Antenna device

Abstract

To provide an antenna device that can achieve wide-angle radiation directivity by using a single patch antenna, without increasing the size of the device or complicating the configuration that would accompany an array.SOLUTION: An antenna device 1 constructed using a dielectric substrate includes a patch antenna 20 formed on a specified conductor layer, a cavity 12 formed in a dielectric layer 11 arranged on the specified conductor layer and having a shape surrounding the patch antenna 20 in a planar view seen from the Z direction, which is the thickness direction of the dielectric substrate, and ground conductors 21, 22, and 23 arranged opposite the dielectric layer 11 in the Z direction, sandwiching the specified conductor layer therebetween.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Mobile communications such as 5G and 6G require high-frequency signals in various environments, such as inside buildings and outdoors. In order to transmit and receive radio waves in the frequency band, the antenna device is provided with a device that can transmit and receive radio waves in various directions. It is required to have a wide angle of radiation directivity. An array antenna is formed by arranging several antenna elements in an array, and the overall radiation angle is wide. For example, Patent Document 1 discloses a method for realizing directivity by using an array of multiple antennas. In an array antenna arranged in a pattern, beamforming is performed by giving each antenna a phase difference. This technique makes it possible to obtain wide-angle radiation directivity. [Prior art documents] [Patent documents]

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

[0004] In recent years, antenna devices have been widely constructed using dielectric substrates in order to reduce size and weight. For example, if one patch antenna is formed on a dielectric substrate, it becomes an antenna device. It is easy to miniaturize the antenna, but it is difficult to achieve a wide radiation angle. In order to achieve a wide-angle radiation directivity of the antenna device, multiple patch antennas are placed on the dielectric substrate. It is necessary to configure an array antenna by arranging antennas such as antennas in an array. However, array antennas using dielectric substrates require space for arranging multiple antennas. This requires a large space, which increases the size and makes it difficult to miniaturize the antenna device. It is necessary to create a complex electronic circuit that gives the antenna a phase difference for beamforming. This increases both component and mounting costs, and also increases the cost of manufacturing the dielectric substrate. Dimensional tolerances also become stricter. As described above, when an antenna device using a dielectric substrate is constructed by the above-mentioned conventional method, However, it has been difficult to achieve wide-angle radiation directivity in a small size and at low cost.

[0005] The present invention has been made to solve the above problems, and is directed to an antenna using a dielectric substrate. When configuring a tuner device, only one patch antenna is placed to maintain a wide angle of radiation directivity. The present invention aims to realize an antenna device that can be made smaller and less expensive while maintaining the same performance. .

[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 arranged at a lower part of the dielectric substrate; a second dielectric layer arranged at an upper part of the dielectric substrate and laminated on the first dielectric layer, the second dielectric layer having a cavity formed at its center in a plan view seen from a first direction that 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 arranged in the first direction and that is arranged within the cavity in the plan view seen from the first direction; and a ground conductor arranged on the first dielectric layer side of the predetermined conductor layer in the first direction, wherein the patch antenna is exposed to the outside through the cavity, and an area of ​​the ground conductor is larger than an area of ​​the patch antenna in the plan view seen from the first direction.In a plan view seen from the first direction, the outer edge of the cavity is set to be larger than the wavelength λ of the frequency used in the dielectric substrate by a distance in the range of 0.03λ to 0.07λ from the outer edge of the patch antenna. The present invention can also be realized in the following forms: In order to solve the above problems, the antenna device (1) of the present invention is an antenna device configured using a dielectric substrate, and includes: a patch antenna (20) formed on a predetermined conductor layer of the dielectric substrate; a cavity (12) formed on a dielectric layer (11) arranged above the predetermined conductor layer of the dielectric substrate, the cavity having a shape surrounding the patch antenna in a plan view seen from a first direction (Z) that is the thickness direction of the dielectric substrate; and ground conductors (21, 22, 23) arranged opposite the dielectric layer in the first direction with the predetermined conductor layer sandwiched therebetween.

[0007] The antenna device of the present invention uses a dielectric substrate, and a pad of a predetermined conductor layer is provided. The patch antenna and the ground conductor directly below it are formed, and the layered structure is A cavity is formed in the dielectric layer, and the cavity has a shape similar to that of a dielectric layer in a plan view seen from a first direction. The antenna is configured to have a shape that surrounds the patch antenna. The radio waves radiated from the patch antenna are reflected by the electromagnetic waves on the dielectric surface of the side of the upper cavity. The radiation direction is expanded by the influence of the field distribution, and the radiation directivity becomes wider angle. The space required for arranging the beams in an array is increased, and the number of beams required for phase control during beamforming is also increased. This eliminates the need for complex electronic circuits, making it easier to reduce the size and cost of the antenna device. can.

[0008] In the present invention, the patch antenna and the cavity are each a plane viewed from a first direction. For example, the shape of the rectangular shape in a plan view from the first direction can be and patch antennas and cavities having a circular shape. The height of the cavity in the first direction can be determined by the dielectric The wavelength λ of the frequency used on the substrate must be set within the range of 0.7λ to 0.8λ. In addition, in a plan view seen from the first direction, the outer edge of the cavity is preferably It is desirable to set the distance from the outer edge of the nozzle to be larger by a distance in the range of 0.03λ to 0.07λ. I wish.

[0009] In the present invention, the patch antenna and the cavity are inductively coupled in a plan view from a first direction. The antenna device can be arranged symmetrically with respect to the center of the electric circuit board. It is possible to obtain symmetric radiation directivity in each direction from approximately the center of the substrate plane.

[0010] In the present invention, the ground conductors are interconnected through a plurality of via conductors extending in a first direction. This allows the area of ​​the ground conductor to be reduced by forming it on multiple conductor layers connected to the By expanding it, the ground can be strengthened and the antenna characteristics can be improved.

[0011] In the present invention, the patch antenna is fed with one or both of horizontally polarized waves and vertically polarized waves. This allows for a single patch antenna to be fed with fewer power supplies. Both the horizontally polarized and vertically polarized radio waves can be transmitted and received, and each can be switched depending on the usage situation. They can be used appropriately depending on the situation. [Effects of the Invention]

[0012] According to the present invention, a single patch antenna is arranged on a dielectric substrate, and a cavity is formed above the single patch antenna. This arrangement avoids the increase in size and cost that would accompany the formation of an antenna device array. Furthermore, the wide angle of radiation directivity makes it possible to realize an antenna device that is easy to use. [Brief explanation of the drawings]

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

[0014] A preferred embodiment of the present invention will now be described with reference to FIGS. In the embodiments, an antenna device embodying the present invention will be described. The embodiment is merely an example of the application of the present invention, and the present invention is not limited by the content of this embodiment. It is never determined.

[0015] The structure of an antenna device 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a perspective view of the antenna device 1 as seen from diagonally above. FIG. 2 is a perspective view of the antenna device 1 as seen from diagonally above. 3 is a cross-sectional view of the antenna device 1 taken along the line AA. 4 is a plan view illustrating the conductor structure of the lower part of the antenna device 1. 1 to 4, for convenience of explanation, the X direction, Y direction, and Z direction (the direction of the present invention) are perpendicular to each other. The directions of the arrows are shown in Fig. 1.

[0016] The antenna device 1 of this embodiment is configured using a dielectric substrate made of a dielectric material. The electric board 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 dielectric layer 10, and a A cavity 12 is formed in the dielectric layer 11. The hollow portion where the material is removed in a rectangular shape is the cavity 12. The layer 10 has three-layered ground conductors 21 and 22 at the bottom facing the patch antenna 20. 23 is placed.

[0017] As shown in FIGS. 2 and 3, in plan view from the Z direction, the upper and lower dielectric layers 10 and 11 are All of them have rectangular planar shapes of the same size, and the patch antenna 20 is sufficiently larger than the dielectric layer 11. The cavity 12 has a rectangular planar shape that is very small in size, and is slightly smaller than the patch antenna 20. In other words, the cavity 12 has a large rectangular planar shape in a plan view. The patch antenna 20 is arranged to surround the cavity 12 directly above it. The antenna 20 faces the air outside, and 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 are The height Z2 in the direction (height Z2 of the cavity 12) is shown. Z2 is larger than Z1. 3, the X of the upper and lower dielectric layers 10 and 11 is set to The length X1 in the X direction and the length Y1 in the Y direction of the cavity 12, and the length X2 in the X direction and the length Y1 in the Y direction of the cavity 12 As already mentioned, X1 and Y1 are set larger than X2 and Y2. The size of the patch antenna 20 is set to be slightly smaller than X2 and Y2. 1 to 4, the dielectric layers 10 and 11 and the cavity 12 are set to Both are square planar shapes, and the case where X1=Y1 and X2=Y2 is set is shown as an example. There are.

[0019] In this embodiment, the specific dimensions such as X1, X2, Y1, Y2, Z1, and Z2 mentioned above The conditions must be determined appropriately depending on the frequency band used, antenna characteristics, etc. For example, Assuming a frequency of 28 GHz, an example of setting the dimensional conditions is as follows: Regarding 1, X1=Y1=7.6mm, Z1=0.6mm, Z2=3.3mm, and the cavity Regarding the cavity 12, X2 = Y2 = 2.35 mm can be given. The height of the patch antenna 20 is equal to Z2, and the size of the patch antenna 20 is slightly smaller than X2 and Y2 by 2 mm. Generally, the lower the frequency band used, the larger the dimension parameters must be set. The higher the frequency band used, the smaller the dimension parameters must be set.

[0020] Next, the conductor structure of the antenna device 1 will be described with reference to FIG. The lower dielectric layer 10 is shown with the upper dielectric layer 11 removed, and the patch In addition to the tenon 20 and ground conductors 21, 22, and 23, the dielectric layer 10 extends in the stacking direction. The figure shows a plurality of via conductors 30, 31, and 32. First, the three-layer ground conductors 21, 22, 23, the ground conductor 21, the ground conductor 22, and the ground conductor 23 are arranged in this order from the bottom. Each of the ground conductors 21, 22, and 23 covers almost the entire rectangular area of ​​the dielectric layer 10. The three-layer ground conductors 21, 22, and 23 are connected to each other by a plurality of vias. The large-area ground conductor 21 is electrically connected to the ground conductor 30. , 22, 23 and the upper patch antenna 20 are arranged opposite to each other, This strengthens the ground and is effective in improving the antenna characteristics.

[0021] As shown in FIG. 4, the patch antenna 20 has two beams that function as feed lines. The via conductors 31 and 32 are connected to each other. A horizontally polarized high frequency signal is supplied to one of the via conductors 31. The other via conductor 32 is fed with a vertically polarized high frequency signal. The antenna 20 has an upper end 31a of a via conductor 31 for horizontal polarization and an upper end 31b of a via conductor 32 for vertical polarization. The upper end 32a is shown, and the upper end 32b is shown extending horizontally and vertically from the center of the patch antenna 20. The lower ends of the via conductors 31 and 32 are connected to the dielectric layer 1. The power supply is connected to a pair of pads (not shown) on the bottom surface of the power supply. With this structure, the antenna device 1 receives horizontally polarized waves via the feeding structure. It is possible to radiate either vertically polarized waves or both vertically polarized waves.

[0022] When a high frequency signal is supplied from the outside to the antenna device 1 of this embodiment, the In this case, with a conventional general structure, as shown in Figure 4, In this structure, the area above the patch antenna 20 on the surface of the dielectric layer 10 is entirely air. This embodiment differs in that a cavity 12 exists above the patch antenna 20. In the embodiment, the role of the cavity 12 is to widen the radiation directivity of the antenna device 1. Conventionally, a single patch antenna 20 alone cannot provide a wide-angle radiation directivity. According to the antenna device 1 of this embodiment, the cavity 1 The effect of providing 2 is to obtain a wide angle of radiation directivity, but verification of this point is needed. The results will be discussed later.

[0023] The antenna characteristics of the antenna device 1 of this embodiment will be verified below with reference to FIGS. 5 to 7. The results are explained below. Here, for comparison with the antenna device 1 of this embodiment, As a comparative example, an antenna device having a structure without the dielectric layer 10 and the cavity 12 is shown. The comparative example has the structure shown in Figure 4, and the patch antenna characteristics were compared. The nozzle 20 is disposed on the top of the dielectric layer 10. The dimensional parameters of the comparative example are the same as those of the present embodiment. The parts are generally the same as those of the antenna device 1 of the embodiment.

[0024] 5 and 6 show the radiation characteristics of the antenna device 1 of this embodiment and the antenna device of the comparative example. Fig. 5 shows the directivity in the XZ plane, and Fig. 6 shows the directivity in the YZ plane. In both cases, a signal with a frequency of 28 GHz is input, and the signal is transmitted from the patch antenna 20. The results of simulations verifying the directivity of the radiated radio waves are shown in Figures 5 and 6. 1 shows the radiation directivity of this embodiment (solid line) and the radiation directivity of the comparative example (dashed line) superimposed on each other. do.

[0025] As shown in Figures 5 and 6, the radiation directivity is such that the gain peaks when the radiation direction is directed upward in the Z direction. The gain decreases as the radiation direction deviates from the Z direction in the XZ and YZ planes. At this time, in Figures 5 and 6, the range of angles where the gain is half the peak value is When the half-width is calculated as the half-width, the half-width is about 90° in the comparative example, In the case of this embodiment (solid line), the half-width exceeds 180°, which is more than twice that of the comparative example. Therefore, from the results of FIGS. 5 and 6, it can be seen that the antenna device 1 of this embodiment has a wide angle. It was verified that a radiation directivity of 100° could be achieved.

[0026] FIG. 7 shows the reflection characteristics of the antenna device 1 of this embodiment and an antenna device of a comparative example. The reflection characteristics show the relationship between the input signal and the reflected signal depending on the frequency. The VSWR (Voltage Standing Wave Ratio) is calculated by simulation. In FIG. 7, the VSWR (solid line) of this embodiment and the VSWR (dashed line) of the comparative example are superimposed. This is expressed as follows.

[0027] As shown in Figure 7, the reflection characteristics show that the VSWR reaches a minimum value near a frequency of 28 GHz. The VSWR deteriorates from there toward the lower and higher frequency ranges. The frequency range where WR is good is relatively wide, whereas in the comparative example, the frequency range where VSWR is good is The wave number range is relatively narrow. Specifically, in this embodiment, the VSWR is 2 or less. The frequency range is four times larger than that of the comparative example. It has been verified that the antenna device 1 of this type can obtain good reflection characteristics over a wide frequency range. .

[0028] Next, the 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 patch antenna 20 and the cavity 12 are arranged in the Z direction. The antenna device 1 having a rectangular planar shape in plan view has been described. The device 1 has a modified patch antenna 20a and a modified cavity 12a. FIG. 8 is a perspective view of the antenna device 1 of this modified example seen from diagonally above, and FIG. 9 is a perspective view of the antenna device 1 of FIG. 8 and 9 are plan views of the tena device 1 as seen from above. 2 and 4 are omitted as they are generally common to this modification. do.

[0029] As shown in FIGS. 8 and 9, in the antenna device 1 of this modified example, the structure shown in FIGS. The difference is that both the patch antenna 20a and the cavity 12a are planar when viewed from the Z direction. The cavity 12a has a circular planar shape in plan view. The patch antenna 2 is formed by removing a circular area of ​​dielectric material in the center of layer 11. 0a is formed in a circular shape at the center of the surface of the lower dielectric layer 10. Note that, as shown in FIGS. In this figure, the upper and lower dielectric layers 10 and 11 are both rectangular in plan view, as in FIGS. 2, the lower dielectric layer 10 has a three-layered ground conductor 21. , 22, 23 are arranged. Similarly, the feed structure shown in FIG. 4 and the horizontally polarized and vertically polarized The arrangement of the upper end 31a and the lower end 32a of each of the via conductors 31 and 32 for the wave (FIG. 9) This is the same as the above embodiment.

[0030] As shown in FIG. 9, the circular cavity 12a has a diameter D in plan view from the Z direction. The diameter of the circular patch antenna 20a is set to be slightly smaller than the diameter D. That is, the cavity 12a is arranged to surround the patch antenna 20a in a plan view. 3. In addition, among the dimensional conditions of this modification, the dielectric layers 10 and 1 1 in the Z direction and the heights Z1 and Z2 of the upper and lower dielectric layers 10 and 11 in the X direction (FIG. 2). The length X1 and the length Y1 in the Y direction are the same as those in the above embodiment. As with other dimensional conditions, it is necessary to determine the appropriate value depending on the frequency band used, antenna characteristics, etc. be.

[0031] 10 and 11 show the antenna device 1 of this modified example, with the same radiation beam as in FIGS. 5 and 6. In both cases, a signal with a frequency of 28 GHz is input to the patch antenna 20a. The results of simulations verifying the directionality of radio waves emitted from the In FIG. 11, the radiation directivity of the present modified example (solid line) is superimposed on the radiation directivity of FIG. 5 and a comparative example similar to FIG. The radiation directivity in Figures 10 and 11 is roughly the same as that in Figures 5 and 6. Even when the structure of this modified example is adopted, a wide angle of radiation directivity can be obtained. Although not shown in the figure, the reflection characteristics of this modification were Even if the number of samples is larger than 1, the results are generally the same as those in Figure 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 achieve good antenna characteristics including wide-angle radiation directivity. In this structure in which the patch antenna 20 is arranged on the surface of the dielectric layer 10, the radiation angle is relatively narrow. In contrast, in the embodiment including the above-described modified example (hereinafter referred to as the present embodiment), The cavity 12 in the dielectric layer 11 laminated on the dielectric layer 10 provides radiation directivity. The electric current radiated from the patch antenna 20 in the upward Z direction can be The waves generate an electromagnetic field distribution on the dielectric surfaces that form the four sides of the cavity 12, which When the light propagates along the Z direction to the opening at the top of the cavity 12, it spreads in various directions and radiates. It is expected that the beam directionality will become wider.

[0033] In the conventional configuration, in order to achieve a wide-angle radiation directivity, multiple antennas are arranged in an array. The phase of each antenna is adjusted by beamforming. In contrast, in the case of the antenna device 1 of this embodiment, the array A wide angle of radiation directivity can be obtained with only one patch antenna 20 without configuring an antenna. This eliminates the need for space to place multiple antennas, and each antenna There is no need for a complicated electronic circuit to provide a phase difference. In addition to the superiority of the antenna performance mentioned above, the dielectric It is suitable for downsizing the substrate and miniaturizing the antenna device 1, and therefore, the time required for manufacturing the dielectric substrate is reduced. Dimensional tolerances can also be relaxed, and component costs and mounting costs can be reduced, making it possible to lower costs.

[0034] In this embodiment, good antenna characteristics including wide-angle radiation directivity are realized. As mentioned above, it is important to set the dimensional parameters appropriately when The dimensional parameters of the laser device 1 are not limited to the structures shown in FIGS. 1 to 4. It is desirable to set the wavelength λ corresponding to the frequency to be used. This wavelength takes into consideration the wavelength shortening effect in the substrate. Specifically, the Z direction of the cavity 12 The height along the line is the wavelength λ of the frequency used in the dielectric substrate. The height (height of the cavity 12) Z2 can be set within the range of 0.7λ to 0.8λ. It is also desirable to set the lengths X2 and Y2 of the cavity 12 in the X and Y directions by the patch antenna. The distance is within the range of 0.03λ to 0.07λ from the length of the rectangle in the X and Y directions. It is desirable to set the dimensional parameters as large as possible. To ensure the desired antenna characteristics such as wide-angle radiation directivity and good reflection characteristics in This is the desired setting.

[0035] In this embodiment, as shown in FIG. 3, the patch antenna 20 and the cavity 12 has been described as having a rectangular or circular planar shape when viewed from the Z direction. For example, the patch antenna 20 and the cavity antenna 21 may have different planar shapes. The present invention can be applied even if the body 12 has a polygonal planar shape other than a rectangle. Even in this case, the advantageous effects 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 arranged in a direction perpendicular to the Z axis. The above description has been given of a case where the dielectric substrates 10 and 11 are arranged symmetrically with respect to the center thereof in a plan view. The present invention can be applied even to an asymmetric arrangement with respect to the center.

[0036] The present invention has been specifically described above based on the present embodiment. The present invention is not limited to the above-mentioned forms, and modifications can be made without departing from the spirit of the invention. That is, the basic structure of the antenna device 1 described with reference to FIGS. 1 to 4 provides the effects of the present invention. The present invention can be widely applied to various antenna devices 1 having other structures and shapes as far as possible. For example, the shape, power feeding method, size, etc. of the patch antenna 20 can be Various modifications can be made to the present invention 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 conductors 33, 31, 32...Via conductors

Claims

1. An antenna device configured using a dielectric substrate, a first dielectric layer disposed below the dielectric substrate; a second dielectric layer disposed above the dielectric substrate and stacked on the first dielectric layer, the second dielectric layer having a cavity formed at its center in a plan view seen from a first direction, which is a thickness direction of the dielectric substrate, and penetrating the first direction; 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 closer to the first dielectric layer than the predetermined conductor layer in the first direction; Equipped with the patch antenna is exposed to the outside through the cavity; an area of ​​the ground conductor is larger than an area of ​​the patch antenna in a plan view seen from the first direction; An antenna device characterized in that, in a planar view from the first direction, the outer edge of the cavity is set to be larger by a distance in the range of 0.03λ to 0.07λ from the outer edge of the patch antenna than the wavelength λ of the 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. 2. The antenna device according to claim 1, wherein the height of the cavity in the first direction is set within a range of 0.7λ to 0.8λ, where λ is the wavelength of the frequency used in the dielectric substrate.

5. 2. The antenna device according to claim 1, wherein the patch antenna and the cavity are arranged symmetrically with respect to the 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 on 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 one or both of horizontally polarized waves and vertically polarized waves.

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