Antenna device

Abstract

[Problem] To realize an antenna device compatible with radio waves in a wide frequency band region. [Solution] This antenna device comprises a first element, a second element capacitively coupled to the first element, and a base to which the first element and the second element are connected. The first element, together with the second element, are compatible at least with radio waves in a first frequency band.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an antenna device including an antenna for a low frequency band and an antenna for a high frequency band.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since the antenna for a telephone in Patent Document 1 has a particularly narrow band in the low frequency band, it has been difficult for the antenna device to cope with radio waves in a wide band from low frequency to high frequency.

[0005] An example of an object of the present invention is to realize an antenna device capable of coping with radio waves in a wide frequency band. Other objects of the present invention will become apparent from the description herein.

Means for Solving the Problems

[0006] One aspect of the present invention includes a first element, a second element capacitively coupled to the first element, and a base to which the first element and the second element are connected, and the first element, together with the second element, corresponds to radio waves in at least a first frequency band, and is an antenna device.

Effects of the Invention

[0007] According to one aspect of the present invention, an antenna device capable of coping with radio waves in a wide frequency band can be realized.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Embodiments for Carrying Out the Invention

[0009] From the descriptions in this specification and the accompanying drawings, at least the following matters become clear.

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are denoted by the same reference numerals, and repeated explanations will be omitted as appropriate.

[0011] ==First Embodiment== FIG. 1 is an exploded perspective view of the antenna device 1A of the first embodiment. FIG. 2 is a three-view drawing of the antenna device 1A of the first embodiment. Note that FIG. 2A is a plan view of the antenna device 1A, FIG. 2B is a front view of the antenna device 1A, and FIG. 2C is a right side view of the antenna device 1A.

[0012] FIG. 1 shows an exploded perspective view of the antenna device 1A with the case 2 (described later) moved to the upper part in order to illustrate the internal configuration of the antenna device 1A. Also, in FIG. 2, the case 2 is not shown in the antenna device 1A.

[0013] <<Definition of Directions and the Like>> First, while referring to FIG. 1, define the directions (left - right direction, front - back direction, and up - down direction) in the antenna device 1A.

[0014] In FIG. 1, the direction in which the first element 11A (described later) and the second element 21A (described later) are arranged is defined as the left - right direction. Also, in FIG. 1, the side from the second element 21A toward the first element 11A is defined as the left direction, and the opposite direction (the side from the first element 11A toward the second element 21A) is defined as the right direction.

[0015] Also, in FIG. 1, the direction in which the extending portion 13A (described later) extends with respect to the standing portion 12A (described later) is defined as the front - back direction. Also, the direction from the extending portion 13A toward the standing portion 12A is defined as the front direction, and the opposite direction (the direction from the standing portion 12A toward the extending portion 13A) is defined as the back direction.

[0016] Also, in FIG. 1, the direction perpendicular to the left - right direction and the front - back direction is defined as the up - down direction. Also, the direction from the ground portion 3 (described later) toward the antenna 10A is defined as the up direction, and the opposite direction (the direction from the antenna 10A toward the ground portion 3) is defined as the down direction.

[0017] Note that the front - back direction may be referred to as the "X - direction", the left - right direction may be referred to as the "Y - direction", and the up - down direction may be referred to as the "Z - direction". Also, as shown in FIG. 1, the back direction may be referred to as the +X direction, the left direction may be referred to as the +Y direction, and the up direction may be referred to as the +Z direction. Also, the left - right direction may be referred to as the "lateral direction" or the "width direction", and the up - down direction may be referred to as the "longitudinal direction" or the "height direction".

[0018] Note that the definitions of the directions and the like described above are common in other embodiments of this specification unless otherwise specified.

[0019] <<Outline of Antenna Device 1A>> Next, while referring to FIGS. 1 and 2, explain the outline of the antenna device 1A in this embodiment.

[0020] The antenna device 1A is a vehicle antenna device used in a vehicle (not shown). In the present embodiment, the antenna device 1A is mounted, for example, on the roof of the vehicle or inside the instrument panel. However, the antenna device 1A may be located at a part of the vehicle other than inside the roof or the instrument panel, such as a spoiler of the vehicle or an overhead console. Further, the antenna device 1A may be an antenna device other than for vehicles.

[0021] The antenna device 1A includes a case 2, a ground portion 3, an antenna 10A, an antenna 20A, a base portion 30A, and a filter 40 shown in FIG. 3 described later.

[0022] <Case 2> The case 2 is a member that constitutes the upper surface of the antenna device 1A. In the present embodiment, the case 2 is formed of, for example, an insulating resin. However, the case 2 may be formed of a material other than the insulating resin that transmits radio waves. Further, the case 2 may be composed of a portion of the insulating resin and a portion of another material that transmits radio waves, and the members may be freely combined.

[0023] Note that the case 2 is fixed to the ground portion 3 by a plurality of screws (not shown). However, the case 2 is not limited to being fixed by screws, and may be fixed to the ground portion 3 by snap fit, welding, adhesion, or the like. At this time, the antenna 10A, the antenna 20A, the base portion 30A, and the filter 40 are arranged in an accommodation space formed by the case 2 that constitutes the upper surface of the antenna device 1A and the ground portion 3 that constitutes the bottom surface of the antenna device 1A.

[0024] Also, the case 2 may be fixed other than the ground portion 3. The case 2 may be fixed to a base (not shown), which is, for example, a member different from the ground portion 3. The base is formed of, for example, an insulating resin. However, the base may be formed of other materials that transmit radio waves instead of the insulating resin. Further, the base may be composed of a portion of an insulating resin and a portion of other materials that transmit radio waves, and the members may be freely combined. Then, the ground portion 3, the antenna 10A, the antenna 20A, the base portion 30A, and the filter 40 may be arranged in an accommodation space formed by the case 2 that constitutes the upper surface of the antenna device 1A and the base that constitutes the bottom surface of the antenna device 1A.

[0025] <Ground portion 3> The ground portion 3 is a member that functions as the ground of the antennas (here, the antenna 10A and the antenna 20A) of the antenna device 1A. In the present embodiment, the ground portion 3 functions as a common ground for the antenna 10A and the antenna 20A. However, the ground portion 3 may function as the ground of some of the antennas of the antenna device 1A. For example, the ground portion 3 may function as the ground of the antenna 10A, and another ground portion may function as the ground of the antenna 20A.

[0026] Also, in the present embodiment, the ground portion 3 is formed as an integral metal plate (sheet metal) as shown in FIGS. 1 and 2. However, the ground portion 3 may be composed of a plurality of separate metal plates. For example, the ground portion 3 may be configured such that a metal plate provided with the antenna 10A and another metal plate provided with the antenna 20A are electrically connected.

[0027] Note that the ground portion 3 may be formed in a shape other than a plate shape as long as it functions as the ground of the antenna included in the antenna device 1A. Further, the ground portion 3 may be configured by freely combining a metal member and a member other than a metal member as long as it functions as the ground of the antenna included in the antenna device 1A. For example, the ground portion 3 may have a configuration including a metal plate and a resin insulator. Further, the ground portion 3 may be configured by a single substrate on which a conductor pattern is formed on a printed circuit board (PCB).

[0028] Further, as shown in FIG. 2A, the ground portion 3 is formed of a substantially quadrilateral member in a plan view when viewed in the -Z direction (downward). In the following description, "substantially quadrilateral" refers to a shape composed of four sides including, for example, a square or a rectangle, and for example, at least a part of a corner may be cut obliquely with respect to the side, or at least a part of a corner may include a curve. Further, in the shape of "substantially quadrilateral", a notch (recess) or a protrusion (protrusion) may be provided in a part of the side.

[0029] In the present embodiment, the ground portion 3 has a pedestal portion 4 that supports the base portion 30A. The pedestal portion 4 is formed such that a part of the ground portion 3 is bent by bending and protrudes upward. Then, the base portion 30A is installed above the pedestal portion 4. As a result, the base portion 30A is positioned at a predetermined distance above the front surface (+Z direction side surface) of the ground portion 3.

[0030] In addition, if the base 30A can be positioned at a predetermined distance above the front surface of the ground portion 3, for example, the base 30A may be supported by a holder or a case 2 (not shown). In this case, the ground portion 3 may not have the pedestal portion 4. When the base 30A is supported by the case 2, for example, antenna elements such as the first element 11A described later may be fixed to the base 30A via solder or an M-shaped spring. Also, the ground portion 3 may not have the pedestal portion 4, and the base 30A may be directly disposed on the front surface of the ground portion 3. That is, the base 30A may be positioned without being separated from the front surface of the ground portion 3.

[0031] <Antenna 10A> The antenna 10A is a broadband antenna for mobile communication based on an inverted-F antenna. In the present embodiment, the antenna 10A corresponds to radio waves in the frequency band of 699 MHz to 5000 MHz for, for example, GSM, UMTS, LTE, and 5G. However, the antenna 10A is not limited thereto, and may correspond to radio waves in a partial (for example, only for 5G) frequency band among GSM, UMTS, LTE, and 5G.

[0032] Also, the antenna 10A may correspond to radio waves in a frequency band other than those for GSM, UMTS, LTE, and 5G. The antenna 10A may be an antenna that corresponds to radio waves in a frequency band used for, for example, telematics, V2X (Vehicle to Everything: vehicle-to-vehicle communication, road-vehicle communication), Wi-Fi, Bluetooth, etc. Further, as will be described later, the antenna 10A may correspond to communication by MIMO (Multiple-Input Multiple-Output).

[0033] In the following description, a predetermined frequency band on the low-frequency side among the frequency bands of radio waves to which the antenna 10A corresponds may be referred to as the "low-frequency band". In the present embodiment, the low-frequency band is, for example, the 699 MHz to 960 MHz band.

[0034] Also, among the frequency bands of the radio waves corresponding to the antenna 10A, a predetermined frequency band on the high-frequency side may be referred to as the "high-frequency band". In the present embodiment, the high-frequency band is, for example, the 3300 MHz to 5000 MHz band.

[0035] Also, among the frequency bands of the radio waves corresponding to the antenna 10A, a predetermined frequency band between the low-frequency band and the high-frequency band may be referred to as the "mid-frequency band". In the present embodiment, the mid-frequency band is, for example, the 1710 MHz to 2690 MHz band.

[0036] As described above, the low-frequency band is a frequency band lower than the mid-frequency band. Also, the mid-frequency band is a frequency band higher than the low-frequency band and lower than the high-frequency band. Also, the high-frequency band is a frequency band higher than the mid-frequency band.

[0037] Note that the mid-frequency band and the high-frequency band may be collectively referred to as the "mid- and high-frequency band". Also, the values of the frequency bands exemplified in the above low-frequency band, mid-frequency band, and high-frequency band are not limited to these, and may vary according to the frequency band of the radio waves corresponding to the antenna 10A.

[0038] The antenna 10A includes a first element 11A and a power feeding unit 18.

[0039] The first element 11A is an element that resonates in the frequency band of the radio waves corresponding to the antenna 10A (for example, the low-frequency band and the mid- and high-frequency band). As shown in FIGS. 1 and 2B, the first element 11A is connected to the base 30A. Here, "connected" is not limited to being physically connected, and includes "electrically connected". Therefore, "the first element 11A is connected to the base 30A" specifically includes not only connecting the first element 11A and the base 30A with a conductor, but also connecting them with an electronic circuit, electronic components, etc.

[0040] The first element 11A includes a standing portion 12A, an extending portion 13A, and a short-circuit portion 17A.

[0041] The standing part 12A is a part of the first element 11A that is formed to rise with respect to the base part 30A. In the present embodiment, the standing part 12A is formed to rise upward with respect to the base part 30A. Note that the rising direction of the standing part 12A with respect to the base part 30A is not limited to the upward direction (+Z direction), and it may be inclined at a predetermined angle with respect to the base part 30A.

[0042] In the present embodiment, as shown in FIG. 2B, the standing part 12A has a self-similar shape. Thereby, it becomes possible to achieve broadband. Here, the self-similar shape is a shape in which the shape remains similar even when the scale (size ratio) is changed. However, the standing part 12A does not necessarily have a self-similar shape.

[0043] As shown in FIG. 2B, a first element connection part 19 is provided at the lower end part (-Z direction) of the standing part 12A. The first element connection part 19 is a part of the first element 11A that is connected to the base part 30A. Thereby, the first element 11A is connected to the base part 30A.

[0044] According to the corresponding frequency band of the first element 11A, the connection of the first element 11A to the base part 30A may be performed by screwing. In this case, a boss for screwing is formed in the case 2, and by screwing together with the base part 30A, both mechanical support of the first element 11A and electrical connection to the base part 30A can be achieved. Also, in this case, by adjusting the length of the screw, it can also be operated as a part of the antenna.

[0045] The extension part 13A is a part formed to extend from the standing part 12A. Also, the extension part 13A is a part formed to face the ground part 3. In the present embodiment, as shown in FIG. 1, the extension part 13A is formed to extend from the upper end of the standing part 12A. However, the extension part 13A may be formed to extend from other than the upper end of the standing part 12A. That is, the extension part 13A may be formed to extend from the middle in the vertical direction of the standing part 12A. Note that the extending direction of the extension part 13A is not limited to the direction parallel to the surface of the ground part 3, and may be a direction inclined at a predetermined angle from the direction parallel to the surface of the ground part 3.

[0046] The extension part 13A has a main part 14A, a first additional part 15A, and a second additional part 16A.

[0047] The main part 14A is a part of the extension part 13A that extends from the standing part 12A. The main part 14A is shown in FIGS. 1 and 2A in the region other than the two regions (the region corresponding to the first additional part 15A and the region corresponding to the second additional part 16A) surrounded by the broken line.

[0048] The first additional part 15A is a part that extends from the main part 14A and is located away from the standing part 12A. In the present embodiment, the first additional part 15A extends rearward from the rear end of the main part 14A, bends to the right direction, and further extends. The first additional part 15A is shown in FIGS. 1 and 2A in the region located on the rear side (+X direction side) of the two regions surrounded by the broken line. Here, "being located away from the standing part 12A" means that in the positional relationship between the first additional part 15A and the second additional part 16A, one (the first additional part 15A) is located farther away from the other (the second additional part 16A). That is, it can be said that the distance between the standing part 12 and the first additional part 15A is larger than the distance between the standing part 12 and the second additional part 16A.

[0049] The second additional part 16A extends from the main part 14A and is located in a part close to the standing part 12A. In FIGS. 1 and 2A, the second additional part 16A is shown in the region located on the front side (-X direction side) among the two regions surrounded by the broken line. Here, "being located close to the standing part 12A" means that in the positional relationship between the first additional part 15A and the second additional part 16A, one (the second additional part 16A) is located closer to the standing part 12 with respect to the other (the first additional part 15A).

[0050] The short - circuit part 17A branches from the extending part 13A and is a part connected to the base part 30A. Also, the short - circuit part 17A is electrically connected to the ground part 3. By the first element 11A having the short - circuit part 17A, the antenna 10A can easily achieve impedance matching in the frequency band of the corresponding radio wave.

[0051] Note that the connection of the short - circuit part 17A to the base part 30A may be by soldering, welding, etc., or may be by screwing. In this case, a screw - fixing boss is formed on the case 2, and by screwing together with the base part 30A, both mechanical support of the short - circuit part 17A and electrical connection to the base part 30A can be achieved. Also, in this case, by adjusting the length of the screw, it can also be made to operate as a part of the antenna.

[0052] In the antenna 10A of this embodiment, the standing part 12A, the main part 14A, the first additional part 15A, and the short - circuit part 17A mainly correspond to the low - frequency band. That is, among the first element 11A, the part composed of the standing part 12A, the main part 14A, the first additional part 15A, and the short - circuit part 17A is formed to have a length and width corresponding to the operating wavelength in the low - frequency band (for example, the wavelength at 699 MHz).

[0053] Also, in the antenna 10A of the present embodiment, the standing portion 12A, the main portion 14A, the second additional portion 16A, and the short - circuit portion 17A mainly correspond to the mid - frequency band. That is, among the first elements 11A, the portion composed of the standing portion 12A, the main portion 14A, the second additional portion 16A, and the short - circuit portion 17A is formed to have a length and width corresponding to the wavelength of the mid - frequency band (for example, the wavelength at 2 GHz).

[0054] Also, in the antenna 10A of the present embodiment, the standing portion 12A mainly corresponds to the high - frequency band. That is, among the first elements 11A, the portion composed of the standing portion 12A is formed to have a length and width corresponding to the wavelength of the high - frequency band (for example, the wavelength at 5 GHz).

[0055] The feeding portion 18 is an area including the feeding point of the antenna 10A. In the present embodiment, as shown in FIG. 2B, the feeding portion 18 is located at the portion (the first - element connection portion 19) where the first element 11A is connected to the base portion 30A.

[0056] <Antenna 20A> The antenna 20A is a broadband antenna for mobile communication based on a monopole antenna. In the present embodiment, the antenna 20A corresponds to radio waves in a frequency band different from the frequency band of the radio waves to which the antenna 10A corresponds. The antenna 20A corresponds to, for example, radio waves in the 1710 MHz - 5000 MHz band for Sub6. However, the antenna 20A may also correspond to radio waves in a frequency band other than for Sub6. The antenna 20A may be an antenna corresponding to radio waves in a frequency band used for, for example, telematics, V2X, Wi - Fi, Bluetooth, etc.

[0057] Note that the antenna 20A may correspond to radio waves in the same frequency band as the radio waves corresponding to the antenna 10A. That is, the antenna 20A may correspond to radio waves in the 699 MHz to 5000 MHz band for GSM, UMTS, LTE, and 5G, for example. In this case, the antenna device 1A may be an antenna device that performs communication by MIMO, for example. In communication by MIMO, data is transmitted from each of a plurality of antennas, and data is received by a plurality of antennas simultaneously. In the antenna device 1A that performs communication by MIMO, data is transmitted from each of the antenna 10A and the antenna 20A that constitute the antenna device 1A, and data is received by the antenna 10A and the antenna 20A simultaneously.

[0058] The antenna 20A has a second element 21A and a power feeding unit 27. The second element 21A has an antenna unit 22 and an additional element unit 23.

[0059] The antenna unit 22 is an element that resonates in the frequency band of the radio waves corresponding to the antenna 20A (for example, the 1710 MHz to 5000 MHz band for Sub6). The antenna unit 22 is formed to have a length and a width corresponding to the frequency band of the radio waves corresponding to the antenna 20A (here, the 1710 MHz to 5000 MHz band for Sub6).

[0060] Similar to the standing portion 12A and the extending portion 13A in the first element 11A described above, the antenna unit 22 has a standing portion 24 and an extending portion 25.

[0061] The standing portion 24 is a portion of the antenna unit 22 that is formed to rise with respect to the base portion 30A. In the present embodiment, the standing portion 24 is formed to rise upward with respect to the base portion 30A. Note that the rising direction of the standing portion 24 with respect to the base portion 30A is not limited to the upward direction (+Z direction), and may be a direction inclined at a predetermined angle with respect to the base portion 30A.

[0062] At the downward (-Z direction) end of the standing portion 24, as shown in FIG. 2B, a second element connection portion 26 is provided. The second element connection portion 26 is a portion of the second element 21A that is connected to the base portion 30A. As a result, the second element 21A will be connected to the base portion 30A.

[0063] The extending portion 25 is a portion formed to extend from the standing portion 24. Also, the extending portion 25 is a portion formed to face the ground portion 3. In the present embodiment, as shown in FIGS. 1 and 2C, the extending portion 25 is formed to extend from the upper end of the standing portion 24. However, the extending portion 25 may be formed to extend from other than the upper end of the standing portion 24. That is, the extending portion 25 may be formed to extend from the middle in the vertical direction of the standing portion 24. Note that the extending direction of the extending portion 25 is not limited to a direction parallel to the surface of the ground portion 3, and may be a direction inclined at a predetermined angle from a direction parallel to the ground portion 3.

[0064] The additional element portion 23 is a portion formed to further extend from the extending portion 25 of the antenna portion 22. The additional element portion 23, together with the antenna portion 22, is a portion that resonates in the corresponding radio wave frequency band of the antenna 20A (for example, the 1710 MHz to 5000 MHz band for Sub6). Also, the additional element portion 23 has a portion that capacitively couples with the first element 11A.

[0065] Specifically, as shown in FIGS. 1, 2A, and 2C, the additional element portion 23 extends from the extending portion 25 of the antenna portion 22 in the +X direction. Then, the additional element portion 23 bends from there in the +Y direction so that the end of the additional element portion 23 is provided close to the end of the first additional portion 15A in the extending portion 13A of the first element 11A. Therefore, in the present embodiment, the additional element portion 23 is provided to capacitively couple with the end of the first element 11A.

[0066] Here, when the end of the additional element portion 23 is close to the end of the first element 11A, the "end" does not mean a strict end, but means a predetermined region including the end.

[0067] In this embodiment, although the end of the additional element portion 23 and the end of the first additional portion 15A are positioned so as to overlap in a plan view shown in FIG. 2A, they are separated in the vertical direction in a front view shown in FIG. 2B. However, the positional relationship between the end of the additional element portion 23 and the end of the first additional portion 15A is not limited to the positional relationship shown in FIGS. 2A and 2B.

[0068] In this embodiment, as shown in FIG. 2B, the end of the first additional portion 15A is positioned above the end of the additional element portion 23, but the end of the additional element portion 23 may be provided so as to be positioned above the end of the first additional portion 15A.

[0069] Also, the end of the additional element portion 23 and the end of the first additional portion 15A may be separated in the left - right direction, for example, in a plan view shown in FIG. 2A. In this case, the end of the additional element portion 23 and the end of the first additional portion 15A may have the same vertical position or different vertical positions in a side view shown in FIG. 2B, for example.

[0070] Furthermore, in this embodiment, the end of the additional element portion 23 and the end of the first additional portion 15A coincide in the front - rear direction as shown in FIG. 2A, but they may not coincide and may be different in the front - rear direction. For example, the end of the additional element portion 23 may be positioned in front of the end of the first additional portion 15A, or may be positioned such that at least a part thereof overlaps in the front - rear direction, or may be positioned so as to be separated from each other in the front - rear direction.

[0071] From the above, the end of the additional element portion 23 and the end of the first additional portion 15A may be provided at positions close to each other such that the first element 11A and the second element 21A are capacitively coupled.

[0072] In the antenna device 1A of the present embodiment, as described above, the end of the first element 11A and the end of the second element 21A are provided at positions where they are capacitively coupled, and the capacitive coupling portion 35 is realized.

[0073] Thereby, in the low frequency band, two resonances can be generated between the first element 11A of the antenna 10A and the second element 21A of the antenna 20A having the additional element portion 23. That is, by superimposing two resonances, namely, the resonance of the first element 11A alone of the antenna 10A and the resonance of the antenna 10A considering capacitive coupling, the band of the corresponding low frequency band of the first element 11A can be further extended to the lower frequency side. Therefore, in the antenna device 1A of the present embodiment, the broadbanding of the antenna 10A can be easily realized.

[0074] The power feeding portion 27 is a region including the power feeding point of the antenna 20A. In the present embodiment, as shown in FIG. 2B, the power feeding portion 27 is located at a portion (second element connection portion 26) where the second element 21A is connected to the base portion 30A.

[0075] <Base portion 30A> The base portion 30A is a plate-like member to which the first element 11A of the antenna 10A and the second element 21A of the antenna 20A are connected. Note that elements, circuits, etc. for processing signals from the antenna 10A and the antenna 20A may be provided on the base portion 30A.

[0076] In the antenna device 1A of the present embodiment, the base portion 30A is, for example, a printed circuit board (PCB). The base portion 30A has a conductor pattern formed on a resin material such as glass epoxy resin. However, the base portion 30A may have a conductor pattern formed on a resin material other than glass epoxy resin such as phenolic resin. Further, the base portion 30A may be, for example, a flexible substrate.

[0077] However, it is not necessary for the entire base 30A to be formed in a plate shape, and the base 30A may have a portion formed in a shape other than a plate shape. For example, the base 30A may be a part of the case 2, or may be a part of a holder (not shown) that holds the above-described first element 11A and second element 21A. At this time, the case 2 and the holder (not shown) may be made of, for example, resin.

[0078] Note that the base 30A is not limited to the above-described configuration and may be composed of only a conductor pattern. Further, when the base 30A is configured by forming a conductor pattern in a resin material, for example, MID (Molded Interconnect Device) technology may be used. Thereby, a conductor pattern can be formed on a resin material having a complex three-dimensional shape. For example, a conductor pattern can also be formed using MID technology on a resin material having a shape like the base 30A shown in FIGS. 1 and 2.

[0079] By the way, when the antenna 10A and the antenna 20A are arranged close to each other so as to be capacitively coupled as in the antenna device 1A of the present embodiment, the isolation between the antenna 10A and the antenna 20A may deteriorate. Specifically, when the antenna 10A and the antenna 20A are arranged close to each other, the antenna 10A and the antenna 20A may be affected by signals in the frequency band corresponding to each other's antennas. For example, a signal having a frequency of the radio wave corresponding to the antenna 10A may leak to the base 30A side through the power feeding unit 27 of the antenna 20A. For this reason, the antenna 10A is affected by the adjacent antenna 20A, and for example, the characteristics of the antenna 10A in the low frequency band may deteriorate.

[0080] Therefore, the antenna device 1A of the present embodiment has a filter 40 as described later, thereby improving the isolation between the antenna 10A and the antenna 20A.

[0081] <Filter 40> FIG. 3 is a diagram showing the periphery of the bottom surface of the base 30A to which the second element 21A is connected.

[0082] The filter 40 is a circuit element that suppresses signals in a predetermined frequency band. In the present embodiment, among the frequency bands of the corresponding radio waves of the antenna 20A, signals in an undesired frequency band are suppressed. In the present embodiment, the undesired frequency band is, for example, a low frequency band (699 MHz to 960 MHz band) among the frequency bands of the corresponding radio waves of the antenna 10A. Note that the filter 40 does not necessarily suppress signals in the entire low frequency band, and may suppress signals in a part of the low frequency band.

[0083] In the antenna device 1A of the present embodiment, as shown in FIG. 3, a power line (microstrip line) formed of a conductor part is provided between the second element connection part 26 and the feeding line connection part 5 to which the feeding line is connected. The filter 40 is provided so as to be connected in series to the microstrip line. Specifically, the filter 40 is provided between the first region 31 and the second region 32. Here, the first region 31 is a conductive region on the side of the microstrip line of the base 30A where the feeding line of the antenna device 1A is connected. The second region 32 is a conductive region on the side of the microstrip line of the base 30A where the second element 21A is connected.

[0084] In the present embodiment, as shown in FIG. 3, the filter 40 is arranged on the side closer to the second element connection part 26 (that is, the side closer to the feeding part 27 of the antenna 20A) than the feeding line connection part 5 to which the feeding line is connected in the microstrip line of the base 30A. Thereby, deterioration of signals due to coupling between transmission lines in the microstrip line can be suppressed. However, when the problem of signal deterioration due to coupling between transmission lines can be tolerated, the filter 40 may be arranged on the side closer to the feeding line connection part 5 than the second element connection part 26.

[0085] In addition, in FIG. 3, the filter 40 is shown by a dashed-line enclosure as a single block for convenience. However, in reality, the filter 40 actually includes two circuit elements, an inductor L and a capacitor C, as shown in FIG. 4 described later.

[0086] FIG. 4 is a circuit diagram showing an example of the filter 40. Note that FIG. 4A is a circuit diagram of a high-pass filter 41, FIG. 4B is a circuit diagram of a band-pass filter 42, and FIG. 4C is a circuit diagram of a band-elimination filter 43.

[0087] The filter 40 may be, for example, a high-pass filter 41 (HPF) as shown in FIG. 4A. The high-pass filter 41 is a circuit element that suppresses signals in a low-frequency band and passes signals in a medium- and high-frequency band, for example. The high-pass filter 41 includes a capacitor C and an inductor L connected to the ground potential, as shown in FIG. 4A.

[0088] Also, the filter 40 may be, for example, a band-pass filter 42 (BPF) as shown in FIG. 4B. The band-pass filter 42 is a circuit element that passes only signals in a specific frequency band (here, the medium- and high-frequency band) and suppresses signals in other frequency bands (here, the low-frequency band). The band-pass filter 42 includes an inductor L, a capacitor C, and a parallel circuit of the inductor L and the capacitor C connected to the ground potential, as shown in FIG. 4B.

[0089] Also, the filter 40 may be, for example, a band-elimination filter 43 (BEF) as shown in FIG. 4C. The band-elimination filter 43 is a circuit element that suppresses signals in a specific frequency band (here, the low-frequency band) and passes signals in other frequency bands (here, the medium- and high-frequency band). The band-elimination filter 43 includes a series circuit composed of an inductor L and a capacitor C connected to the ground potential and a parallel circuit of the inductor L and the capacitor C, as shown in FIG. 4C.

[0090] In addition, for each filter shown in FIGS. 4A to 4C, one terminal IN is connected to, for example, the first region 31, and the other terminal OUT is connected to, for example, the second region 32. In this way, the filter 40 will be connected in series to the microstrip line.

[0091] From the above, the antenna device 1A of the present embodiment has a filter 40 composed of a high-pass filter 41, a band-pass filter 42, or a band elimination filter 43, whereby the isolation between the antenna 10A and the antenna 20A can be improved. Note that the filter 40 of the present embodiment is a circuit element that suppresses signals in a predetermined frequency band, but for example, a SAW (Surface Acoustic Wave) filter may be used. Note that when the isolation problem can be tolerated depending on the communication standard and the reception signal level of the antenna 10A or the antenna 20A, the antenna device 1A may not have the filter 40.

[0092] <Other configurations of the antenna device 1A> In addition, the antenna device 1A may have a holder (not shown) that supports at least any one of the antenna 10A, the antenna 20A, and the base 30A. The holder is formed of resin and is provided on the ground portion 3. However, the holder may be formed of materials other than resin.

[0093] However, the antenna 10A and the antenna 20A may be fixed to the case 2 by screwing, welding, adhesion, snap fit, etc., instead of the above-described holder. Thereby, the assemblability of the antenna device 1A can be improved. In addition, the distance at which the end of the first element 11A and the end of the second element 21A are close to each other can be stabilized, and the capacitive coupling can be stabilized. In addition, holes may be formed in the first element 11A of the antenna 10A and the second element 21A of the antenna 20A for welding to the case 2.

[0094] The antenna device 1A may have another antenna other than the antennas 10A and 20A. The other antenna may be, for example, a planar antenna for a Global Navigation Satellite System (GNSS), a Satellite Digital Audio Radio Service (SDARS), or an Electronic Toll Collection (ETC).

[0095] Note that the planar antennas for GNSS and SDARS may be multi-layered or multi-stage antennas when the limitation on the vertical size in the antenna device 1A is not strict. Thereby, the planar antenna can correspond to radio waves in a plurality of frequency bands. Also, the planar antenna may have a radiation element provided with an opening such as a slot and correspond to radio waves in a plurality of frequency bands.

[0096] Also, the other antenna other than the antennas 10A and 20A is not limited to the above, and may be an antenna corresponding to radio waves in the frequency bands used for telematics, V2X, Wi-Fi, Bluetooth, and DAB.

[0097] <<Antenna device 1X of the comparative example>> As described above, in the antenna device 1A of the present embodiment, the capacitive coupling portion 35 is realized by the end of the first element 11A and the end of the second element 21A. Thereby, in the antenna device 1A of the present embodiment, the band of the corresponding low-frequency band of the first element 11A can be further extended to the lower frequency side. Hereinafter, the characteristics of the antenna 10A of the antenna device 1A of the present embodiment will be verified using a comparative example. First, the antenna device 1X of the comparative example shown in FIG. 5 will be described.

[0098] FIG. 5 is a perspective view of the antenna device 1X of the comparative example. In FIG. 5, in the antenna device 1X, the case 2 which is the same as the antenna device 1A of the present embodiment is not shown.

[0099] In the antenna device 1X of the comparative example, as shown in FIG. 5, the second element 21X of the antenna 20X does not have a configuration corresponding to the additional element portion 23 in the antenna device 1A of the present embodiment. Therefore, the antenna device 1X of the comparative example does not have the capacitive coupling portion 35 in the antenna device 1A of the present embodiment. Further, the antenna device 1X of the comparative example does not have a configuration corresponding to the filter 40 either.

[0100] Note that, regarding the configuration of the antenna device 1X of the comparative example other than not having the above-described additional element portion 23 and the filter 40, it is the same as that of the antenna device 1A of the present embodiment. Specifically, the antenna device 1X of the comparative example has an antenna 10X similar to the antenna 10A in the antenna device 1A of the present embodiment, and a base portion 30X similar to the base portion 30A in the antenna device 1A of the present embodiment. Further, the first element 11X of the antenna 10X and the second element 21X of the antenna 20X are connected to the base portion 30X.

[0101] Note that the configuration of the first element 11X of the antenna 10X of the comparative example is the same as the configuration of the first element 11A of the antenna 10A of the present embodiment. Specifically, the first element 11X has a standing portion 12X similar to the standing portion 12A of the present embodiment, an extending portion 13X similar to the extending portion 13A of the present embodiment, and a short-circuit portion 17X similar to the short-circuit portion 17A of the present embodiment. Although detailed illustration is omitted, the first element 11X has portions corresponding to the low frequency band, the middle frequency band, and the high frequency band, similar to the antenna device 1A of the present embodiment.

[0102] Next, a comparison of the frequency characteristics between the antenna 10A of the present embodiment and the antenna 10X of the comparative example is performed.

[0103] <<Comparison of Frequency Characteristics>> FIG. 6 is a graph showing an example of the frequency characteristics of the antenna 10A of the first embodiment and the antenna 10X of the comparative example in the low frequency band. Note that FIG. 6A is a graph of the VSWR of the antenna 10A and the antenna 10X in the low frequency band, and FIG. 6B is a graph of the isolation of the antenna 10A and the antenna 10X in the low frequency band.

[0104] Further, FIG. 7 is a graph showing an example of the frequency characteristics of the antenna 10A of the first embodiment and the antenna 10X of the comparative example in the middle frequency band. Note that FIG. 7A is a graph of the VSWR of the antenna 10A and the antenna 10X in the middle frequency band, and FIG. 7B is a graph of the isolation of the antenna 10A and the antenna 10X in the middle frequency band.

[0105] Further, FIG. 8 is a graph showing an example of the frequency characteristics of the antenna 10A of the first embodiment and the antenna 10X of the comparative example in the high frequency band. Note that FIG. 8A is a graph of the VSWR of the antenna 10A and the antenna 10X in the high frequency band, and FIG. 8B is a graph of the isolation of the antenna 10A and the antenna 10X in the high frequency band.

[0106] In each of FIGS. 6A, 7A, and 8A, the horizontal axis represents the frequency, and the vertical axis represents the VSWR. In each of FIGS. 6B, 7B, and 8B, the horizontal axis represents the frequency, and the vertical axis represents the isolation. Also, in each graph, the results of the antenna 10X of the comparative example are indicated by a dashed line.

[0107] Note that, regarding the frequency characteristics of the antenna 10A of the present embodiment, a comparison is made between the case of the antenna 10A without the filter 40 (antenna 10A without filter 40) and the case of the antenna 10A with the filter 40 (antenna 10A with filter 40). In each graph, the results of the antenna 10A without the filter 40 are indicated by a solid line, and the results of the antenna 10A with the filter 40 are indicated by a dashed line.

[0108] First, as shown in FIG. 6A, compare the VSWR characteristics (dashed-dotted line) of the antenna 10X of the comparative example with the VSWR characteristics (solid line) of the antenna 10A without the filter 40 of the present embodiment. Then, it can be seen that in most of the bands in the low-frequency band, the VSWR characteristics of the antenna 10A without the filter 40 of the present embodiment are improved compared to the antenna 10X of the comparative example.

[0109] Next, as shown in FIG. 6A, compare the VSWR characteristics (dashed-dotted line) of the antenna 10X of the comparative example with the VSWR characteristics (broken line) of the antenna 10A with the filter 40 of the present embodiment. Then, similarly in this case, it can be seen that in most of the bands in the low-frequency band, the VSWR characteristics of the antenna 10A with the filter 40 of the present embodiment are improved compared to the antenna 10X of the comparative example. However, as shown in FIG. 6A, the antenna 10A with the filter 40 of the present embodiment has a smaller degree of improvement in VSWR characteristics than the antenna 10A without the filter 40 described above.

[0110] Here, as shown in FIG. 6B, compare the isolation (dashed-dotted line) of the antenna 10X of the comparative example with the isolation (solid line) of the antenna 10A without the filter 40 of the present embodiment. Then, it can be seen that in all bands in the low-frequency band, the isolation of the antenna 10A without the filter 40 of the present embodiment deteriorates compared to the antenna 10X of the comparative example.

[0111] On the other hand, as shown in FIG. 6B, compare the isolation (solid line) of the antenna 10A without the filter 40 of the present embodiment with the isolation (broken line) of the antenna 10A with the filter 40 of the present embodiment. Then, it can be seen that in all bands in the low-frequency band, the isolation of the antenna 10A with the filter 40 is improved compared to the antenna 10A without the filter 40 of the present embodiment. Also, although there are some exceptions, it can be seen that the isolation of the antenna 10A with the filter 40 is improved compared to the antenna 10X of the comparative example.

[0112] Therefore, from the above verification results, it can be seen that in the antenna device 1A of the present embodiment, compared with the antenna device 1X of the comparative example, the frequency characteristics in the low frequency band are improved. As described above, in the antenna device 1A of the present embodiment, the end of the first element 11A and the end of the second element 21A are provided at positions close to each other, so that capacitive coupling occurs. As a result, the capacitive coupling portion 35 is realized, and in the antenna device 1A of the present embodiment, the band of the corresponding low frequency band of the first element 11A can be further extended to the lower frequency side.

[0113] In addition, since the antenna device 1A of the present embodiment has the filter 40, the isolation can be improved.

[0114] Although detailed description is omitted, as shown in FIGS. 7 and 8, the antenna 10A of the present embodiment has good characteristics (VSWR and isolation) in the medium and high frequency bands, although there are some exceptions.

[0115] ==Second Embodiment== In the antenna device 1A of the first embodiment described above, the capacitive coupling portion 35 is realized by the end of the first element 11A and a part of the antenna 20A (the end of the second element 21A). However, like the antenna devices 1B and 1C described later in the present embodiment, the second element (the second elements 21B to 21D) may be configured as a non-powered element.

[0116] <<Antenna Device 1B of the First Example>>

[0117] FIG. 9 is an exploded perspective view of the antenna device 1B of the first example of the second embodiment. Note that FIG. 9 shows an exploded perspective view of the antenna device 1B with the case 2 moved upward to illustrate the internal configuration of the antenna device 1B.

[0118] In the antenna device 1B of the first example of the present embodiment, the second element 21B in which the capacitive coupling portion 35 is realized is a non-powered element. The second element 21B rises from the ground portion 3 and is formed so as to be close to the first additional portion 15B of the first element 11B of the antenna 10B.

[0119] Also by this, in the antenna device 1B of the first example of the present embodiment, in the low frequency band, two resonances can be generated between the first element 11B of the antenna 10B and the second element 21B which is a non-powered element, and the corresponding low frequency band of the first element 11B can be further extended to the lower frequency side. Therefore, also in the antenna device 1B of the present embodiment, broadbanding of the antenna 10B can be easily realized.

[0120] Regarding the configuration of the antenna device 1B of the first example of the present embodiment other than the configuration of the second element 21B described above, although it is slightly different in shape, it is the same as the antenna device 1A of the first embodiment described above. That is, the first element 11B of the antenna 10B is connected to the base portion 30B in the same manner as the antenna device 1A of the first embodiment, and has a standing portion 12B, an extending portion 13B having a main portion 14B, a first additional portion 15B, and a second additional portion 16B, and a short-circuit portion (not shown in FIG. 9).

[0121] Also, in the antenna device 1B of the first example of the present embodiment, the standing portion 12B, the main portion 14B, the first additional portion 15B, and the short-circuit portion (not shown) mainly correspond to the low frequency band. Also, in the antenna device 1B of the first example of the present embodiment, the standing portion 12B, the main portion 14B, the second additional portion 16B, and the short-circuit portion (not shown) mainly correspond to the middle frequency band. Also, in the antenna device 1B of the first example of the present embodiment, the standing portion 12B mainly corresponds to the high frequency band.

[0122] In the antenna device 1B of the first example of the present embodiment described above, the standing portion 12B of the first element 11B was formed to rise above the base portion 30B. However, the configuration of the first element is not limited to this.

[0123] <<Antenna Device 1C of the Second Example>> FIG. 10 is an exploded perspective view of the antenna device 1C of the second example of the second embodiment. FIG. 11 is a three-view drawing of the antenna device 1C of the second example of the second embodiment. Note that FIG. 11A is a plan view of the antenna device 1C, FIG. 11B is a front view of the antenna device 1C, and FIG. 11C is a right side view of the antenna device 1C. FIG. 12 is a view showing the front and bottom surfaces of the antenna device 1C of the second example of the second embodiment. Note that FIG. 12A is an enlarged view of the front surface of the first element 11C, and FIG. 12B is a view showing the periphery of the bottom surface of the base 30C to which the second element 21C is connected.

[0124] Further, FIG. 10 shows an exploded perspective view of the antenna device 1C with the case 2 moved upward in order to illustrate the internal configuration of the antenna device 1C. Also, in FIG. 11, the case 2 of the antenna device 1C is not shown.

[0125] The antenna device 1C of the second example of this embodiment has an antenna 10C and a base 30C, similar to the antenna device 1A of the first embodiment and the antenna device 1B of the first example of this embodiment.

[0126] Also, the antenna 10C in the second example of this embodiment has a first element 11C and a power supply unit 18, similar to the antenna 10A in the first embodiment and the antenna 10B in the first example of this embodiment. Further, the first element 11C in the second example of this embodiment has the same configuration as the first element 11A in the first embodiment and the first element 11B in the first example of this embodiment. That is, the first element 11C has an erecting portion 12C, an extending portion 13C having a main portion 14C, a first additional portion 15C, and a second additional portion 16C, and a short-circuit portion 17C (shown in FIGS. 11B and 11C). However, the erecting portion 12C in the second example of this embodiment is separated from the base 30C, unlike the erecting portion 12A in the first embodiment and the erecting portion 12B in the first example of this embodiment, as will be described later.

[0127] In the first element 11C of the second example of the present embodiment, similar to the first element 11A of the first embodiment, it mainly corresponds to the low frequency band by the standing portion 12C, the main portion 14C, the first additional portion 15C, and the short - circuit portion 17C. Further, in the antenna device 1C of the second example of the present embodiment, it mainly corresponds to the middle frequency band by the standing portion 12C, the main portion 14C, the second additional portion 16C, and the short - circuit portion 17C. Further, in the antenna device 1C of the second example of the present embodiment, it mainly corresponds to the high frequency band by the standing portion 12C.

[0128] In the antenna 10C of the second example of the present embodiment, the standing portion 12C is provided at a distance in the +X direction from the base portion 30C. In other words, the standing portion 12C is located at a predetermined distance (offset) in the +X direction from the base portion 30C. Similarly, the end portion on the base portion 30C side of the first element 11C (that is, the end portion on the base portion 30C side of the main portion 14C) is also located at a predetermined distance (offset) in the +X direction from the end portion on the first - element - 11C side of the base portion 30C, as shown in FIG. 11A.

[0129] In the antenna 10C of the second example of the present embodiment, by the standing portion 12C being spaced apart from the base portion 30C, the standing portion 12C can be provided so as to extend toward the ground portion 3 side rather than the base portion 30C. In the antenna device 1C of the second example of the second embodiment, as shown in FIG. 12A, the standing portion 12C and the ground portion 3 are non - conductive.

[0130] Here, the base portion 30C is located between the extension portion 13C and the ground portion 3, as shown in FIG. 12A, similar to the base portion 30A of the first embodiment. That is, the base portion 30C is located above the ground portion 3. With respect to the base portion 30C positioned in this way, in the antenna device 1C of the second example of the present embodiment, the lower end portion of the standing portion 12C can be provided so as to extend more toward the ground portion 3 side.

[0131] For example, when the limitation on the vertical size of the antenna device 1C is severe, it may be difficult to secure the length of the standing portion 12C. Further, as in the case of the antenna device 1C of the second example of the present embodiment, when the base portion 30C is located above the ground portion 3, if the standing portion 12C is provided so as to rise from the base portion 30C, it becomes more difficult to secure the vertical length of the standing portion 12C.

[0132] Therefore, as in the case of the antenna 10C of the second example of the present embodiment, by providing the lower end portion of the standing portion 12C so as to extend more toward the ground portion 3, it becomes easy to secure the vertical length of the standing portion 12C. As a result, it becomes easy to form it so as to have a length corresponding to the use wavelength in the low frequency band (for example, the wavelength at 699 MHz).

[0133] In the antenna device 1C of the second example of the present embodiment, a first element connection portion 19 is provided at the lower end portion (-Z direction) of the standing portion 12C as shown in FIGS. 10 and 11A. The first element connection portion 19 is a portion of the first element 11C that is connected to the base portion 30C. As a result, the first element 11C is connected to the base portion 30C.

[0134] Also in the antenna device 1C of the second example of the present embodiment, similar to the first example, the second element 21C in which the capacitive coupling portion 35 is realized is a non-powered element. The second element 21C in the second example of the present embodiment has a standing portion 28 and an extending portion 29.

[0135] The standing portion 28 is a portion of the second element 21C that is formed so as to rise with respect to the base portion 30C. In the second example of the present embodiment, the standing portion 28 is formed so as to rise upward with respect to the base portion 30C. Note that the rising direction of the standing portion 28 with respect to the base portion 30C is not limited to the upward direction (+Z direction), and may be a direction inclined at a predetermined angle with respect to the base portion 30C.

[0136] In the antenna device 1C of the second example of the present embodiment, a second element connection portion 26 is provided at the lower (-Z direction) end of the standing portion 28, as shown in FIG. 10. The second element connection portion 26 is a portion of the second element 21C that is connected to the base portion 30C. As a result, the second element 21C is connected to the base portion 30C.

[0137] The extending portion 29 is a portion formed to extend from the standing portion 28. Further, the extending portion 29 is a portion formed to face the ground portion 3. In the second example of the present embodiment, the extending portion 29 is formed to extend from the upper end of the standing portion 28, as shown in FIGS. 10 and 11C. However, the extending portion 29 may be formed to extend from other than the upper end of the standing portion 28. That is, the extending portion 29 may be formed to extend from the middle in the vertical direction of the standing portion 28. Note that the extending direction of the extending portion 29 is not limited to a direction parallel to the surface of the ground portion 3, and may be a direction inclined at a predetermined angle from a direction parallel to the ground portion 3.

[0138] Also, in the antenna device 1C of the second example of the present embodiment, the end of the extending portion 29 is provided so as to be close to the end of the first additional portion 15C in the extending portion 13C of the first element 11C. Therefore, in the second example of the present embodiment, the extending portion 29 is provided so as to capacitively couple with the end of the first element 11C. As a result, also in the second example of the present embodiment, a capacitive coupling portion 35 is realized at the end of the extending portion 29.

[0139] Incidentally, in the antenna device 1C of the second example of the present embodiment, as shown in FIG. 12B, a circuit element 50 is provided at the connection portion of the second element 21C with the base portion 30C. In the second example of the present embodiment, the circuit element 50 is a resistor. However, the circuit element 50 may be configured to include other circuit elements such as a filter in addition to the resistor. Also, the circuit element 50 may be an attenuator instead of the resistor. As a result, the signal in the low frequency band corresponding to the antenna 10C can be terminated, and the characteristics of the antenna 10C in the low frequency band can be improved.

[0140] In the antenna device 1C of the second example of the present embodiment, as shown in FIG. 12B, a circuit element 50 is provided between the second element connection portion 26 and the region of the base portion 30C connected to the ground portion 3. Specifically, the circuit element 50 is provided between the third region 33 and the fourth region 34. Here, the third region 33 is a conductive region on the side connected to the ground portion 3. The fourth region 34 is a conductive region on the side to which the second element 21C is connected. Thereby, the characteristics of the antenna (here, the antenna 10C) included in the antenna device 1C in the low frequency band (699 MHz to 960 MHz) can be improved.

[0141] <<Verification of Frequency Characteristics>> Hereinafter, a comparison of the frequency characteristics between the antenna 10B and the antenna 10C of the present embodiment will be made.

[0142] FIG. 13 is a graph showing an example of the frequency characteristics of the antenna 10B and the antenna 10C of the second embodiment in the low frequency band. Note that FIG. 13A is a graph of the VSWR of the antenna 10B and the antenna 10C in the low frequency band, and FIG. 13B is a graph of the radiation efficiency of the antenna 10B and the antenna 10C in the low frequency band.

[0143] Further, FIG. 14 is a graph showing an example of the frequency characteristics of the antenna 10B and the antenna 10C of the second embodiment in the middle frequency band. Note that FIG. 14A is a graph of the VSWR of the antenna 10B and the antenna 10C in the middle frequency band, and FIG. 14B is a graph of the radiation efficiency of the antenna 10B and the antenna 10C in the middle frequency band.

[0144] Further, FIG. 15 is a graph showing an example of the frequency characteristics of the antenna 10B and the antenna 10C of the second embodiment in the high frequency band. Note that FIG. 15A is a graph of the VSWR of the antenna 10B and the antenna 10C in the high frequency band, and FIG. 15B is a graph of the radiation efficiency of the antenna 10B and the antenna 10C in the high frequency band.

[0145] In each of FIGS. 13A, 14A, and 15A, the horizontal axis represents frequency, and the vertical axis represents VSWR. In each of FIGS. 13B, 14B, and 15B, the horizontal axis represents frequency, and the vertical axis represents radiation efficiency. Also, in each graph, the result of antenna 10B is shown by a solid line, and the result of antenna 10C is shown by a solid line.

[0146] As shown in FIG. 13A, the VSWR characteristic (solid line) of antenna 10B is compared with the VSWR characteristic (dashed line) of antenna 10C. As a result, it can be seen that in the low-frequency band, particularly in the low region (for example, 600 MHz to 700 MHz), the VSWR characteristic of antenna 10C is improved compared to antenna 10B. Similarly, as shown in FIG. 13B, it can be seen that in the low-frequency band, particularly in the low region (for example, 600 MHz to 700 MHz), the radiation efficiency of antenna 10C is improved compared to antenna 10B.

[0147] That is, in antenna 10C, as described above, the lower end of the standing portion 12C can be provided to extend more toward the ground portion 3 side, and since it has become easy to secure the vertical length of the standing portion 12C, it can be seen that it has become easy to form it to have a length corresponding to the wavelength used in the low-frequency band (for example, the wavelength at 699 MHz).

[0148] Although detailed description is omitted, as shown in FIGS. 14 and 15, the antennas 10B and 10C of the present embodiment have good characteristics (VSWR and radiation efficiency) in the medium- and high-frequency bands as well, although there are some exceptions.

[0149] Note that in the antenna device 1C of the second example of the present embodiment, similar to the antenna device 1A of the first embodiment, the antenna 10C and the base 30C are arranged in the accommodation space formed by the case 2 and the ground portion 3. However, as in the antenna device 1D of the third example of the present embodiment described later, a part of the first element 11D of the antenna 10D may be arranged outside the accommodation space.

[0150] <<Antenna Device 1D of the Third Example>> FIG. 16 is a perspective view of the antenna device 1D of the third example of the second embodiment. Note that FIG. 16A is an overall perspective view of the antenna device 1D, and FIG. 16B is a perspective view of the antenna device 1D with the case 2 removed. In FIG. 16B, the case 2 is not shown in order to illustrate the internal configuration of the antenna device 1D.

[0151] In the antenna device 1D of the third example of this embodiment, the configuration other than the positions where the first element 11D and the second element 21D are arranged is slightly different in shape, but is the same as the antenna device 1D of the second example of the above-described embodiment. Therefore, the differences from the antenna device 1D of the second example of this embodiment will be mainly described below.

[0152] In the antenna device 1D of the third example of this embodiment, as shown in FIG. 16A, a part of the first element 11D of the antenna 10D is arranged outside the case 2. Also, a part of the second element 21D is arranged outside the case 2. Specifically, a part of the upper side of the standing portion 12D of the first element 11D is arranged in front of the case 2, and the entire extending portion 13D of the first element 11D is arranged above the case 2. Also, a part of the upper side of the standing portion 28 of the second element 21D is arranged in front of the case 2, and the entire extending portion 29 of the second element 21D is arranged above the case 2.

[0153] Note that also in the antenna device 1D of the third example of this embodiment, similar to the antenna 10C in the second example of this embodiment, the end of the extending portion 29 is provided so as to be close to the end of the first additional portion 15D in the extending portion 13D of the first element 11D. Therefore, in the third example of this embodiment, the extending portion 29 is provided so as to capacitively couple with the end of the first element 11D. As a result, also in the third example of this embodiment, as shown in FIG. 16B, a capacitive coupling portion 35 is realized at the end of the extending portion 29.

[0154] However, the positions where the first element 11D and the second element 21D are arranged are not limited to the case shown in FIG. 16. All of the first element 11D may be arranged outside the case 2, or all of the second element 21D may be arranged outside the case 2. While all or part of the first element 11D is arranged outside the case 2, all of the second element 21D may be arranged inside the case 2. Also, while all of the first element 11D is arranged inside the case 2, all or part of the second element 21D may be arranged outside the case 2.

[0155] <<Verification of Frequency Characteristics>> Hereinafter, the frequency characteristics of the antenna 10D of the present embodiment will be verified.

[0156] FIG. 17 is a graph showing an example of the frequency characteristics of the antenna 10D of the second embodiment in the low frequency band. Note that FIG. 17A is a graph of the VSWR of the antenna 10D in the low frequency band, and FIG. 17B is a graph of the radiation efficiency of the antenna 10D in the low frequency band.

[0157] Also, FIG. 18 is a graph showing an example of the frequency characteristics of the antenna 10D of the second embodiment in the middle frequency band. Note that FIG. 18A is a graph of the VSWR of the antenna 10D in the middle frequency band, and FIG. 18B is a graph of the radiation efficiency of the antenna 10D in the middle frequency band.

[0158] Also, FIG. 19 is a graph showing an example of the frequency characteristics of the antenna 10D of the second embodiment in the high frequency band, FIG. 19A is a graph of the VSWR of the antenna 10D in the high frequency band, and FIG. 19B is a graph of the radiation efficiency of the antenna 10D in the high frequency band.

[0159] In each of FIGS. 17A, 18A, and 19A, the horizontal axis represents the frequency, and the vertical axis represents the VSWR. In each of FIGS. 17B, 18B, and 19B, the horizontal axis represents the frequency, and the vertical axis represents the radiation efficiency. Also, in each graph, the result of the antenna 10D is shown by a solid line.

[0160] As shown in FIG. 17A, it can be seen that the VSWR in the antenna 10D is, for example, 3.5 or less, which is a desired value, in the low frequency band, and the characteristics are good. Similarly, as shown in FIG. 17B, the radiation efficiency of the antenna 10D is also good in the low frequency band.

[0161] Therefore, from the above verification results, it can be seen that the frequency characteristics in the low frequency band are also improved in the antenna device 1D of the present embodiment. As described above, in the antenna device 1D of the present embodiment, the end of the first element 11D and the end of the second element 21D are provided at positions close to each other, so that capacitive coupling occurs. As a result, the capacitive coupling portion 35 is realized, and in the antenna device 1D of the present embodiment, the band of the corresponding low frequency band of the first element 11D can be further extended to the lower frequency side.

[0162] Although detailed description is omitted, as shown in FIGS. 18 and 19, the antenna 10D of the third example of the present embodiment has good characteristics (VSWR and radiation efficiency) in the medium and high frequency bands, although there are some exceptions.

[0163] ==Summary== The antenna devices 1A to 1D according to the embodiments of the present invention have been described above.

[0164] The antenna device 1A of the first embodiment includes, for example, as shown in FIGS. 1 and 2, a first element 11A, a second element 21A that is capacitively coupled to the first element 11A, and a base 30A to which the first element 11A and the second element 21A are connected. The first element 11A corresponds to radio waves in at least the low frequency band (699 MHz to 960 MHz) together with the second element 21A. Thereby, an antenna device 1A capable of corresponding to radio waves in a wide frequency band can be realized.

[0165] Further, as shown in FIG. 9 for example, the antenna device 1B of the first example of the second embodiment includes a first element 11B, a second element 21B capacitively coupled to the first element 11B, and a base 30B to which the first element 11B and the second element 21B are connected. The first element 11B, together with the second element 21B, corresponds to at least radio waves in the low frequency band (699 MHz to 960 MHz). Thereby, an antenna device 1B capable of corresponding to radio waves in a wide frequency band can be realized.

[0166] Further, as shown in FIGS. 10 and 11 for example, the antenna device 1C of the second example of the second embodiment includes a first element 11C, a second element 21C capacitively coupled to the first element 11C, and a base 30C to which the first element 11C and the second element 21C are connected. The first element 11C, together with the second element 21C, corresponds to at least radio waves in the low frequency band (699 MHz to 960 MHz). Thereby, an antenna device 1C capable of corresponding to radio waves in a wide frequency band can be realized.

[0167] Further, as shown in FIG. 16 for example, the antenna device 1C of the third example of the second embodiment includes a first element 11D, a second element 21D capacitively coupled to the first element 11D, and a base 30D to which the first element 11D and the second element 21D are connected. The first element 11D, together with the second element 21D, corresponds to at least radio waves in the low frequency band (699 MHz to 960 MHz). Thereby, an antenna device 1D capable of corresponding to radio waves in a wide frequency band can be realized.

[0168] Here, the low frequency band (699 MHz to 960 MHz) corresponds to the "first frequency band".

[0169] Also, in the antenna device 1A of the first embodiment, for example, as shown in FIGS. 1 and 2, the second element 21A corresponds to radio waves in a frequency band different from the low-frequency band (699 MHz to 960 MHz) (for example, the frequency band for Sub6 / 1710 MHz to 5000 MHz). Thereby, an antenna device 1A capable of corresponding to radio waves in a wide frequency band can be realized.

[0170] Also, in the antenna device 1A of the first embodiment, for example, as shown in FIG. 4, the base 30A has a first region 31 to which a feeding line is connected and a second region 32 to which the second element 21A is connected, and between the first region 31 and the second region 32, a filter 40 for suppressing signals in the low-frequency band (699 MHz to 960 MHz) is provided. Thereby, the isolation between the antenna having the first element 11A (here, antenna 10A) and the antenna having the second element 21A (here, antenna 20A) can be improved.

[0171] Also, in the antenna device 1B of the first example of the second embodiment, for example, as shown in FIG. 9, the second element 21B is a non-powered element. Thereby, two resonances can be generated by the first element 11B of the antenna 10B and the second element 21B which is a non-powered element, and an antenna device 1B capable of corresponding to radio waves in a wide frequency band can be realized.

[0172] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIGS. 10 and 11, the second element 21C is a non-powered element. Thereby, two resonances can be generated by the first element 11C of the antenna 10C and the second element 21C which is a non-powered element, and an antenna device 1C capable of corresponding to radio waves in a wide frequency band can be realized.

[0173] Also, in the antenna device 1D of the third example of the second embodiment, for example, as shown in FIG. 16, the second element 21D is a passive element. Thereby, two resonances can be generated by the first element 11D of the antenna 10D and the second element 21D which is a passive element, and an antenna device 1D capable of corresponding to radio waves in a wide frequency band can be realized.

[0174] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIG. 12B, the base 30C has a third region 33 connected to the ground portion 3 and a fourth region 34 to which the second element 21C is connected, and includes a circuit element 50 that connects the third region 33 and the fourth region 34. Thereby, the characteristics of the antenna (here, the antenna 10C) included in the antenna device 1C in the low frequency band (699 MHz to 960 MHz) can be improved.

[0175] Also, although not shown, similarly, the antenna device 1B of the first example of the second embodiment may also include the circuit element 50. Thereby, the characteristics of the antenna (here, the antenna 10B) included in the antenna device 1B in the low frequency band (699 MHz to 960 MHz) can be improved.

[0176] Also, although not shown, similarly, the antenna device 1D of the third example of the second embodiment may also include the circuit element 50. Thereby, the characteristics of the antenna (here, the antenna 10D) included in the antenna device 1D in the low frequency band (699 MHz to 960 MHz) can be improved.

[0177] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIG. 12B, the circuit element 50 is a resistor that terminates the signal of the first frequency band. Also, the circuit element 50 may be an attenuator instead of a resistor. Thereby, the characteristics of the antenna (here, the antenna 10C) included in the antenna device 1C in the low frequency band (699 MHz to 960 MHz) can be improved.

[0178] Also, although not shown, similarly in the antenna device 1B of the first example of the second embodiment, the circuit element 50 may be a resistor. Thereby, the characteristics of the antenna (here, antenna 10B) included in the antenna device 1B in the low frequency band (699 MHz to 960 MHz) can be improved.

[0179] Also, although not shown, similarly in the antenna device 1D of the third example of the second embodiment, the circuit element 50 may be a resistor. Thereby, the characteristics of the antenna (here, antenna 10D) included in the antenna device 1D in the low frequency band (699 MHz to 960 MHz) can be improved.

[0180] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIGS. 10, 11, and 12A, a ground portion 3 is provided, and the first element 11C has a standing portion 12C formed to rise with respect to the ground portion 3, and an extending portion 13C extending from the standing portion 12C and formed to face the ground portion 3. Then, in the top view shown in FIG. 11A, the standing portion 12C is spaced apart from the base portion 30C, and in the side view shown in FIG. 11B, the base portion 30C is located between the extending portion 13C and the ground portion 3, and the standing portion 12C extends to the ground portion 3 side rather than the base portion 30C. Thereby, the characteristics of the antenna (here, antenna 10C) included in the antenna device 1C in the low frequency band (699 MHz to 960 MHz) can be improved.

[0181] Also, in the antenna device 1D of the third example of the second embodiment, for example, as shown in FIG. 16, it includes a ground portion 3, and the first element 11D has an erected portion 12D formed to rise with respect to the ground portion 3, and an extended portion 13D extending from the erected portion 12D and formed to face the ground portion 3. And the erected portion 12D is spaced apart from the base portion 30D, the base portion 30D is located between the extended portion 13D and the ground portion 3, and the erected portion 12D extends toward the ground portion 3 side from the base portion 30D. Thereby, the characteristics of the antenna (here, the antenna 10D) included in the antenna device 1D in the low frequency band (699 MHz to 960 MHz) can be improved.

[0182] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIG. 12A, the erected portion 12C and the ground portion 3 are non-conductive. Thereby, the characteristics of the antenna (here, the antenna 10C) included in the antenna device 1C in the low frequency band (699 MHz to 960 MHz) can be improved.

[0183] Also, in the antenna device 1D of the third example of the second embodiment, for example, as shown in FIG. 16, the erected portion 12D and the ground portion 3 are non-conductive. Thereby, the characteristics of the antenna (here, the antenna 10D) included in the antenna device 1D in the low frequency band (699 MHz to 960 MHz) can be improved.

[0184] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIGS. 10 and 11, the extended portion 13C has a main portion 14C extending from the erected portion 12C, a first additional portion 15C extending from the main portion 14C and located away from the erected portion 12C, and a second additional portion 16C extending from the main portion 14C and located close to the erected portion 12C. Thereby, the antenna (here, the antenna 10C) included in the antenna device 1C can also respond to radio waves in frequency bands other than the low frequency band (699 MHz to 960 MHz).

[0185] Also, in the antenna device 1D of the third example of the second embodiment, for example, as shown in FIG. 16, the extension part 13D has a main part 14D extending from the standing part 12D, a first additional part 15D extending from the main part 14D and located away from the standing part 12D, and a second additional part 16D extending from the main part 14D and located close to the standing part 12D. Thereby, the antenna (here, antenna 10D) included in the antenna device 1D can also respond to radio waves in frequency bands other than the low frequency band (699 MHz to 960 MHz).

[0186] Also, in the antenna device 1C of the second example of the second embodiment, for example, as shown in FIGS. 10 and 11, the first element 11C has a short - circuit part 17C connected to the ground part 3. Then, the second element 21C, the standing part 12C, the main part 14C, the first additional part 15C, and the short - circuit part 17C mainly correspond to the low frequency band (699 MHz to 960 MHz). Also, the standing part 12C, the main part 14C, the second additional part 16C, and the short - circuit part 17C mainly correspond to the middle frequency band (1710 MHz to 2690 MHz), which is a frequency band higher than the low frequency band. Also, the standing part 12C mainly corresponds to a frequency band higher than the middle frequency band (for example, the high frequency band / 3300 MHz to 5000 MHz). Thereby, the antenna (here, antenna 10C) included in the antenna device 1C can also respond to radio waves in frequency bands other than the low frequency band (699 MHz to 960 MHz).

[0187] Also, although not shown, similarly in the antenna device 1D of the third example of the second embodiment, the first element 11D may have a short-circuit portion connected to the ground portion 3. Then, the second element 21D, the standing portion 12D, the main portion 14D, the first additional portion 15D, and the short-circuit portion may mainly correspond to the low-frequency band (699 MHz to 960 MHz). Further, the standing portion 12D, the main portion 14D, the second additional portion 16D, and the short-circuit portion may mainly correspond to the medium-frequency band (1710 MHz to 2690 MHz), which is a frequency band higher than the low-frequency band. Also, the standing portion 12D may mainly correspond to a frequency band higher than the medium-frequency band (for example, the high-frequency band / 3300 MHz to 5000 MHz). Thereby, the antenna (here, the antenna 10D) included in the antenna device 1D can also respond to radio waves in frequency bands other than the low-frequency band (699 MHz to 960 MHz).

[0188] Here, the medium-frequency band (1710 MHz to 2690 MHz) corresponds to the "second frequency band".

[0189] Also, in the antenna device 1A of the first embodiment, for example, as shown in FIGS. 1 and 2, the first element 11A has a short-circuit portion 17A connected to the ground portion 3. Thereby, in the antenna (here, the antenna 10A) included in the antenna device 1A, impedance matching can be easily achieved.

[0190] Also, similarly in the antenna device 1B of the first example of the second embodiment, for example, although not shown, the first element 11B may have a short-circuit portion connected to the ground portion 3. Thereby, in the antenna (here, the antenna 10B) included in the antenna device 1B, impedance matching can be easily achieved.

[0191] Similarly, in the antenna device 1C of the second example of the second embodiment as well, for example, as shown in FIG. 11C, the first element 11C may have a short-circuit portion 17C connected to the ground portion 3. Thereby, impedance matching can be easily achieved in the antenna (here, antenna 10C) included in the antenna device 1C.

[0192] Similarly, in the antenna device 1D of the third example of the second embodiment as well, although not shown, the first element 11D may have a short-circuit portion connected to the ground portion 3. Thereby, impedance matching can be easily achieved in the antenna (here, antenna 10D) included in the antenna device 1D.

[0193] The above embodiments are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. Also, the present invention can be changed and improved without departing from its gist, and it goes without saying that equivalents of the present invention are included therein.

Explanation of Reference Numerals

[0194] 1A~1D,1X Antenna device 2 Case 3 Ground portion 4 Pedestal portion 5 Feeder line connection portion 10A~10D,10X,20A,20X Antenna 11A~11D,11X First element 12A~12D,12X Standing portion 13A~13D,13X Extension portion 14A~14D Main portion 15A~15D First additional portion 16A~16D Second additional portion 17A,17C,17X Short-circuit portion 18,27 Feeding portion 19 First element connection portion 21A~21D,21X Second element 22 Antenna portion 23 Additional element portion 24, 28 Standing part 25, 29 Extension part 26 Second element connection part 30A~30D, 30X Base part 31 First region 32 Second region 33 Third region 34 Fourth region 35 Capacitance coupling part 40 Filter 41 High-pass filter (HPF) 42 Band-pass filter (BPF) 43 Band-elimination filter (BEF) 50 Circuit element

Claims

1. a first element, a second element capacitively coupled to the first element, and a base to which the first element and the second element are connected, wherein the first element corresponds to radio waves in at least a first frequency band together with the second element, the second element corresponds to radio waves in a frequency band different from the first frequency band, the base has a first region to which a feeding line is connected and a second region to which the second element is connected, and a filter for suppressing signals in the first frequency band is provided between the first region and the second region, an antenna device.

2. The second element is a non-powered element, The antenna device according to claim 1.

3. The base has a third region connected to the ground and a fourth region to which the second element is connected, and includes a circuit element connecting the third region and the fourth region, The antenna device according to claim 1.

4. The circuit element terminates signals in the first frequency band, The antenna device according to claim 3.

5. A first element, a second element capacitively coupled to the first element, and a base to which the first element and the second element are connected, wherein the first element corresponds to radio waves in at least a first frequency band together with the second element, comprises a ground portion, the first element, has an upright portion formed to rise with respect to the ground portion, and an extension portion extending from the upright portion and formed to face the ground portion, in a top view, the upright portion is spaced apart from the base, in a side view, the base is located between the extension portion and the ground portion, and the upright portion extends to the ground portion side more than the base, an antenna device.

6. The upright portion and the ground portion are non-conductive, The antenna device according to claim 5.

7. The extension portion, has a main portion extending from the upright portion, a first additional portion extending from the main portion and located away from the upright portion, and a second additional portion extending from the main portion and located close to the upright portion, The antenna device according to claim 5 or 6.

8. The first element has a short-circuit portion connected to the ground portion, the second element, the upright portion, the main portion, the first additional portion, and the short-circuit portion correspond to the first frequency band, The standing portion, the main portion, the second additional portion, and the short-circuit portion correspond to a second frequency band that is higher than the first frequency band, The standing portion corresponds to a frequency band higher than the second frequency band, The antenna device according to claim 7.

9. The first element has a short-circuit portion connected to the ground. The antenna device according to any one of claims 1 to 8.

Images