Antenna device

Abstract

To provide an antenna device capable of achieving appropriate communication by obtaining a desired resonance frequency even when a metal or a dielectric approaches.SOLUTION: An antenna device 10 includes a flat substrate 100, an element part 101 provided on a first plane and having a first short part 121 and a first power supply part 111, and a first ground part 201 provided on the surface of the first plane and having a first through-hole part 211. The antenna device 10 includes a second ground part 202 provided on the second plane and having a second short part 122, a second power supply part 112, and a second through-hole part 212 connected to the first short part 121, the first power supply part 111, and the first through-hole part 211, respectively. The first plane is formed by three regions, i.e., a first region in which the element part 101 is provided, a second region in which the first ground part 201 is provided, and a third region that is sandwiched between the first region and the second region and has no metal foil on its surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antenna device. [Background technology]

[0002] Conventionally, in a planar antenna, a technology has been proposed for obtaining desired characteristics in a communication environment by changing the shape of a conductor that is an antenna element. Patent Document 1 discloses a pattern antenna. The pattern antenna disclosed in Patent Document 1 has an inverted F-shaped antenna pattern, and constitutes a pattern antenna that can handle a wide frequency band and be miniaturized. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-201278 Summary of the Invention [Problem to be solved by the invention]

[0004] In the pattern antenna disclosed in Patent Document 1, the VSWR characteristics deteriorate when metal or a dielectric is in the vicinity. Therefore, in the case of the pattern antenna, when metal or a dielectric is in the vicinity, the antenna cannot perform the desired function, and communication may be disrupted.

[0005] The present invention has been made in view of the problems inherent in the conventional technology, and an object of the present invention is to provide an antenna device that can achieve appropriate communication by obtaining a desired resonant frequency even when a metal or dielectric is in the vicinity. [Means for solving the problem]

[0006] An antenna device according to an embodiment of the present invention comprises a planar substrate, an element portion made of metal foil on the surface of a first plane of the planar substrate and having a first short portion and a first power supply portion, a first ground portion made of metal foil on the surface of the first plane and having a first through-hole portion, and a second ground portion made of metal foil on a second plane different from the first plane and having a second short portion connected to the first short portion, a second power supply portion connected to the first power supply portion, and a second through-hole portion connected to the first through-hole portion, wherein the first plane is formed of three regions: a first region in which the element portion is provided, a second region in which the first ground portion is provided, and a third region sandwiched between the first region and the second region and having no metal foil on its surface. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an antenna device that can achieve appropriate communication by obtaining a desired resonant frequency even when metal or a dielectric is in the vicinity. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view showing a configuration of an antenna device according to an embodiment of the present invention. [Figure 2] 1 is a plan view showing a configuration of an antenna device according to an embodiment of the present invention. [Figure 3] 1 is a side view showing the configuration of an antenna device according to an embodiment of the present invention. [Figure 4A] 10A and 10B are diagrams for explaining changes in resonant frequency when the length in the short-side direction of the element section in the antenna device according to the present embodiment is changed. [Figure 4B] 10A and 10B are diagrams for explaining changes in resonant frequency when the length in the short-side direction of the element section in the antenna device according to the present embodiment is changed. [Figure 5A] 5A and 5B are diagrams for explaining changes in impedance when the position of a first feeding point in the antenna device according to the present embodiment is changed. [Figure 5B]5A and 5B are diagrams for explaining changes in impedance when the position of a first feeding point in the antenna device according to the present embodiment is changed. [Figure 6A] 5A and 5B are diagrams for explaining changes in the resonant frequency when the position of the first short part in the antenna device according to the present embodiment is changed. [Figure 6B] 5A and 5B are diagrams for explaining changes in the resonant frequency when the position of the first short part in the antenna device according to the present embodiment is changed. [Figure 7A] 5A and 5B are diagrams for explaining an electric field distribution in the antenna device according to the present embodiment. [Figure 7B] 5A and 5B are diagrams for explaining an electric field distribution in the antenna device according to the present embodiment. [Figure 8A] FIG. 10 is a plan view showing the configuration of an inverted-F antenna device as a comparative example. [Figure 8B] FIG. 10 is a plan view showing the configuration of an inverted-F antenna device as a comparative example. [Figure 9A] 10A and 10B are diagrams for explaining a configuration in which an inverted-F antenna device is sandwiched between metal plates as a comparative example. [Figure 9B] 10 is a side view for explaining a configuration in which an inverted-F antenna device is sandwiched between metal plates as a comparative example. FIG. [Figure 10] 10A and 10B are diagrams for explaining the VSWR characteristics of an inverted-F antenna device as a comparative example. [Figure 11] FIG. 10 is a diagram for explaining a Smith chart for an inverted-F antenna device as a comparative example. [Figure 12A] 10A and 10B are diagrams for explaining a configuration in which the antenna device according to the present embodiment is sandwiched between metal plates. [Figure 12B] 10 is a side view for explaining a configuration in which the antenna device according to the present embodiment is sandwiched between metal plates. FIG. [Figure 13] 5A and 5B are diagrams for explaining VSWR characteristics of the antenna device according to the present embodiment. [Figure 14]4A and 4B are diagrams for explaining a Smith chart for the antenna device according to the present embodiment. [Figure 15A] FIG. 1 is a diagram for explaining electric field coupling in a typical antenna. [Figure 15B] 5A and 5B are diagrams for explaining electric field coupling in the antenna device according to the present embodiment. [Figure 16A] 10A and 10B are diagrams for explaining a configuration in which the antenna device according to the present embodiment is sandwiched between resin. [Figure 16B] 10 is a side view for explaining a configuration in which the antenna device according to the present embodiment is sandwiched between resin. FIG. [Figure 17] 5A and 5B are diagrams for explaining VSWR characteristics of the antenna device according to the present embodiment. [Figure 18] 5A and 5B are diagrams for explaining a gain for the antenna device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The antenna device 10 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0010] (Configuration of antenna device 10) Fig. 1 is a plan view showing the configuration of an antenna device 10 according to this embodiment. Fig. 2 is a plan view corresponding to the rear surface of the antenna device 10 of Fig. 1. Fig. 3 is a side view showing the configuration of the antenna device 10 according to this embodiment.

[0011] The antenna device 10 includes a planar substrate 100, an element portion 101 which is an antenna element provided on the surface of the planar substrate 100, and a first ground portion 201. The antenna device 10 according to this embodiment functions as an antenna compatible with the 2.4 GHz frequency band.

[0012] In the antenna device 10, the plane shown in Fig. 1 corresponds to a first plane, and in the antenna device 10, the plane shown in Fig. 2 corresponds to a second plane.

[0013] 1 to 3, the horizontal direction in Fig. 1 and Fig. 2 corresponds to the X-axis direction, the vertical direction in Fig. 1 and Fig. 2 corresponds to the Y-axis direction, and the horizontal direction in Fig. 3, which is the thickness direction of the planar substrate 100 (the depth direction in Fig. 1 and Fig. 2), corresponds to the Z-axis direction.

[0014] 1, the length of the planar substrate 100 in the short direction is indicated by L1, and the length in the long direction is indicated by L2. In the antenna device 10 according to this embodiment, L1 is 30 mm, and L2 is 42 mm. Note that the lengths of L1 and L2 are not limited to 30 mm and 42 mm, respectively, and may be longer or shorter than 30 mm and 42 mm, respectively. Furthermore, L1 is preferably λ / 2 (half wavelength) for the applicable frequency band.

[0015] An element portion 101, which is a conductor corresponding to an antenna element, is provided on a planar substrate 100 using metal foil. In the example shown in Fig. 1, the element portion 101 has a first short portion 121 and a first power supply portion 111. In this embodiment, the metal foil is copper foil.

[0016] In this embodiment, the element section 101 is formed in contact with one end in the longitudinal direction of the planar substrate 100. In the example shown in Fig. 1, the element section 101 is formed on the uppermost side of the planar substrate 100 in the Y-axis direction.

[0017] In this embodiment, the element portion 101 preferably has a longitudinal length of λ / 2 (half wavelength) of the applicable frequency band, which enables the antenna device 10 to transmit and receive radio waves efficiently through appropriate resonance.

[0018] Furthermore, the corresponding resonant frequency of the element section 101 varies depending on the length in the short side direction. That is, the antenna device 10 can adjust the resonant frequency by adjusting the length in the short side direction of the element section 101.

[0019] 4A and 4B are diagrams showing changes in the resonant frequency when the short-side length of the element section 101 is changed. FIG. 4B shows examples of the resonant frequency when the short-side length L2a of the element section 101 in FIG. 4A is set to 7.7 mm, 7.4 mm, and 7.1 mm. As shown in FIG. 4B, the resonant frequency increases as the short-side length L2a of the element section 101 decreases.

[0020] Furthermore, in this embodiment, the impedance of the element section 101 differs depending on the position of the first power feeding section 111 in the element section 101. That is, the antenna device 10 can adjust the impedance of the antenna device 10 by adjusting the position of the first power feeding section 111 in the element section 101.

[0021] 5A and 5B are diagrams showing changes in impedance characteristics when the position of the first power feeding portion 111 of the element portion 101 is changed. Fig. 5B shows an example of impedance characteristics when the position of the first power feeding portion 111 of the element portion 101 in Fig. 5A is changed downward by 0.5 mm and upward by 0.5 mm (L2b=1 mm) in the short direction of the element portion 101 (direction indicated by the arrow in the figure). As shown in Fig. 5B, by changing the position of the first power feeding portion 111 of the element portion 101, it is possible to adjust the impedance of the antenna device 10.

[0022] Furthermore, in this embodiment, the element section 101 has a different corresponding resonant frequency depending on the position of the first short section 121 in the element section 101. That is, by adjusting the position of the first short section 121 in the element section 101, the antenna device 10 can adjust the resonant frequency of the communication system to which the antenna device 10 is applied.

[0023] 6A and 6B are diagrams showing changes in the resonant frequency when the position of the first short-circuit portion 121 of the element portion 101 is changed. Fig. 6B shows an example of the resonant frequency when the position of the first short-circuit portion 121 of the element portion 101 in Fig. 6A is changed downward by 0.5 mm and upward by 0.5 mm (L2c = 1 mm) in the short direction of the element portion 101 (direction of the arrow in the figure). As shown in Fig. 6B, by changing the position of the first short-circuit portion 121 of the element portion 101, it is possible to adjust the resonant frequency of a communication system to which the antenna device 10 is applied.

[0024] The antenna device 10 has a first ground portion 201 made of metal foil and provided on the surface of the first plane shown in Fig. 1. The first ground portion 201 has a plurality of first through-hole portions 211.

[0025] In this embodiment, the first ground portion 201 is formed so as to contact one end in the longitudinal direction of the planar substrate 100, which end is different from the end on which the element portion 101 is formed. In the example shown in Fig. 1, the first ground portion 201 is formed on the lowest side of the planar substrate 100 in the Y-axis direction.

[0026] That is, in the antenna device 10, the first plane is formed of three regions: a first region in which the element portion 101 is provided, a second region in which the first ground portion 201 is provided, and a third region that is sandwiched between the first and second regions and does not have metal foil on its surface. In the example shown in Figures 1 and 3, rectangular regions are formed in the longitudinal direction of the planar substrate 100 in the order from the top in the figure: the first region in which the element portion 101 is formed, the third region, and the second region in which the first ground portion 201 is formed.

[0027] 2, the antenna device 10 also includes a second ground section 202 made of metal foil and provided on a second plane different from the first plane. The second ground section 202 has a second power supply section 112 connected to the first power supply section 111. The second ground section 202 also has a second short section 122 connected to the first short section 121. The second ground section 202 also has a second through-hole section 212 connected to the first through-hole section 211. That is, the first ground section 201 and the second ground section 202 are electrically connected via the first through-hole section 211 and the second through-hole section 212.

[0028] FIG. 7A is a diagram illustrating the electric field distribution in the antenna device 10 according to this embodiment. FIG. 7B is a diagram illustrating the intensity of the electric field in the electric field distribution. As shown in FIG. 7A, a strong electric field is generated between the element portion 101 and the second ground portion 202. This electric field couples the element portion 101 and the second ground portion 202 to form a resonant circuit (antenna). In this embodiment, by providing a third region (copper foil-free portion 300) that is free of metal foil (copper foil), it is possible to appropriately adjust the electric field generated between the element portion 101 and the second ground portion 202.

[0029] (Affected by proximity to metal) Fig. 8A is a plan view showing the configuration of an inverted-F antenna device 11 as a comparative example. Fig. 8B is a plan view showing the configuration of the back side of an inverted-F antenna device 11 as a comparative example. The inverted-F antenna device 11 shown in Fig. 8A has an inverted-F element at the top in the figure. In the example shown in Fig. 8B, the top is an area without copper foil, and the bottom is formed by a ground section made of copper foil.

[0030] Fig. 9A is a diagram illustrating a configuration in which an inverted-F antenna device 11 is sandwiched between metal plates 400 as a comparative example. Fig. 9B is a side view illustrating a configuration in which an inverted-F antenna device 11 is sandwiched between metal plates 400 as a comparative example, and corresponds to a cross-sectional view in the AA direction of Fig. 9A. Note that the inverted-F antenna device 11 shown in Figs. 9A and 9B corresponds to the inverted-F antenna device 11 shown in Figs. 8A and 8B.

[0031] In Fig. 9A, metal plate 400 is configured as a square with lengths L3 and L4 of 500 mm, and in Fig. 9B, length L5 is 10.5 mm, and length L6 is 4 mm.

[0032] Fig. 10 is a diagram for explaining the VSWR (Voltage Standing Wave Ratio) characteristics of a comparative example inverted-F antenna device 11. The two waveforms shown in Fig. 10 show the VSWR characteristics of the inverted-F antenna device 11 when metal is nearby (metal nearby) and when no metal is nearby (free space).

[0033] The VSWR characteristic is used as an index to evaluate the performance of an antenna. Specifically, the VSWR characteristic is expressed as the ratio of the peaks to the valleys of the voltage amplitude distribution of the standing wave generated on the feed line when a reflected wave is generated due to impedance mismatch between the antenna element and the feed line. For example, in an ideal state where the impedance is matched and there is no reflection, the VSWR is 1.0.

[0034] As shown in Figure 10, in the 2.4 GHz band, in free space, the VSWR characteristics are low (close to 1.0) and good antenna characteristics are obtained, but when sandwiched between metal (close to metal), the characteristics deteriorate significantly.

[0035] Fig. 11 is a diagram for explaining a Smith chart for a comparative example of an inverted-F antenna device 11. As shown in Fig. 11, it can be seen that the antenna impedance changes significantly when metal is nearby compared to when it is in free space.

[0036] The antenna device 10 according to this embodiment can achieve appropriate communication by obtaining a desired resonant frequency even when metal or a dielectric is in the vicinity.

[0037] (Characteristics of the antenna device 10) Fig. 12A is a diagram for explaining a configuration in which the antenna device 10 according to this embodiment is sandwiched between metal plates 400. Fig. 12B is a side view for explaining a configuration in which the antenna device 10 according to this embodiment is sandwiched between metal plates 400, and corresponds to a cross-sectional view in the BB direction of Fig. 12A.

[0038] In Fig. 12A, metal plate 400 is configured as a square with each side measuring 500 mm, similar to Fig. 9A. In Fig. 12B, length L5 is 10.5 mm, and length L6 is 4 mm.

[0039] Fig. 13 is a diagram for explaining the VSWR characteristics of the antenna device 10. The two waveforms shown in Fig. 13 show the VSWR characteristics of the antenna device 10 when metal is nearby (metal proximity) and when no metal is nearby (free space). As shown in Fig. 13, the antenna device 10 according to this embodiment has a change in antenna characteristics between when metal is nearby and when in free space, but there is no extreme change like in the comparative example shown in Fig. 10, and the antenna has characteristics that allow it to function sufficiently as an antenna.

[0040] Fig. 14 is a diagram for explaining the Smith chart for the antenna device 10 according to this embodiment. Even in the case of the Smith chart, although the antenna characteristics of the antenna device 10 according to this embodiment change between the proximity of metal and free space, there is no extreme change as in the comparative example shown in Fig. 11, and the antenna has characteristics that allow it to function sufficiently as an antenna.

[0041] 15A and 15B are diagrams illustrating the electric field distribution of a conventional antenna device as a comparative example and the antenna device 10 according to this embodiment. Generally, electric field coupling occurs when metal approaches an antenna. As shown in FIG. 15A, the conventional example has a strong electric field toward the outside of the antenna, but the antenna device 10 according to this embodiment has a strong electric field mainly within the antenna (inside the substrate). The antenna device 10 has a strong electric field within the antenna substrate and weak coupling with the metal on the outside, so it is less susceptible to this influence. On the other hand, the conventional antenna has strong coupling with the outer metal, so it is more susceptible to this influence.

[0042] Fig. 16A is a diagram for explaining a configuration in which the antenna device 10 according to this embodiment is sandwiched between resin 500. Fig. 16B is a side view for explaining a configuration in which the antenna device 10 according to this embodiment is sandwiched between resin 500, and corresponds to a cross-sectional view in the CC direction with respect to Fig. 16A.

[0043] 16A, resin 500 is configured as a square with one side measuring 100 mm. In FIG. 16B, resin 500 has a thickness of 10 mm.

[0044] Fig. 17 is a diagram for explaining the VSWR characteristics of the antenna device 10 and the inverted-F antenna device 11. The four waveforms shown in Fig. 17 show the VSWR characteristics of the antenna device 10 and the inverted-F antenna device 11 when resin is in proximity (resin proximity) and when resin is not in proximity (free space).

[0045] 17, when resin is placed in the vicinity, the inverted-F antenna device 11 experiences a large shift of several hundred MHz in the resonant frequency, whereas the antenna device 10 according to this embodiment experiences a shift of approximately 20 to 30 MHz. That is, the antenna device 10 according to this embodiment is less affected by not only metal but also the dielectric (resin) compared to the inverted-F antenna device 11 as a comparative example, and has characteristics that allow it to function satisfactorily as an antenna.

[0046] Fig. 18 is a diagram for explaining the gain of the antenna device 10 according to this embodiment. As shown in Fig. 18, the antenna characteristics of the antenna device 10 according to this embodiment change in free space, in proximity to metal, and in proximity to resin, but do not change drastically, and the antenna has characteristics that allow it to function sufficiently as an antenna.

[0047] As described above, the antenna device 10 according to this embodiment includes a planar substrate 100 and an element section 101 that is made of metal foil and provided on the surface of a first plane of the planar substrate 100, and that has a first short section 121 and a first power supply section 111. The antenna device 10 also includes a first ground section 201 that is made of metal foil and provided on the surface of the first plane, and that has a first through-hole section 211. The antenna device 10 also includes a second ground section 202 that is made of metal foil and provided on a second plane different from the first plane. The second ground section 202 also includes a second short section 122 that is connected to the first short section 121, a second power supply section 112 that is connected to the first power supply section 111, and a second through-hole section 212 that is connected to the first through-hole section 211. The first plane is formed of three regions: a first region in which the element portion 101 is provided, a second region in which the first ground portion 201 is provided, and a third region sandwiched between the first and second regions and having no metal foil on its surface.

[0048] As a result, the antenna device 10 can achieve appropriate communication by obtaining a desired resonant frequency even when a metal or dielectric is in the vicinity.

[0049] Furthermore, the longitudinal length of the element unit 101 of the antenna device 10 may be half the wavelength of the applicable frequency band, thereby enabling the antenna device 10 to transmit and receive radio waves efficiently through appropriate resonance.

[0050] Furthermore, the corresponding resonant frequency may differ depending on the length in the short-side direction of the element section 101 of the antenna device 10. This makes it possible for the antenna device 10 to adjust the resonant frequency by adjusting the length in the short-side direction of the element section 101.

[0051] Furthermore, the impedance may differ depending on the position of the first power feeding portion 111 in the element section 101 of the antenna device 10. This makes it possible to adjust the impedance of the antenna device 10 by adjusting the position of the first power feeding portion 111 in the element section 101.

[0052] Furthermore, the corresponding resonant frequency may differ depending on the position of the first short-circuit portion 121 in the element portion 101 of the antenna device 10. This allows the antenna device 10 to adjust the resonant frequency of a communication system to which the antenna device 10 is applied by adjusting the position of the first short-circuit portion 121 in the element portion 101.

[0053] (Other embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiments are not limited to the contents described in the above embodiments. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0054] In the above-described embodiment, the planar substrate 100 may be a printed circuit board such as a rigid substrate, a flexible substrate, a rigid-flexible substrate, etc. The planar substrate 100 may also be formed of a dielectric material (resin, rubber, ceramic, etc.) or air (air layer).

[0055] The features of the antenna device 10 will be described below.

[0056] An antenna device 10 according to a first aspect includes a planar substrate 100 and an element section 101 that is made of metal foil and provided on a surface of a first plane of the planar substrate 100, and that has a first short section 121 and a first power supply section 111. The antenna device 10 also includes a first ground section 201 that is made of metal foil and provided on the surface of the first plane, and that has a first through-hole section 211. The antenna device 10 also includes a second ground section 202 that is made of metal foil and provided on a second plane different from the first plane. The second ground section 202 also includes a second short section 122 that is connected to the first short section 121, a second power supply section 112 that is connected to the first power supply section 111, and a second through-hole section 212 that is connected to the first through-hole section 211. The first plane is formed of three regions: a first region in which the element portion 101 is provided, a second region in which the first ground portion 201 is provided, and a third region sandwiched between the first and second regions and having no metal foil on its surface.

[0057] According to the above configuration, the antenna device 10 can achieve appropriate communication by obtaining a desired resonant frequency even when a metal or a dielectric is in the vicinity.

[0058] The element section 101 of the antenna device 10 according to the second embodiment may have a length in the longitudinal direction that is half the wavelength of the applicable frequency band.

[0059] According to the above configuration, the antenna device 10 can transmit and receive radio waves efficiently through appropriate resonance.

[0060] The element section 101 of the antenna device 10 according to the third embodiment may have different resonant frequencies depending on the length in the short side direction.

[0061] According to the above configuration, the antenna device 10 can adjust the resonant frequency by adjusting the length of the element section 101 in the short side direction.

[0062] The impedance may vary depending on the position of the first feeding portion 111 in the element portion 101 of the antenna device 10 according to the fourth embodiment.

[0063] According to the above configuration, the antenna device 10 can adjust the impedance of the antenna device 10 by adjusting the position of the first feeding portion 111 in the element portion 101.

[0064] The corresponding resonant frequency may vary depending on the position of the first short portion 121 in the element portion 101 of the antenna device 10 according to the fifth embodiment.

[0065] According to the above configuration, by adjusting the position of the first short-circuit portion 121 in the element portion 101, the antenna device 10 can adjust the resonant frequency of the communication system to which the antenna device 10 is applied. [Explanation of symbols]

[0066] 10 Antenna device 11 Inverted F antenna device 100 flat board 101 Element section 111 First power supply section 112 Second power supply section 121 First Short Section 122 Second Short Section 201 First Ground Section 202 Second Ground Section 211 First through-hole section 212 Second through-hole section 300 No copper foil 400 metal plate 500 resin

Claims

1. A planar substrate; an element portion made of metal foil on the surface of the first plane of the planar substrate, the element portion having a first short portion and a first power supply portion; a first ground portion provided on the surface of the first plane using the metal foil and having a first through-hole portion; a second ground portion provided on a second plane different from the first plane by the metal foil, the second ground portion having a second short portion connected to the first short portion, a second power supply portion connected to the first power supply portion, and a second through-hole portion connected to the first through-hole portion; The first plane of the antenna device is formed of three regions: a first region in which the element portion is provided, a second region in which the first ground portion is provided, and a third region sandwiched between the first region and the second region and not having the metal foil on its surface.

2. 2. The antenna device according to claim 1, wherein the element portion has a length in the longitudinal direction that is half the wavelength of an applicable frequency band.

3. The antenna device according to claim 1 , wherein the element portion has a corresponding resonant frequency that varies depending on the length in the short side direction.

4. The antenna device according to claim 1 , wherein impedance varies depending on the position of the first feeding portion in the element portion.

5. The antenna device according to claim 1 , wherein a corresponding resonant frequency varies depending on the position of the first short portion in the element portion.

Images