JP7109016B2 - antenna device - Google Patents

Description

The present invention relates to a small-sized directional antenna device for receiving weak radio waves from short-range wireless communication, particularly RF (Radio Frequency) tags and the like.

2. Description of the Related Art In recent years, RF tags have been used to manage people, various objects, vehicles, etc. using short-range wireless communication using weak radio waves. For example, when using the 315 MHz radio wave specified by the weak wireless standard that does not require a license, the size of the entire antenna device is about 1/4 to 1/2 of the wavelength (about 95 cm) in the case of a conventional antenna. size, i.e. at least about 25 cm in length and width. However, depending on the place of installation, it may not be possible to install an antenna of such a size, and a smaller antenna is desired.

Furthermore, in an area where many people and objects with RF tags move, it is necessary to receive only radio waves from a specific direction that do not contain unnecessary signals, or to control the entry and exit of objects. An antenna with a directional characteristic that emits radio waves only in one direction is required.

On the other hand, it has been reported that a substrate having a special periodic structure called a photonic crystal or an Electromagnetic Band Gap (EBG) structure can control transmission and reflection characteristics of electromagnetic waves. Physically, this is the energy bandgap of electromagnetic waves realized by a periodic structure, and exhibits steep and periodic frequency characteristics. has the property of being reflective. Such characteristics are electromagnetically classified as right-handed or left-handed electromagnetic wave propagation characteristics. In the right-hand system, the direction of vibration of the electric field, the direction of vibration of the magnetic field, and the direction of travel of the electromagnetic waves refer to the directions of the thumb, index finger, and middle finger of Fleming's right hand. Conversely, in the left-handed system, the vibration direction of the electric field, the vibration direction of the magnetic field, and the traveling direction of the electromagnetic waves point to the directions of the thumb, index finger, and middle finger of Fleming's left hand. That is, the right-handed system represents the normal propagation phenomenon of electromagnetic waves, and the left-handed system represents the state of electromagnetic waves that propagate in the opposite direction to normal. However, it is known that in the left-handed system, the propagation direction of energy is the same as that of the right-handed system, except that the apparent direction of propagation is opposite to that of the right-handed system.

Furthermore, the frequency band on the boundary between the right-handed system and the left-handed system may have a blocking characteristic that does not propagate electromagnetic waves, and such a frequency band is called an energy bandgap. In the frequency band of the energy bandgap, electromagnetic waves have a band rejection characteristic that cannot propagate on the substrate surface, and this can be equivalently considered as a state of high impedance. For this reason, this state is also referred to as the high impedance surface state. Conversely, a normal metal surface is a low impedance surface with a low surface resistance, or surface impedance, and is an electrical conductor. Also, the high-impedance surface is in a state called a magnetic conductor in terms of electromagnetism, and has dual characteristics with an electrical conductor.

Materials and structures in general that artificially realize a unique left-handed electromagnetic state and its boundary state in contrast to the normal right-handed electromagnetic state described above are called metamaterials. The photonic crystal and the Electromagnetic Band Gap (EBG) structure described above are a kind of metamaterial, and are electrically equivalent by an inductor (hereinafter referred to as L) and a capacitor (hereinafter referred to as C). It is experimentally shown that it can be represented by a circuit. A metamaterial is an artificial structure that does not occur in the natural world, and an antenna using this metamaterial technology has been proposed as a more compact and highly functional antenna device.

As an antenna using a metamaterial, there is an antenna device disclosed in Patent Document 1. In the antenna device that radiates or injects radio waves, this antenna device is electromagnetically coupled to a dipole antenna that feeds or receives power, radiates or injects radio waves, and the dipole antenna, and the overall operation mode is a left-handed system. A ladder-shaped auxiliary line that is not supplied or received, and in a resonant state, induces an induced current in the dipole antenna in the direction opposite to the direction of its own resonant current, forming a stopband in the frequency characteristics of the dipole antenna. It is an antenna device having an auxiliary line for Furthermore, the auxiliary line is a ladder-shaped line that is arranged parallel to the dipole antenna, has a plurality of parallel metal wires, and connects a plurality of identical or similar unit circuits in series in the direction of the metal wires. a unit circuit comprising: a connecting portion connecting each of a plurality of metal wires using at least one inductor; and at least one conductor inserted on at least one of the plurality of metal wires A circuit with a capacitor is disclosed.

Patent Document 2 discloses an EBG material that can be used for an antenna device, comprising a conductor plate, a plurality of metal plates having the same shape, a plurality of connectors, a capacitance element, and an inductance element, Each of the plurality of small metal plates is regularly arranged in a matrix, opposed to the upper portion of the conductor plate, electrically connected to the conductor plate through a connector, and has a plurality of metal plates adjacent to each other. Adjacent metal plates are electrically connected to each other through distributed capacitance elements. Each of the plurality of small metal plates is composed of a pair of a first small metal plate having a hollow portion and a second small metal plate disposed in the hollow portion of the first small metal plate via a gap. , a plurality of small metal plates are regularly arranged and arranged opposite to each other on the upper part of the conductor plate, and the second metal small plate and the conductor plate are electrically connected via the connector. Then, the adjacent first metal plates are electrically connected to each other via a plurality of capacitance elements dispersedly arranged for each adjacent metal plate, and one is arranged at the end of the second metal plate. Disclosed is an EBG material in which a first metal plate and a second metal plate forming a pair are electrically connected via a plurality of inductance elements arranged in a distributed manner.

JP 2009-296559 A Japanese Patent Application Laid-Open No. 2008-288770

The antenna device of Patent Document 1 is a dipole antenna or the like using a rod-shaped reflector formed by a linear one-dimensional LC circuit. In order to avoid interference of radio waves, it is intended to realize a steep filter characteristic, and is not intended to control the direction of transmission and reception or to reduce the size of the antenna device. Therefore, neither a structure for miniaturizing the antenna device while improving reception sensitivity nor a condition or structure for regulating the directivity characteristics of the antenna is disclosed, nor is there any theoretical explanation or suggestion.

The EBG material disclosed in Patent Document 2 is an example of a metamaterial that can be used for an antenna device. structure. Therefore, since it is a unit element having a wide metal plate, the characteristic impedance is relatively low, and the parasitic capacitance between it and the ground conductor is too large. It is a difficult structure to achieve both

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna device that has high sensitivity, can be easily miniaturized, and can easily control directivity characteristics. .

The present invention fundamentally changes the reflection phenomenon of electromagnetic waves by using a magnetic conductor type reflector which is a metamaterial composed of an LC auxiliary circuit in which a plurality of unit LC circuits are two-dimensionally connected. That is, since the tangential electric field component on the surface of the magnetic conductor reflector is non-zero, the electromagnetic waves from field emission antennas such as monopole antennas and dipole antennas and the reflected waves from the magnetic conductor reflector are in phase, and they do not cancel each other out. By bringing the antenna closer to the reflector, the electromagnetic wave can be effectively reflected, and the size of the reflector can be made smaller than the wavelength. By combining this magnetic conductor type reflector and an antenna, an antenna device which is extremely small compared to the size of the wavelength and whose directional characteristics are controlled can be realized.

The present invention is an antenna device that radiates or injects radio waves, and is mainly composed of an antenna that feeds or receives power, and a magnetic conductor type reflector that is close to the antenna and does not receive power, wherein the magnetic conductor type reflector is an inductor. and a capacitor are connected in series, and the LC auxiliary circuit is set to be able to reflect the electric field component in the same phase in a predetermined frequency band, the antenna and the magnetic conductor type reflector This is an antenna device in which plates are arranged close to each other and relatively strong radio waves are radiated or incident in a specific partial direction in which the antenna faces.

The LC auxiliary circuit is configured three-dimensionally by connecting a plurality of the unit LC circuits two-dimensionally and connecting other inductors to the unit LC circuits.

The LC auxiliary circuit is provided on an auxiliary circuit substrate, a ground substrate having a ground potential is provided in parallel with the LC auxiliary circuit, and each unit of the LC auxiliary circuit is provided between the LC auxiliary circuit and the ground substrate. A pillar having a conductor is provided to connect the LC circuit to the ground potential. The other inductor is preferably made of the conductor of the support.

The inductance of the other inductor of the LC auxiliary circuit can be adjusted by adjusting the length of the support that connects the auxiliary circuit substrate and the ground substrate.

The two-dimensional LC auxiliary circuits are connected in a triangular grid, a rectangular grid, or a hexagonal grid. Further, the radio waves can use linearly polarized waves, orthogonal two-polarized waves, or circularly polarized waves. In particular, the frequency of the radio wave is 315 MHz band, and the size of the entire device is 1/5 to 1/20 of the wavelength of the radio wave.

A plurality of antenna devices of the present invention may be used to configure an antenna system that detects the direction of arrival of radio waves from the difference in the strength of radio waves received by each of the antenna devices.

The antenna device of the present invention uses a magnetic conductor type reflector made up of LC auxiliary circuits of unit LC circuits arranged two-dimensionally to limit the radiation direction or reception direction of electromagnetic waves to only a predetermined direction. It has a directional characteristic that does not radiate or receive electromagnetic waves in directions other than the above. Furthermore, the antenna device disclosed in Patent Document 1 has a problem that the polarization direction, which is the direction of oscillation of the electromagnetic wave that can be reflected, is limited to the main polarization in the axial direction of the rod-shaped reflector. , the antenna device of the present invention can control not only the directivity of the main polarization but also the directivity of the cross-polarization component orthogonal thereto. Furthermore, the directional characteristics of circularly polarized waves can also be controlled. In particular, radio waves from RF tags, which is the field of application of the present invention, have different polarization directions depending on how the RF tag is attached. It is possible.

Moreover, the present invention greatly contributes to miniaturization of the antenna device. For example, at 315 MHz, which is the frequency of the weak radio standard, it is possible to realize a compact antenna device with a size of about one tenth of the wavelength. For example, the antenna device of Patent Document 1 shows an embodiment in which an auxiliary circuit with a length of 10 cm is placed close to a dipole antenna with a working frequency of about 580 MHz and a length of 25 cm. Therefore, in the case of the antenna device of Patent Document 1, the wavelength is about 52 cm and the size of the antenna is about half the wavelength. In contrast, in the present invention, the wavelength is about 95 cm, and the size of the antenna device can be made 9 to 10 cm. It is possible to realize a device having excellent directional characteristics.

An antenna system using a plurality of small antenna devices with high directivity characteristics of the present invention can easily and accurately detect the direction of arrival of radio waves.

It is a schematic perspective view showing a part of the antenna device of one embodiment of the present invention. 1 is a conceptual diagram showing a part of an LC auxiliary circuit in which unit LC circuits of the present invention are two-dimensionally arranged; FIG. It is an equivalent circuit which shows the unit LC circuit of the structure of one Embodiment of the antenna device of this invention. It is a graph which shows the frequency characteristic of the real part of the impedance of the unit LC circuit of this invention, and an imaginary part. In the LC auxiliary circuit of the antenna device of the present invention, FIG. It is a photograph (a) of the antenna device which is an experimental device of one example of the present invention, and a graph (b) showing the radiation pattern measurement result (316 MHz) of the antenna device.

An embodiment of the antenna device of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the antenna device 10 of this embodiment includes an antenna 12 that feeds or receives power and radiates or injects radio waves, and a magnetic conductor that is connected to or directly above the antenna 12 and arranged close to the antenna 12 and does not receive or receive power. and a type reflector 14 . The magnetic conductor type reflector 14 is a metamaterial composed of an LC auxiliary circuit 16 in which unit LC circuits 16a in which an inductor L and a capacitor C are connected in series and in parallel are two-dimensionally connected. is in phase with the electromagnetic waves from the antenna 12 .

1 and 2, the LC auxiliary circuit 16 is formed on the auxiliary circuit substrate 20, and the inductor L and the capacitor C of the unit LC circuit 16a are connected in series and parallel to form a two-dimensional arrangement. It is formed in the shape of a rectangular grid. The inductor L of the unit LC circuit 16a consists of a chip inductor L1 provided on the auxiliary circuit substrate 20, an inductance component L2 due to conductors between elements of the wiring pattern 22 forming the LC auxiliary circuit 16, and a column (to be described later). It consists of an inductance component L3 of 24 conductors. The inductance component L2 due to the conductor between the elements is due to all the wiring patterns 22 in the area forming the unit LC circuit 16a.

The inductance value of the inductance component L2 due to the conductor between the elements of the wiring pattern 22 can be adjusted by the pattern width d1 of the conductor in the vertical direction and the pattern width d2 in the horizontal direction of the wiring pattern 22 on the drawing. Similarly, the inductance of the inductance component L3 of the conductor of the column 24 is adjusted by the length of the column 24, which is a conductor, and set by the frequency of the radio waves used. The capacitance C of the unit LC circuit 16a is composed of chip capacitors C1 and C2, and its value is set according to the frequency of radio waves used.

The auxiliary circuit board 20 is integrally provided in parallel with a ground board 26 which is set to a ground potential via a support 24 . The post 24 is made of a metal that is a conductor, and as described above, the value of the inductance component L3 is set according to the length and thickness of the post 24 that is a conductor. When the post 24 is made of a non-conductor, the value of the inductance component L3 is set according to the width and length of the conductor pattern provided on the post 24 .

Next, the operating principle of the LC auxiliary circuit 16 constituting the magnetic conductor type reflector 14 as a metamaterial will be described below. Since the tangential direction electric field component on the surface of the magnetic conductor type reflector 14 is non-zero, the electromagnetic wave from the antenna 12 and the reflected wave from the magnetic conductor type reflector 14 are in phase and cancel each other out. Therefore, the distance between the antenna 12 and the magnetic conductor type reflector 14 can be minimized, and can be zero in principle. By bringing the antenna 12 and the magnetic conductor type reflector 14 close to each other, radio waves can be effectively reflected, and the size of the magnetic conductor type reflector 14 can be made extremely small compared to the wavelength. In this way, by combining the antenna 12 and the magnetic conductor type reflector 14 as close as possible, it is possible to realize an antenna device that is particularly small compared to the size of the wavelength of the radio waves to be used and whose directivity is controlled. becomes.

The fact that the LC auxiliary circuit 16 operates as the magnetic conductor reflector 14 and the electric field component of the reflected wave from the LC auxiliary circuit 16 is in phase with the electric field component of the incident wave can also be explained as follows. Each unit LC circuit 16a approaches a parallel resonance state, and a loop-shaped induced current is generated by the incident electromagnetic field. An induced current at a low frequency is generated in a direction that hinders changes in the magnetic field according to Faraday's law of electromagnetic induction. At this time, the direction of the induced current is opposite to the current of the antenna 12, and the phase of the induced current lags behind the phase of the current of the antenna 12 by 90 degrees. However, when the frequency becomes higher than that, the induced current cannot follow the change in the electromagnetic field due to the slight resistance component of the LC auxiliary circuit 16, and its phase begins to lag further. When the phase is delayed by 180 degrees, the direction of the induced current becomes completely opposite to the direction of the current of the antenna 12, resulting in an "anti-resonance state" in which the current resonates in the opposite phase. However, in the anti-resonance state, the radiation directivity characteristics of the antenna device 10 cannot be controlled. As the frequency further increases, the phase of the induced current is further delayed to 360 degrees, and this time the direction of the induced current becomes the same as the direction of the current of the antenna 12, and the phases are the same, ie, the "tuned resonance state". At this time, the electromagnetic field radiated from the antenna 12 is strongly radiated from the LC auxiliary circuit 16 toward the antenna 12, and is canceled on the opposite side of the antenna 12 to become weaker. This is the same phenomenon as the scattering of electromagnetic waves by harmonic oscillators. When the parameters of the LC circuit and wiring structure are adjusted so as to achieve a tuned resonance state at a desired frequency, the LC circuit behaves as the magnetic conductor type reflector 14 .

The reason why the anti-resonance state and the tuned resonance state occur in the LC circuit of the LC auxiliary circuit 16 can be theoretically explained as follows. Consider a parallel LCG circuit 18 as shown in FIG. 3, in which a conductance G is added to the parallel LC circuit. This conductance G represents the loss of the circuit. The physical elements are the dielectric loss of the substrate, the series electrical resistance of the metal terminals of the LC element converted into equivalent parallel elements, and the load resistance connected to the antenna coupled to the LC circuit by electromagnetic induction. Including things.

のように表され、その実部は、以下の式（２）で表される。

および虚部は、以下の式（３）で表される。

The impedance Z between terminals AB of this circuit is

and its real part is represented by the following equation (2).

and the imaginary part are represented by the following equation (3).

虚部が最大および最小となる角周波数ωは、式（５）で表される。

ここで、複合が負の場合に虚部が最大、複合が正の場合に虚部が最小となる。ただし、

である。 FIG. 4 is a graph showing the real part and the imaginary part as a function of the angular frequency ω. Here, the point at which the real part becomes maximum is the resonance frequency ω ₀ , which is expressed by Equation (4).

The angular frequency ω at which the imaginary part is maximum and minimum is expressed by Equation (5).

Here, the imaginary part is maximized when the composite is negative, and minimized when the composite is positive. however,

is.

That is, an anti-resonance point appears on the low frequency side close to the resonance frequency, and a tuning resonance point appears on the high frequency side. Since the above theory is strictly derived without using approximation, it can be seen that the phenomenon always occurs in a parallel resonant circuit with a loss.

In practice, the state of the current induced in the antenna and the LC circuit is as shown in FIG. FIG. 5(a) shows an anti-resonant state, in which the directions of the current in the antenna 12 in FIG. This is a resonance state, and the direction of the current of the antenna 12 and the loop current of the LC auxiliary circuit 16 on the side of the antenna 12 are the same.

Therefore, the operation of the LC circuit in Patent Document 1 is specified as anti-resonant as shown in the diagram of the LC circuit 6 and the antenna 12 in FIG. The operation of 16 can be said to be the tuned resonance of FIG. 5(b), which is a completely different operation.

In addition, the antenna device 10 of this embodiment can configure an antenna system using a plurality of them, and can detect the direction of arrival of radio waves from the difference in the strength of the radio waves received by each of the antenna devices 10 . With this antenna system, it is possible to grasp the moving direction and the moving state of the owner of the RF tag.

According to the antenna device 10 of this embodiment, the electromagnetic wave is radiated only in front of the magnetic conductor type reflector 14 by using the magnetic conductor type reflector 14 composed of the two-dimensional LC auxiliary circuit 16, or is emitted from the front. It has a directional characteristic that receives only electromagnetic waves, does not emit electromagnetic waves to the rear, and does not receive electromagnetic waves from the rear. Furthermore, the antenna device 10 can control not only the main polarized wave but also the cross-polarized wave component orthogonal thereto. For example, radio waves from RF tags have different polarization directions depending on how the RF tags are attached, and it is necessary to be able to control both vertical and horizontal polarizations. However, the antenna device 10 can easily cope with radio waves such as RF tags having different polarization directions. In addition, in the antenna device 10, the antenna 12 that receives and feeds power may use not only linearly polarized waves such as a simple dipole antenna or a helical antenna, but also orthogonal two-polarized waves and circularly polarized waves. Therefore, it is possible to deal with antennas with complicated shapes and non-linear antennas.

Further, it is characterized in that a small antenna device having a size of about one-tenth of the wavelength can be realized especially at 315 MHz, which is the frequency of the weak wireless standard. Regarding this point, Patent Document 1 shows an embodiment in which an auxiliary circuit of 10 cm in length is placed close to a dipole antenna with a frequency of about 580 MHz and a length of 25 cm. The wavelength in this case is about 52 cm and the size of the antenna is about half the wavelength. On the other hand, in the antenna device 10 of the present invention, when the wavelength is about 95 cm, the size of the device is reduced to 9 to 10 cm, that is, about 1/10 of the wavelength, and at the same time, a device having good directivity characteristics is realized. is doing.

In addition, the electromagnetic field radiated by orthogonal two-polarized antennas, patch antennas, meander-line antennas, and the like includes not only main polarized waves but also cross-polarized waves that are polarized waves in a direction perpendicular to the main polarized waves. Such cross-polarized waves cannot be reflected by a one-dimensional rod reflector. Therefore, a two-dimensional LC circuit is required to reflect both the main polarized wave and the cross polarized wave and control the directivity characteristics. It is possible to form an antenna device 10 that reflects both and can be controlled to have desired directivity characteristics.

Note that the antenna device of the present invention is not limited to the above embodiments, and the type of antenna can be appropriately selected from dipole antennas, helical antennas, orthogonal two-polarized antennas, patch antennas, meander line antennas, and the like. It is possible. The distance between the antenna and the magnetic conductor type reflector can be made as close as possible, and they may be assembled in contact with each other. The applied radio waves can utilize linearly polarized waves, orthogonal bi-polarized waves, or circularly polarized waves. The frequency of the radio wave is appropriately selected, and may be 315 MHz, 420-430 MHz, 920 MHz, 1200 MHz, or the like, depending on the application.

Measurement results of the antenna device according to the embodiment of the present invention will be described below. Directivity characteristics at a frequency of 315 MHz were measured for the antenna device 10 using the metamaterial magnetic conductor type reflector 14 by the LC auxiliary circuit 16 in which the unit LC circuit 16a is provided two-dimensionally. As a result, it was confirmed that the main polarized wave from the monopole antenna was strongly radiated forward even though the size of the magnetic conductor type reflector 14 was as small as 10 cm square. The front-to-back ratio of radiant intensity was greater than 10 dB.

Next, for the magnetic conductor type reflector 14 of the LC auxiliary circuit 16 in which the unit LC circuits 16a are provided two-dimensionally, measurement was performed by placing the meander line type antenna 12 facing each of the unit LC circuits 16a. . FIG. 6 shows an experimental device (a) of the antenna device 10 and a radiation pattern (b) of the measurement results thereof.

The normalized radiation pattern by the combination of the two-dimensional reflector (316 MHz) and the meander line type antenna is shown in FIG. , the right horizontal direction of the drawing is the front, and the front gain of the main polarization is normalized to 0 dB.

In the meander line type antenna 12 of the antenna device of this embodiment, the entire antenna 12 could be shielded by the magnetic conductor type reflector 14, and the backward radiation could be sufficiently suppressed. Furthermore, in the meander line type antenna 12, it was confirmed that the direction of radiation is not so sensitive to the positional relationship between the antenna 12 and the magnetic conductor type reflector 14, and that both the main polarized wave and the cross polarized wave are correctly directed forward. rice field.

10 Antenna Device 12 Antenna 14 Magnetic Conductive Reflector 16 LC Auxiliary Circuit 16a Unit LC Circuit 20 Auxiliary Circuit Board 22 Wiring Pattern 24 Post 26 Grounding Board

Claims (6)

In an antenna device that radiates or injects radio waves,
Mainly composed of an antenna that feeds or receives power, and a magnetic conductor type reflector that is close to the antenna and does not receive power,
The magnetic conductor type reflector is two-dimensionally connected with a unit LC circuit in which an inductor and a capacitor are connected in series,
The radio wave has a main polarization and a cross-polarization component orthogonal thereto,
prescribedover frequencyin the frequency band, the electromagnetic wave from the antenna and the reflected wave from the magnetic conductor type reflector areEquipped with an LC auxiliary circuit that is set to be able to reflect electric field components in phase,
The magnetic conductor type reflector has a non-zero tangential electric field component on its surface,
The LC auxiliary circuit is configured three-dimensionally by connecting a plurality of the unit LC circuits two-dimensionally, and other inductors are connected to the unit LC circuits, and is provided on the auxiliary circuit substrate, A grounded substrate of ground potential is provided in parallel with the LC auxiliary circuit, and a conductor is provided between the LC auxiliary circuit and the grounded substrate for connecting each of the unit LC circuits of the LC auxiliary circuit to the ground potential. A support is provided, and the auxiliary circuit board is provided integrally in parallel with the ground substrate set to a ground potential via the support,
the other inductor is composed of the conductor of the support, and the inductance of the other inductor of the LC auxiliary circuit is adjusted by the length of the support connecting the auxiliary circuit substrate and the ground substrate;
In order to operate in the frequency band, the values of the inductance component of the conductors forming the wiring pattern in the LC auxiliary circuit and the values of the inductance component of the support are adjusted to predetermined values,
In a frequency band equal to or higher than the predetermined frequency, the phase of the induced current in the LC auxiliary circuit is delayed by 360 degrees due to a tuning resonance phenomenon due to the resistance component of the LC auxiliary circuit, and the phase becomes the same as the phase of the current in the antenna. and the electric field component of the reflected wave from the LC auxiliary circuit is in phase with the electric field component of the incident wave. relatively strongly with respect to a specific partial direction in which the antenna facessaid radio waveAn antenna device characterized by emitting or injecting The radio waves use linearly polarized waves, orthogonal two-polarized waves, or circularly polarized waves The antenna device according to claim 1. 3. An antenna device according to claim 2, wherein the size of the whole device is 1/10 to 1/20 of the wavelength of said radio waves. 4. The antenna device according to claim 3 , wherein the radio wave has a frequency of 315 MHz. The unit LC circuit includes a chip inductor and a chip capacitor set to operate in the frequency band. 4. The antenna device according to claim 3. 6. The antenna device according to claim 5 , wherein the two-dimensional LC auxiliary circuits are connected in a triangular grid, a rectangular grid, or a hexagonal grid .

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