JP4921282B2 - Vehicle and antenna device - Google Patents

Description

  The present invention relates to a vehicle and an antenna device, and more particularly to a vehicle including an antenna element and an antenna device provided in the vehicle.

  Conventionally, as a vehicle-mounted antenna device, as shown in the schematic diagram of FIG. 6, a type in which an antenna element 130 is built in a vehicle rear bumper 126 below a trunk lid 122 is known (for example, see Patent Document 1 below). ).

  In the configuration of FIG. 6, for example, an emblem 124 is provided on the trunk lid 122. The trunk lid 122 is formed of, for example, resin, and the emblem 124 is formed of, for example, a metal part attached to a resin component or a metal powder-containing material plated.

JP 2006-203714 A

  When the emblem 124 containing a metal material is provided on the trunk lid 122 made of resin, the emblem 124 is not electrically connected to the vehicle body and can electrically resonate to absorb radio waves. For this reason, when the antenna element 130 exists in the vicinity of the emblem 124, the reception state of the antenna device, in other words, the reception gain may be reduced due to radio wave absorption by the emblem 124. That is, the emblem 124 may interfere with reception by the antenna device.

  Here, the radio wave absorbed by the emblem 124, that is, the resonating radio wave, is a radio wave whose half wavelength corresponds to the length of the emblem 124 (the length in the polarization direction of the radio wave). For this reason, reception interference occurs when the resonance frequency of the emblem 124 is within the reception frequency band of the antenna device.

  In this regard, FIG. 7 shows a diagram for explaining the influence of the emblem 124 on the antenna reception sensitivity (in other words, the antenna gain). In FIG. 7, the characteristic line (a) shows the case where the emblem 124 is not present, and the characteristic line (b) shows the case where the emblem 124 is present. From FIG. 7, it can be seen that the emblem 124 decreases the antenna reception sensitivity by ΔG.

  In view of the above, it is conceivable to prevent the emblem 124 from resonating within the reception frequency band of the antenna device by adjusting the length of the emblem 124 as a countermeasure against reception interference.

  As another countermeasure, it is conceivable to reduce the influence of the emblem 124 on the antenna element 130 by increasing the distance between the emblem 124 and the antenna element 130.

  In this regard, FIG. 8 shows a graph for explaining the influence of the separation distance between the antenna element 130 and the emblem 124 on the antenna reception sensitivity. In FIG. 8, the abscissa represents the distance as a ratio to the wavelength, normalized by the wavelength. According to FIG. 8, when the separation distance between the antenna element 130 and the emblem 124 is about 60% or less of the reception wavelength, the influence of the emblem 124 on the antenna gain decreases as the separation distance increases, and the change is almost linear. It turns out that it is. It can also be seen that when the separation distance is about 60% or more, the influence of the emblem 124 converges almost uniformly. For this reason, it can be seen that if the distance between the antenna element 130 and the emblem 124 is about 60% or more of the reception wavelength, reception interference by the emblem 124 can be avoided.

  However, the emblem 124 may be an important element in the design value of the vehicle. In such a case, a change in the length or position of the emblem 124 causes a decrease in the design value of the vehicle.

  In addition, since the mounting position of the antenna element 130 is determined by the positional relationship with a metal member such as a vehicle body or various parts so that good antenna performance can be obtained, easy change of the mounting position of the antenna element 130 decreases the antenna performance. There is no doubt.

  In the above description, the emblem 124 is illustrated, but reception interference may occur due to other members that are not electrically connected to the vehicle body. When the other member is a design part other than the emblem 124, for example, the change in the size and the installation position affects the design value of the vehicle, like the emblem 124. Moreover, when the said other member is a thing regarding safety, for example, the change of the dimension and an installation position is often not easy on the law.

  An object of the present invention is to provide a vehicle and an antenna device that can reduce the influence of a conductive member that is not electrically connected to a vehicle body on reception by an antenna element and can perform good reception.

  A vehicle according to the present invention is a vehicle provided with an antenna element, and has a predetermined separation distance between the antenna element and a conductive member that is provided on the vehicle body and is not electrically connected to the vehicle body. A conductive additional member added to the conductive member, the additional member being provided so as to be capable of electrical resonance integrally with the conductive member, the electrical resonance frequency of which is It exists outside the receiving frequency band of the antenna element.

  Here, it is preferable that the predetermined separation distance is about 60% or less of a wavelength received by the antenna element.

  Moreover, it is preferable that the said additional member is provided in the location which is not visually recognized at the time of normal use of the said vehicle.

  The additional member preferably includes at least one of a plate-like member, a film-like member, and a film obtained by solidifying a fluid material.

  An antenna device according to the present invention is an antenna device provided in a vehicle, and is provided on a vehicle body having a predetermined separation distance between the antenna element and the antenna element, and is electrically connected to the vehicle body. A conductive additional member that is superimposed on the conductive member, and the additional member electrically resonates integrally with the conductive member, thereby causing the antenna to resonate with the electrical resonance of the conductive member. The reduction is performed within the reception frequency band of the element.

  Here, it is preferable that the additional member shifts the frequency at which the conductive member electrically resonates out of the reception frequency band of the antenna element by electrically resonating integrally with the conductive member. .

  In addition, the additional member has a length in the reception polarization direction of the antenna element, and an integral electric resonance frequency between the additional member and the conductive member exists outside the reception frequency band of the antenna element. It is preferable that the condition is set.

  The additional member preferably includes at least one of a plate-like member, a film-like member, and a film obtained by solidifying a fluid material.

  According to the above configuration, the influence of the conductive member that is not electrically connected to the vehicle body on reception by the antenna element is reduced, and reception by the antenna element can be improved. Such an effect can be obtained, for example, without impairing the design value of the conductive member and the reception performance of the antenna element.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of an automobile vehicle 20 and an antenna device 28 according to the embodiment. FIG. 1 shows a rear perspective view of the vehicle 20.

  In the example of FIG. 1, an emblem 24 is attached to the outer surface of the trunk lid 22 that is a part of the vehicle body (vehicle body) of the vehicle 20, that is, the design surface.

  The trunk lid 22 is made of an insulating material such as resin. A part or all of the emblem 24 is made of a conductive material such as metal. That is, at least a part of the emblem 24 has conductivity. For example, the entire emblem 24 is made of a conductive material by punching a metal plate or the like. Further, a part of the emblem 24 is made of a conductive material by attaching a metal plate or a metal foil to the resin part, or by plating a metal powder-containing material on the resin part.

  The emblem 24 is attached to the insulating trunk lid 22 as described above, but is not electrically connected to the vehicle body or various circuits.

  In FIG. 1, the emblem 24 is schematically illustrated as a constant length member that is long in the vehicle width direction, but the shape, dimensions, and the like of the emblem 24 are not limited by the illustration. In the example of FIG. 1, the emblem 24 is provided at the left corner of the trunk lid 22 in the rear view of the vehicle 20, but the position of the emblem 24 is not limited to this example.

  An antenna device 28 is mounted on the vehicle 20. In FIG. 1, the antenna element 30 and the additional member 32 of the antenna device 28 are schematically illustrated, and other components such as various circuits are not illustrated.

  The antenna element 30 is provided in the vicinity of the emblem 24 so as to be separated from the emblem 24. In the example of FIG. 1, the antenna element 30 is provided in a rear bumper 26 positioned below the trunk lid 22. Here, the case where the reception polarization direction of the antenna element 30 is the vehicle width direction of the vehicle 20 is illustrated.

  In FIG. 1, the antenna element 30 is schematically illustrated, and the shape, dimensions, and the like of the antenna element 30 are not limited by the illustration. In the example of FIG. 1, the antenna element 30 is provided almost directly below the emblem 24, but the installation position of the antenna element 30 is not limited to this example.

  The additional member 32 is added to the inner surface (trunk room side surface) of the trunk lid 22, that is, the back side of the design surface, and is provided so as to overlap the emblem 24 through the trunk lid 22. The additional member 32 includes a metal such as iron and has conductivity. The additional member 32 can be composed of, for example, a plate-like member or a film-like member, and can be installed by screwing or pasting the member. The additional member 32 can also be formed by applying and printing a fluid material such as a conductive paste or liquid on the trunk lid 22. In this case, a film formed by solidifying the fluid material having conductivity constitutes the additional member 32. Further, the additional member 32 may be configured by variously combining the above-described exemplary plate-like member, film-like member, solidified film of fluid material, and the like.

  Since the trunk lid 22 is made of an insulating material as described above, the additional member 32 is not electrically connected to the vehicle body. In this case, the additional member 32 resonates integrally with the emblem 24. The resonance here is an electrical resonance, and the same applies hereinafter. The additional member 32 and the emblem 24 that resonate integrally behave as one electrically conductive member. For convenience of explanation, the additional member 32 that resonates integrally and the one conductive member that corresponds to the emblem 24 will be referred to as a “member 34 that resonates integrally”.

  As long as the additional member 32 and the emblem 24 can resonate integrally, the positional relationship between them can be designed in various ways. The schematic diagram explaining the installation example of the additional member 32 is shown in FIGS. 2 to 4 correspond to cross-sectional views in which the trunk lid 22 is cut in a horizontal direction at a position including the additional member 32 and the emblem 24. 2 to 4 schematically show the elements 22, 24, and 32, and do not show actual size ratios.

  FIG. 2 illustrates a case where a part of the additional member 32 overlaps the entire emblem 24 and the additional member 32 is installed with the emblem 24 aligned with an edge. FIG. 3 illustrates a case where a part of the additional member 32 overlaps a part of the emblem 24. In FIG. 4, a part of the additional member 32 overlaps the entire emblem 24, but unlike FIG. 2, the case where the edge of the additional member 32 is located away from the edge of the emblem 24 is illustrated. . The integrated resonance of the additional member 32 and the emblem 24 is possible in any of the examples of FIGS.

  Here, the case where the additional member 32 and the emblem 24 are not in direct contact with each other by the interposition of the insulating trunk lid 22 is illustrated. However, even if the additional member 32 is directly stacked on the emblem 24, integrated resonance is possible. It is. However, it is preferable to provide the additional member 32 at a location that is not visually recognized during normal use of the vehicle 20, in other words, at a location hidden from the exterior and interior of the vehicle 20. According to such an installation form, the design value of the vehicle 20 is not reduced by the addition of the additional member 32.

  According to the additional member 32, it is possible to reduce the resonance effect of only the emblem 24 by the integral resonance with the emblem 24. Thereby, it is possible to reduce the resonance action of the emblem 24 within the reception frequency band of the antenna element 30, in other words, reception interference by the emblem 24.

  Specifically, the frequency at which the emblem 24 resonates is shifted out of the reception frequency band of the antenna element 30 by integral resonance with the additional member 32. Thereby, the resonance action of the emblem 24 within the reception frequency band of the antenna element 30 is reduced. As a result, the frequency at which the additional member 32 and the emblem 24 resonate integrally, in other words, the resonance frequency of the member 34 that resonates integrally exists outside the reception frequency band of the antenna element 30. It will be.

  Therefore, according to the additional member 32, the influence which the emblem 24 has on reception by the antenna element 30 can be reduced, and reception by the antenna element 30 can be improved.

  The frequency shift is possible by adjusting the length L32 of the additional member 32. Specifically, the length L32 of the additional member 32 is set such that the length L34 of the integrally resonating member 34 is longer than ½ wavelength of the received radio wave of the antenna element 30. . As a result, the wavelength at which the emblem 24 resonates (in other words, the frequency) can be shifted to the long wavelength side (in other words, the low frequency side) as compared with the case where only the emblem 24 resonates.

  2 and 4, the length L34 of the member 34 that resonates integrally corresponds to the length L32 of the additional member 32. In the case of the configuration example of FIG. 3, the length L34 of the integrally resonating member 34 is obtained by calculating the length of the overlapping portion from the total value of the length L32 of the additional member 32 and the length L24 of the emblem 24. Corresponds to the subtracted value. The lengths L34, L32, and L24 and the length of the overlapping portion are the lengths (dimensions) of the antenna element 30 in the reception polarization direction (here, the vehicle width direction as described above). 2 to 4 exemplify the case of L32> L24, there are cases where L32 ≦ L24.

  FIG. 5 shows an antenna reception sensitivity graph for explaining the frequency shift due to the additional member 32. In FIG. 5, the characteristic line (a) shows the case where there is no additional member 32, and the characteristic lines (b) and (c) show that the length L34 of the member 34 that resonates integrally is about 0.273 m and about 0.309 m. Each case is shown. From the characteristic line (a), it can be seen that the resonance frequency of only the emblem 24 is about 590 MHz. Further, from the characteristic lines (b) and (c), it is understood that integral resonance between the emblem 24 and the additional member 32 occurs at about 550 MHz and about 485 MHz, respectively, and the above-described frequency shift is possible by the additional member 32. . Further, it can be seen that the resonance frequency shifts to the lower frequency side as the length L34 of the member 34 that resonates integrally, that is, the length L32 of the additional member 32 is longer.

  When there are a plurality of reception frequencies (reception channels) in the reception frequency band of the antenna element 30, the reception frequency is set by setting the length L32 of the additional member 32 in the same manner as described above based on the reception polarization of the longest wavelength. Good reception is obtained over the entire band, ie for all reception channels. For example, when the object to be received by the antenna device 28 is terrestrial digital broadcasting, the frequency band is 470 MHz to 710 MHz (wavelength 0.423 m to 0.638 m). In this case, the length L32 of the additional member 32 is set so that the length L34 of the integrally resonating member 34 is longer than 0.319 m which is 1/2 of 0.638 m. Can be received well.

  In FIG. 1, the additional member 32 is schematically illustrated as a fixed length member having the same width as the emblem 24 and long in the vehicle width direction. However, the additional member 32 and the emblem 24 have different widths. It is possible to obtain the above effect.

  As described above, according to the additional member 32, reception interference of the emblem 24 within the reception frequency band of the antenna element 30 can be reduced. Moreover, such an effect can be obtained without changing the length L24 of the emblem 24 or the installation position, or changing the installation position of the antenna element 30. That is, according to the additional member 32, the reception interference reduction effect is exhibited without impairing the design value of the vehicle 20 by the emblem 24 and the reception performance of the antenna element 30 (that is, independently of these).

  By the way, in the case of the conventional configuration as described above, reception interference by the emblem 124 can be avoided by setting the separation distance between the antenna element 130 and the emblem 124 to about 60% or more of the reception wavelength (see FIG. 8). In other words, in the case of the conventional configuration that does not have the additional member 32, it is not preferable to set the separation distance to about 60% or less of the reception wavelength.

  On the other hand, in the case of the configuration in which the additional member 32 is provided, the additional member 32 has an effect of reducing reception interference. Therefore, the distance between the antenna element 30 and the emblem 24 is set to about 60% or less of the wavelength received by the antenna element 30. Even with this, good reception is possible. That is, the antenna element 30 and the emblem 24 can be installed in a positional relationship different from the conventional configuration, and the degree of design freedom increases.

  For example, in the case of terrestrial digital broadcasting (as described above, the frequency band is 470 MHz to 710 MHz and the wavelength is 0.423 m to 0.638 m), in order to perform good reception in the entire frequency band in the conventional configuration, the antenna The element 130 and the emblem 124 had to be separated from each other by about 0.383 m (= 0.638 m × 60%) or more. On the other hand, in the structure provided with the additional member 32, the emblem 24 and the antenna element 30 can be provided within a range of about 0.383 m or less. However, the emblem 24 and the antenna element 30 are provided apart from each other.

  Although the case where the antenna element 30 was built in the back bumper 26 was illustrated above, the installation location of the antenna element 30 is not limited to this. For example, you may install the antenna element 30 in a front bumper, a roof, a spoiler, etc.

  In the above description, the emblem 24 is exemplified as a conductive member that is not electrically connected to the vehicle body. Also good. Further, as another example of the conductive member, for example, a safety-related component or an internal member thereof may be used. For example, a reflector in a fog lamp attached to a bumper, a metal plate (circuit pattern) in a high-mount stop lamp attached to a spoiler, and the like can be given. Application of the additional member 32 is effective because it is not easy to change the installation position of the parts related to safety in accordance with the law.

  Moreover, although the terrestrial digital broadcasting was illustrated above, the additional member 32 can be applied to various radio waves such as FM, UHF, and VHF. Further, the additional member 32 can be applied even when the polarization direction is other than the vehicle width direction illustrated above.

  Moreover, although the case where the vehicle 20 was an automobile vehicle was illustrated above, the additional member 32 can be applied even if the vehicle 20 is, for example, a railway vehicle.

1 is a schematic configuration diagram illustrating a vehicle and an antenna device according to an embodiment of the present invention. It is a schematic diagram explaining the installation example of the additional member which concerns on embodiment of this invention. It is a schematic diagram explaining the installation example of the additional member which concerns on embodiment of this invention. It is a schematic diagram explaining the installation example of the additional member which concerns on embodiment of this invention. It is an antenna receiving sensitivity graph explaining the frequency shift by the additional member which concerns on embodiment of this invention. It is a schematic diagram explaining the conventional vehicle-mounted antenna apparatus. It is a figure explaining the influence which an emblem has on antenna receiving sensitivity. It is a graph explaining the influence which the separation distance of an antenna element and an emblem exerts on antenna reception sensitivity.

Explanation of symbols

  20 vehicle, 22 trunk lid, 24 emblem (conductive member not electrically connected to vehicle body), 26 bumper, 28 antenna device, 30 antenna element, 32 additional member, 34 member that resonates integrally, L24, L32 , L34 Length.

Claims (8)

A vehicle equipped with an antenna element,
A conductive member that is provided on the vehicle body with a predetermined distance between the antenna element and is not electrically connected to the vehicle body;
A conductive additional member added to the conductive member,
With
The additional member is provided so as to be capable of electrical resonance integrally with the conductive member, and the electrical resonance frequency is outside the reception frequency band of the antenna element. The vehicle according to claim 1,
The vehicle according to claim 1, wherein the predetermined separation distance is about 60% or less of a wavelength received by the antenna element. The vehicle according to claim 1 or 2,
The said additional member is provided in the location which is not visually recognized at the time of normal use of the said vehicle. The vehicle according to any one of claims 1 to 3,
The additional member includes at least one of a plate-like member, a film-like member, and a film obtained by solidifying a fluid material. An antenna device provided in a vehicle,
An antenna element;
A conductive additional member that is added to a conductive member that is provided on the vehicle body and has a predetermined separation distance between the antenna element and not electrically connected to the vehicle body;
Including
The antenna device according to claim 1, wherein the additional member is electrically resonated integrally with the conductive member to reduce an electrical resonance action of the conductive member within a reception frequency band of the antenna element. The antenna device according to claim 5, wherein
The additional member is configured to shift the frequency at which the conductive member electrically resonates out of the reception frequency band of the antenna element by electrically resonating integrally with the conductive member. apparatus. The antenna device according to claim 5 or 6, wherein
The length of the additional member in the reception polarization direction of the antenna element is such that the frequency of an electrical resonance between the additional member and the conductive member is outside the reception frequency band of the antenna element. An antenna device characterized by being set. The antenna device according to any one of claims 5 to 7,
The additional member includes at least one of a plate-shaped member, a film-shaped member, and a film obtained by solidifying a fluid material.

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