Antenna Device

Abstract

To provide an antenna device capable of achieving a wide angle of radiation directivity without causing an increase in the size of the device and complication of a constitution in association with array formation, by using a single patch antenna.SOLUTION: An antenna device 1 constituted by using a dielectric substrate comprises: a patch antenna 20 that is formed in a predetermined conductor layer; a cavity 12 that is formed in a dielectric layer 11 arranged above the predetermined conductor layer and that assumes such a shape as to surround the patch antenna 20 in a plan view seen from a Z-direction which is a thickness direction of the dielectric substrate; and ground conductors 21, 22 and 23 that are arranged in the state of facing the dielectric layer 11 with the predetermined conductor layer in between in the Z-direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an antenna device configured using a dielectric substrate. [Background technology]

[0002] In mobile communications such as 5G and 6G, radio waves in high frequency bands are transmitted and received in various environments such as inside a building and outdoors, so that an antenna device is required to have a wide-angle radiation directivity capable of transmitting and receiving radio waves in various directions. In order to meet such requirements, a method is known in which an array antenna is configured by arranging a plurality of antenna elements in an array, and an overall wide-angle radiation directivity is realized. For example, Patent Document 1 discloses a technology capable of obtaining a wide-angle radiation directivity in an array antenna in which a plurality of antennas are arranged in an array by giving a phase difference to each antenna and performing beamforming. [Prior art documents] [Patent documents]

[0003] Patent No. 6818757 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent antenna devices, structures using dielectric substrates are widely used from the viewpoint of miniaturization and weight reduction. For example, forming one patch antenna on a dielectric substrate makes it easy to miniaturize the antenna device, but it is difficult to achieve a wide-angle radiation directivity. As mentioned above, in order to achieve a wide-angle radiation directivity of an antenna device, it is necessary to configure an array antenna by arranging multiple antennas such as patch antennas in an array on a dielectric substrate. However, an array antenna using a dielectric substrate requires space for arranging multiple antennas, which increases the size and makes it difficult to miniaturize the antenna device. In addition, it is necessary to form a complex electronic circuit to give multiple antennas a phase difference for beamforming, which increases both the component cost and the mounting cost, and also makes the dimensional tolerance of the dielectric substrate stricter. As described above, when configuring an antenna device using a dielectric substrate by the above-mentioned conventional method, it is difficult to realize a small-sized, low-cost antenna device with a wide-angle radiation directivity.

[0005] The present invention has been made to solve the above-mentioned problems, and realizes an antenna device that, when constructed using a dielectric substrate, allows for the arrangement of only one patch antenna, while maintaining a wide-angle radiation directivity, and allows for the antenna device to be made smaller and less expensive.

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following form: An antenna device constructed using a dielectric substrate, comprising: a first dielectric layer disposed at a lower portion of the dielectric substrate; a second dielectric layer disposed at an upper portion of the dielectric substrate and laminated on the first dielectric layer, the second dielectric layer having a cavity formed at its center penetrating in the first direction in a plan view seen from a first direction which is a thickness direction of the dielectric substrate; a patch antenna formed on a predetermined conductor layer on the surface of the first dielectric layer on which the second dielectric layer is disposed in the first direction and disposed within the cavity in a plan view seen from the first direction; and a ground conductor disposed on the first dielectric layer side of the predetermined conductor layer in the first direction, the height of the cavity in the first direction being set within a range of 0.7λ to 0.8λ with respect to a wavelength λ of a frequency used in the dielectric substrate. The present invention can also be realized in the following form. In order to solve the above problem, the antenna device (1) of the present invention is an antenna device constructed using a dielectric substrate, and includes a patch antenna (20) formed on a predetermined conductor layer of the dielectric substrate, a cavity (12) formed in a dielectric layer (11) arranged above the predetermined conductor layer of the dielectric substrate and having a shape surrounding the patch antenna in a planar view seen from a first direction (Z) which is the thickness direction of the dielectric substrate, and ground conductors (21, 22, 23) arranged opposite the dielectric layer in the first direction, sandwiching the predetermined conductor layer therebetween.

[0007] The antenna device of the present invention is configured such that, in the antenna device using a dielectric substrate, a patch antenna and a ground conductor directly below are formed on a predetermined conductor layer, and a cavity is formed in a dielectric layer laminated above the patch antenna, and the cavity has a shape surrounding the patch antenna in a plan view seen from a first direction. With such a structure, the radio waves radiated from the patch antenna via the power supply structure are expanded in the radiation direction due to the influence of the electromagnetic field distribution on the dielectric surface on the side surface of the upper cavity, and the radiation directivity becomes a wide angle. Therefore, there is no need for an increase in space for arranging multiple antennas in an array, and a complex electronic circuit for phase control during beamforming, and it is easy to achieve a reduction in size and cost of the antenna device.

[0008] In the present invention, the patch antenna and the cavity can have various shapes in plan view from the first direction. For example, a patch antenna and a cavity having a rectangular shape or a circular shape in plan view from the first direction can be adopted. The height of the cavity along the first direction is preferably set within a range of 0.7λ to 0.8λ, where λ is the wavelength of the frequency used in the dielectric substrate. The outer edge of the cavity is preferably set to be larger than the outer edge of the patch antenna by a distance within a range of 0.03λ to 0.07λ in plan view from the first direction.

[0009] In the present invention, the patch antenna and the cavity can be arranged symmetrically with respect to the center of the dielectric substrate in a plan view from a first direction, thereby providing the antenna device with symmetric radiation directivity in each direction from approximately the center of the substrate plane.

[0010] In the present invention, the ground conductor can be formed in a plurality of conductor layers that are connected to each other through a plurality of via conductors extending in a first direction, thereby increasing the area of ​​the ground conductor and strengthening the ground, thereby improving the antenna characteristics.

[0011] In the present invention, the patch antenna can be provided with a feeding structure for feeding either or both of horizontally polarized waves and vertically polarized waves, thereby enabling a single patch antenna to transmit and receive at least horizontally polarized radio waves and vertically polarized radio waves, and allowing them to be used appropriately depending on the usage situation. Effect of the Invention

[0012] According to the present invention, a single patch antenna is placed on a dielectric substrate and a cavity is arranged above it, thereby making it possible to realize an antenna device that is easy to use by widening the angle of radiation directivity while avoiding the increase in size and cost that would accompany arraying the antenna device. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of an antenna device 1 according to the present embodiment, seen obliquely from above. [Diagram 2] 2 is a cross-sectional structural diagram of the antenna device 1 of FIG. 1 taken along the section AA. [Diagram 3] FIG. 2 is a plan view of the antenna device 1 of the present embodiment, seen from above. [Figure 4] 10A and 10B are diagrams illustrating a conductor structure at the bottom of another antenna device 1 of this embodiment. [Diagram 5] 1 is a diagram illustrating a comparison of radiation directivities in the XZ plane for the antenna device 1 of the present embodiment and an antenna device of a comparative example. [Figure 6] 1 is a diagram illustrating a comparison of radiation directivities in the YZ plane for the antenna device 1 of the present embodiment and an antenna device of a comparative example. [Figure 7] 1 is a diagram showing a comparison of reflection characteristics of the antenna device 1 of the present embodiment and an antenna device of a comparative example. [Figure 8] FIG. 1 is a perspective view of an antenna device 1 according to a modified example to which the present invention is applied, viewed obliquely from above. [Figure 9] FIG. 11 is a plan view of the antenna device 1 of this modified example, as viewed from above. [Figure 10]10 is a diagram illustrating a comparison of radiation directivities in the XZ plane for the antenna device 1 of this modified example and an antenna device of a comparative example. [Figure 11] 10 is a diagram illustrating a comparison of radiation directivities in the YZ plane for the antenna device 1 of this modified example and an antenna device of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A preferred embodiment of the present invention will be described below with reference to Figs. 1 to 11. In this embodiment, an antenna device embodying the present invention will be described. However, the embodiment described below is merely one example of an application of the present invention, and the present invention is not limited to the content of this embodiment.

[0015] The structure of an antenna device 1 according to one embodiment of this embodiment will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view of the antenna device 1 as viewed obliquely from above. Fig. 2 is a cross-sectional view of the antenna device 1 taken along the line AA in Fig. 1. Fig. 3 is a plan view of the antenna device 1 as viewed from above. Fig. 4 is a diagram illustrating the conductor structure of the lower part of the antenna device 1. For ease of explanation, the mutually orthogonal X, Y, and Z directions (first directions according to the present invention) are indicated by arrows in Figs. 1 to 4.

[0016] The antenna device 1 of this embodiment is configured using a dielectric substrate made of a dielectric material, and the dielectric substrate has a structure in which a lower dielectric layer 10 and an upper dielectric layer 11 are laminated. A patch antenna 20 is formed at the center of the surface of the lower dielectric layer 10, and a cavity 12 is formed at the center of the upper dielectric layer 11. That is, the hollow portion in which the dielectric material at the center of the dielectric layer 11 is removed in a rectangular shape becomes the cavity 12. In addition, ground conductors 21, 22, and 23 having a three-layer structure are arranged on the lower part of the lower dielectric layer 10 facing the patch antenna 20.

[0017] 2 and 3, in a plan view seen from the Z direction, the upper and lower dielectric layers 10, 11 both have rectangular planar shapes of the same size, the patch antenna 20 has a rectangular planar shape that is sufficiently smaller than the dielectric layer 11, and the cavity 12 has a rectangular planar shape that is slightly larger than the patch antenna 20. In other words, since the cavity 12 is disposed to surround the patch antenna 20 in a planar view, the patch antenna 20 faces the air inside the cavity 12 directly above, resulting in a structure in which the patch antenna 20 is exposed to the outside.

[0018] In FIG. 2, the height Z1 of the lower dielectric layer 10 in the Z direction and the height Z2 of the upper dielectric layer 11 in the Z direction (height Z2 of the cavity 12) are shown. It can be seen that Z2 is set larger than Z1. In addition, in FIG. 3, the length X1 in the X direction and the length Y1 in the Y direction of the upper and lower dielectric layers 10 and 11, and the length X2 in the X direction and the length Y2 in the Y direction of the cavity 12 are respectively shown, and as already mentioned, X1 and Y1 are set larger than X2 and Y2. In addition, the size of the patch antenna 20 is set slightly smaller than X2 and Y2. In FIG. 1 to FIG. 4, the dielectric layers 10 and 11 and the cavity 12 are all square planar shapes, and a case where X1=Y1 and X2=Y2 are set is illustrated.

[0019] In this embodiment, the specific dimensional conditions such as X1, X2, Y1, Y2, Z1, and Z2 described above must be appropriately determined according to the frequency band used, antenna characteristics, and the like. For example, assuming a frequency of 28 GHz, an example of the dimensional conditions is as follows: X1=Y1=7.6 mm, Z1=0.6 mm, and Z2=3.3 mm for the dielectric layers 10 and 11, and X2=Y2=2.35 mm for the cavity 12. The height of the cavity 12 is equal to Z2, and the size of the patch antenna 20 is slightly smaller than X2 and Y2, about 2 mm. In general, the lower the frequency band used, the larger the dimensional parameters must be set, and the higher the frequency band used, the smaller the dimensional parameters must be set.

[0020] Next, the conductor structure of the antenna device 1 will be described with reference to FIG. 4. In FIG. 4, only the area of ​​the lower dielectric layer 10 is shown with the upper dielectric layer 11 removed, and in addition to the patch antenna 20 and ground conductors 21, 22, 23, a plurality of via conductors 30, 31, 32 extending in the lamination direction of the dielectric layer 10 are shown. First, the three-layer ground conductors 21, 22, 23 are arranged in the order of the ground conductor 21, the ground conductor 22, and the ground conductor 23 from the lower layer side. Each of the ground conductors 21, 22, 23 is formed to extend over almost the entire rectangular area of ​​the dielectric layer 10. The three-layer ground conductors 21, 22, 23 are electrically connected to each other via a plurality of via conductors 30. Since the ground conductors 21, 22, 23 having a large area are arranged opposite the patch antenna 20 above, the ground of the antenna device 1 is strengthened, which is effective in improving the antenna characteristics.

[0021] As shown in FIG. 4, two via conductors 31 and 32 functioning as power feed lines are connected to the patch antenna 20. A horizontally polarized high-frequency signal is fed to one of the via conductors 31, and a vertically polarized high-frequency signal is fed to the other via conductor 32. In the patch antenna 20 of FIG. 3, an upper end 31a of the via conductor 31 for horizontal polarization and an upper end 32a of the via conductor 32 for vertical polarization are shown, and are connected at positions shifted horizontally and vertically from the center of the patch antenna 20, respectively. The lower ends of the respective via conductors 31 and 32 are connected to a pair of pads (not shown) on the bottom surface of the dielectric layer 10, and a structure is formed in which power can be fed from the outside to the pair of power feed lines. With such a structure, the antenna device 1 can radiate either or both of a horizontally polarized wave and a vertically polarized wave via the power feed structure.

[0022] When a high-frequency signal is fed from the outside to the antenna device 1 of this embodiment, radio waves are basically emitted upward in the Z direction. In this case, according to a conventional general structure, the area above the patch antenna 20 on the surface of the dielectric layer 10 in the structure shown in FIG. 4 is entirely air, whereas in this embodiment, a cavity 12 exists above the patch antenna 20. In this embodiment, the role of the cavity 12 is to make the radiation directivity of the antenna device 1 wide-angle. Conventionally, it was difficult to achieve a wide-angle radiation directivity by providing only one patch antenna 20. According to the antenna device 1 of this embodiment, it is possible to obtain a wide-angle radiation directivity mainly due to the effect of providing the cavity 12, and the verification results of this point will be described later.

[0023] The following describes the results of verification of the antenna characteristics of the antenna device 1 of this embodiment with reference to Figs. 5 to 7. Here, for comparison with the antenna device 1 of this embodiment, an antenna device having a structure without an upper dielectric layer 10 and a cavity 12 was used as a comparative example to compare the antenna characteristics. This comparative example has a structure as shown in Fig. 4, in which a patch antenna 20 is disposed on the top of the dielectric layer 10. The dimensional parameters of the comparative example are generally the same as those of the corresponding parts of the antenna device 1 of this embodiment.

[0024] Fig. 5 and Fig. 6 are diagrams showing a comparison of radiation directivity between the antenna device 1 of this embodiment and an antenna device of a comparative example. Fig. 5 shows the directivity in the XZ plane, and Fig. 6 shows the directivity in the YZ plane. Both are the results of inputting a signal with a frequency of 28 GHz and verifying the directivity of the radio waves radiated from the patch antenna 20 by simulation. Fig. 5 and Fig. 6 show the radiation directivity of this embodiment (solid line) and the radiation directivity of the comparative example (dashed line) superimposed on each other.

[0025] As shown in Figures 5 and 6, the gain of the radiation directivity reaches a peak when the radiation direction faces upward in the Z direction, and the gain decreases as the radiation direction deviates from the Z direction in the XZ plane and the YZ plane. In this case, if the half-width is calculated as the angle range where the gain is half the value from the peak in Figures 5 and 6, the half-width is about 90° in the comparative example, whereas the half-width exceeds 180° in the present embodiment (solid line), which is more than twice as large as that of the comparative example. Therefore, it was verified from the results of Figures 5 and 6 that the antenna device 1 of this embodiment can obtain a wide angle radiation directivity.

[0026] Moreover, Fig. 7 is a diagram showing a comparison of reflection characteristics of the antenna device 1 of this embodiment and an antenna device of a comparative example. The reflection characteristics are obtained by simulating VSWR (Voltage Standing Wave Ratio), which indicates the relationship between an input signal and a reflected signal according to frequency. In Fig. 7, the VSWR of this embodiment (solid line) and the VSWR of the comparative example (dashed line) are shown overlapping each other.

[0027] As shown in Fig. 7, the reflection characteristic has a minimum VSWR near a frequency of 28 GHz, and the VSWR deteriorates toward the lower and higher frequency sides from there. In this embodiment, the frequency range in which the VSWR is good is relatively wide, whereas in the comparative example, the frequency range in which the VSWR is good is relatively narrow. Specifically, in this embodiment, the frequency range in which the VSWR is 2 or less is more than four times that of the comparative example. Therefore, it was verified from the result in Fig. 7 that the antenna device 1 of this embodiment can obtain good reflection characteristics over a wide frequency range.

[0028] Next, an antenna device 1 according to a modified example to which the present invention is applied will be described with reference to Figs. 8 and 9. In the above embodiment, the antenna device 1 in which the patch antenna 20 and the cavity 12 have a rectangular planar shape when viewed from the Z direction has been described, but the antenna device 1 of this modified example has a patch antenna 20a and a cavity 12a with modified shapes. Fig. 8 is a perspective view of the antenna device 1 of this modified example viewed obliquely from above, and Fig. 9 is a plan view of the antenna device 1 of Fig. 8 viewed from above. Here, Figs. 8 and 9 correspond to Figs. 1 and 3. Figs. 2 and 4 are omitted because they are generally common to this modified example.

[0029] As shown in Figs. 8 and 9, the antenna device 1 of this modification is different from the structures of Figs. 1 and 3 in that the patch antenna 20a and the cavity 12a both have a circular planar shape when viewed from the Z direction. That is, the cavity 12a is formed by removing the central dielectric material in the upper dielectric layer 11 in a circular shape, and the patch antenna 20a is formed in a circular shape in the center of the surface of the lower dielectric layer 10. Note that in Figs. 8 and 9, the upper and lower dielectric layers 10 and 11 both have a rectangular planar shape as in Figs. 1 and 3. Also, as in Fig. 2, the ground conductors 21, 22, and 23 having a three-layer structure are arranged on the lower dielectric layer 10. Similarly, the power supply structure shown in Fig. 4 and the arrangement of the upper end 31a and the lower end 32a (Fig. 9) of each of the via conductors 31 and 32 for horizontal polarization and vertical polarization are also the same as in the above embodiment.

[0030] As shown in Fig. 9, in a plan view seen from the Z direction, the circular cavity 12a is set to a diameter D, and the circular patch antenna 20a is set to a diameter slightly smaller than the diameter D. That is, the cavity 12a is arranged to surround the patch antenna 20a in a plan view, as in the case of Fig. 3. Among the dimensional conditions of this modification, the heights Z1 and Z2 (Fig. 2) of the dielectric layers 10 and 11 in the Z direction, and the lengths X1 and Y1 of the upper and lower dielectric layers 10 and 11 in the X direction and the Y direction, respectively, are the same as those of the above embodiment. The diameter D in Fig. 9, like the other dimensional conditions, needs to be appropriately determined depending on the frequency band to be used, the antenna characteristics, and the like.

[0031] 10 and 11 are diagrams showing radiation directivities similar to those shown in FIGS. 5 and 6 with respect to the antenna device 1 of this modified example. Both diagrams show results obtained by inputting a signal having a frequency of 28 GHz and verifying the directivity of radio waves radiated from the patch antenna 20a by simulation. In FIGS. 10 and 11, the radiation directivities (solid lines) of this modified example are superimposed on the radiation directivities (dashed lines) of FIGS. 5 and 5, respectively, and it has been verified that the radiation directivities in FIGS. 10 and 11 are generally the same as those in FIGS. 5 and 6, and that even when the structure of this modified example is adopted, it is possible to obtain a wide-angle radiation directivity. Although not shown, the reflection characteristics of this modified example also show generally the same results as those in FIG. 7.

[0032] As described above, by adopting the structure of the antenna device 1 to which the present invention is applied, it is possible to realize good antenna characteristics including wide-angle radiation directivity. That is, in a conventional structure in which the patch antenna 20 is arranged on the surface of the dielectric layer 10, the radiation directivity has a relatively narrow angle, whereas in the embodiment including the above-mentioned modified example (hereinafter referred to as the present embodiment), the effect of providing the cavity 12 in the dielectric layer 11 laminated on the upper part of the dielectric layer 10 makes it possible to widen the angle of the radiation directivity. It is assumed that the radio wave radiated upward in the Z direction from the patch antenna 20 generates an electromagnetic field distribution on the dielectric surfaces constituting the four side surfaces of the cavity 12, and when this propagates along the Z direction to the opening at the top of the cavity 12, it spreads in various directions, widening the radiation directivity.

[0033] According to the conventional configuration, in order to realize a wide-angle radiation directivity, it was necessary to configure an array antenna in which multiple antennas are arranged in an array and to control the phase of each antenna by beamforming. In contrast, in the case of the antenna device 1 of this embodiment, a wide-angle radiation directivity can be obtained with only one patch antenna 20 without configuring an array antenna, so that space for arranging multiple antennas is not required and complex electronic circuits for giving phase differences to each antenna are also not required. Therefore, in addition to the above-mentioned superiority in antenna performance, the antenna device 1 of this embodiment is suitable for miniaturizing the antenna device 1 by reducing the dielectric substrate compared to the case of arraying with the conventional configuration, and accordingly, the dimensional tolerance during manufacturing of the dielectric substrate can be relaxed, and the cost can be reduced by reducing the component cost and the mounting cost.

[0034] In this embodiment, when realizing good antenna characteristics including wide-angle radiation directivity, it is important to appropriately set the dimensional parameters as described above. That is, the dimensional parameters of the antenna device 1 are not limited to the structures of Figs. 1 to 4, but are desirably set to match the wavelength λ corresponding to the frequency used in the dielectric substrate. This wavelength λ is a wavelength taking into consideration the wavelength shortening effect in the dielectric substrate. Specifically, the height of the cavity 12 along the Z direction is desirably set to a height Z2 of the upper dielectric layer 11 (height of the cavity 12) within a range of 0.7λ to 0.8λ with respect to the wavelength λ of the frequency used in the dielectric substrate. In addition, it is desirably set the lengths X2 and Y2 of the cavity 12 in the X and Y directions to be larger by a distance within a range of 0.03λ to 0.07λ than the lengths of the rectangle of the patch antenna 20 in the X and Y directions. Such dimensional parameter conditions are desirable settings for ensuring desired antenna characteristics such as wide-angle radiation directivity and good reflection characteristics in the antenna device 1.

[0035] In addition, in this embodiment, as shown in Fig. 3, the patch antenna 20 and the cavity 12 have a rectangular and circular planar shape in plan view from the Z direction, but the planar shape is not limited to a rectangular or circular shape and may be a different planar shape. For example, the present invention can be applied even if the patch antenna 20 and the cavity 12 have a polygonal planar shape other than a rectangle. Even in this case, the effect of the antenna device 1 to which the present invention is applied can be obtained. Furthermore, in this embodiment, the patch antenna 20 and the cavity 12 are symmetrically arranged with respect to the center of the dielectric substrates 10 and 11 in plan view from the Z direction, but the present invention can be applied even if they are asymmetrically arranged with respect to the center.

[0036] Although the contents of the present invention have been specifically described based on the present embodiment, the present invention is not limited to the above embodiment and can be modified without departing from the gist of the present invention. That is, the basic structure of the antenna device 1 described using Figures 1 to 4 can be widely applied to various antenna devices 1 with other structures and shapes as long as the effects of the present invention can be obtained. For example, various changes can be made to the shape, power supply method, size, etc. of the patch antenna 20 as long as the effects of the present invention can be obtained. [Explanation of symbols]

[0037] 1...Antenna device 10, 11...Dielectric layers 12, 12a…Cavity 20, 20a…Patch antenna 21, 22, 23...Ground conductor 33, 31, 32…Via conductor

Claims

1. An antenna device constructed using a dielectric substrate, a first dielectric layer disposed below the dielectric substrate; a second dielectric layer disposed in an upper portion of the dielectric substrate and laminated on the first dielectric layer, the second dielectric layer having a cavity formed in a center thereof penetrating in the first direction in a plan view seen from a first direction which is a thickness direction of the dielectric substrate; a patch antenna formed on a predetermined conductor layer on a surface of the first dielectric layer on which the second dielectric layer is disposed in the first direction and disposed within the cavity in a plan view seen from the first direction; a ground conductor disposed on the first dielectric layer side of the predetermined conductor layer in the first direction; Equipped with An antenna device, characterized in that a height of the cavity in the first direction is set within a range of 0.7λ to 0.8λ, where λ is a wavelength of a frequency used in the dielectric substrate.

2. 2. The antenna device according to claim 1, wherein the patch antenna and the cavity each have a rectangular shape in a plan view seen from the first direction.

3. 2. The antenna device according to claim 1, wherein the patch antenna and the cavity each have a circular shape in a plan view seen from the first direction.

4. The antenna device according to claim 1, characterized in that, in a planar view from the first direction, the outer edge of the cavity is set to be larger than the outer edge of the patch antenna by a distance in the range of 0.03λ to 0.07λ.

5. 2. The antenna device according to claim 1, wherein the patch antenna and the cavity are arranged symmetrically with respect to a center of the dielectric substrate in a plan view seen from the first direction.

6. The antenna device according to claim 1 , wherein the ground conductor is formed in a plurality of conductor layers that are connected to each other through a plurality of via conductors that extend in the first direction.

7. 2. The antenna device according to claim 1, wherein the patch antenna is provided with a feeding structure for feeding either or both of a horizontally polarized wave and a vertically polarized wave.

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