JP2022039175A - Antenna and radio communication device - Google Patents

Abstract

To provide an antenna etc. operated at a plurality of arbitrary frequencies and capable of individually controlling an operating frequency.SOLUTION: An antenna 10 includes: a GND plate 1 having an opening formed inside; a first split part 31 composed of two opposite conductors 311, 312 which are arranged inside the opening in a manner to face each other with a predetermined gap, and two connection conductors 313, 314 which connect each of the two opposite conductors to the outer periphery of the opening; a second split part 32 composed of two opposite conductors 321, 322 which are arranged inside the opening in a manner to face each other with a predetermined gap, and two connection conductors 323, 324 which connect each of the two opposite conductors to the outer periphery of the opening; and a power supply conductor 4 connected to one side of the opening. The antenna can be operated at a plurality of operating frequencies.SELECTED DRAWING: Figure 1

Description

The present invention relates to an antenna and a wireless communication device.

In recent years, the progress of miniaturization of wireless devices has been remarkable, the printed circuit boards inside the wireless devices have become high-density mounting, and the antennas mounted on the wireless devices can be more flexibly placed at various positions. There is a strong demand for further miniaturization.

The current technology related to the antenna device will be described below with reference to the drawings. FIG. 18 is a diagram showing the configuration of the antenna device 100 shown in Patent Document 1. The small antenna can be arranged at any position inside the GND plate 101. An opening 102 (openings 1020 to 1022 in FIG. 20) is formed inside the GND plate 101 so as not to touch any side of the outer circumference of the GND plate 101. The split portion 103 is arranged inside the opening 102. One end of the feeding conductor 104 is connected to one side of the opening 102, and the other end of the feeding conductor 104 is connected to the feeding portion 105. The feeding unit 105 supplies AC power via the feeding conductor 104. In this way, the parallel split ring resonator 106 is configured.

FIG. 19 is an enlarged view of the parallel split ring resonator 106 of FIG. A detailed configuration of the split portion 103 of FIG. 18 will be described with reference to FIG. Inside the opening 102 formed in the GND plate 101, the first split portion conductor 1031 and the second split portion conductor 1032 are arranged so as to be separated from each other and face each other. The first split portion conductor 1031 is connected to one side of the opening 102 via the third split portion conductor 1033. Similarly, the second split portion conductor 1032 is connected to the other side of the opening 102 via the fourth split portion conductor 1034. In this way, the split portion 103 is configured. Further, one end of the feeding conductor 104 arranged in parallel with the third split portion conductor 1033 and the fourth split portion conductor 1034 is connected to one side of the opening 102, and the other end is connected to the feeding portion 105. The power feeding unit 105 supplies AC power to the split unit 103 via the power feeding conductor 104 and the like.

FIG. 20 is a diagram schematically showing the current flow at the operating frequency of the antenna shown in FIGS. 18 and 19. In FIG. 20, the current flow is indicated by a dotted arrow. The current I ₁ is the feeding conductor 104, the third split conductor 1033, the first split conductor 1031, the second split conductor 1032, the fourth split conductor 1034, and the opening 102. It flows through a loop-shaped path composed of a part of the outer circumference (opening 1021). The current I ₂ is the opening of the third split conductor 1033, the first split conductor 1031, the second split conductor 1032, the fourth split conductor 1034, and the feed conductor 104 on the opposite side. It flows through a loop-shaped path composed of a part of the outer periphery of the portion 112 (opening 1022). The currents I ₁ and I ₂ radiate an electromagnetic wave as a wave source.

FIG. 21 is a circuit diagram showing an equivalent circuit of the parallel split ring resonator shown in FIGS. 18 and 19.
The equivalent circuit consists of a coil portion L1 equivalently configured in the path through which the current I ₁ flows, a coil portion L2 equivalently configured in the path through which the current I ₂ flows, and a first split portion conductor 1031 and a second. It is composed of a capacitor portion C equivalently configured by the split portion conductor 1032. That is, the equivalent circuit has a configuration in which two series resonant circuits are equivalently connected in parallel (see FIG. 21). The operating frequency of the antenna shown in this example is determined by the resonance frequency of this resonance circuit.

FIG. 22 shows the impedance characteristics of the antennas shown in FIGS. 18 and 19. This is a diagram showing the trajectory of impedance with respect to frequency using a Smith chart. The point where the impedance locus is closest to the center of the Smith chart or the point where it intersects the horizon passing through the center is the operating frequency of the antenna.

FIG. 23 shows the return loss characteristics of the antennas shown in FIGS. 18 and 19. The return loss is a measurement that is exactly the same as the impedance characteristic shown in FIG. 22, only the chart (chart) is different. It is a chart made so that the closer the impedance is to 50Ω, the smaller the value. That is, in the Smith chart of FIG. 22, the closer the impedance locus is to the center, the smaller the return loss in FIG. 23, and the smaller the return loss, the better the antenna characteristics. Further, in FIG. 22, the frequency corresponding to the valley portion of the Lintern loss is called the resonance frequency of the antenna, and shows the frequency operating as the antenna. In order for the antenna to operate well, it is generally desirable that the return loss is -5 dB or less at the frequency at which the antenna operates. It can be seen that the antenna shown in this example operates as a good antenna with a return loss of −5 dB or less at the resonance frequency indicated by the arrow in FIG. 23.

Japanese Patent No. 6548271

However, the antennas shown in FIGS. 18 and 19 are antennas that operate at a single frequency, operate at a plurality of arbitrary frequencies, and cannot individually control the operating frequencies.
Today's wireless devices have become significantly smaller, and the boards inside the wireless devices are also mounted at high density. Therefore, the built-in antenna can be flexibly arranged at various positions like the conventional antennas shown in FIGS. 18 and 19, and a small one is required. At the same time, today's wireless devices have a plurality of wireless communication standards. In many cases, the antenna also needs to support multiple frequency bands.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an antenna that operates at a plurality of arbitrary frequencies and can individually control the operating frequency.

The antenna according to one aspect of the present disclosure includes a GND plate having an opening formed inside and a GND plate.
A first composed of two opposing conductors arranged inside the opening at predetermined intervals so as to face each other, and two connecting conductors connecting each of the two opposing conductors to the outer periphery of the opening. Split part and
A second composed of two opposing conductors arranged inside the opening at predetermined intervals so as to face each other, and two connecting conductors connecting each of the two opposing conductors to the outer periphery of the opening. Split part and
It is characterized by having a feeding conductor connected to one side of the opening and being able to operate at a plurality of operating frequencies.

The wireless communication device according to one aspect of the present disclosure includes the above-mentioned antenna.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an antenna or the like that operates at a plurality of arbitrary frequencies and can individually control the operating frequency.

It is a figure which shows the structure of the antenna which concerns on Embodiment 1. FIG. It is an enlarged view of the part of the multi-resonant parallel split ring resonator 6 of the antenna which concerns on Embodiment 1. FIG. It is a figure which schematically represented the flow of the electric current in the 1st operating frequency of the antenna which concerns on Embodiment 1. FIG. It is a figure which schematically represented the flow of the electric current in the 2nd operating frequency of the antenna which concerns on Embodiment 1. FIG. It is a circuit diagram which shows the equivalent circuit in the 1st operating frequency of the antenna which concerns on Embodiment 1. FIG. It is a circuit diagram which shows the equivalent circuit in the 2nd operating frequency of the antenna which concerns on Embodiment 1. FIG. It is a figure which shows the impedance characteristic of the antenna which concerns on Embodiment 1. FIG. It is a figure which shows the return loss characteristic of the antenna which concerns on Embodiment 1. FIG. It is an enlarged view of the part of the multi-resonant parallel split ring resonator of the antenna by Embodiment 2. FIG. It is a figure which schematically represented the flow of the electric current in the 1st operating frequency of the antenna which concerns on Embodiment 2. FIG. It is a figure which schematically represented the flow of the electric current in the 2nd operating frequency of the antenna which concerns on Embodiment 2. FIG. It is a figure which schematically represented the flow of the electric current in the 3rd operating frequency of the antenna which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the equivalent circuit in the 1st operating frequency of the antenna which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the equivalent circuit in the 2nd operating frequency of the antenna which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the equivalent circuit in the 3rd operating frequency of the antenna which concerns on Embodiment 2. FIG. It is a figure which shows the impedance characteristic of the antenna which concerns on Embodiment 2. It is a figure which shows the return loss characteristic of the antenna which concerns on Embodiment 2. FIG. It is a figure which shows the structure of the antenna device shown in Patent Document 1. FIG. It is an enlarged view of the parallel split ring resonator of FIG. It is a figure which schematically represented the current flow at the operating frequency of the antenna shown in FIGS. 18 and 19. It is a circuit diagram which shows the equivalent circuit of the parallel split ring resonator shown in FIGS. 18 and 19. It is a Smith chart which shows an example of the impedance characteristic of the antenna shown in FIGS. 18 and 19. It is a characteristic diagram which shows an example of the return loss characteristic of the antenna shown in FIG. 18 and FIG.

Embodiment 1
Hereinafter, the antenna and the wireless communication device according to the embodiment of the present invention will be described with reference to the drawings. Hereinafter, the antenna will be mainly described, but the antenna according to the present invention may be mounted on a portable wireless communication device provided with an antenna for transmitting and receiving radio signals.

FIG. 1 is a diagram showing a configuration of an antenna 10 according to the first embodiment. The change from FIG. 18 which is a conventional configuration example is that the first split portion 31 and the second split portion 32 are provided inside the opening 2 arranged so as not to contact any side of the outer periphery of the GND plate 1. It is arranged to form a multi-resonant parallel split ring resonator 6. By doing so, the small antenna can be arranged at any position inside the GND plate 1. As shown in FIG. 1, an opening 2 is formed inside the GND plate 1 so as not to contact any side of the outer circumference of the GND plate 1. The first split portion 31 and the second split portion 32 are arranged inside the opening 2. One end of the feeding conductor 4 is connected to one side of the opening 2, and the other end of the feeding conductor 4 is connected to the feeding portion 5. The power feeding unit 5 supplies AC power to the first split unit 31 and the second split unit 32 and the like via the power feeding conductor 4 and the like. In this way, the multi-resonant parallel split ring resonator 6 is configured.

FIG. 2 is an enlarged view of the multi-resonant parallel split ring resonator 6 of the antenna according to the first embodiment of the present invention of FIG.
Inside the opening 2 (openings 20 to 23 in FIG. 2) formed inside the GND plate 1, the facing conductors 311 and the facing conductors 312 are arranged so as to face each other in the first split portion 31. .. The connecting conductor 313 is arranged so as to connect the opposed conductor 311 and one side of the outer periphery of the opening 2. The connecting conductor 314 is arranged so as to connect the facing conductor 312 and one side of the outer circumference of the opening 2. By doing so, the T-shaped conductor formed by the opposing conductor 311 and the connecting conductor 313 is connected to one side of the opening 2 to be formed, and the T-shaped conductor formed by the opposing conductor 312 and the connecting conductor 314 is formed. Is formed by being connected to one side of the opening 2 facing the one side.

Similarly, inside the opening 2, the opposing conductor 321 is arranged at a predetermined distance (space) from the opposing conductor 311. Further, the opposing conductor 322 is arranged at a predetermined distance from the opposing conductor 312. The connecting conductor 323 is arranged so as to connect the facing conductor 321 and one side of the opening 2. In this way, the opposing conductor 321 and the opposing conductor 322 are arranged so as to face each other with a predetermined distance. The connecting conductor 324 is arranged so as to connect the facing conductor 322 and one side of the opening 2. By doing so, the T-shaped conductor formed by the opposing conductor 321 and the connecting conductor 323 is connected to one side of the opening 2 to be formed, and the T-shaped conductor formed by the opposing conductor 322 and the connecting conductor 324 is formed. Is formed by being connected to one side of the opening 2 facing the one side.

One end of the feeding conductor 4 is connected to one side of the opening 2, and the other end of the feeding conductor 4 is connected to the feeding portion 5. The power feeding unit 5 supplies AC power to the first split unit 31 and the second split unit 32 via the power feeding conductor 4 and the like.

FIG. 3 is a diagram schematically showing the current flow at the first operating frequency of the antenna according to the present embodiment shown in FIGS. 1 and 2. A current flows in a loop-shaped path along the dotted line path indicated by the current I ₁₁ and the current I ₁₂ . The current I ₁₁ actually branches into a path passing through the opposing conductor 311 and the opposing conductor 312, the connecting conductor 313 and the connecting conductor 314, and a path passing through the opposing conductor 321 and the opposing conductor 322 and the connecting conductor 323 and the connecting conductor 324. Although it flows, it is schematically represented as a combined current I ₁₁ .

Similarly, the current I ₁₂ is also actually in the path through the opposing conductor 311 and the opposing conductor 312, the connecting conductor 313 and the connecting conductor 314, and the path through the opposed conductor 321 and the opposed conductor 322 and the connecting conductor 323 and the connecting conductor 324. Although the current is branched and flows, it is schematically represented as a combined current I ₁₂ . At the first operating frequency, the current I ₁₁ and the current I ₁₂ radiate an electromagnetic wave as a wave source. In this way, it functions as an antenna that operates at the first operating frequency.

FIG. 4 is a diagram schematically showing the current flow at the second operating frequency of the antennas shown in FIGS. 1 and 2. The current I ₂ is a part of the outer periphery (opening) of the facing conductor 311 and the facing conductor 312, the connecting conductor 313 and the connecting conductor 314, the facing conductor 321 and the facing conductor 322, the connecting conductor 323 and the connecting conductor 324, and the opening 2. It flows through a loop-shaped path composed of a part of the outer peripheral portion of 22). This current I ₂ radiates an electromagnetic wave having a second operating frequency as a wave source. In this way, it functions as an antenna that operates at the second operating frequency.

FIG. 5 is a circuit diagram showing an equivalent circuit at the first operating frequency of the antenna according to the present embodiment. The equivalent circuit at the first operating frequency includes a coil portion L11 equivalently configured by the path through which the current I ₁₁ flows, a coil portion L12 equivalently configured by the path through which the current I ₁₂ flows, and an opposed conductor 311. It is composed of a capacitor portion C1 equivalently configured by the opposing conductor 312, and a capacitor portion C2 equivalently composed of the opposing conductor 321 and the opposing conductor 322. That is, an equivalent circuit in which two series resonant circuits are connected in parallel is constructed.

The resonance frequency of this resonance circuit determines the first operating frequency of the antenna shown in the present embodiment. Therefore, the inductance of the coil portions L11 and L12, which are equivalently configured by changing the size of the opening 2 when forming the opening and changing the length of the path through which the current I ₁₁ and the current I ₁₂ flow, are obtained. It is possible to adjust the first operating frequency by changing it.

Further, the lengths of the opposing conductors 311 and the opposing conductors 312 (the longitudinal length L of the opposing conductors 311 and the longitudinal length L of the opposing conductors 312 in FIG. 3), and the lengths of the opposing conductors 321 and the opposing conductors 322. By changing (the length L of the opposite conductor 321 and the length L of the opposite conductor 322 in FIG. 3), the capacitances of the capacitor portions C1 and C2 which are equivalently configured are changed to adjust the first operating frequency. It is possible to do.

Further, the distance between the opposing conductor 311 and the opposing conductor 312 (distance I between the opposing conductor 311 and the opposing conductor 312 in FIG. 3) and the distance between the opposing conductor 321 and the opposing conductor 322 (the distance between the opposing conductor 321 and the opposing conductor 322 in FIG. 3). It is also possible to adjust the first operating frequency by changing the interval I) of the above and changing the capacitance of the equivalently configured capacitor portion.

The length L in the longitudinal direction (length in the lateral direction) L of the opposing conductor 311 in FIG. 3 and the length L in the longitudinal direction (length in the lateral direction) L of the opposing conductor 312 are the same. Similarly, the length L of the opposed conductor 321 in FIG. 3 and the length L of the opposed conductor 322 are also made the same. By making the lengths L of the two sets of opposing conductors the same in this way, good antenna performance can be obtained.

Further, the loop path O ₁ and the loop path O ₂ in FIG. 2 have the same length. That is, the first formed by the two connecting conductors 313, 314 of the first split portion 31, the two opposing conductors 311, 312, a part of the outer periphery of the opening 21, and a part of the feeding conductor 4. Loop path O ₁ (indicated by dashed arrow O ₁ in FIG. 2), two connecting conductors 323 and 324 of the second split portion 32, two opposed conductors 321 and 322, and one of the outer circumferences of the opening 23. The second loop path O ₂ (indicated by the dashed arrow O ₂ in FIG. 2) formed by the portions has the same length. This makes it possible to obtain better antenna performance. Further, the lengths of the two connecting conductors 313 and 314 of the first split portion 31 and the lengths of the two connecting conductors 323 and 324 of the second split portion 32 may all be the same.

FIG. 6 is a circuit diagram showing an equivalent circuit at a second operating frequency of the antenna according to the present embodiment. As shown in FIG. 6, the equivalent circuit includes a coil portion L2 equivalently configured by a path through which a current I ₂ flows, a capacitor portion C1 equivalently composed of an opposing conductor 311 and an opposing conductor 312, and an opposing conductor 321. It is composed of a capacitor portion C2 equivalently configured by the facing conductor 322 and the capacitor portion C2. That is, the equivalent circuit is composed of a series resonant circuit. The resonance frequency of this resonance circuit determines the second operating frequency of the antenna according to the present embodiment.

Therefore, the distance between the path composed of the opposing conductor 311, the opposing conductor 312, the connecting conductor 313, and the connecting conductor 314, and the path composed of the opposing conductor 321 and the opposing conductor 322, the connecting conductor 323, and the connecting conductor 324 (in FIG. 4). By changing (indicated by the broken line arrow S), the length of the path through which the current I ₂ flows can be changed. That is, by changing the distance between the first split portion 31 and the second split portion 32, the length of the path through which the current I ₂ flows can be changed. Thereby, it is possible to adjust the second operating frequency by changing the inductance of the coil portion L2 having the equivalent configuration shown in FIG.

Further, similarly to the first operating frequency, the lengths of the opposing conductor 311 and the opposing conductor 312 (indicated by the dashed arrow L in FIG. 4), and the lengths of the opposing conductor 321 and the opposing conductor 322 (the dashed arrow L in FIG. 4). By changing (shown by), the capacitances of the equivalently configured capacitor portions C1 and C2 shown in FIG. 6 can be changed. This makes it possible to adjust the second operating frequency.

Further, the distance between the opposed conductor 311 and the opposed conductor 312 (distance I between the opposed conductor 311 and the opposed conductor 312 in FIG. 3) and the distance between the opposed conductor 321 and the opposed conductor 322 (the distance between the opposed conductor 321 and the opposed conductor 322 in FIG. 3). It is also possible to change the capacitances of the capacitor portions C1 and C2 which are equivalently configured by changing the interval I). This makes it possible to adjust the second operating frequency as well as the first operating frequency.

Further, a part of the outer periphery of the feeding conductor 4 and the opening 2 on the opposite side of the first split portion 31 and the second split portion 32 in FIG. 1 (a part of the outer circumference of the opening 20 in FIG. 2). The configured path (the path in which neither the current I ₁₁ nor the current I ₁₂ flows) equivalently short-circuits the feeding conductor 4. This acts as an impedance matching element that brings the impedance trajectory at the first operating frequency of the antenna according to the present embodiment close to 50Ω.

FIG. 7 is a diagram showing the impedance characteristics of the antenna according to the present embodiment. The points where the impedance locus and the horizon passing through the center intersect and the points where the impedance locus approaches the center of the Smith chart are the first operating frequency and the second operating frequency, respectively.

FIG. 8 is a diagram showing the return loss characteristics of the antenna according to the present embodiment. It can be seen that the return loss is -15 dB or less at the first operating frequency and the second operating frequency, and the antenna operates as a good antenna. As described above, good return loss characteristics can be obtained by making the lengths L of the two sets of opposing conductors the same and making the _two sets of loop paths O1 and _O2 the same.

According to the antenna according to the present embodiment described above, it is possible to operate at a plurality of arbitrary frequencies and to individually adjust the operating frequencies.

Embodiment 2
FIG. 9 is an enlarged view of a portion of the multi-resonant parallel split ring resonator of the antenna according to the second embodiment. The difference from the embodiment shown in FIGS. 1 and 2 is that the opening 2 has a third split portion 33 in addition to the first split portion 31 and the second split portion 32. .. That is, in the third split portion 33, the opposing conductor 331 and the opposing conductor 332 are arranged so as to face each other. The connecting conductor 333 is arranged so as to connect the facing conductor 331 and one side of the opening 2. The connecting conductor 334 is arranged so as to connect the facing conductor 332 and one side of the opening 2. By doing so, the T-shaped conductor formed by the opposing conductor 331 and the connecting conductor 333 is connected to one side of the opening 2 to be formed, and the T-shaped conductor formed by the opposing conductor 332 and the connecting conductor 334 is formed. Is formed by being connected to one side of the opening 2 facing the one side.

FIG. 10 is a diagram schematically showing the current flow at the first operating frequency of the antenna according to the present embodiment shown in FIG. 9. A current flows in a loop-shaped path along the dotted line path indicated by the current I ₁₁ and the current I ₁₂ . The current I ₁₁ is a path passing through the opposing conductor 311 and the opposing conductor 312, the connecting conductor 313 and the connecting conductor 314, a path passing through the opposing conductor 321 and the opposing conductor 322, the connecting conductor 323 and the connecting conductor 324, and the opposing conductor 331 and the opposing conductor. The current flows by branching to the path passing through the 332, the connecting conductor 333, and the connecting conductor 334, and is schematically represented as the combined current I ₁₁ .

Similarly, the current I ₁₂ also passes through the counter conductor 311 and the counter conductor 312, the connecting conductor 313, the path through the connecting conductor 314, the counter conductor 321 and the counter conductor 322, the connecting conductor 323, and the connecting conductor 324. The path, the opposing conductor 331, the opposing conductor 332, the connecting conductor 333, and the connecting conductor 334 branching to the path through which the current flows, are schematically represented as the combined current I ₁₂ .

At the first operating frequency, the current I ₁₁ and the current I ₁₂ radiate an electromagnetic wave having the first operating frequency as a wave source. In this way, it functions as an antenna that operates at the first operating frequency.

FIG. 11 is a diagram schematically showing the current flow at the second operating frequency of the antenna according to the present embodiment shown in FIG. The current I ₂ is a part of the outer periphery (opening) of the facing conductor 311 and the facing conductor 312, the connecting conductor 313 and the connecting conductor 314, the facing conductor 331, the facing conductor 332, the connecting conductor 333 and the connecting conductor 334, and the opening 2. It flows through a loop-shaped path composed of 22 and a part of the outer periphery of the opening 23). This current I ₂ radiates an electromagnetic wave having a second operating frequency as a wave source. In this way, it functions as an antenna that operates at the second operating frequency.

Further, FIG. 12 is a diagram schematically showing the current flow at the third operating frequency of the antenna according to the present embodiment shown in FIG. Opposing conductor 311 and opposing conductor 312, connecting conductor 313 and connecting conductor 314, opposing conductor 321 and opposing conductor 322, connecting conductor 323 and connecting conductor 324, and a part of the outer circumference of the opening 2 (one of the outer circumferences of the opening 22). The current I ₃₁ flows through the loop-shaped path composed of the parts). Opposing conductor 321 and opposing conductor 322, connecting conductor 323 and connecting conductor 324, opposing conductor 331, opposing conductor 332, connecting conductor 333 and connecting conductor 334, and a part of the outer circumference of the opening 2 (one of the outer circumferences of the opening 23). The current I ₃₂ flows through the loop-shaped path composed of the parts). The current I ₃₁ and the current I ₃₂ radiate an electromagnetic wave having a third operating frequency as a wave source. In this way, it functions as an antenna that operates at the third operating frequency.

FIG. 13 is a circuit diagram showing an equivalent circuit at the first operating frequency of the antenna according to the present embodiment. Equivalently added to the equivalent circuit (FIG. 5) at the first operating frequency of the antenna according to the first embodiment is C3, which is equivalently composed of the opposed conductor 331, the opposed conductor 332, the connecting conductor 333, and the connecting conductor 334. (That is, C1, C2, and C3 are connected in parallel).

FIG. 14 equivalently shows a circuit diagram at the second operating frequency of the antenna according to the present embodiment. C3, which is also equivalently configured by the equivalent circuit (FIG. 6) at the second operating frequency of the antenna according to the first embodiment, is equivalently composed of the opposed conductor 331, the opposed conductor 332, the connecting conductor 333, and the connecting conductor 334. Is added (that is, C1, C2, and C3 are connected in series).

FIG. 15 equivalently shows a circuit diagram at a third operating frequency of the antenna according to the present embodiment. The equivalent circuit is equivalent to the coil portion L31 equivalently configured by the path through which the current I ₃₁ flows, the capacitor portion C1 equivalently composed of the opposed conductor 311 and the opposed conductor 312, and the opposed conductor 321 and the opposed conductor 322. A series resonance circuit composed of a capacitor unit C2, a coil unit L32 equivalently configured by a path through which a current I ₃₂ flows, and a capacitor equivalently composed of a counter conductor 321 and a counter conductor 322. It is a circuit in which a series resonance circuit composed of a portion C2 and a capacitor portion C3 equivalently composed of the facing conductor 331 and the facing conductor 332 is connected in parallel. The resonance frequency of this resonance circuit determines the third operating frequency of the antenna according to the present embodiment.

FIG. 16 shows the impedance characteristics of the antenna according to the present embodiment. The points where the impedance locus and the horizontal line passing through the center intersect and the points where the impedance locus approaches the center of the Smith chart are the first operating frequency, the second operating frequency, and the third operating frequency, respectively.

FIG. 17 shows the return loss characteristics of the antenna according to the present embodiment. It can be seen that the return loss is -5 dB or less at the first operating frequency, the second operating frequency, and the third operating frequency, and the antenna operates as a good antenna.

According to the antenna of the present embodiment described above, it is possible to operate at a plurality of arbitrary frequencies, and the operating frequencies can be individually adjusted.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit. For example, in the above embodiment, two or three split portions are formed in the opening, but four or more split portions may be formed inside the opening.

1 GND plate 2 Opening 4 Feeding conductor 10 Antenna 20 Opening 21 Opening 22 Opening 23 Opening 31 First split part 311 Opposing conductor 312 Opposing conductor 313 Connecting conductor 314 Connecting conductor 32 Second split part 321 Opposing conductor 322 Opposing conductor 323 Connecting conductor 324 Connecting conductor 33 Third split part 331 Opposing conductor 332 Opposing conductor 333 Connecting conductor 334 Connecting conductor

Claims (10)

A GND plate with an opening formed inside,
A first composed of two opposing conductors arranged inside the opening at predetermined intervals so as to face each other, and two connecting conductors connecting each of the two opposing conductors to the outer periphery of the opening. Split part and
A second composed of two opposing conductors arranged inside the opening at predetermined intervals so as to face each other, and two connecting conductors connecting each of the two opposing conductors to the outer periphery of the opening. Split part and
An antenna comprising a feeding conductor connected to one side of the opening and capable of operating at a plurality of operating frequencies. The antenna according to claim 1, wherein the lengths of the two opposing conductors of the first split portion and the lengths of the two opposing conductors of the second split portion are the same. A first formed by the two connecting conductors of the first split portion, the two opposing conductors of the first split portion, a part of the outer circumference of the opening, and a part of the feeding conductor. A second loop path formed by the loop path 1, the two connecting conductors of the second split portion, the two opposing conductors of the second split portion, and a portion of the outer circumference of the opening. The antenna according to claim 1 or 2, wherein the loop path has the same length. The antenna according to claim 1, wherein the operating frequency can be individually adjusted by changing the distance between the first split portion and the second split portion. The length of the opposing conductors arranged so as to face each other constituting the first split portion, or
The antenna according to claim 1, wherein a plurality of operating frequencies can be adjusted by changing the lengths of the opposing conductors arranged so as to face each other constituting the first split portion. The antenna according to claim 1, wherein a plurality of operating frequencies can be adjusted by changing the spacing between the opposing conductors arranged so as to face each other constituting the first split portion. The antenna according to claim 1, wherein a plurality of operating frequencies can be adjusted by changing the size of the opening. According to claim 1, the path composed of the feeding conductor and a part of the outer periphery of the opening on the opposite side of the first split portion and the second split portion equivalently short-circuits the feeding conductor. Described antenna. A split portion composed of two opposing conductors arranged inside the opening at predetermined intervals so as to face each other, and two connecting conductors connecting each of the two opposing conductors to the outer periphery of the opening. The antenna according to claim 1, further comprising a plurality of antennas and capable of operating at a plurality of operating frequencies. A wireless communication device provided with the antenna according to any one of claims 1 to 9.

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