JP5878366B2 - In-vehicle antenna device and in-vehicle antenna - Google Patents

Description

  The present invention relates to a vehicle-mounted antenna that can reduce noise mixed from vehicle-mounted electrical components when receiving radio waves.

  For in-vehicle antennas, when receiving radio waves with the in-vehicle antenna, noise from in-vehicle electrical components is mixed into the received radio waves, reducing the reception performance of the in-vehicle antenna, and in some cases it has been confirmed that communication is interrupted .

  In order to reduce this noise, two main antennas, a main antenna for receiving a desired band and a noise scanning antenna, have been provided, and the signal received by the noise scanning antenna is added to the signal received by the main antenna. By doing so, there is an antenna having a structure that cancels and reduces noise components (see, for example, Patent Document 1).

  In addition, there is an antenna having a structure in which a radio wave absorber is disposed on the front surface of the back surface of the GND of the patch antenna, and noise is circulated to the patch antenna when receiving radio waves with the patch antenna (see, for example, Patent Document 2). ).

JP 2010-004451 A JP 2003-110351 A

  However, in the antenna having the above structure, an antenna for noise cancellation, a negative phase addition circuit, or a radio wave absorber is required in addition to the main antenna, and the structure of the antenna becomes complicated and large. Or high cost.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a vehicle-mounted antenna that has a simple structure, is low in cost, and is less susceptible to noise from vehicle-mounted electrical components.

  In this column, in order to facilitate understanding of the invention, the reference numerals used in the “Mode for Carrying Out the Invention” column are attached as necessary, which means that the scope of claims is limited by this reference numeral. is not.

  The invention made in order to solve the problems described in “Problems to be Solved by the Invention” includes a GND plate (10) having a conductive shape and a single side of the GND plate (10). And a monopole antenna element (20) installed at a position decentered from the center position of the GND board, wherein the monopole antenna element (20) on the GND plate (10) A hole (12) is provided in a part on the center position side of the GND plate (10) with respect to the disposed position.

  Such a vehicle-mounted antenna (1) can be a vehicle-mounted antenna (1) that has a simple structure, is low in cost, and is less susceptible to noise from vehicle-mounted electrical components. The reason will be described below.

  When the hole (12) is provided in the GND plate (10), the path length with respect to the induced current (noise) generated in the vehicle-mounted electrical component and mixed in the received radio wave is longer than that when there is no hole (12). Therefore, resonance does not occur at the frequency of the induced current, thereby reducing the influence of noise at that frequency.

  For example, FIG. 3A shows a current path of an induced current in the case of an antenna having a shape in which a monopole antenna element is provided on one side of the GND plate (10) (use frequency band 700 [MHz]). In FIG. 3, an arrow indicates the direction in which the induced current flows.

On the other hand, when the GND plate (10) has the hole (12), the induced current bypasses the hole (12) on the substrate as shown in FIG. 3 (b).
Thus, by bypassing the induced current through the hole (12), the path length for the induced current is lengthened, resonance is prevented, and the influence of noise (induced current) is reduced.

Thus, the vehicle-mounted antenna (1) can be made a simple structure in which the hole (12) is provided in a part of the GND plate (10), and is less susceptible to noise at a low cost.
The hole (12) may be a through hole or a stop hole. Further, as in the case of being provided at the end of the GND plate (10), it may be a partially opened hole.

  Here, “having conductivity and formed in a plate shape” means that the GND plate (10) only needs to have conductivity as a whole. It may be formed by printing a conductive material such as copper on the surface of such a non-conductive material, or may be formed only by a conductive material.

  The “center position of the GND plate (10)” means a geometric center position. For example, when the GND plate (10) is square, rectangular, or circular, the position of the center point is meant. In the case of an ellipse, it means the position of the center point of two focal points.

Further , even if the hole (12) is filled with any one of a dielectric material, a non-conductive material, and a magnetic material, the path length becomes longer than when the hole (12) is not provided. Therefore, resonance can be prevented at the operating frequency, and the influence of noise can be reduced.

Further , in the GND plate (10), when the hole (12) is provided at a position away from the end closest to the installation position of the monopole antenna element (20) by λ / 16 or more of the operating frequency, the noise reduction effect Becomes larger.

The hole portion (12) does not include the end portion of the GND plate (10), and the end portion closest to the installation position of the monopole antenna element (20) on the GND plate (10) and the monopole antenna element If the width in the direction perpendicular to the straight line connecting the installation positions of (20) is 60% or more of the width of the GND plate (10) at the position of the hole (12), the noise reduction effect is large. Become.

  Here, “the width of the GND plate (10)” means the length in the direction perpendicular to the straight line connecting the end closest to the installation position of the monopole antenna element (20) and the installation position of the monopole antenna element (20). For example, when the GND plate (10) is rectangular, the length is the short side or the long side, and when the GND plate (10) is ellipse, the length is the short axis or the long axis.

Furthermore , the hole (12) includes the end of the GND plate (10), and the end of the GND plate (10) closest to the installation position of the monopole antenna element (20) and the monopole antenna element ( 20) In a direction perpendicular to the straight line connecting the installation positions of 20), at the position of the hole (12), the conductive material is formed so as to leave 30% or more of the width of the GND plate (10). However, the noise reduction effect is increased.

Another aspect of the present invention is a conductive GND plate (10) formed in a plate shape, and a monolithic device installed on one side of the GND plate (10) at a position eccentric from the center position of the GND substrate. A pole antenna element (20), and a magnetic material on a part of the GND plate (10) closer to the center position than the position where the monopole antenna element (20) is arranged on the GND plate (10). An in-vehicle antenna (2) characterized in that the formed magnetic part (50, 52) is arranged.

Such, the vehicle antenna (2), similar to the car mounting antenna (1), a magnetic material, the path length for induced current is longer than that when there is no hole (12). Accordingly, resonance does not occur due to the induced current at the use frequency, thereby reducing the influence of noise at the use frequency.

Magnetic unit (50, 52), in the G ND plate (10), the monopole antenna elements (20) parallel to the straight line connecting the installation position of the end nearest the monopole antenna element in the installation position (20) When two places are arranged, the noise reduction effect is increased.

Further , in the GND plate (10) of each of the magnetic parts (50, 52) arranged at two locations, the end closest to the installation position of the monopole antenna element (20) and the monopole antenna element (20) When the length in the direction perpendicular to the straight line connecting the installation positions is 15% or more of the length of the GND plate (10) in the same direction, the noise reduction effect is increased.

It is the figure which showed the state which mounted the vehicle-mounted antenna in the vehicle. 1 is a structural diagram illustrating a schematic structure of a vehicle-mounted antenna according to a first embodiment. It is a figure which shows the electric current path | route when an induced electric current flows into a GND board. It is a figure which shows the relationship of the amount of noise reduction with respect to the position and width | variety of a hole in a GND board. It is a figure which shows the relationship of the amount of noise reduction with respect to the width | variety of two holes in a GND board. It is a figure which shows the general | schematic structure of the vehicle-mounted antenna using a magnetic material instead of a hole. It is a figure which shows the change of the electric current distribution by the physical-property value of the magnetic body of a magnetic part. The relationship between the short side length of two magnetic parts and the amount of noise reduction with respect to the short side length of the GND plate is shown.

Embodiments to which the present invention is applied will be described below with reference to the drawings. The embodiment of the present invention is not limited to the following embodiment, and can take various forms as long as they belong to the technical scope of the present invention.
[First Embodiment]
FIG. 1 is a diagram showing a state in which a vehicle-mounted antenna 1 to which the present invention is applied is mounted on a vehicle 60. As shown in FIG. 1A, the in-vehicle antenna 1 is installed on a roof 62 of the vehicle 60, and the output of the in-vehicle antenna 1 is connected to an ECU 70 that is an in-vehicle electrical component by a cable 40. The on-vehicle antenna 1 is covered with a resin case 7 as shown in FIG.

In addition, in FIG. 1, the vehicle-mounted antenna 1 mounted in the vehicle 60 is one, However, Two or more vehicle-mounted antennas 1 may be mounted.
FIG. 2 is a structural diagram showing a schematic structure of the in-vehicle antenna 1 to which the present invention is applied. As shown in FIG. 2, the vehicle-mounted antenna 1 includes a GND plate 10, a monopole antenna element 20, a power feeding unit 30, and a cable 40.

  The GND plate 10 is a plate made of a conductive material such as a metal material such as iron, copper, silver, or aluminum in a rectangular shape, and maintains the reference potential of the in-vehicle antenna 1 at the GND potential.

Further, a hole 12 is provided in a part of the GND board 10 on the center position side of the position where the monopole antenna element 20 is arranged.
The hole 12 is a stop hole formed in a rectangular shape by removing the conductive material film printed on the GND board 10.

  The hole 12 is provided at a position away from the short side closest to the installation position of the monopole antenna element 20 among the sides of the rectangular GND plate 10 by λ / 16 or more of the use frequency. In other words, as shown in FIG. 4A, the distance between the short side of the GND plate 10 and the long side of the hole 12 near the short side of the GND 10 is λ / 16. It is that. “Λ” is a wavelength with respect to the center frequency f of the frequency band of the radio wave transmitted and received by the vehicle-mounted antenna 1.

Moreover, the hole part 12 is good also as a through-hole instead of a stop hole. Further, the hole 12 may be filled with any one of a dielectric material, a non-conductive material, and a magnetic material.
The hole 12 does not include the long side end portion of the rectangular GND plate 10 and connects the short side closest to the installation position of the monopole antenna element 20 to the installation position of the monopole antenna element 20 on the GND plate 10. The width in a direction perpendicular to the straight line (indicated by “S2” in FIG. 3A) is 60% or more of the width of the GND plate 10 at the position of the hole 12.

That is, the length (S2) of the long side of the hole portion 12 is formed to be 60% or more of the length of the short side of the GND plate 10.
The monopole antenna element 20 is installed so as to be substantially perpendicular to the GND plate 10, and one end thereof is connected to the power feeding unit 30. Further, the monopole antenna element 20 is installed at a position eccentric from the center position of the GND plate 10 toward the short side.

The cable 40 supplies a radio wave as an output signal to the power feeding unit 30 of the monopole antenna element 20 and supplies a radio wave received by the monopole antenna element 20 from the power feeding unit 30 to an on-vehicle electrical component such as a receiver (not shown). For high-frequency cables such as coaxial cables and feeder wires.
(Features of in-vehicle antenna 1)
When an induced current that can be regarded as noise from in-vehicle electrical components flows with respect to a conventional in-vehicle antenna in which a monopole antenna element is installed on one side of a GND plate (use frequency band: 700 [MHz]) The current path is shown in FIG.

  In the conventional in-vehicle antenna, as shown in FIG. 3 (a), the induced current flows substantially uniformly from the monopole antenna element side to the opposite end side (right side to left side in FIG. 3 (a)). ing.

On the other hand, in the case of the in-vehicle antenna 1 having the hole 12 in the GND plate 10, the induced current bypasses the hole 12 on the substrate as shown in FIG.
That is, when the GND plate 10 has the hole 12, the path length for the induced current is longer than when the hole 12 is not provided, and no resonance occurs at a frequency of 700 [MHz] band. This reduces the influence of noise.

In this way, by using a simple structure in which the hole 12 is provided in a part of the GND plate 10, the vehicle-mounted antenna 1 can be obtained at low cost and hardly affected by noise.
Moreover, even if the hole 12 is filled with any one of a dielectric material, a non-conductive material, and a magnetic material, the path length is longer than when the hole 12 is not provided. Therefore, resonance can be prevented at the operating frequency, and the influence of noise can be reduced.

  Here, based on FIG. 4, the influence which the position and width | variety of the hole 12 in the GND board 10 have on the noise reduction effect is demonstrated. FIG. 4 is a diagram showing the relationship of the noise reduction amount with respect to the position and width of the hole 12 in the GND plate 10.

First, the relationship between the position of the hole 12 in the GND board 10 and the amount of noise reduction will be described.
4B, the horizontal axis indicates the position of the hole 12 with respect to the short side length (X) of the GND plate 10 (distance S1 from the short side of the GND plate 10 shown in FIG. 4A). This is expressed with reference to the wavelength λ of the used frequency (λ / X).

  As shown in FIG. 4 (b), in the GND plate 10, the hole 12 is away from the short side (length X) closest to the installation position of the monopole antenna element 20 by λ / 16 or more of the operating frequency. When provided, the result that the noise reduction effect became large was obtained.

  Next, the relationship between the width of the hole 12 and the amount of noise reduction will be described. In FIG. 4C, the horizontal axis indicates the ratio of the width of the hole 12 (the long side length of the hole 12) to the short side length of the GND plate 10.

As shown in FIG. 4C, the result that the noise reduction effect is increased when the width of the hole 12 with respect to the short side length of the GND plate 10 is 60% or less is obtained.
[Second Embodiment]
Next, a second embodiment in which the hole 12 is formed at two locations so as to include both long sides of the GND plate 10 will be described with reference to FIG. FIG. 5 is a diagram showing the relationship of the amount of noise reduction with respect to the widths of the two holes 14 and 15 in the GND plate 10.

  In 2nd Embodiment, as shown to Fig.5 (a), the holes 14 and 15 are formed in the inner side from both long sides of the GND board 10. As shown in FIG. That is, the two holes 14 and 15 are formed in a rectangular shape from both long sides, leaving a portion perpendicular to the center of the short side of the GND plate 10.

  The sum of the lengths of the long sides of the two holes 14 and 15 is smaller than 70% of the length of the short side of the GND plate 10 (in other words, the width of the conductive material (FIG. 5 ( a) indicated by “S3” in (a) is left so as to remain 30% or more of the width of the GND plate 10).

  Here, FIG. 4B shows the relationship between the sum of the lengths of the long sides of the two holes 14 and 15 and the amount of noise reduction with respect to the length of the short side of the GND plate 10. As shown in FIG. 4B, when the ratio of the sum of the long side lengths of the two holes 14 and 15 to the short side length of the GND plate 10 is smaller than 70 [%], the noise reduction amount is reduced. growing.

Therefore, if the sum of the lengths of the long sides of the two holes 14 and 15 is made smaller than 70 [%] of the length of the short side of the GND plate 10, the noise reduction effect is increased.
[Third Embodiment]
Next, a third embodiment using a magnetic material instead of the hole 12 will be described with reference to FIG. FIG. 6 is a diagram showing a schematic structure of the in-vehicle antenna 2 using a magnetic material instead of the hole 12.

  The in-vehicle antenna 2 has a magnetic material on a part of the GND plate 10 closer to the center position than the position where the monopole antenna element 20 is arranged in the GND plate 10 instead of the hole 12 of the in-vehicle antenna 1 in the first embodiment. The magnetic part 50 made of a material is arranged.

More specifically, as shown in FIG. 6, magnetic portions 50 and 52 in which a magnetic material is formed in a rectangular shape are arranged along two long sides of the GND plate 10.
Here, the physical property of the magnetic material is represented by the complex permeability μ = μ′−jμ ″. The blocking effect is known as the behavior of the magnetic material to the electromagnetic field.

  The blocking effect (assumed to be S) is expressed by the following formula 1.

  here,

t: thickness of the magnetic material σ: electrical conductivity of the magnetic material r: resistivity of the magnetic material x: length of the magnetic material in the longitudinal direction y: length of the magnetic material in the short direction f: frequency of the used radio wave When μ ′ and μ ″ of the complex magnetic permeability μ = μ′−jμ ″ are analyzed as parameters, the induced current on the substrate can be suppressed only when μ ′ is set. This is because the induced current from the vehicle body of the vehicle 60 to the GND plate 10 is suppressed by the shielding effect of the magnetic material.

  FIG. 7 shows changes in the current distribution depending on the physical properties of the magnetic bodies of the magnetic parts 50 and 52 when the operating frequency is 700 [MHz]. FIG. 7A shows the current distribution when μ ′ = 15 and μ ″ = 0, and FIG. 7B shows the current distribution when μ ′ = 1 and μ ″ = 20. .

Thus, the noise reduction effect can be changed by changing the physical properties of the magnetic parts 50 and 52.
Further, in the GND plate 10 of each of the magnetic parts 50 and 52 arranged at two locations, a right angle to a straight line connecting the end closest to the installation position of the monopole antenna element 20 and the installation position of the monopole antenna element 20. The length in the direction (that is, the length of the short sides of the rectangular magnetic parts 50 and 52) is 15% or more of the length of the GND plate 10 in the same direction.

  Here, FIG. 8 shows the relationship between the length of the short sides of the two magnetic portions 50 and 52 and the amount of noise reduction with respect to the length of the short side of the GND plate 10. As shown in FIG. 8B, the ratio of the short side length of each of the two magnetic parts 50 and 52 to the short side length of the GND plate 10 (indicated by “D1” in FIG. 8A). When the value is smaller than 15%, the amount of noise reduction increases.

Therefore, if the length of the short sides of the two magnetic parts 50 and 52 is smaller than 15 [%] of the short side of the GND plate 10, the noise reduction effect is increased.
Thus, the noise reduction effect with respect to the vehicle-mounted antenna 2 can be obtained even if the magnetic parts 50 and 52 formed of a magnetic material are used instead of the hole 12 in the first embodiment.
[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, A various aspect can be taken.

  For example, in the first to third embodiments, the shape of the GND plate 10 is a rectangle, but it may be a square, a circle, or an ellipse. Further, the shape may be asymmetric so that mounting on the vehicle 60 is facilitated.

  DESCRIPTION OF SYMBOLS 1 ... Car-mounted antenna, 2 ... Car-mounted antenna, 7 ... Case, 10 ... GND board, 12, 14, 15 ... Hole part, 20 ... Monopole antenna element, 30 ... Feeding part, 40 ... Cable, 50, 52 ... Magnetic part 60 ... Vehicle.

Claims (8)

A conductive GND plate formed in a plate shape;
A monopole antenna element installed on one side of the GND plate at a position eccentric from the center position of the GND substrate;
And a vehicle-mounted antenna that Ru with a,
A resin case covering the in-vehicle antenna;
With
A vehicle-mounted antenna device , wherein a hole is provided in a part of the GND plate on a side closer to a center position than a position where the monopole antenna element is arranged on the GND plate. The in-vehicle antenna device according to claim 1,
The in-vehicle antenna device , wherein the hole is filled with any one of a dielectric material, a non-conductive material, and a magnetic material. In the vehicle-mounted antenna device according to claim 1 or 2,
The in-vehicle antenna device according to claim 1, wherein the hole is provided in the GND plate at a distance of λ / 16 or more of a use frequency from an end closest to the installation position of the monopole antenna element. In the vehicle-mounted antenna device according to any one of claims 1 to 3,
The hole is
Does not include the end of the GND plate, and in the GND plate, the width in the direction perpendicular to the straight line connecting the end closest to the installation position of the monopole antenna element and the installation position of the monopole antenna element is An in-vehicle antenna device characterized by being formed so as to be 60% or more of the width of the GND plate at the position of the hole. In the vehicle-mounted antenna device according to any one of claims 1 to 3,
The hole is
The hole portion includes an end portion of the GND plate and is perpendicular to a straight line connecting the end portion closest to the installation position of the monopole antenna element and the installation position of the monopole antenna element in the GND plate. The in-vehicle antenna device is characterized in that the conductive material is left at 30 [%] or more of the width of the GND plate at the position. A conductive GND plate formed in a plate shape;
A monopole antenna element installed on one side of the GND plate at a position eccentric from the center position of the GND substrate;
With
An in-vehicle antenna, wherein a magnetic part made of a magnetic material is arranged at a part of the GND plate at a center position side of the GND plate from a position where the monopole antenna element is arranged. The in-vehicle antenna according to claim 6,
The magnetic part is
The in-vehicle antenna, wherein the GND plate is arranged at two locations parallel to a straight line connecting the end portion closest to the installation position of the monopole antenna element and the installation position of the monopole antenna element. The in-vehicle antenna according to claim 7,
In the GND plate of each of the magnetic parts arranged at the two locations, the length in the direction perpendicular to the straight line connecting the end closest to the installation position of the monopole antenna element and the installation position of the monopole antenna element is the same. A vehicle-mounted antenna characterized by being 15% or more of the length of the GND plate in the direction.