JP2023024146A - antenna device - Google Patents

Abstract

To provide an antenna device for a high frequency with improved manufacturability.SOLUTION: A millimeter-wave band antenna device (100, 110, 120) using 0th-order resonance consists of a ground plane (P2) and a patch unit (P1, P1a, P1b), a power supply unit (20, 50), and a short via 30, and the ground plane is a flat conductor member. The patch unit is a conductor member that is spaced apart from and opposed to the ground plane. The power supply unit is connected to the patch unit and supplies a signal to the patch unit. The short via connects the ground plane and the patch unit. The patch unit is inscribed on all sides of a rectangle having a first side and a second side longer than the first side, and has a shape asymmetrical with respect to a center line (CL) along the diameter of the short-circuit via.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to antenna devices.

The antenna device described in Patent Document 1 includes a ground plane of a conductive member, a square-shaped patch section facing the ground plane, a feeding via that penetrates the ground plane and has a tip connected to the patch section, and is connected to the ground plane and the patch section. and a shorting via.

JP 2020-174285 A

In the above antenna device, the shorter the via-to-via distance between the feed via and the short-circuit via, the higher the frequency of the radiated wave. However, when the via-to-via distance is shorter than a predetermined value, it becomes impossible to form a short-circuited via land. On the other hand, if the via-to-via distance is increased so as to form a short-circuit via land, the antenna device will not resonate in a high frequency band.

The present disclosure provides a high-frequency antenna device with improved manufacturability.

One aspect of the present disclosure is a millimeter-wave band antenna device (100, 110, 120) using 0th-order resonance, comprising: a ground plane (P2); patch sections (P1, P1a, P1b); (20,50) and a shorting via (30). The ground plane is a flat conductor member. The patch portion is a conductor member that is spaced apart from and opposed to the ground plane. The power supply unit is connected to the patch unit and supplies a signal to the patch unit. The short via connects the ground plane and the patch section. The patch portion is inscribed in all sides of a rectangle having a first side and a second side longer than the first side, and is asymmetrical with respect to a center line (CL) along the diameter of the short-circuit via. have a shape.

In the antenna device according to one aspect of the present disclosure, the patch portion has a non-symmetrical shape with respect to the centerline along the diameter of the short-circuit via. Also, the area of the patch portion can be reduced. As a result, the capacitance between the patch portion and the ground plane can be reduced while increasing the distance between vias. Therefore, even if the via-to-via distance between the power supply portion and the short-circuit via is increased, the resonance frequency can be increased. Therefore, it is possible to realize a high-frequency antenna device with improved manufacturability. Furthermore, the directivity of the radiated wave can be controlled by utilizing the fact that the patch portion has an asymmetrical shape so that the distribution of the electric field becomes asymmetrical with respect to the center line.

It is a figure which shows the outline of the external appearance of the antenna device which concerns on 1st Embodiment. FIG. 2 is a cross-sectional view of the antenna device shown in FIG. 1 taken along line II-II; FIG. 3 is a plan view showing the arrangement of patch portions, feeding vias, and short-circuit vias of the antenna device according to the first embodiment; It is a figure which shows the gain of the antenna device which concerns on 1st Embodiment. FIG. 3 is a cross-sectional view of an antenna device according to a reference example; It is a figure which shows the back surface of the antenna device which concerns on a reference example. It is a figure which shows the gain of the antenna apparatus which concerns on a reference example. It is a graph which shows the voltage standing wave ratio with respect to the frequency of the antenna device which concerns on a reference example. 5 is a graph showing average radiated power with respect to the vertical length of the patch portion according to the first embodiment; 4 is a graph showing average radiated power with respect to the lateral length of the patch portion according to the first embodiment; 5 is a graph showing average radiated power with respect to via diameter of the feeding via according to the first embodiment; 5 is a graph showing average radiated power with respect to via diameter of short-circuited vias according to the first embodiment; It is a figure which shows another example of the patch part which concerns on 1st Embodiment. It is a figure which shows another another example of the patch part which concerns on 1st Embodiment. It is a sectional view of the antenna device concerning a 2nd embodiment. It is a sectional view of the antenna device concerning a 3rd embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
(1. First embodiment)
<1-1. Configuration>
An antenna device 100 according to this embodiment will be described with reference to the drawings. The antenna device 100 is mounted on a mobile object such as a vehicle. The antenna device 100 transmits and/or receives radio waves. The antenna device 100 is a high-frequency antenna device that utilizes 0th-order resonance. Antenna device 100 is connected to a wireless device, for example, via a coaxial cable. In this embodiment, the antenna device 100 is a millimeter-wave band antenna device having an operating frequency of 79 GHz.

The antenna device 100 converts a high-frequency electrical signal supplied from a wireless device into radio waves and radiates them into space. Further, the antenna device 100 converts the received radio wave into an electric signal and outputs the electric signal to the wireless device.

As shown in FIGS. 1 and 2, the antenna device 100 includes a patch portion P1, a ground plane P2, a support plate L1, feed vias 20, and short-circuit vias 30. FIG.
The patch portion P1 is a conductor such as copper configured in a plate shape. The patch portion P1 has an asymmetrical shape with respect to a center line CL, which will be described later. Details of the shape of the patch portion P1 will be described later. The patch portion P1 may be a thin member such as foil. That is, the patch portion P1 may be a conductor pattern formed on the surface of a resin plate such as a printed wiring board.

The ground plane P2 is a flat conductor such as copper. Ground plane P2 forms a ground potential in antenna device 100 . Note that the base plate P2 may be a thin member such as foil. That is, the ground plane P2 may be a conductive pattern formed on the surface of a resin plate such as a printed wiring board.

The support plate L1 is an insulating material such as glass epoxy resin. The patch portion P1 is spaced apart from the base plate P2 via the support plate L1 so as to face the base plate P2. The patch portion P1 is arranged on the front surface of the support plate L1, and the base plate P2 is arranged on the rear surface of the support plate L1.

The support plate L1 has a rectangular flat plate shape and has substantially the same size as the base plate P2. The ground plane P2 has a size equal to or larger than that of the patch portion P1. The shape of the support plate L1 is not limited to a plate shape. The support plate L1 may be a plurality of pillars that support the patch portion P1 so as to separate it from the base plate P2 so as to face the base plate P2. Moreover, the space between the patch portion P1 and the base plate P2 is not limited to the structure filled with resin (that is, the support plate L1), and may be a hollow structure or a vacuum structure. Also, the space between the patch portion P1 and the ground plane P2 may be filled with a dielectric material having a predetermined dielectric ratio. Furthermore, the structure between the patch portion P1 and the ground plane P2 may be a combination of these structures.

When the antenna device 100 is configured by a printed wiring board, a plurality of conductor layers included in the printed wiring board may be used as the base plate P2 and the patch portion P1, and a resin layer separating the conductor layers may be used as the support plate L1.

The feed via 20 is a cylindrical member plated with a conductive material such as copper and has a via diameter φa. The feed via 20 passes through the ground plate P2 and the support plate L1 and connects to the patch portion P1. The feed via 20 has an axis perpendicular to the patch portion P1 and the ground plane P2. The feed via 20 has a first land 21 and a second land 22 . The first land 21 is provided at the upper end of the power supply via 20, contacts the patch portion P1, and is electrically connected to the patch portion P1. The second land 22 is provided at the lower end of the feed via 20 . The first land 21 and the second land 22 extend radially from the outer edge of the cylindrical main body. In this embodiment, the outer diameter of the second land 22 is larger than the outer diameter of the first land 21 .

A coaxial cable for feeding power to the patch portion P1 is connected to the second land 22, and a high-frequency signal is fed from the feeding point 23 of the second land 22 to the patch portion P1. Here, the ground plane P2 forms a ground potential. Therefore, a hole for accommodating the second land 22 and its periphery is formed in the ground plane P2 so that the second land 22 and the ground plane P2 are not electrically connected. Therefore, a gap is formed between the ground plane P<b>2 and the second land 22 , and the ground plane P<b>2 is not electrically connected to the second land 22 .

The short-circuit via 30 is a cylindrical member plated with a conductive material such as copper and has a via diameter φb. The short-circuit via 30 passes through the support plate L1 and connects the patch portion P1 and the ground plane P2. The short via 30 has an axis perpendicular to the patch portion P1 and the ground plane P2. The short via 30 has two lands 31 . Two lands 31 are provided at the top and bottom ends of the short via 30 . The land 31 at the upper end contacts the patch portion P1 and conducts with the patch portion P1, and the land 31 at the lower end contacts the ground plane P2 and conducts with the ground plane P2.

The feed via 20 is spaced apart from the short via 30 so that the first land 21 and the second land 22 do not interfere with the two lands 31 .
Next, the shape of the patch portion P1 will be described with reference to FIG. Two directions perpendicular to each other on the plane shown in FIG. 3 are defined as a first direction and a second direction. The feed via 20 and the short via 30 are arranged side by side along the second direction. In the second direction, the side on which the feed via 20 is arranged is the left side, and the side on which the short via 30 is arranged is the right side.

The patch portion P<b>1 has a non-symmetrical shape with respect to the center line CL, and covers the first land 21 and the land 31 . The center line CL is a line along the diameter of the short via 30, more specifically, a line passing through the center of the short via 30 and along the first direction.

The patch portion P1 includes a trapezoidal portion P11, a rectangular portion P12, and a semicircular portion P13. A semicircular portion P13 is arranged on the left side, and a rectangular portion P12 is arranged on the right side. The trapezoidal portion P11 is arranged between the semicircular portion P13 and the rectangular portion P12.

The semicircular portion P13 is formed in a semicircular shape, has approximately the same area as half of the first land 21, and covers the left half of the first land 21. As shown in FIG. The trapezoidal portion P11 is configured in a trapezoidal shape and has parallel short sides and long sides along the first direction. The short sides of the trapezoidal portion P11 are connected to the straight portions of the semicircular portion P13, and the long sides of the trapezoidal portion P11 are connected to the square portion P12. The trapezoidal portion P<b>11 covers the right half of the first land 21 . The square portion P<b>12 has a square shape and covers the land 31 .

The patch portion P1 is inscribed on all sides of a rectangle having a first side of length Da and a second side of length Db. Also, Da<Db. That is, the length of the side of the square portion P12 in the first direction is Da. Also, in the second direction, the length from the end of the semicircular portion P13 to the end of the square portion P12 is Db.

<1-2. Operation>
The short-circuit via 30 provides an inductance L corresponding to the length of the short-circuit via 30 and the via diameter φb. Also, the patch portion P1 provides a capacitance C. As shown in FIG. Since the high-frequency signal supplied to the patch portion P1 mainly flows on the side surface of the short-circuit via 30 and hardly flows inside the short-circuit via 30, there is a high-frequency signal between the outer portion of the short-circuit via 30 and the ground plane P2 in the patch portion P1. contributes to the formation of capacitance C. The length of the short-circuit via 30 and the diameter φb of the via are adjusted so that the inductance L and the capacitance C are parallel-resonated.

In the antenna device 100, a zero-order parallel resonance circuit is formed in which the capacitance C, the inductance L, and the feeding point 23 are connected in parallel. The operating frequency of the antenna device 100 is determined by the frequency at which this parallel resonance circuit resonates.

The area of the patch portion P1 on the left side of the center line CL is larger than the area on the right side of the center line CL. Therefore, the distribution of the current supplied to the patch portion P1 is biased to the left, and the electric field vector of the radiation wave emitted from the patch portion P1 is biased to the left. Therefore, as shown in FIG. 4, the antenna device 100 has directivity in the left direction, and the power in the left direction is 9 dB larger than the power in the right direction. Also, the maximum gain of the antenna device 100 is 3.4 dBi.

Antenna device 100 is mounted on a mobile object so that the traveling direction of the mobile object and the direction of directivity match. For example, when the moving body is a vehicle, the antenna device 100 is mounted on the vehicle so that the forward direction of the vehicle and the direction of directivity match.

Here, the capacitance C increases as the area of the patch portion P1 increases. As the capacitance C increases, the resonance frequency of the zero-order parallel resonance circuit formed in the antenna device 100 decreases. Therefore, in order to increase the operating frequency, it is necessary to reduce the area of the patch portion P1.

FIG. 5 shows an antenna device 400 according to a reference example. The antenna device 400 includes a patch portion P100, a ground plane P200, a support plate L11, a feed via 200, and a short via 300. The patch part P100 is configured in a square shape.

Here, if the inter-via distance between the power supply via 200 and the short-circuit via 300 is reduced in order to reduce the area of the patch portion P100, the land cannot be provided. That is, as shown in FIG. 6, when the via-to-via distance is reduced, the land 210 of the feed via 200 and the land 310 of the short-circuit via 300 interfere with each other.

Therefore, in the antenna device 400, the distance between the feed via 200 and the short-circuit via 300 is made large enough to provide a land. Since the patch portion P100 is formed in a square shape, if the via interval is increased, the area of the patch portion P100 increases and the capacitance C increases. As a result, as shown in FIG. 8, 0th-order resonance does not occur at 79 GHz, but 0th-order resonance occurs at 67 GHz. As a result, as shown in FIG. 7, the antenna device 400 has a maximum gain of -1.1 dBi at 79 GHz.

On the other hand, in the patch portion P1 of the antenna device 100, the trapezoidal portion P11 is arranged between the feed via 20 and the short-circuit via 30 to increase the inter-via distance and reduce the overall area of the patch portion P1. are doing. As a result, the capacitance C is reduced and the resonance frequency is increased. Thereby, the maximum gain of the antenna device 100 at 79 GHz is 12 dBi larger than the maximum gain of the antenna device 400 .

<1-3. Design>
Next, the dimensions of the patch portion P1 (specifically, the length of the first side Da and the length of the second side Db) that enable zero-order resonance that maximizes the radiation efficiency of the antenna device 100, and the power supply The via diameter φa of the via 20 and the via diameter φb of the short via 30 will be described with reference to FIGS.

FIG. 9 shows a graph of the average power of radiated radio waves versus the length of the first side Da/λe. λe is the effective wavelength obtained by dividing the wavelength λ by the square root of the effective dielectric constant. From the graph, the length Da is preferably in the range of 0.4λe<Da<0.6λe. However, there is a restriction of 0.9 mm<Da<0.583 λe depending on the wavelength λ. Therefore, the design value of the length Da is 0.458λe (that is, 1.1 mm).

FIG. 10 shows a graph of the average power of radiated radio waves with respect to the length Db/λe of the second side. From the graph, the length Db is desirably in the range of 0.5λe<Da<0.9λe. However, there is a restriction of 0.625λe<Db depending on the wavelength λ. Therefore, the design value of the length Db is 0.688λe (that is, 1.65 mm).

FIG. 11 shows a graph of the average power of radiated radio waves with respect to the via diameter φa. From the graph, it is desirable that the via diameter φa is in the range of 0.05λe<Da<0.3λe. However, there is a restriction of φa<0.208λe depending on the wavelength λ. Therefore, the design value of the via diameter φa is 0.125λe (that is, 0.3 mm).

FIG. 12 shows a graph of the average power of radiated radio waves with respect to the via diameter φb. From the graph, it is desirable that the via diameter φb is in the range of 0.2λe<Da<0.4λe. However, there is a restriction of φa<0.375λe depending on the wavelength λ. Therefore, the design value of the via diameter φb is 0.25λe (that is, 0.6 mm).

<1-4. Example>
The antenna device 100 may include a patch section P1a shown in FIG. 13 instead of the patch section P1. The patch portion P1a has a polygonal shape and is inscribed in all sides of a rectangle having a first side of length Da and a second side of length Db. Also, the antenna device 100 may include a patch section P1b shown in FIG. 14 instead of the patch section P1. The patch portion P1b has an elliptical shape and is inscribed in all sides of a rectangle having a first side of length Da and a second side of length Db. That is, the antenna device 100 may include a patch section having a shape inscribed in all sides of a rectangle having a first side of length Da and a second side of length Db.

<1-4. Effect>
According to 1st Embodiment detailed above, there exist the following effects.
(1) The area of the patch portion P1 can be reduced compared to the case where the patch portion P1 has an asymmetric shape with respect to the center line CL, compared with a case where the patch portion P1 has a line symmetric shape with respect to the center line CL. As a result, the capacitance between the patch portion P1 and the ground plane P2 can be reduced while increasing the via-to-via distance. Therefore, even if the via-to-via distance between the feed via 20 and the short-circuit via 30 is increased, the resonance frequency can be increased. Therefore, the high-frequency antenna device 100 with improved manufacturability
can be realized.

(2) Directivity of radiated waves can be controlled by utilizing the fact that the distribution of the electric field vector becomes asymmetrical with respect to the center line CL due to the asymmetrical shape of the patch portion P1. .
(3) The diameter φa of the feed via 20, the diameter φb of the short-circuit via 30, and the effective wavelength λe satisfy the conditions of 0.05λe<φa<0.3λe and 0.2λe<φb<0.4λe. It is possible to realize the 0th-order resonance that maximizes the radiation efficiency while improving the efficiency.

(4) The length Da, the length Db, and the effective wavelength λe satisfy the conditions of 0.4λe<a<0.6λe and 0.5λe<b<0.9λe, thereby improving the manufacturability and radiation. A zero-order resonance that maximizes efficiency can be realized.

(5) Manufacturability can be further improved by making the patch portion P1 connected to the power supply via 20 trapezoidal as the shape of the patch portion P1 that reduces the capacitance C while increasing the inter-via distance.
(6) By orienting the directivity of the radiated waves in the traveling direction of the moving body, it is possible to improve the detection performance of an object existing in front of the moving body.

(2. Second embodiment)
<2-1. Difference from First Embodiment>
Since the basic configuration of the second embodiment is the same as that of the first embodiment, differences will be described below. Note that the same reference numerals as in the first embodiment indicate the same configurations, and refer to the preceding description.

In the first embodiment described above, the antenna device 100 includes the feeding via 20 . On the other hand, as shown in FIG. 15, the second embodiment differs from the first embodiment in that the antenna device 110 includes a coaxial core wire 50 instead of the feeding via 20 .

The coaxial core wire 50 passes through the base plate P2 and the support plate L1 and is connected to the patch portion P1. A coaxial ground 40 forming a coaxial line together with the coaxial core wire 50 is electrically connected to the ground plane P2. In the second embodiment, a high frequency signal is supplied to patch section P1 via coaxial core wire 50 .

<2-2. Effect>
According to the second embodiment described in detail above, the same effects as the effects (1) to (6) of the first embodiment described above are obtained.

(2. Third Embodiment)
<3-1. Difference from First Embodiment>
Since the basic configuration of the third embodiment is the same as that of the first embodiment, differences will be described below. Note that the same reference numerals as in the first embodiment indicate the same configurations, and refer to the preceding description.

In the first embodiment described above, the antenna device 100 includes the feeding via 20 . On the other hand, as shown in FIG. 16, the third embodiment is different from the first embodiment in that the antenna device 120 is not equipped with anything.

That is, in the third embodiment, a high frequency signal is supplied to the patch section P1 by capacitive coupling between the patch section P1 and the ground plane P2.
<3-2. Effect>
According to the third embodiment described in detail above, the same effects as the effects (1) to (6) of the first embodiment described above are obtained.

(3. Other Embodiments)
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be made.

(a) A plurality of functions possessed by one component in the above embodiment may be realized by a plurality of components, or a function possessed by one component may be realized by a plurality of components. . Also, a plurality of functions possessed by a plurality of components may be realized by a single component, or a function realized by a plurality of components may be realized by a single component. Also, part of the configuration of the above embodiment may be omitted. Moreover, at least part of the configuration of the above embodiment may be added or replaced with respect to the configuration of the other above embodiment.

20 Feeding via 23 Feeding point 30 Shorting via 40 Coaxial ground 50 Coaxial core 100, 110, 120 Antenna device CL Center line P1, P1a, P1b, Patch part P2 ... main plate, P11 ... trapezoidal part, P12 ... rectangular part, P13 ... semicircular part.

Claims (7)

A millimeter-wave band antenna device (100, 110, 120) using zero-order resonance,
a base plate (P2), which is a flat conductor member;
a patch portion (P1, P1a, P1b), which is a conductor member installed so as to be spaced from the ground plane and opposed to the ground plane;
a power supply unit (20, 50) connected to the patch unit and supplying a signal to the patch unit;
a short-circuit via (30) connecting the ground plane and the patch section,
The patch portion is inscribed in all sides of a rectangle having a first side and a second side longer than the first side, and is non-linear with respect to a center line (CL) along the diameter of the short-circuit via. having a symmetrical shape,
antenna device. The power supply portion (20) includes a power supply via penetrating the ground plane and connected to the patch portion,
The antenna device according to claim 1. The power supply portion (50) includes a coaxial core wire that penetrates the ground plane and is connected to the patch portion,
The antenna device according to claim 1. The diameter φa of the feed via, the diameter φb of the short-circuit via, and the effective wavelength λe of the high-frequency signal fed to the patch section through the feed via are
0.05λe<φa<0.3λe
0.2λe<φb<0.4λe
satisfies the conditions of
The antenna device according to claim 2. The first side length Da, the second side length Db, and the effective wavelength λe are
0.4λe<Da<0.6λe
0.5λe<Db<0.9λe
satisfies the conditions of
The antenna device according to claim 4. The patch part (P1) includes a trapezoidal part (P11) having a trapezoidal shape,
The trapezoidal portion has two sides parallel to the first side,
wherein the power feeding section is connected to the trapezoidal section;
The antenna device according to any one of claims 1-5. The antenna device is mounted on a mobile body,
Radiated waves emitted from the antenna device have directivity in a traveling direction of the moving object,
The antenna device according to any one of claims 1-6.

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