JP7019366B2 - Antenna device - Google Patents

Description

The present invention relates to an antenna device.

Conventionally, as in Patent Document 1, an in-vehicle antenna device including a GPS patch antenna has been proposed.

Japanese Unexamined Patent Publication No. 2012-34226

However, when the radio wave reflected by the substrate around the GPS patch antenna is received, there is a possibility that an error may occur in the subsequent calculation or fading may occur.

Therefore, an object of the present invention is to provide an antenna device that is not easily affected by radio waves reflected around the antenna element.

The antenna device according to the present invention includes an antenna element and a substrate, and the substrate is formed with a hole in which at least the upper surface of the substrate is recessed at a position where it does not overlap with the antenna element when viewed from above. Of the radio waves received by the antenna element, those that reach the region of the substrate having holes are provided to suppress reflection and reach the antenna element, and the holes are provided with a plurality of holes and one or more holes. Consists of at least one of the slits.

The radio wave incident on the upper part of the hole is reflected on the side surface of the hole and reaches the bottom of the hole.
For this reason, among the radio waves received by the antenna element, those that reach the region having a hole in the substrate are less likely to be reflected on the substrate and reach the antenna element, and the radio waves reflected around the antenna element are reduced. It becomes possible to form an antenna device that is not easily affected.

Preferably, the hole portion is composed of a plurality of through holes, a metal body is provided on each side surface of the plurality of through holes, and the plurality of through holes are positioned so as to surround the antenna element when viewed from above. It will be provided.

The through-holes used in the present invention can be formed together in the process of forming a normal through-hole for mounting a component provided on the substrate.

More preferably, a radio wave absorbing portion containing a radio wave absorbing material is provided under the hole portion.

Since the radio wave absorbing portion is provided under the hole portion, it is possible to suppress the radio wave from being radiated to the outside from the upper surface of the substrate after the reflection on the side surface of the hole portion.

More preferably, the hole portion has a first hole portion and a second hole portion, the first hole portion is provided in a positional relationship surrounding the antenna element when viewed from above, and the second hole portion is above. It is provided in a positional relationship surrounding the first hole when viewed from the viewpoint.

More preferably, the electronic component electrically connected to the antenna element is mounted inside the region surrounded by the holes when viewed from above.

It is easy to install both on the substrate while avoiding physical interference between the electronic component and the hole.

Further, preferably, the hole portion is provided in a region in a specific direction with respect to the antenna element without surrounding the antenna element when viewed from above, and the hole portion is the first hole portion and the second hole portion. The first hole portion is provided in a positional relationship between the antenna element and the second hole portion when viewed from above.

Since the holes are not formed in the region of the substrate other than the specific direction, there is an advantage that the strength of the substrate can be easily secured as compared with the form in which the holes are provided in the positional relationship surrounding the antenna element when viewed from above.

Further, preferably, the antenna element is a GNSS antenna element.

As described above, according to the present invention, it is possible to provide an antenna device that is not easily affected by radio waves reflected around the antenna element.

It is sectional drawing of the antenna apparatus in 1st Embodiment to 3rd Embodiment. FIG. 3 is a perspective view of the substrate according to the first embodiment, which is a region including the periphery of the antenna element, as viewed from above. FIG. 5 is a perspective view of the substrate according to the second embodiment, which is a region including the periphery of the antenna element, as viewed from above. FIG. 3 is a perspective view of the substrate according to the third embodiment, which is a region including the periphery of the antenna element, as viewed from above.

Hereinafter, the first embodiment will be described with reference to the drawings. The antenna device 1 in the first embodiment is attached to the upper surface (mounting surface 21) of a vehicle such as a roof, and has an antenna case 2, a pad 3, a base 5, an antenna element 11, an electronic component 12, a substrate 15, a hole 16, and a radio wave. The absorption unit 17 and the cable 18 are provided (see FIGS. 1 and 2).

In order to explain the direction, the front-rear direction of the vehicle to which the antenna device 1 is attached will be described as the x direction, the left-right direction perpendicular to the x direction will be described as the y direction, and the substantially vertical direction perpendicular to the x direction and the y direction will be described as the z direction. In FIG. 2, the directions pointed to by the arrows on the xyz axis are defined as the forward direction, the right direction, and the upward direction, respectively.

The antenna case 2 is a member that covers the members constituting the antenna device 1, and is made of a synthetic resin having non-translucency and radio wave transmission (polycarbonate) and a synthetic resin containing ASA (Acrylate Styrene Acrylonitrile). It is a resin molded product), and has, for example, a shark fin shape in which the front in the x direction is inclined so as to be lower than the rear in the x direction, and both side surfaces are curved inward (see FIG. 1).

The antenna case 2 has an open lower surface and is a member constituting the antenna device 1 and covers a member other than the antenna case 2 (antenna element 11 or the like) from above in the z direction.
That is, the antenna element 11 described later is located in the space covered by the antenna case 2.

Although the antenna case 2 has a so-called shark fin shape in the first embodiment, it may have another shape such as a substantially rectangular parallelepiped shape having an open lower surface.

The pad 3 is an annular elastic member made of elastomer, rubber, or the like, is fitted into the lower end peripheral portion of the antenna case 2, and is arranged in a state of being sandwiched between the antenna case 2 and the base 5. It functions as a blindfold for the gap between the lower edge of the antenna case 2 and the vehicle.

The base 5 holds the substrate 15, and a mounting hole (not shown) for screwing to the antenna case 2 and the pad 13 is provided on the peripheral portion, and the cable 18 is passed through the central portion and the like in the z direction. A cable hole 5a for the purpose is provided.

A mounting member (not shown) is provided at the lower portion of the base 5, and the antenna device 1 is mounted on a mounting surface 21 such as a roof of a vehicle via the mounting member.

The antenna element 11 is used to receive position information and time information of the satellite from a GPS (Global Positioning System) satellite or the like.
The antenna element 11 is composed of a patch antenna (antenna element for GNSS (Global Navigation Satellite System)).

The electronic component 12 includes an amplifier that is electrically connected to the antenna element 11 and amplifies the signal obtained by the antenna element 11.

The substrate 15 is a substrate for mounting the antenna element 11, the electronic component 12, and the cable 18. The antenna element 11 is on the upper surface, the electronic component 12 and the cable 18 are on the lower surface, and the hole portion 16 is viewed from above in the z direction. It is mounted inside the area surrounded by (for example, directly under the antenna element 11).

The ground electrode (not shown) at the bottom of the antenna element 11 and the ground metal portion (not shown) provided directly below the antenna element 11 on the substrate 15 are close to each other and electrostatically coupled to each other, and the substrate 15 can also be used as a main plate. used.

The antenna element 11 is connected to an electric device of a vehicle such as a car navigation system via an electronic component 12, a substrate 15, and a cable 18.
By mounting the electronic component 12 on the lower surface of the substrate 15 and inside the region surrounded by the hole 16, it is easy to provide both on the substrate 15 while avoiding physical interference between the electronic component 12 and the hole 16. Become.

However, the electronic component 12 and the cable 18 may be mounted on the upper surface of the substrate 15.
Further, the antenna element 11 may be attached to a member other than the substrate 15 (for example, the inside of the antenna case 2).

At a position on the substrate 15 that does not overlap with the antenna element 11 when viewed from above in the z direction, a hole portion 16 passing through the upper surface and the lower surface of the substrate 15 is formed in a straight line or a curved line.
The hole portion 16 is provided to prevent radio waves received by the antenna element 11 that reach a certain region of the substrate 15 from being reflected and reaching the antenna element 11.

In the first embodiment, the hole portion 16 is composed of a plurality of through holes penetrating the substrate 15 in the z direction, and the plurality of through holes constituting the hole portion 16 are around the antenna element 11 when viewed from above in the z direction. It is provided in a positional relationship surrounding.

Specifically, as the hole portion 16, the first hole portion (first through hole group 16a) that surrounds the periphery of the antenna element 11 with a substantially rectangular shape, and the second hole portion that surrounds the circumference of the first hole portion with a substantially rectangular shape. (2nd through hole group 16b), 3rd hole portion (3rd through hole group 16c) surrounding the 2nd hole portion with a substantially rectangular shape, and 4th hole portion surrounding the 3rd hole portion with a substantially rectangular shape. (4th through-hole group 16d) is provided, and the hole portion 16 surrounds the periphery of the antenna element 11 in a quadruple manner when viewed from above in the z direction.
However, the number of through-hole groups surrounding the antenna element 11 is not limited to four.

The through hole is a hole that penetrates the substrate 15 in the z direction, and a metal body is provided on the side surface of the hole by processing such as plating or paste printing.

A radio wave absorbing portion 17 is provided below the hole portion 16 in the z direction.
Specifically, an absorber mixed with a radio wave absorbing material such as ferrite is attached to a region located on the lower surface of the substrate 15 or the upper surface of the base 5 and located below the hole 16 in the z direction, or the radio wave. The paint in which the absorbent material is dissolved is applied to the lower surface of the substrate 15 or the upper surface of the base 5 and the region located below the hole 16 in the z direction.
FIG. 1 shows an example in which the radio wave absorbing unit 17 is attached to the lower surface of the substrate 15.

The radio wave incident on the vicinity of the upper part of the hole 16 is reflected on the side surface of the through hole and reaches the vicinity of the lower part of the hole 16.
Specifically, the radio wave incident on the periphery of the hole of the through hole reaches the lower part of the hole portion 16 while reflecting on the outer wall of the through hole and further reflecting on the outer wall of the adjacent through hole.
The radio wave incident on the hole of the through hole is reflected on the inner wall of the through hole and reaches the lower part of the hole portion 16.

Therefore, among the radio waves received by the antenna element 11, those that reach the region having the hole 16 in the substrate 15 are less likely to be reflected on the substrate 15 and reach the antenna element 11, and the antenna element 11 It becomes possible to form an antenna device 1 that is not easily affected by radio waves reflected from the surroundings.

The radio wave that has a low elevation angle and is reflected on the substrate 15 and reaches the antenna element 11 is often a multipath radio wave reflected by a building or the like, and when the radio wave reaches the antenna element 11, information from the antenna element 11 There is a possibility of increasing the error of the calculation performed based on (for example, the position information calculation).

In the first embodiment, a radio wave that has reached a region of the hole 16 in the substrate 15 at a low elevation angle can be suppressed from being reflected toward the antenna element 11 by using the hole 16 and the radio wave absorbing unit 17. It will be possible.
When the thickness of the substrate 15 is thin, the length of the hole 16 provided in the substrate 15 in the z direction becomes short, and the low elevation angle radio wave incident on the hole 16 is between through holes or through holes. There is a possibility that the number of reflections inside will be small and it will not be possible to sufficiently attenuate.
However, in the first embodiment, since the radio wave absorbing portion 17 is provided under the hole portion 16, the radio wave is radiated from the upper surface of the substrate 15 to the outside after reflection between the through holes or in the through holes. It can be suppressed.

In the first embodiment, the embodiment in which the hole portion 16 is formed by using a plurality of through holes has been described, but one or more slits (or both the slit and the through hole) penetrating the substrate 15 in the z direction are used. The hole 16 may be formed (see the second embodiment, FIGS. 1 and 3).

Similar to the through hole in the first embodiment, the slit is a hole penetrating the substrate 15 in the z direction, and a metal body is provided on the side surface of the hole by processing such as plating or paste printing. be.

FIG. 3 shows a first hole portion (first slit group 16e) that surrounds the periphery of the antenna element 11 with a substantially rectangular shape, and a second hole portion (first hole portion 16e) that surrounds the periphery of the first hole portion with a substantially rectangular shape. 2 slit group 16f), a third hole portion (third slit group 16g) surrounding the circumference of the second hole portion with a substantially rectangular shape, and a fourth hole portion (fourth slit) surrounding the circumference of the third hole portion with a substantially rectangular shape. An example in which a group 16h) is provided and fourfoldly surrounds the antenna element 11 when viewed from above in the z direction, and each slit group is formed into a substantially rectangular shape by an L-shaped slit and a linear slit. Is shown.
Further, in FIG. 3, a form in which a plurality of slits surround the antenna element 11 will be described, but one slit having a substantially C shape may surround the antenna element 11.

Since a plurality of through holes (first embodiment) and one or more slits (second embodiment) can be formed by providing through holes having a predetermined shape in the substrate 15, they are made to protrude above the substrate 15. It becomes possible to easily form a wall for radio wave reflection as compared with a form in which a wall is provided.

In particular, the through holes can be formed together in the process of forming a normal through hole for mounting a component provided on the substrate 15.

In the first embodiment and the second embodiment, it has been described that the hole forming the hole portion 16 passes through the upper surface and the lower surface of the substrate 15, but it does not pass through the lower surface and is recessed downward from the upper surface. It may be in the form of a dent.
In this case, a metal body is provided on the side surface of the recess, and a radio wave absorbing portion 17 is provided at the bottom of the recess.

Further, in the first embodiment and the second embodiment, the embodiment in which the hole portion 16 is provided in the positional relationship surrounding the antenna element 11 when viewed from above in the z direction has been described, but only the low elevation angle radio wave from a specific direction is blocked. In this case, the hole 16 does not surround the antenna element 11 and is in a part of the region (for example, in the x direction with respect to the antenna element 11) that does not overlap with the antenna element 11 when viewed from above in the z direction. A hole 16 may be provided in the region) (see the third embodiment, FIGS. 1 and 4).

FIG. 4 shows the first hole portion (first through hole group 16a) formed in a straight line extending in the y direction in front of and behind the antenna element 11 as the hole portion 16, and is farther from the antenna element 11 than the first hole portion. A second hole portion (second through hole group 16b) formed in a straight line extending in the y direction is provided at the position, and the first hole portion is formed into the second hole portion and the antenna element 11 when viewed from above in the z direction. An example of being sandwiched is shown.

In this case, since the hole portion 16 is not formed in the region of the substrate 15 other than the specific direction, the substrate 15 is compared with the form in which the hole portion 16 is provided in the positional relationship surrounding the antenna element 11 when viewed from above in the z direction. There is a merit that it is easy to secure the strength of.

In the first to third embodiments, the embodiment in which one antenna element 11 is provided in the space covered by the antenna case 2 has been described. However, there are a plurality of antenna elements 11 and each of them is on the substrate 15. The hole portion 16 may be provided around the antenna element 11 of the above, and the radio wave absorbing portion 17 may be provided under the hole portion 16.

Further, although the form in which the antenna element 11 is composed of the antenna element for GNSS has been described, the form may be composed of other antenna elements, and even in the case of other antenna elements, the hole portion 16 and the radio wave absorption By providing the unit 17, fading due to the multipath radio wave reaching the other antenna element is suppressed, that is, the antenna device 1 that is not easily affected by the radio wave reflected around the antenna element 11 is formed. Will be possible.

Further, although the form in which the metal body is provided on the side surface of the through hole or the slit provided in the substrate 15, the form in which the metal body is provided as a whole so as to close the hole of the through hole or the slit may be used. ..
In this case, the radio wave absorbing unit 17 may be provided in the through hole or the hole of the slit closed by the metal body.

1 Antenna device 2 Antenna case 3 Pad 5 Base 5a Cable hole 11 Antenna element 12 Electronic component 15 Board 16 Hole 16a ~ 16d 1st through hole group ~ 4th through hole group 16e ~ 16h 1st slit group ~ 4th slit group 17 Radio absorber 18 Cable 21 Mounting surface

Claims (7)

Antenna element which is a patch antenna and
A substrate on which the antenna element is mounted is provided.
At least a hole having a recessed upper surface of the substrate is formed on the substrate at a position where it does not overlap with the antenna element when viewed from above.
The hole portion is provided to prevent radio waves received by the antenna element that reach the region of the substrate from which the hole portion is present are reflected and reach the antenna element.
The antenna device is characterized in that the hole portion is composed of at least one of a plurality of holes and one or more slits. The hole is composed of a plurality of through holes.
A metal body is provided on each side surface of the plurality of through holes.
The antenna device according to claim 1, wherein the plurality of through holes are provided in a positional relationship surrounding the antenna element when viewed from above. The antenna device according to claim 1 or 2, wherein a radio wave absorbing portion including a radio wave absorbing material is provided below the hole portion. The hole portion has a first hole portion and a second hole portion.
The first hole portion is provided in a positional relationship surrounding the antenna element when viewed from above.
The antenna device according to any one of claims 1 to 3, wherein the second hole portion is provided in a positional relationship surrounding the first hole portion when viewed from above. The antenna device according to claim 4, wherein the electronic component electrically connected to the antenna element is mounted inside the region surrounded by the hole when viewed from above. The hole portion has a first hole portion and a second hole portion.
The invention according to any one of claims 1 to 3, wherein the first hole portion is provided in a positional relationship between the antenna element and the second hole portion when viewed from above. Antenna device. The antenna device according to any one of claims 1 to 6, wherein the antenna element is a GNSS antenna element.

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