this configuration, an SRR is formed by the first conductor and the second conductor, and a large wavelength shortening effect can be obtained by multiplying it with a change in effective permeability in the vicinity of the resonance frequency of the SRR. Therefore, the antenna device can be downsized. Become. In addition, by controlling the capacitance value of the variable capacitance element, the resonance frequency of the antenna device forming the LC resonance circuit can be freely switched, and a plurality of frequency bands can be handled. Furthermore, since the resonance frequency is varied by controlling the capacitance value, unlike the configuration in which the resonance frequency is switched by a switch or the like, the number of parts does not increase even if the number of frequency bands to be supported increases, and the size of the device is reduced. It doesn't get bigger. As a result, the antenna device and the wireless communication device equipped with the antenna device can be further reduced in size. Further, even if the number of frequency bands to be handled increases, it is only necessary to control the capacitance value of the variable capacitance element, so that the control is not complicated.

  The capacitive element may be formed in the opening of the first conductor. In this case, the variable capacitive element is formed in the opening of the second conductor. Furthermore, the antenna device may further include a control unit that adjusts the capacitance value of the variable capacitance element so as to obtain a desired resonance frequency. Further, the control unit may be configured to change the capacitance value of the variable capacitance element within a predetermined range that exceeds the capacitance value of the capacitance element. The first conductor and the second conductor form an SRR (Split Ring Resonator).

  In order to solve the above-described problem, according to an aspect of the present invention, a wireless communication device equipped with the antenna device is provided. With this configuration, a small wireless communication apparatus that can support a plurality of frequency bands is realized. Note that the control unit may be a control function of the wireless communication device.

  As described above, according to the present invention, it is possible to realize an antenna device having a frequency variable function that can be further reduced in size and a wireless communication device equipped with this antenna device.

It is the figure which showed the example of a structure of the antenna apparatus carrying SRR. It is the figure which showed the structural example of the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment. It is the figure which showed the dielectric constant characteristic of the antenna device which concerns on this embodiment. It is the figure which showed the magnetic permeability characteristic of the antenna device which concerns on this embodiment. It is the figure which showed the VSWR characteristic of the antenna device which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment. It is the figure which showed the structural example of the SRR conductor which comprises the antenna apparatus which concerns on this embodiment.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Overview)
The antenna device according to the present embodiment uses a material characteristic in the vicinity of the resonance frequency of an SRR (Split Ring Resonator), provides a variable capacitance element at the opening of each conductor constituting the SRR, and its capacitance value The resonance frequency can be varied by changing. The SRR referred to here is a structure made of an annular metal (conductive member) separated at least partially, and expresses the characteristics described later.

(Characteristics of SRR)
First, general characteristics of the SRR will be briefly described.

  In general, the SRR has a structure in which two metal rings having “Split (opening)” in a part of the ring are arranged concentrically. Because of these structural features, it is also called “double ring SRR”. The ring portion of the SRR functions as an inductance (L), and the gap portion between the rings functions as a capacitance (C).

For example, when an electromagnetic wave (incident magnetic field) including a magnetic field component perpendicular to the plane including the ring is incident on the SRR, an induced current (J) that creates a repulsive magnetic field that cancels the incident magnetic field is induced on the ring according to the principle of electromagnetic induction. . This induced current flows along each ring, but the flow of the induced current is blocked by an opening provided in a part of the ring, and an equal amount of positive and negative charges is accumulated between the two rings. Furthermore, the charge accumulated between the two rings flows from the inner side to the outer side (and from the outer side to the inner side) via the capacitance (C) between the rings, thereby forming a closed circuit of LC resonance in the SRR. Accordingly, the resonance frequency f ₀ of the SRR is expressed as the following equation (1) based on the capacitance (C) and the inductance (L) that form the SRR.

…（１）

... (1)

  A large induced current is induced in the vicinity of this resonance frequency, and a large repulsive magnetic field is created. Therefore, the effective permeability of the SRR changes greatly. When an electromagnetic wave having a frequency close to the resonance frequency is incident, the electromagnetic wave resonates with the SRR and is largely absorbed. That is, the imaginary part of the magnetic permeability corresponding to the absorption of the electromagnetic wave increases as the frequency of the electromagnetic wave approaches the resonance frequency of the SRR. Further, the real part (Real) of the magnetic permeability changes according to the change of the imaginary part. The amount of change in the real part increases as the amount of change in the imaginary part increases (that is, the Q value of the SRR increases). When adjusted to an appropriate condition, a negative permeability is realized on the high frequency side of the resonance frequency. be able to.

  The characteristics of SRR have been described above. As described above, the SRR is based on the principle of operation of a magnetically driven LC resonance circuit, and the resonance frequency of the SRR can be freely designed depending on the design of the resonator structure.

(Conventional example: Configuration of antenna device 100 using SRR)
Next, the configuration of the antenna device 100 using SRR will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of an antenna device 100 using SRR.

  As shown in FIG. 1, the antenna device 100 includes a first SRR conductor 101, a second SRR conductor 102, a dielectric substrate 103, an element conductor 104, a feeding point 105, and a ground conductor 106. The element conductor 104 is formed in an L shape, for example. Further, the element conductor 104 is connected to the ground conductor 106 through the feeding point 105. The element conductor 104 functions as an inverted L-type antenna (Inverted-L antenna).

  The first SRR conductor 101 is formed on one surface (hereinafter, the front surface) of the dielectric substrate 103. The second SRR 102 is formed on the other surface (hereinafter referred to as the back surface) of the dielectric substrate 103. In the example of FIG. 1, the first SRR conductor 101 and the second SRR conductor 102 are formed in a rectangular ring shape. The first SRR conductor 101 has an opening 101a that separates a part of the rectangular ring. Similarly, the 2nd SRR conductor 102 has the opening part 102a which isolate | separated a part of rectangular ring. Note that the shapes of the first SRR conductor 101 and the second SRR conductor 102 are not limited to the rectangular ring shape, and can be deformed into an arbitrary ring shape (see, for example, FIGS. 5A to 5C). Further, the first SRR conductor 101 and the second SRR conductor 102 may have different shapes.

  The first SRR conductor 101 and the second SRR conductor 102 are disposed at positions facing each other with the dielectric substrate 103 interposed therebetween. Further, the first SRR conductor 101 and the second SRR conductor 102 are alternately arranged such that the opening 101a of the first SRR conductor 101 and the opening 102a of the second SRR conductor 102 face each other. For example, when the opening 101 a of the first SRR conductor 101 faces the right side on the surface of the dielectric substrate 103, the opening 102 a of the second SRR conductor 102 faces the left side on the back surface of the dielectric substrate 103.

  With the above-described structure, the first SRR conductor 101 and the second SRR conductor 102 each function as an inductance (L) similarly to each ring of a general SRR. In addition, a capacitance (C) is formed between the first SRR conductor 101 and the second SRR conductor 102 that are arranged to face each other with the dielectric substrate 103 interposed therebetween. Therefore, the first SRR conductor 101 and the second SRR conductor 102 function as an SRR. Therefore, the antenna device 100 includes the inductance (L) depending on the lengths of the first SRR conductor 101 and the second SRR conductor 102, the arrangement of the first SRR conductor 101 and the second SRR conductor 102, and the dielectric constant and thickness of the dielectric substrate 103. It operates at a resonance frequency determined by a capacitance (C) that depends on.

  The configuration of the antenna device 100 using SRR has been described above. In the antenna device 100, the inductance (L) and the capacitance (C) are fixed at the time of design. Therefore, in order to make the resonance frequency variable, it is necessary to provide a mechanism for making the inductance (L) or the capacitance (C) variable. Therefore, the present inventor has devised a mechanism that allows the lengths of the first SRR conductor 101 and the second SRR conductor 102 to be switched by a switch (Japanese Patent Laid-Open No. 2011-103630). However, when switches are used, more switches are required as the number of frequency bands to be used increases. When many switches are provided, the size of the apparatus increases and the control becomes complicated.

  In view of these problems, the present inventors have devised a mechanism for making the resonance frequency variable without using a switch. When this mechanism is applied, an antenna device (an antenna device 200 described later) that is smaller and easy to control is realized. Hereinafter, the configuration of the antenna device 200 according to the present embodiment will be described in detail.

(Embodiment: Configuration of Antenna Device 200)
The configuration of the antenna device 200 according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a configuration example of the antenna device 200 according to the present embodiment.

  As shown in FIG. 2, the antenna device 200 includes a first SRR conductor 201, a second SRR conductor 202, a dielectric substrate 203, an element conductor 204, a feeding point 205, a ground conductor 206, and a first capacitive element 211. And a second variable capacitance element 212.

  The element conductor 204 is formed in an L shape, for example. The element conductor 204 is connected to the ground conductor 206 via the feeding point 205. The element conductor 204 functions as an inverted L-type antenna (Inverted-L antenna). Further, the inverted L-shaped antenna formed by the element conductor 204 operates at a frequency whose length in free space is approximately ¼ wavelength. Note that the inverted L-shaped antenna formed by the element conductor 204 disposed on the dielectric substrate 203 is affected by the wavelength shortening effect corresponding to the material constant of the dielectric substrate 203.

  The first SRR conductor 201 is formed on one surface (hereinafter, surface) of the dielectric substrate 203. The second SRR 202 is formed on the other surface (hereinafter referred to as the back surface) of the dielectric substrate 203. In the example of FIG. 2, the first SRR conductor 201 and the second SRR conductor 202 are formed in a rectangular ring shape. The first SRR conductor 201 has an opening 201a that separates a part of the rectangular ring. Similarly, the second SRR conductor 202 has an opening 202a that separates a part of the rectangular ring. Note that the shapes of the first SRR conductor 201 and the second SRR conductor 202 are not limited to the rectangular ring shape, and can be deformed to an arbitrary ring shape. Further, the first SRR conductor 201 and the second SRR conductor 202 may have different shapes.

  The first SRR conductor 201 and the second SRR conductor 202 are disposed at positions facing each other with the dielectric substrate 203 interposed therebetween. Further, the first SRR conductor 201 and the second SRR conductor 202 are alternately arranged such that the opening 201a of the first SRR conductor 201 and the opening 202a of the second SRR conductor 202 face each other. For example, when the opening 201 a of the first SRR conductor 201 faces the right side on the surface of the dielectric substrate 203, the opening 202 a of the second SRR conductor 202 faces the left side on the back surface of the dielectric substrate 203. Thus, by providing the SRR formed by the first SRR conductor 201 and the second SRR conductor 202, a large wavelength shortening effect can be obtained by multiplying with the change of the effective magnetic permeability in the vicinity of the resonance frequency of the SRR, and the antenna device can be made compact. Can be realized.

  In other words, the positional relationship between the first SRR conductor 201 and the second SRR conductor 202 can be freely designed to some extent if the change in effective permeability near the resonance frequency of the SRR becomes sufficiently large. For example, when viewed in the X direction, the first SRR conductor 201 and the second SRR conductor 202 may overlap each other as shown in FIG. 9A, or as shown in FIG. 9B. And the second SRR conductor 202 may be partially overlapped. Alternatively, as shown in FIGS. 9C and 9D, the first SRR conductor 201 and the second SRR conductor 202 may be arranged so as not to overlap at all.

  A capacitive element 211 is formed in the opening 201a of the first SRR conductor 201 so as to close the opening 201a. That is, each end of the capacitive element 211 is connected to each end of the first SRR conductor 201, and the capacitive element 211 is electrically connected to both ends of the first SRR conductor 201. Similarly, a variable capacitance element 212 is formed in the opening 202a of the second SRR conductor 202 so as to close the opening 202a. That is, each end of the variable capacitance element 212 is connected to each end of the second SRR conductor 202, and both ends of the second SRR conductor 202 are electrically connected to the variable capacitance element 212. The variable capacitance element 212 varies the capacitance value of the second SRR conductor 202. Therefore, by controlling the capacitance value of the variable capacitance element 212, it becomes possible to freely switch the resonance frequency of the antenna device 200 that forms the LC resonance circuit.

  Here, with reference to FIG. 3 and FIG. 4, the configuration of the first SRR conductor 201 formed on the surface of the dielectric substrate 203 and the configuration of the second SRR conductor 202 formed on the back surface of the dielectric substrate 203 will be described in more detail. Explained.

  As shown in FIG. 3, a first SRR conductor 201 whose opening 201 a is closed by a capacitive element 211 and an inverted L-shaped element conductor 204 are formed on the surface of the dielectric substrate 203. On the other hand, as shown in FIG. 4, a second SRR conductor 202 in which an opening 202 a is closed with a variable capacitor 212 and a ground conductor 206 are formed on the back surface of the dielectric substrate 203. The SRR formed by the first SRR conductor 201 and the second SRR conductor 202 is disposed in a region sandwiched between the element conductor 204 and the ground conductor 206 in the Z direction. The capacitance value of the capacitive element 211 is set to 1 pF, for example. In this case, the capacitance value of the variable capacitance element 212 is set to a range of 1 pF to 2.4 pF.

  The configuration of the antenna device 200 has been described above. In the example of FIG. 2, the configuration is shown in which the capacitance value of the element formed in the opening 202 a of the second SRR conductor 202 is varied. However, the capacitance value of the element formed in the opening 201 a of the first SRR conductor 201 is varied. It may be configured.

(Characteristics of antenna device 200)
Next, the characteristics of the antenna device 200 will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram illustrating a dielectric constant characteristic of the antenna device 200. On the other hand, FIG. 7 is a diagram showing the magnetic permeability characteristics of the antenna device 200. 6 and 7, the solid line indicates the characteristic of the real part (Real), and the broken line indicates the characteristic of the imaginary part (Imaginary).

When c is the speed of light in vacuum, μ _γ is the relative permeability of the medium, and ε _γ is the relative permittivity of the medium, the phase velocity V _p is generally expressed by the following equation (2). That is, according to the material constants μ _γ and ε _γ , a wavelength shortening effect of (ε _γ μ _γ ) ^−1/2 times expressed by the following formula (3) is obtained. Therefore, the wavelength shortening effect obtained by multiplying the material constants μ _γ and ε _{γ of} the dielectric substrate 203 by the change in the effective magnetic permeability in the vicinity of the resonance frequency of the SRR can be obtained.

…（２）

... (2)

  The resonance frequency of the SRR can be set by adjusting the conductor lengths of the first SRR conductor 201 and the second SRR conductor 202. Therefore, by adjusting the conductor lengths of the first SRR conductor 201 and the second SRR conductor 202, the resonance frequency can be set in the vicinity of the LTE frequency band indicated by hatching in FIGS. With such a setting, as shown in FIG. 7, a characteristic that the effective permeability greatly changes within the LTE frequency band can be obtained.

  As described above, by providing the SRR formed by the first SRR conductor 201 and the second SRR conductor 202 with the dielectric substrate 203 sandwiched between the inverted L-shaped element conductor 204 and the ground conductor 206, A change in effective permeability in the vicinity of the resonance frequency of the SRR is multiplied by the material coefficient of the dielectric substrate 203, and a wavelength shortening effect larger than the wavelength shortening effect caused by the material constant of the dielectric substrate 203 is obtained. Therefore, the resonance frequency shifts to a low frequency range. Further, the resonance frequency can be varied by changing the capacitance value of the variable capacitance element 212 provided in the opening 202 a of the second SRR conductor 202. For example, as shown in FIG. 8 (VSWR characteristics), the resonance frequency can be varied between the LTE frequency band and the GSM frequency band.

  Note that LTE (Long Term Evolution) is a next-generation communication system that is being standardized by the standardization organization 3GPP for the third-generation mobile phone system “W-CDMA”, which is one of high-speed data communication specifications for mobile phones. For example, a frequency band of 700 MHz is used. GSM (Global System for Mobile Communications) is one of wireless communication systems used for mobile phones, and uses, for example, frequency bands such as 850 MHz and 900 MHz.

(About control method)
By the way, the capacitance value of the variable capacitance element 212 is controlled by a control unit (not shown) of a wireless communication device in which the antenna device 200 is mounted. For example, the control unit detects the frequency of the received signal and controls the capacitance value of the variable capacitance element 212 according to the detected frequency. For example, when detecting the frequency of the received signal corresponding to LTE, the control unit controls the capacitance value of the variable capacitance element 212 so that the resonance frequency is in the vicinity of the LTE frequency band. On the other hand, when the frequency of the received signal corresponding to GSM is detected, the control unit controls the capacitance value of the variable capacitance element 212 so that the resonance frequency is in the vicinity of the GSM frequency band.

  When the capacitance value of the capacitive element 211 is 1 pF, the characteristic impedance is 50Ω, and the capacitance value of the variable capacitive element 212 is varied from 1 pF to 2.4 pF, the VSWR characteristic of the antenna device 200 changes as shown in FIG. When the capacitance value of the variable capacitance element 212 is 1 pF, the resonance frequency (minimum value of VSWR) is located on the high frequency side. As the capacitance value of the variable capacitance element 212 increases, the resonance frequency shifts to the low frequency side. As shown in FIG. 8, in this example, the GSM frequency band and the LTE frequency band are covered by varying the capacitance value of the variable capacitance element 212 in the range of 1 pF to 2.4 pF.

  The characteristics of the antenna device 200 have been described above. As described above, it is possible to vary the resonance frequency in a desired frequency band by varying the capacitance value of the variable capacitance element 212. In addition, since the frequency band is changed by switching the capacitance value of the variable capacitance element 212, the size of the apparatus does not increase even when the number of frequency bands of the wireless communication system to be used increases. Therefore, it is possible to provide a small wireless communication apparatus that can be applied to a plurality of wireless communication systems. Furthermore, since the resonance frequency can be freely changed simply by adjusting the capacitance value of the variable capacitance element 212, the control is easy.

  By the way, it is also possible to perform an auto-tuning operation in the control unit of the wireless communication device by using the variable operation of the resonance frequency. In this case, as an initial state, for example, the capacitance value of the variable capacitance element 212 is set to be the same as the capacitance value of the capacitance element 211. The control unit may be configured to automatically tune to a desired reception signal by gradually shifting the resonance frequency to the low frequency side or the high frequency side while gradually changing the capacitance value of the variable capacitance element 212. Good.

(Modification: SRR shape)
Next, other shapes of the SRR applicable to the antenna device 200 will be described with reference to FIGS. 5A to 5C. FIG. 5A shows the shape of the SRR conductor 401 having the opening 401a from which a part of the polygonal shape is separated. FIG. 5B shows the shape of the SRR conductor 402 having the opening 402a from which a part of the quadrangular shape is separated. FIG. 5C shows the shape of the SRR conductor 403 having an opening 403a from which a part of the ring shape is separated. Note that the shape is not limited to this as long as the above-described SRR characteristics can be realized.

  The first SRR conductor 201 and the second SRR conductor 202 can be transformed into various ring shapes like the SRR conductors 401, 402, and 403 shown in FIGS. 5A to 5C. Even when the shape is changed to such a shape, the capacitive element 211 or the variable capacitive element 212 is provided in the openings 401a, 402a, and 403a of the SRR conductors 401, 402, and 403. Therefore, the resonance frequency of the antenna device 200 can be varied by varying the capacitance value of the variable capacitance element 212.

(About manufacturing method)
Since the antenna device 200 is formed by forming the first SRR conductor 201 and the second SRR conductor 202 on the front and back surfaces of the dielectric substrate 203 positioned between the inverted L-shaped element conductor 204 and the ground conductor 206, respectively. It can be manufactured by a simple manufacturing method. For example, the front and back surfaces of the dielectric substrate 203 are etched to form the first SRR conductor 201 and the second SRR conductor 202, or the first SRR conductor 201 and the second SRR conductor 202 are attached to the front and back surfaces of the dielectric substrate 203. Or can be formed. Since the manufacturing method is simple, it is possible to easily cope with a change in design of the antenna device 200, which contributes to a reduction in manufacturing cost.

  Further, the dielectric substrate 203 may be made of a flexible dielectric film or the like. When the dielectric substrate 203 is made of a flexible dielectric film, the dielectric substrate 203 can be bent, so that it can be easily mounted on a wireless communication device. In addition to the dielectric substrate 203, the element conductor 204 and the ground conductor 206 may be made of a flexible material.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood. For example, in the above description, the element conductor has an inverted L shape, but the open end of the element conductor may be further refracted to have a U shape. In other words, the SRR may be surrounded by a U-shaped element conductor and surrounded by a ground conductor and an element conductor. In this case, the arrangement area of the element conductor is reduced, which contributes to further miniaturization of the antenna device.

100, 200 Antenna device 101, 201 First SRR conductor 102, 202 Second SRR conductor 103, 203 Dielectric substrate 104, 204 Element conductor 105, 205 Feed point 106, 206 Ground conductor 211 Capacitor element 212 Variable capacitor element

Claims (6)

An inverted L-shaped element conductor having a feeding point and formed on one surface of a dielectric substrate;
An annular first conductor having an opening formed on one surface of the dielectric substrate;
An annular first electrode formed on the other surface of the dielectric substrate, having an opening at a position facing a direction opposite to the direction in which the opening of the first conductor faces, and facing the first conductor across the dielectric substrate. Two conductors,
A ground conductor formed in a region on the other surface of the dielectric substrate corresponding to a region facing the element conductor across the first conductor on one surface of the dielectric substrate;
A capacitive element formed so as to close the opening of the first or second conductor;
Of the first or second conductor, a variable capacitance element formed so as to close an opening of a conductor in which the capacitance element is not formed in an opening;
An antenna device comprising: The capacitive element is formed in an opening of the first conductor,
The antenna device according to claim 1, wherein the variable capacitance element is formed in an opening of the second conductor. The antenna device according to claim 1, further comprising a control unit that adjusts a capacitance value of the variable capacitance element so as to obtain a desired resonance frequency. The antenna device according to claim 3, wherein the control unit changes a capacitance value of the variable capacitance element within a predetermined range that exceeds a capacitance value of the capacitance element. The antenna device according to claim 1, wherein the first conductor and the second conductor form an SRR (Split Ring Resonator). A wireless communication device comprising the antenna device according to any one of claims 1 to 5.

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