JP7108913B2 - Communication device - Google Patents

Description

The present disclosure relates to a communication device suitable for use in vehicles such as automobiles.

One of network connection means used in vehicles such as automobiles is a TCU (Telematics Communication Unit), which is described in Patent Document 1, for example. The in-vehicle communication unit described in Patent Document 1 performs communication with a server terminal that provides services for vehicles by starting a mobile communication network in order to receive the provision of services. The operation of the communication module is reset when the communication for receiving the service from the server terminal that provides the service is impossible.

WO2015/146233

However, in the case of a TCU with a built-in antenna element, there is no need for an in-vehicle antenna such as a shark fin that is attached to the outside (for example, the vehicle roof), but the antenna performance may be affected by the location and orientation of the vehicle body (metal). There is a problem of deterioration. This problem will be described with reference to the drawings. Here, the vehicle body is hereinafter simply referred to as a "metal plate". FIG. 10 shows a schematic configuration of a conventional TCU 100 having a built-in antenna, where (a) is an external view and (b) is a longitudinal side view of the interior. As shown in FIG. 10(a), a housing 101 of the TCU 100 is formed in a rectangular parallelepiped shape, and an antenna element 102 is arranged at one of the four corners inside. Further, as shown in FIG. 10B, the antenna element 102 is connected to the substrate 104 via the feeding section 103 .

FIG. 11 shows an example in which the TCU 100 shown in FIG. b) is a perspective view in which the longitudinal side surface of the housing 101 is arranged facing the metal plate 300. FIG. As shown in FIG. 11A, even if the side of the housing 101 having the largest area faces the metal plate 300, as shown in FIG. Even if the side surface side faces the metal plate 300, it is close to the metal plate 300, so that the metal plate 300 affects the antenna performance in any arrangement.

For example, in the example shown in FIG. Although it is less likely to be affected, it imposes a constraint on the placement of the TCU 100, which lowers the degree of freedom in design.

The present disclosure provides a communication device that can reduce the effects of proximity of an antenna element to metal.

A communication device according to the present disclosure is a communication device provided in a vehicle, and includes a housing, a first antenna element provided inside the housing, and a second antenna provided inside the housing. a switching unit for switching between the first antenna element and the second antenna element; a first metal plate corresponding to the first antenna element and provided on one surface of the housing; a second metal plate corresponding to the second antenna element and provided on a surface different from one surface of the housing; and a first detection unit for detecting a first capacitance value of the first metal plate , a second detection unit for detecting a second capacitance value of the second metal plate, the first capacitance value detected by the first detection unit, and the second capacitance value detected by the second detection unit a control unit that controls the switching unit to select the first antenna element or the second antenna element based on the second capacitance value selected by the control unit; and the first antenna element selected by the control unit . a main body that controls communication with a device external to the vehicle via the antenna element or the second antenna element .

According to the present disclosure, when one surface of the housing approaches metal, the first capacitance value of the first metal plate provided on the one surface increases, and when a surface different from the one surface of the housing approaches metal, , the second capacitance value of the second metal plate provided on the surface increases, and switching between the first antenna element and the second antenna element is performed according to the difference in these capacitance values. 1. The influence of the proximity of the second antenna element to the metal can be reduced.

In the communication device of the present disclosure, in the configuration described above, the control unit controls the switching unit according to the magnitude relationship between the first capacitance value and the second capacitance value to select the first antenna element or selecting the second antenna element.

According to the present disclosure, switching between the first antenna element and the second antenna element according to the magnitude relationship between the first capacitance value of the first metal plate and the second capacitance value of the second metal plate can reduce the influence of the proximity of the first and second antenna elements to the metal.

In the communication device of the present disclosure, in the configuration described above, when the first capacitance value is smaller than the second capacitance value, the control unit controls the switching unit to select the first antenna element, When the first capacitance value is greater than the second capacitance value, the switching unit is controlled to select the second antenna element.

According to the present disclosure, when the first capacitance value of the first metal plate is smaller than the second capacitance value of the second metal plate, switching to the first antenna element, the first antenna element of the first metal plate If the capacitance value is greater than the second capacitance value of the second metal plate, switching to the second antenna element can reduce the influence of proximity of the first and second antenna elements to the metal.

In the communication device of the present disclosure, in the configuration described above, the first antenna element and the first metal plate are provided close to each other, and the second antenna element and the second metal plate are provided close to each other. is provided.

According to the present disclosure, a first metal plate is provided proximate to the first antenna element and a second metal plate is provided proximate to the second antenna element so that the first metal plate is metal. By switching to the second antenna element when the first capacitance value increases due to proximity, and switching to the first antenna element when the second metal plate approaches the metal and the second capacitance value increases, It is possible to reduce the influence of the proximity of the first and second antenna elements to the metal.

In the communication device of the present disclosure, in the configuration described above, the first metal plate is provided on a surface of the housing that has the largest area, and the second metal plate has the smallest area of the housing. It is provided on the surface so as to be separated from the first metal plate.

According to the present disclosure, when the side with the largest area of the housing faces the metal, the first capacitance value of the first metal plate increases, thereby switching to the second antenna element and the smallest area of the housing. When the surface having the surface facing the metal, the second capacitance value of the second metal plate increases, and by switching to the first antenna element, the proximity of the first and second antenna elements to the metal increases. can reduce the impact.

A communication device according to the present disclosure is a communication device provided in a vehicle, and includes a housing, a first antenna element provided inside the housing, and a second antenna provided inside the housing. a switching unit for switching between the first antenna element and the second antenna element; a first detection unit for detecting a first impedance of the first antenna element; and the second antenna element. based on the second impedance detected by the second detection unit, the first impedance detected by the first detection unit, and the second impedance detected by the second detection unit , a control unit that controls the switching unit to select the first antenna element or the second antenna element; and the first antenna element or the second antenna element selected by the control unit . a main body that controls communication with a device external to the vehicle via the vehicle .

According to the present disclosure, by switching between the first antenna element and the second antenna element according to the difference between the first impedance of the first antenna element and the second impedance of the second antenna element , the influence of the proximity of the first and second antenna elements to the metal can be reduced.

In the communication device according to the present disclosure, in the configuration described above, the controller controls the absolute value of a first reflection coefficient corresponding to the first impedance and the absolute value of a second reflection coefficient corresponding to the second impedance, and The switching unit is controlled to select the first antenna element or the second antenna element according to the magnitude relationship of .

According to the present disclosure, a first absolute value of a reflection coefficient corresponding to a first impedance of a first antenna element and a second absolute value of a second reflection coefficient corresponding to a second impedance of a second antenna element; By switching between the first antenna element and the second antenna element according to the magnitude relationship of , it is possible to reduce the influence of the proximity of the first and second antenna elements to the metal.

In the communication device of the present disclosure, in the configuration described above, when the absolute value of the first reflection coefficient is smaller than the absolute value of the second reflection coefficient, the control unit controls the switching unit to select the first reflection coefficient. An antenna element is selected, and when the absolute value of the first reflection coefficient is greater than the absolute value of the second reflection coefficient, the switching unit is controlled to select the second antenna element.

According to the present disclosure, the absolute value of the first reflection coefficient corresponding to the first impedance of the first antenna element is greater than the absolute value of the second reflection coefficient corresponding to the second impedance of the second antenna element. If less, switch to the first antenna element and a second reflection whose absolute value of the first reflection coefficient corresponding to the first impedance of the first antenna element corresponds to the second impedance of the second antenna element If it is greater than the absolute value of the coefficient, switching to the second antenna element can reduce the influence of the proximity of the first and second antenna elements to the metal.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a communication device capable of reducing the influence of proximity of an antenna element to metal.

FIG. 2 is a block diagram showing the configuration of the antenna device of the first embodiment and the configuration of the TCU provided with the antenna device; Schematic diagram showing an arrangement example of the first and second antenna elements and the first and second metal plates of the antenna device of the first embodiment in the housing of the TCU. Schematic diagram showing an installation pattern of a TCU provided with the antenna device of the first embodiment. Schematic diagram showing the magnitude of the capacitance values of the first and second metal plates and the selection state of the first and second antenna elements in the installation pattern shown in FIG. Flowchart showing operation steps of the antenna device of the first embodiment Block diagram showing the configuration of the antenna device of the second embodiment and the configuration of the TCU provided with the antenna device Flowchart showing operation steps of the antenna device of the second embodiment Schematic diagram showing an arrangement example on a metal plate of the TCU having the antenna device of the third embodiment A diagram for explaining the configuration and effect of the antenna device of the third embodiment. A diagram showing a schematic configuration of a conventional TCU with a built-in antenna The figure which shows the example which has arrange|positioned the TCU shown in FIG. 10 facing the metal plate.

Hereinafter, an embodiment specifically disclosing a communication device according to the present disclosure (hereinafter referred to as "this embodiment") will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary verbosity in the following description and to facilitate understanding by those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for a thorough understanding of the present disclosure by those skilled in the art and are not intended to limit the claimed subject matter.

Preferred embodiments for carrying out the present disclosure will be described in detail below with reference to the drawings.

(First embodiment)
The configuration of the antenna device 1 according to the first embodiment will be described below with reference to FIG. FIG. 1 is a block diagram showing the configuration of the antenna device 1 of the first embodiment and the configuration of the TCU 2 provided with the antenna device 1. As shown in FIG. FIG. 2 is a schematic diagram showing an arrangement example of the first and second antenna elements 3 and 4 and the first and second metal plates 6 and 7 of the antenna device 1 of the first embodiment in the housing 21 of the TCU 2. It is a diagram. The antenna device 1 includes first and second antenna elements 3 and 4 and first and second metal plates 6 and 7, as well as a switching section for switching between the first antenna element 3 and the second antenna element 4. 5, a first detection unit 8 that detects the first capacitance value of the first metal plate 6, a second detection unit 9 that detects the second capacitance value of the second metal plate 7, a second Based on the first capacitance value detected by the first detection unit 8 and the second capacitance value detected by the second detection unit 9, the switching unit 5 is controlled to select the first antenna element 3 or the second antenna element 3. and a control unit 10 that selects the antenna element 4 of. The antenna device 1 is built in the housing 21 of the TCU 2 together with the TCU body circuit 20 . Since the antenna device 1 is built in the TCU 2 , the antenna device 1 does not have a dedicated housing, but the housing 21 of the TCU 2 is treated as the housing of the antenna device 1 .

As shown in FIG. 2, the housing 21 is formed in the shape of a rectangular parallelepiped, and has an upper surface 21a and a lower surface 21b having the maximum area, lateral side surfaces 21c and 21d having the minimum area, and lateral side surfaces. longitudinal sides 21e and 21f having a larger area than 21c and 21d. A TCU body circuit 20 built in a housing 21 is connected to the first antenna element 3 or the second antenna element 4 through the switching section 5 of the antenna device 1 . That is, by switching the switching unit 5 to the first antenna element 3, the first antenna element 3 is connected to the TCU main body circuit 20, and by switching to the second antenna element 4, the second antenna element 4 is connected. It is connected to the TCU body circuit 20 . The TCU body circuit 20 performs two-way communication with an external device (not shown) via the first antenna element 3 or the second antenna element 4 connected thereto.

The first antenna element 3 is formed in the shape of a rectangular plate having a thickness, and is arranged at one corner portion on the front side of the left end of the upper surface (one surface) 21a of the housing 21 as viewed in FIG. The second antenna element 4 is formed in the shape of a rectangular plate having the same thickness as the first antenna element 3, and is arranged at a corner portion on the front side of the right end of the lower surface 21b of the housing 21 as viewed in FIG. It is The first metal plate 6 is formed in the shape of a thin rectangular plate, and is arranged on the far left side of the upper surface 21a of the housing 21 as viewed in the drawing so as to be close to the first antenna element 3. . The second metal plate 7 is formed in the same thin rectangular plate shape as the first metal plate 6, and is positioned close to the second antenna element 4 in the lateral direction of the housing 21 (one side and one side). is arranged on the upper end side toward the drawing of the different surface) 21c.

Since the longitudinal length of the lateral side surface 21c of the housing 21 is shorter than the longitudinal length of the upper surface 21a of the housing 21, the length of the second metal plate 7 is equal to that of the first metal plate. It is shorter than the length of 6. The first metal plate 6 is paired with the first antenna element 3 and the second metal plate 7 is paired with the second antenna element 4 .

The first and second metal plates 6 and 7 are used to detect the proximity of the surface of the housing 21 on which the first and second antenna elements 3 and 4 are provided to metal. Since electrostatic capacitance is generated between the first and second metal plates 6 and 7 and the metal, detecting a change in this electrostatic capacitance causes the first and second metal plates 6 and 7 to move to the metal. You can determine if you are facing In the present disclosure, the capacitance value generated between the first metal plate 6 and the metal is defined as the first capacitance value, and the capacitance value generated between the second metal plate 7 and the metal is defined as the second capacitance value. . A first detector 8 detects a first capacitance value of the first metal plate 6 and a second detector 9 detects a second capacitance value of the second metal plate 7 .

FIG. 3 is a schematic diagram showing an installation pattern of the TCU 2 provided with the antenna device 1 of the first embodiment. In the figure, installation pattern A is a pattern when the housing 21 is arranged so that the first metal plate 6 faces the metal plate 300 . The installation pattern B is a pattern when the housing 21 is arranged so that the second metal plate 7 faces the metal plate 300 . In the installation pattern A, since the first metal plate 6 faces the metal plate 300 over the entire surface, the first capacitance value increases. At this time, since only the end face in the thickness direction of the second metal plate 7 faces the metal plate 300, the second capacitance value becomes smaller than the first capacitance value. On the other hand, in the installation pattern B, since the second metal plate 7 faces the metal plate 300 over the entire surface, the second capacitance value increases. At this time, since the end face in the thickness direction of the first metal plate 6 faces the metal plate 300, the first capacitance value becomes smaller than the second capacitance value. In this case, especially since the housing 21 has a vertically long shape, the distance between the first metal plate 6 and the metal plate 300 is long, so the first capacitance value is extremely small.

A first capacitance value of the first metal plate 6 is detected by the first detector 8 , and a second capacitance value of the second metal plate 7 is detected by the second detector 9 . Based on the first capacitance value detected by the first detection unit 8 and the second capacitance value detected by the second detection unit 9, the control unit 10 controls the switching unit 5 to select the first capacitance value. Antenna element 3 or second antenna element 4 is selected. That is, the control unit 10 switches to the first antenna element 3 when the first capacitance value of the first metal plate 6 is smaller than the second capacitance value of the second metal plate 7, and switches to the first antenna element 3. When the first capacitance value of 6 is greater than the second capacitance value of second metal plate 7 , it switches to second antenna element 4 .

FIG. 4 is a schematic diagram showing the magnitude of the capacitance values of the first and second metal plates 6 and 7 and the selected state of the first and second antenna elements 3 and 4 in the installation pattern shown in FIG. As shown in the figure, in the installation pattern A, since the first metal plate 6 faces the metal plate 300 entirely, the first capacitance value is "large" and the first antenna element 3 is "off." ", that is, it is in an unselected state. On the other hand, since the second metal plate 7 faces the metal plate 300 only at the end face in the thickness direction, the second capacitance value is "small" and the second antenna element 4 is "on", ie, selected. state. This enables communication with the second antenna element 4 . On the other hand, in the installation pattern B, since the second metal plate 7 faces the metal plate 300 entirely, the second capacitance value is "large" and the second antenna element 4 is "off", that is, unselected. state. On the other hand, since the first metal plate 6 faces the metal plate 300 only at the end face in the thickness direction, the first capacitance value is "small" and the first antenna element 3 is "on", that is, selected. state. This enables communication with the first antenna element 3 .

Next, operation of the antenna device 1 of the first embodiment will be described.
FIG. 5 is a flow chart showing operation steps of the antenna device 1 of the first embodiment. In the figure, the control unit 10 first controls the switching unit 5 to select the first antenna element 3 (step S10). After selecting the first antenna element 3 , the control unit 10 selects the first capacitance value C 1 of the first metal plate 6 corresponding to the first antenna element 3 and the second capacitance value C ₁ corresponding to the second antenna element 4 . The second capacitance value C2 of the _second metal plate 7 is confirmed (step S11), and the first capacitance value C1 of the _first metal plate 6 is the second capacitance value C of the second metal plate 7 If it is confirmed to be smaller than ₂ , the first antenna element 3 is selected assuming that the first metal plate 6 does not face the metal plate 300 (step S12). After selecting the first antenna element 3, the control unit 10 performs confirmation in step S11 again.

When the control unit 10 confirms in step S11 that the first capacitance value C1 of the first metal plate 6 is greater than the _second capacitance value C2 of the _second metal plate 7, the second antenna element 4 is selected (step S13). After selecting the second antenna element 4, the control unit 10 returns to step S11, and the second capacitance value C2 of the _second metal plate 7 corresponding to the second antenna element 4 and the first antenna element The first capacitance value C1 of the _first metal plate 6 corresponding to 3 is confirmed. Thereafter, similar processing is repeated.

As described above, the antenna device 1 of the first embodiment can determine whether the upper surface 21 a of the housing 21 faces the metal plate 300 or the side surface 21 c different from the upper surface 21 a of the housing 21 faces the metal plate 300 . Based on the first capacitance value of the first metal plate 6 arranged close to one antenna element 3 and the second capacitance value of the second metal plate 7 arranged close to the second antenna element 4 When the upper surface 21a of the housing 21 faces the metal plate 300, the first capacitance value of the first metal plate 6 becomes larger than the second capacitance value of the second metal plate 7. When the second antenna element 4 corresponding to the second metal plate 7 is selected and the side surface 21c of the housing 21 faces the metal plate 300, the second capacitance value of the second metal plate 7 is equal to that of the first metal plate. Since it is larger than the first capacitance value of the plate 6, the first antenna element 3 corresponding to the first metal plate 6 is selected.

As a result, the influence of proximity of the first and second antenna elements 3 and 4 to the metal plate 300 can be reduced.

Although the antenna device 1 of the first embodiment has two antenna elements 3 and 4, it may have three or more. In that case, it is needless to say that the number of metal plates and detection units for detecting the capacitance are required according to the number of antenna elements.

(Second embodiment)
In the antenna device 1 of the first embodiment described above, the first antenna element 3 and the second antenna element 4 are controlled based on the capacitance value that changes when the first and second metal plates 6 and 7 come close to the metal. However, the antenna device 50 of the second embodiment switches between the first antenna element 3 and the The switching of the second antenna element 4 is performed.

FIG. 6 is a block diagram showing the configuration of the antenna device 50 of the second embodiment and the configuration of the TCU 2 provided with the antenna device 50. As shown in FIG. In addition, in FIG. 6, elements common to those in FIG. 1 described above are denoted by the same reference numerals. The antenna device 50 of the second embodiment includes the first antenna element 3 provided inside the housing 21, the second antenna element 4 provided inside the housing 21, and the first antenna element 3 and the second antenna element 4, a first detection unit 51 for detecting the first impedance of the first antenna element 3, and the second impedance of the second antenna element 4. and the first impedance detected by the first detection unit 51 and the second impedance detected by the second detection unit 52, the switching unit 5 is controlled to select the second impedance. and a control unit 53 that selects one antenna element 3 or the second antenna element 4 . The first antenna element 3 and the first detector 51, and the second antenna element 4 and the second detector 52 are connected by coaxial cables or the like.

In the antenna device 50 of the second embodiment, similarly to the antenna device 1 of the first embodiment, the first antenna element 3 is provided on the upper surface 21a of the housing 21, and the second antenna element 4 is provided on the upper surface 21a of the housing 21. It is provided on a side surface 21 c different from the top surface 21 a of the housing 21 .

In the antenna device 50 of the second embodiment, changes in impedance of the first and second antenna elements 3 and 4 are captured by changes in the S parameter S ₁₁ (reflection coefficient). In this case, the first reflection coefficient corresponding to the first impedance of the first antenna element 3 is "S ₁ ", and the second reflection coefficient corresponding to the second impedance of the second antenna element 4 is " S ₂ ”. The first antenna element 3 or the second antenna element 4 is selected according to the magnitude relationship between the absolute value of the first reflection coefficient (|S ₁ |) and the absolute value of the second reflection coefficient (|S ₂ |). select.

When the upper surface 21a of the housing 21 provided with the first antenna element 3 faces a metal (hereinafter referred to as "metal plate 300"), the first reflection coefficient corresponding to the first impedance of the first antenna element 3 has a large absolute value (|S ₁ |). At this time, since the side surface 21c of the housing 21 on which the second antenna element 4 is provided does not face the metal plate 300, the second reflection coefficient corresponding to the second impedance of the second antenna element 4 is The absolute value (|S ₂ |) becomes small. On the other hand, when the side surface 21c of the housing 21 provided with the second antenna element 4 faces the metal plate 300, the absolute value of the second reflection coefficient corresponding to the second impedance of the second antenna element 4 (| S ₂ |) becomes large. At this time, since the upper surface 21a of the housing 21 provided with the first antenna element 3 does not face the metal plate 300, the first reflection coefficient corresponding to the first impedance of the first antenna element 3 is The absolute value (|S ₁ |) becomes small.

The control unit 53 compares the absolute value of the first reflection coefficient (|S ₁ |) and the absolute value of the second reflection coefficient (|S ₂ |) to obtain the absolute value of the first reflection coefficient (|S ₁ |) is smaller than the absolute value of the second reflection coefficient (|S ₂ |), the first antenna element 3 is selected, and the absolute value of the first reflection coefficient (|S ₁ |) is the second reflection coefficient is greater than the absolute value of (|S ₂ |), the second antenna element 4 is selected. When the control unit 53 selects the first antenna element 3 , the first antenna element 3 is connected to the TCU body circuit 20 through the switching unit 5 and communication is performed using the first antenna element 3 . On the other hand, when the control unit 53 selects the second antenna element 4 , the second antenna element 4 is connected to the TCU body circuit 20 through the switching unit 5 and communication is performed using the second antenna element 4 .

Next, operation of the antenna device 50 of the second embodiment will be described.
FIG. 7 is a flow chart showing operation steps of the antenna device 50 of the second embodiment. In the figure, the control unit 53 first controls the switching unit 5 to select the first antenna element 3 (step S20). After selecting the first antenna element 3, the control unit 53 determines the absolute value (|S ₁ |) of the first reflection coefficient corresponding to the first impedance of the first antenna element 3 and the second antenna element 4, the absolute value (|S ₂ |) of the second reflection coefficient corresponding to the second impedance is confirmed (step S21). That is, the magnitude relationship between the absolute value of the first reflection coefficient (|S ₁ |) and the absolute value of the second reflection coefficient (|S ₂ |) is determined. When the controller 53 confirms that the absolute value of the first reflection coefficient (|S ₁ |) is smaller than the absolute value of the second reflection coefficient (|S ₂ |), the first Antenna element 3 is selected (step S22). That is, the first antenna element 3 is selected because the upper surface 21a of the housing 21 provided with the first antenna element 3 does not face the metal plate 300 . After selecting the first antenna element 3, the controller 53 returns to step S21.

On the other hand, when the controller 53 confirms in step S21 that the absolute value of the first reflection coefficient (|S ₁ |) is greater than the absolute value of the second reflection coefficient (|S ₂ |), , selects the second antenna element 4 (step S23). That is, since the side surface 21c of the housing 21 provided with the second antenna element 4 does not face the metal plate 300, the second antenna element 4 is selected. After selecting the second antenna element 4, the controller 53 returns to step S21. Thereafter, similar processing is repeated.

As described above, the antenna device 50 of the second embodiment can determine whether the upper surface 21 a of the housing 21 faces the metal plate 300 or the side surface 21 c different from the upper surface 21 a of the housing 21 faces the metal plate 300 . The absolute value (|S ₁ |) of the first reflection coefficient corresponding to the impedance of the first antenna element 3 provided on the upper surface 21a of the body 21 and the second antenna element 4 provided on the side surface 21c of the housing 21 and the absolute value of the second reflection coefficient (|S ₂ |) corresponding to the impedance of , and the absolute value of the first reflection coefficient ( |S ₁ |) becomes larger than the absolute value of the second reflection coefficient (|S ₂ |), the second antenna element 4 with the smaller absolute value of the reflection coefficient is selected, and the side surface 21c of the housing 21 is selected. faces the metal plate 300, the absolute value of the second reflection coefficient (|S ₂ |) is greater than the absolute value of the first reflection coefficient (|S ₁ |), so the absolute value of the reflection coefficient is small. 1st antenna element 3 of the direction is selected.

As a result, the influence of proximity of the first and second antenna elements 3 and 4 to the metal plate 300 can be reduced.

Although the antenna device 50 of the second embodiment has two antenna elements 3 and 4, it may have three or more. In that case, it goes without saying that the number of detection units for detecting the impedance of the antenna elements is also required according to the number of antenna elements.

(Third embodiment)
In the antenna device 1 of the first embodiment and the antenna device 50 of the second embodiment described above, when one of the first and second antenna elements 3 and 4 faces the metal due to the arrangement of the housing 21 with respect to the metal, However, the antenna device according to the third embodiment reduces the influence of the metal and reduces the influence of the metal. It enables it to aim at efficiency improvement.

FIG. 8 is a schematic diagram showing an arrangement example of the TCU 200 including the antenna device 70 of the third embodiment on the metal plate 300. As shown in FIG. In addition, the same code|symbol is attached to the element which is common in FIG. 8 mentioned above with FIG. As shown in FIG. 8 , the antenna device 70 of the third embodiment includes an antenna element 71 provided inside a housing 21 and an antenna element 71 provided on one surface of the housing 21 having the maximum area so as to overlap the antenna element 71 . and a metal plate 72 .

Antenna element 71 is connected to substrate 104 via power feeder 103 . Both the antenna element 71 and the metal plate 72 are provided along the longitudinal direction of the housing 21 . The one surface having the largest area of the housing 21 is, for example, the same surface as the upper surface 21a in the antenna device 1 of the first embodiment and the antenna device 50 of the second embodiment. Hereinafter, the one surface is referred to as an upper surface 21a. In FIG. 8 , the housing 21 is arranged so that the upper surface 21 a faces the metal plate 300 .

It should be noted that the metal plate 72 does not have to overlap the antenna element 71 completely, as long as it overlaps at least part of it. Also, the metal plate 72 has a length substantially equal to the predetermined wavelength of the antenna element 71 .

As shown in FIG. 8, when the housing 21 is placed on the metal plate 300 so that the upper surface 21a of the housing 21 provided with the metal plate 72 faces the metal plate 300, the metal plate 72 becomes the antenna element. 71, and the influence of the metal plate 300 is reduced. As a result, stable antenna performance can be obtained even if the antenna element 71 is on the metal plate 300 side.

On the other hand, FIG. 9 is a schematic diagram showing an example in which the housing 21 is arranged on the metal plate 300 so that the lower surface 21b facing the upper surface 21a of the housing 21 faces the metal plate 300. As shown in FIG. As shown in the figure, by arranging the housing 21 on the metal plate 300, the metal plate 72 is positioned on one side of the antenna element 71, and the metal plate 300 is positioned on the other side. Therefore, the metal plate 72 acts as a director. As a result, a three-element antenna is formed in which the metal plate 300 acts as a reflector. With this configuration, directivity of the antenna element 71 is obtained in the space while avoiding the metal plate 300, and radio waves can be efficiently radiated forward of the metal plate 72 (upward in FIG. 9).

As described above, in the antenna device 70 of the third embodiment, the metal plate 72 is provided on the upper surface 21a having the maximum area of the housing 21 so as to at least partially overlap with the antenna element 71 provided inside the housing 21. Therefore, the metal plate 72, which is a single parasitic element, can reduce the influence of the metal plate 300 and radiate radio waves with directivity.

A communication device according to the present disclosure is useful for a TCU, which is one of network connection means used in vehicles such as automobiles.

1,50,70 antenna device 2,200 TCU
3 first antenna element 4 second antenna element 5 switching unit 6 first metal plate 7 second metal plate 8 first detection unit for detecting the first capacitance value 9 the second capacitance value Second detection unit for detection 10, 53 Control unit 20 TCU body circuit 21 Housing 21a Top surface of housing 21b Bottom surface of housing 21c, 21d Side surface in short direction of housing 21e, 21f Longitudinal direction of housing 51 first detection unit for detecting the first impedance 52 second detection unit for detecting the second impedance 71 antenna element 72 metal plate 103 feeding unit 104 substrate 300 metal plate

Claims (8)

A communication device provided in a vehicle,
a housing;
a first antenna element provided inside the housing;
a second antenna element provided inside the housing;
a switching unit that switches between the first antenna element and the second antenna element;
a first metal plate provided on one surface of the housing corresponding to the first antenna element;
a second metal plate corresponding to the second antenna element and provided on a surface different from one surface of the housing;
a first detection unit that detects a first capacitance value of the first metal plate;
a second detection unit that detects a second capacitance value of the second metal plate;
Based on the first capacitance value detected by the first detection unit and the second capacitance value detected by the second detection unit, the switching unit is controlled to switch the first antenna. a control unit that selects an element or the second antenna element;
a main unit that controls communication with a device external to the vehicle via the first antenna element or the second antenna element selected by the control unit; with
communication Device. Claim 1communicationa device,
The control unit
controlling the switching unit to select the first antenna element or the second antenna element according to the magnitude relationship between the first capacitance value and the second capacitance value;
communication Device. Claim 2communicationa device,
The control unit
when the first capacitance value is smaller than the second capacitance value, controlling the switching unit to select the first antenna element;
when the first capacitance value is greater than the second capacitance value, controlling the switching unit to select the second antenna element;
communication Device. According to any one of claims 1 to 3communicationa device,
The first antenna element and the first metal plate are provided close to each other,
The second antenna element and the second metal plate are provided close to each other,
communication Device. According to any one of claims 1 to 4communicationa device,
The first metal plate is provided on a surface having the maximum area of the housing,
The second metal plate is provided on the surface having the smallest area of the housing and is separated from the first metal plate,
communication Device. A communication device provided in a vehicle,
a housing;
a first antenna element provided inside the housing;
a second antenna element provided inside the housing;
a switching unit that switches between the first antenna element and the second antenna element;
a first detection unit that detects a first impedance of the first antenna element;
a second detection unit that detects a second impedance of the second antenna element;
Based on the first impedance detected by the first detection unit and the second impedance detected by the second detection unit, the switching unit is controlled to select the first antenna element or a control unit that selects the second antenna element;
a body section that controls communication with a device external to the vehicle via the first antenna element or the second antenna element selected by the control section; with
communication Device. according to claim 6communicationa device,
The control unit
According to the magnitude relationship between the absolute value of the first reflection coefficient corresponding to the first impedance and the absolute value of the second reflection coefficient corresponding to the second impedance, the switching unit is controlled to control the second reflection coefficient. selecting one antenna element or the second antenna element;
communication Device. according to claim 7communicationa device,
The control unit
controlling the switching unit to select the first antenna element when the absolute value of the first reflection coefficient is smaller than the absolute value of the second reflection coefficient;
If the absolute value of the first reflection coefficient is greater than the absolute value of the second reflection coefficient, controlling the switching unit to select the second antenna element;
communication Device.

Images