Antenna device
A dielectric substrate antenna with a single patch antenna and offset cavity achieves wide-angle radiation directivity and controlled peak direction, addressing size and cost issues in existing antenna designs.
Patent Information
- Application Number
- JP2024082177
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2025-12-03
AI Technical Summary
Antenna devices using dielectric substrates face challenges in achieving a wide-angle radiation pattern with a peak in a desired specific direction, requiring space for multiple antennas and complex electronic circuits, which increases size, cost, and manufacturing complexity.
An antenna device is constructed using a dielectric substrate with a single patch antenna surrounded by a cavity on the dielectric layer, where the cavity's center is offset from the substrate's center, allowing for wide-angle radiation directivity with controlled peak direction without needing additional space or complex circuits.
The solution enables a smaller, less expensive antenna device with wide-angle radiation directivity and controlled peak direction, eliminating the need for arrayed antennas and phase control circuits.
Smart Images
Figure 2025175867000001_ABST
Abstract
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 antenna devices to have a wide-angle radiation directivity that can transmit and receive radio waves in various directions, since high-frequency radio waves are transmitted and received in various environments, such as inside and outside buildings. Furthermore, depending on the application of this type of antenna device, in addition to obtaining a wide-angle radiation directivity, it may also be necessary to control the peak of the radiation directivity in a direction tilted laterally from the front direction of the antenna device. To meet this requirement, a method is known in which an array antenna is configured by arranging multiple antenna elements in an array to achieve a wide-angle radiation directivity overall. For example, Patent Document 1 discloses a technology that, in an array antenna in which multiple antennas are arranged in an array, applies a phase difference to each antenna to perform beamforming, thereby achieving a wide-angle radiation directivity with a peak in a desired specific direction. [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 widely adopted structures that use dielectric substrates in order to reduce size and weight. For example, forming a single patch antenna on a dielectric substrate makes it easy to reduce the size of the antenna device, but it is difficult to achieve a wide-angle radiation pattern with a peak in a desired specific direction. To achieve such radiation pattern, as mentioned above, it is necessary to form an array antenna by arranging multiple antennas, such as patch antennas, in an array on a dielectric substrate. However, array antennas using dielectric substrates require space for arranging multiple antennas, which increases the size and makes it difficult to miniaturize the antenna device. Furthermore, complex electronic circuits are required to provide phase differences for beamforming to multiple antennas, which increases both component and mounting costs and requires strict dimensional tolerances when manufacturing the dielectric substrate. As described above, when constructing an antenna device using a dielectric substrate using the above-mentioned conventional methods, it has been difficult to achieve a small, low-cost antenna with a wide radiation angle and a peak in a desired specific direction.
[0005] The present invention has been made to solve the above-mentioned problems, and realizes an antenna device that can be made smaller and less expensive by arranging only one patch antenna when constructing an antenna device using a dielectric substrate, while maintaining radiation directivity with a peak in the desired direction over a wide angle. [Means for solving the problem]
[0006] 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 comprises: 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, and having a shape that surrounds the patch antenna in a planar 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, sandwiching the predetermined conductor layer therebetween, and characterized in that, in a planar view seen from the first direction, the center of the cavity is set at a position that is a predetermined distance (d) away from the center of the dielectric substrate in a predetermined direction.
[0007] According to the antenna device of the present invention, an antenna device using a dielectric substrate includes a patch antenna on a predetermined conductor layer, a ground conductor directly below the patch antenna, and a cavity on a dielectric layer above the patch antenna. The cavity surrounds the patch antenna in a plan view from a first direction, and the center of the cavity is located a predetermined distance in a predetermined direction from the center of the dielectric substrate. With this structure, the radio waves radiated from the patch antenna via the feeding structure have a wide-angle radiation directivity due to the influence of the electromagnetic field distribution on the dielectric surface on the side surface of the upper cavity. Furthermore, the radiation directivity can be controlled so that the peak is in a direction tilted from the front direction due to the influence of the cavity arrangement. This eliminates the need for additional space for arranging multiple antennas in an array or complex electronic circuits for phase control during beamforming, thereby easily achieving a smaller and less expensive antenna device.
[0008] In the present invention, the patch antenna can be arranged in various positions. For example, the center of the patch antenna can be aligned with the center of the cavity in a plan view from a first direction. In this case, in addition to the cavity, the center of the patch antenna is also set at a position a predetermined distance in a predetermined direction from the center of the dielectric substrate.
[0009] In the present invention, the patch antenna and the cavity can each have various shapes in a plan view from a first direction. For example, the patch antenna and the cavity can be configured to have a rectangular shape. In one embodiment, the cavity can be configured to have a rectangular shape with its long sides in a predetermined direction in a plan view from the first direction, and the center of the patch antenna can be arranged not to coincide with the center of the cavity. In this arrangement, for example, the center of the patch antenna can be arranged to coincide with the center of the dielectric substrate in a plan view from the first direction.
[0010] In the present invention, the height of the cavity in the first direction is preferably set within a range of 0.7λ to 0.8λ, where λ is the wavelength of the operating frequency of the dielectric substrate. Furthermore, in the present invention, the ground conductor can be formed on multiple conductor layers that are connected to each other through multiple via conductors extending in the first direction. This increases the area of the ground conductor, strengthening the ground and improving the antenna characteristics. [Effects of the Invention]
[0011] According to the present invention, a single patch antenna and a cavity above it are arranged on a dielectric substrate, and the center of the cavity is shifted from the center of the dielectric substrate when viewed in a plan view from a first direction.This makes it possible to realize an antenna device that can obtain a radiation directivity that peaks in a desired direction while maintaining a wide angle, while avoiding the increase in size and cost that would accompany arraying the antenna device. [Brief explanation of the drawings]
[0012] [Figure 1] 1 is a perspective view of an antenna device 1 according to a first 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] 1 is a plan view of an antenna device 1 according to a first embodiment, viewed from above. [Figure 4] 3A to 3C are diagrams illustrating the conductor structure at the bottom of the antenna device 1 of the first embodiment. [Figure 5] 3 is a diagram showing radiation directivity in the YZ plane of the antenna device 1 of the first embodiment. FIG. [Figure 6] FIG. 10 is a perspective view of an antenna device 1 according to a second embodiment, seen obliquely from above. [Figure 7] 7 is a cross-sectional structural diagram of the antenna device 1 of FIG. 6 taken along the line AA. [Figure 8] FIG. 10 is a plan view of the antenna device 1 of the second embodiment as viewed from above. [Figure 9]10 is a diagram showing radiation directivity in the XZ plane of the antenna device 1 of the second embodiment. FIG. [Figure 10] 10A to 10C are diagrams showing two different arrangements of the antenna device 1 of the second embodiment for comparison with FIG. 9. DETAILED DESCRIPTION OF THE INVENTION
[0013] Two embodiments of an antenna device embodying the present invention will be described below as preferred embodiments of the present invention. However, each of the embodiments described below is merely an example of a form in which the present invention is applied, and the present invention is not limited to the content of these embodiments.
[0014] [First embodiment] First, the structure of the antenna device 1 of the first embodiment will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view of the antenna device 1 of the first embodiment as seen obliquely from above. Fig. 2 is a cross-sectional structural diagram of the antenna device 1 of Fig. 1 taken along the line AA. Fig. 3 is a plan view of the antenna device 1 of the first embodiment as seen from above. Fig. 4 is a diagram illustrating the conductor structure of the lower part of the antenna device 1 of the first embodiment. For ease of explanation, in Figs. 1 to 4, the X direction, Y direction, and Z direction (first directions according to the present invention), which are orthogonal to each other, are indicated by arrows.
[0015] The antenna device 1 of the first embodiment is configured using a dielectric substrate made of a dielectric material, and the dielectric substrate has a laminated structure of a lower dielectric layer 10 and an upper dielectric layer 11. A patch antenna 20 is formed at a predetermined position on the surface of the lower dielectric layer 10, and a cavity 12 is formed in a region of the upper dielectric layer 11 facing the patch antenna 20. In other words, the cavity 12 is a hollow portion in the dielectric layer 11 where the dielectric material has been removed in a rectangular shape. Furthermore, ground conductors 21, 22, and 23 having a three-layer structure are arranged on the lower dielectric layer 10 at a lower portion facing the patch antenna 20.
[0016] 2 and 3, in a plan view seen from the Z direction, the upper and lower dielectric layers 10 and 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 arranged 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.
[0017] 3, in a plan view seen from the Z direction, the entire dielectric substrate including the dielectric layers 10 and 11 is a rectangle centered at position P0. In contrast, the cavity 12 and the patch antenna 20 are a rectangle centered at position P1, which is shifted in the Y direction from position P0. This position P1 is set at a distance d away from position P0 along the Y direction. The reason for shifting the centers of the cavity 12 and the patch antenna 20 from the center of the dielectric substrate in this way is to tilt the radiation directivity horizontally from the Z direction; this point will be described in detail later.
[0018] FIG. 2 shows 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). It can be seen that Z2 is set to be larger than Z1. FIG. 3 shows 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, respectively. As already mentioned, X1 and Y1 are set to be larger than X2 and Y2. Furthermore, the size of the patch antenna 20 is set to be slightly smaller than X2 and Y2. FIGS. 1 to 4 illustrate a case where the dielectric layers 10 and 11 and the cavity 12 all have a square planar shape, and X1 = Y1 and X2 = Y2.
[0019] In the first embodiment, the specific dimensional conditions such as X1, X2, Y1, Y2, Z1, and Z2 described above must be appropriately determined depending on the frequency band used, antenna characteristics, and the like. For example, assuming a frequency of 28 GHz, one example of setting 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 size of the patch antenna 20 is slightly smaller than X2 and Y2, approximately 2 mm. Furthermore, the distance d from position P0 to position P1 can be set to 2 mm. In general, the lower the frequency band used, the larger the dimensional parameters need to be set, and the higher the frequency band used, the smaller the dimensional parameters need to be set.
[0020] Next, the conductor structure of the antenna device 1 of the first embodiment will be described with reference to FIG. 4. In FIG. 4, the upper dielectric layer 11 is removed and only the lower dielectric layer 10 is shown. In addition to the patch antenna 20 and ground conductors 21, 22, and 23, multiple via conductors 30 and 31 extending through the dielectric layer 10 in the stacking direction are also shown. The three-layer ground conductors 21, 22, and 23 are arranged in this order from the bottom up: ground conductor 21, ground conductor 22, and ground conductor 23. Each of the ground conductors 21, 22, and 23 is formed to extend over substantially the entire rectangular region of the dielectric layer 10. The three-layer ground conductors 21, 22, and 23 are electrically connected to each other via multiple via conductors 30. Since the large-area ground conductors 21, 22, and 23 are arranged facing the upper patch antenna 20, the ground of the antenna device 1 is strengthened, which is effective in improving the antenna characteristics.
[0021] As shown in FIG. 4, one via conductor 31 functioning as a feed line is connected to the patch antenna 20. A vertically polarized high-frequency signal is fed to this via conductor 31. In the patch antenna 20 of FIG. 3, an upper end 31a of the vertically polarized via conductor 31 is shown, and the upper end 31a is connected to a position offset in the Y direction from the center position P1 of the patch antenna 20. The lower end of the via conductor 31 is connected to a pad (not shown) on the bottom surface of the dielectric layer 10, allowing power to be fed to the feed line from an external source. With this structure, the antenna device 1 can radiate vertically polarized radio waves via the feed structure. Note that, when radiating horizontally polarized radio waves from the antenna device 1, a feed structure can be formed that includes a via conductor connected to a position offset in the X direction from position P1.
[0022] When a high-frequency signal is externally supplied to the antenna device 1 of the first embodiment, radio waves are generally radiated in a predetermined direction between above and to the side in the Z direction. In this case, in a conventional 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. In contrast, the first embodiment differs in that a cavity 12 is present above the patch antenna 20. The basic role of the cavity 12 in the first embodiment is to widen the radiation directivity of the antenna device 1. In addition, in the antenna device 1 of the first embodiment, the centers of the cavity 12 and the patch antenna 20 are shifted from the center of the dielectric substrate along the Y direction, so that the peak of the radiation directivity in the YZ plane is inclined from above to the side. The direction of the peak in the radiation directivity changes depending on the distance d in FIG. 3 , and specific verification results will be described later.
[0023] The following describes the results of verifying the antenna characteristics of the antenna device 1 of the first embodiment. Fig. 5 shows the results of verifying the radiation directivity in the YZ plane when the distance d in Fig. 3 is changed for the antenna device 1 of the first embodiment, with three graphs overlapping, where d = 2 mm, d = 1 mm, and d = 0 mm. All of these are results of verifying the radiation directivity of radio waves radiated from the patch antenna 20 by inputting a signal with a frequency of 28 GHz. Note that the radiation angle on the horizontal axis is 0° in the front direction (upward in the Z direction), and the change in gain within a range tilted from there to ±180° is shown.
[0024] 5, the condition of d = 0 mm means that position P0 and position P1 in FIG. 3 coincide, and the cavity 12 and patch antenna 20 are located at the center of the dielectric substrate in a planar view from the Z direction. In this case, it can be seen that no gain peak appears at radiation angles away from 0°, which is the front direction, and this is the typical radiation directivity of patch antenna 20 having a conventional structure. In contrast, when d = 1 mm, a gain peak appears at a radiation angle of approximately 50° inclined from 0° in the YZ plane, and when d = 2 mm, a gain peak appears at a radiation angle of approximately 70° inclined further from 0° in the YZ plane.
[0025] Therefore, the greater the shift of the center position P1 of the cavity 12 and the patch antenna 20 from the center position P0 of the entire dielectric substrate, the greater the effect of tilting the radiation directivity in the YZ plane toward the side. However, the greater the distance d, the smaller the gain in the region opposite the radiation angle where the peak appears (the region where the radiation angle is negative). For example, when d = 2 mm, the gain is minimal near a radiation angle of -60°, but a large gain is maintained up to 180° in the positive radiation angle region, resulting in an overall wide-angle radiation directivity. Thus, when configuring the antenna device 1 of the first embodiment, it is desirable to determine an appropriate distance d depending on the desired radiation angle at which the gain peak should be set.
[0026] In the first embodiment, the cavity 12 and the patch antenna 20 are rectangular and centered at position P1, which is shifted in the Y direction from position P0, which is the center of the dielectric substrate. However, even if the cavity 12 and the patch antenna 20 are rectangular and centered at position P1, which is shifted in the X direction from position P0, the effect of tilting the radiation directivity in the XZ plane to the side (X direction) can be obtained. In addition, the range in which the distance d can be set in Fig. 3 needs to be set within a range in which the rectangle of the cavity 12 and the patch antenna 20 does not deviate from the rectangle of the dielectric layers 10 and 11 in a plan view seen from the Z direction.
[0027] [Second embodiment] Next, the structure of the antenna device 1 of the second embodiment will be described with reference to Figs. 6 to 8. Fig. 6 is a perspective view of the antenna device 1 of the second embodiment seen from diagonally above. Fig. 7 is a cross-sectional structural diagram of the antenna device 1 of Fig. 6 taken along the line AA. Fig. 8 is a plan view of the antenna device 1 of the second embodiment seen from above. Figs. 6 to 8 correspond to Figs. 1 to 3 of the first embodiment, and the meanings of the X, Y, and Z directions indicated by the arrows are the same. Note that the conductor structure shown in Fig. 4 is the same in the second embodiment, and therefore description thereof will be omitted.
[0028] The antenna device 1 of the second embodiment is the same as that of the first embodiment in terms of the laminated structure of the upper and lower dielectric layers 10 and 11 and the three-layer ground conductors 21, 22, and 23. Also, the patch antenna 20 is formed on the surface of the dielectric layer 10, and the cavity 12 is formed in the dielectric layer 11. However, the positions of the cavity 12 and the patch antenna 20 and the shape of the cavity 12 in a plan view from the Z direction are different from those of the first embodiment. That is, as shown in FIG. 8 , in a plan view from the Z direction, the patch antenna 20 is rectangular and centered at a position P0 that is the center of the entire dielectric substrate including the dielectric layers 10 and 11, while the cavity 12 is rectangular and centered at a position P2 that is shifted from the position P0 in the X direction. As can be seen from FIG. 8 , the patch antenna 20 has a square planar shape, while the cavity 12 has a rectangular planar shape with its longitudinal direction aligned with the X direction.
[0029] In Figure 8, position P2 is set at a position a distance d away from position P0 in the X direction. What differs from the first embodiment is that, in a plan view seen from the Z direction, the center of the patch antenna 20 does not shift relative to the center of the dielectric substrate, and only the center of the cavity 12 shifts in the X direction. The cavity 12 and the patch antenna 20 are arranged close to each other on three sides of the rectangle, while being separated by a large distance on the other side (the right end of Figure 8). Even with this arrangement, the patch antenna 20 faces the air inside the cavity 12 directly above, and is exposed to the outside, similar to the first embodiment.
[0030] Among the dimensional parameters in FIGS. 7 and 8, the heights Z1 and Z2 in the Z direction, the length X1 in the X direction, and the lengths Y1 and Y2 in the Y direction are the same as those in the first embodiment. Meanwhile, the length X2 in the X direction of the cavity 12 in FIG. 8 is the long side of a rectangle and is extended compared to that in FIG. 3 of the first embodiment. The size of the patch antenna 20 is also the same as that in the first embodiment. In the second embodiment, the specific dimensional conditions such as the aforementioned X1, Y1, Y2, Z1, and Z2 must be appropriately determined depending on the frequency band used, antenna characteristics, etc., and the respective setting examples are the same as those in the first embodiment. An example of setting the length X2 and the distance d in FIG. 8 is X2 = 4.5 mm and d = 1.5 mm.
[0031] In the antenna device 1 of the second embodiment, the basic role of the cavity 12 is to widen the radiation directivity of the antenna device 1, as in the first embodiment. In addition, in the antenna device 1 of the second embodiment, by shifting the center of the cavity 12 from the center of the dielectric substrate along the X direction, the peak of the radiation directivity in the XZ plane is tilted from above in the Z direction toward the side. As in the first embodiment, the direction of the peak in the radiation directivity changes depending on the distance d in FIG. 3, and specific verification results will be described later.
[0032] The following describes the results of testing the antenna characteristics of the antenna device 1 of the second embodiment. FIG. 9 shows the results of testing the radiation directivity in the XZ plane when the arrangements of the cavity 12 and the patch antenna 20 of the antenna device 1 of the second embodiment are changed. In FIG. 9, in a plan view from the Z direction, in addition to the graph corresponding to the arrangement of FIG. 8, graphs corresponding to two arrangements shown in FIG. 10 are superimposed for comparison. That is, as shown in FIG. 10(a), the graphs are superimposed for a layout in which the centers of the cavity 12 and the patch antenna 20 are shifted to a position d=1.5 mm along the X direction, and as shown in FIG. 10(b), the graphs are superimposed for comparison, with the graphs for a layout in which the centers of the cavity 12 and the patch antenna 20 are aligned with the center of the dielectric substrate at a position d=0 mm. The meaning of the radiation directivity graph in FIG. 9 and the simulation conditions are as described in FIG. 5.
[0033] In FIG. 9, when d = 0 mm, the gain changes roughly similarly to the graph for d = 0 mm in FIG. 5, and no gain peak appears at radiation angles far from 0°, which is the front direction. In contrast, when d = 1.5 mm, the gain peak appears in the XZ plane at a radiation angle of approximately 30°, which is tilted from 0°. Furthermore, in the arrangement of FIG. 8, the gain peak appears in the XZ plane at a radiation angle of approximately 70°, which is tilted further from 0°. In other words, even when the center of the cavity 12 is shifted in the X direction and the planar shape is rectangular without shifting the center of the patch antenna 20, it was confirmed that tilting the radiation directivity in the XZ plane toward the side is highly effective. When configuring the antenna device 1 of the second embodiment, it is desirable to determine an appropriate distance d and planar shape of the cavity 12 depending on the desired radiation angle at which the gain peak should be set.
[0034] In the second embodiment, the cavity 12 alone is rectangular, with its center at position P2 shifted in the X direction from position P0, which is the center of the dielectric substrate, and its longitudinal direction in the X direction. However, even if the cavity 12 is rectangular, with its center at position P2 shifted in the Y direction from position P0, and its longitudinal direction in the Y direction, the effect of tilting the radiation directivity in the YZ plane to the lateral direction (Y direction) can be obtained. In addition, the range in which the distance d can be set in Fig. 8 needs to be set within a range in which the rectangle of the cavity 12 does not deviate from the rectangle of the dielectric layers 10 and 11 in a plan view seen from the Z direction.
[0035] As described above, the antenna device 1 of the first and second embodiments has been described, and it has been confirmed that both have the effect of tilting the radiation directivity in the lateral direction. Below, we provide a supplementary explanation of the effect that providing the cavity 12 in the antenna device 1 of the first and second embodiments has on the radiation directivity. Specifically, for comparison with the antenna device 1 of the first and second embodiments, an antenna device without the cavity 12 was assumed. In this antenna device, the patch antenna 20 was positioned at the center of the dielectric substrate, shifted by a distance d = 1 mm in the X or Y direction, and shifted by a distance d = 2 mm in the X or Y direction. The radiation directivity in the XZ plane and the YZ plane was examined for four cases: when the patch antenna 20 was positioned at the center of the dielectric substrate, when the patch antenna 20 was shifted by a distance d = 1 mm in the X or Y direction, and when the patch antenna 20 was shifted by a distance d = 2 mm in the X or Y direction. As a result, the radiation directivity peaked generally in the front direction, and the maximum tilt of the peak in the lateral direction was approximately 30°, and the effect described in the first and second embodiments was not confirmed. Furthermore, when the cavity 12 was not present, a wide-angle radiation directivity could not be obtained under any of the conditions, confirming that the cavity 12 is also important for widening the radiation directivity angle.
[0036] As described above based on the first and second embodiments, by adopting the structure of the antenna device 1 according to the present invention, it is possible to obtain the effect of maintaining a wide-angle radiation directivity while controlling it so that a desired specific direction becomes the peak. Specifically, the above effect can be achieved by providing a cavity 12 above the patch antenna 20 and positioning the center of the cavity 12 offset from the center of the dielectric substrate. Furthermore, to obtain the same effect using a conventional configuration, an array antenna in which multiple antennas are arranged in an array and a method of controlling the phase of each antenna using beamforming was required. In contrast, the antenna device 1 according to the present embodiment achieves a wide-angle radiation directivity using only a single patch antenna 20 without configuring an array antenna. This eliminates the need for space for multiple antennas and the need for complex electronic circuits to impart phase differences to each antenna. Therefore, the antenna device 1 according to the present invention is suitable for miniaturization by reducing the size of the dielectric substrate, which in turn reduces dimensional tolerances during the fabrication of the dielectric substrate, thereby enabling cost reduction through reduced component and mounting costs.
[0037] In the first and second embodiments, in order to achieve antenna characteristics including wide-angle radiation directivity, it is desirable to set the height Z2 of the upper dielectric layer 11 (height of the cavity 12) to a wavelength λ corresponding to the frequency used in the dielectric substrate. This wavelength λ is a wavelength that takes into consideration the wavelength shortening effect of the dielectric substrate. Specifically, the radiation directivity can be made wider-angle by setting Z2 within the range of 0.7λ to 0.8λ.
[0038] 3 and 8, the patch antenna 20 and the cavity 12 have a rectangular planar shape when viewed from the Z direction. However, the planar shape is not limited to a rectangle and may be other shapes. For example, the present invention can be applied even when the patch antenna 20 and the cavity 12 have a circular or polygonal planar shape other than a rectangle. Even in this case, the effects of the antenna device 1 of the present invention can be obtained by shifting the center of the cavity 12 from the center of the dielectric substrate.
[0039] Although the present invention has been specifically described above based on the first and second embodiments, the present invention is not limited to the above-described embodiments and can be modified without departing from the spirit of the invention. In other words, the basic structure of the antenna device 1 of the present invention 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, the shape, power feeding method, size, etc. of the patch antenna 20 can be modified in various ways as long as the effects of the present invention can be obtained. [Explanation of symbols]
[0040] 1...Antenna device 10, 11...Dielectric layers 12...cavity 20...Patch antenna 21, 22, 23...Ground conductors 30, 31...Via conductor
Claims
1. An antenna device configured using a dielectric substrate, a patch antenna formed on a predetermined conductor layer of the dielectric substrate; a cavity formed in a dielectric layer disposed 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 which is a thickness direction of the dielectric substrate; a ground conductor disposed opposite the dielectric layer across the predetermined conductor layer in the first direction; Equipped with An antenna device characterized in that, in a plan view seen from the first direction, the center of the cavity is set at a position a predetermined distance in a predetermined direction from the center of the dielectric substrate.
2. 2. The antenna device according to claim 1, wherein the center of the patch antenna coincides with the center of the cavity 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 rectangular shape in a plan view seen from the first direction.
4. The antenna device according to claim 3, characterized in that, in a planar view from the first direction, the cavity has a rectangular shape with its long side in the predetermined direction, and the center of the patch antenna does not coincide with the center of the cavity.
5. 5. The antenna device according to claim 4, wherein the center of the patch antenna coincides with the center of the dielectric substrate in a plan view seen from the first direction.
6. 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.
7. 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.