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 response in various environments, including inside buildings and outdoors. In order to transmit and receive radio waves in the frequency band, the antenna device is provided with a device capable of transmitting and receiving radio waves in various directions. It is required to have a wide angle radiation directivity. The array antenna is made up of a number of antenna elements arranged in an array, and has a wide overall radiation angle. For example, Patent Document 1 discloses a method for achieving directivity by using an array of multiple antennas. In an array antenna arranged in a square shape, beamforming is performed by giving each antenna a phase difference. There is disclosed a technology that can obtain a wide-angle radiation directivity by performing the above. [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, forming one patch antenna on a dielectric substrate makes an antenna device. It is easy to miniaturize the antenna, but it is difficult to realize a wide-angle radiation directivity. In order to realize a wide-angle radiation directivity of an antenna device, multiple patch antennas are mounted on a dielectric substrate. In order to achieve this, 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 to give the antenna a phase difference for beamforming. This leads to an increase in both component and mounting costs, and also increases the manufacturing cost of the dielectric board. 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 realize a 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 navigator 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 still maintaining the same characteristics. .

[0006] In order to solve the above problems, the antenna device (1) of the present invention is configured using a dielectric substrate. The antenna device is a patch antenna formed on a predetermined conductor layer of the dielectric substrate. a dielectric layer (11) disposed above the predetermined conductor layer of the dielectric substrate; When viewed from a first direction (Z) which is a thickness direction of the dielectric substrate, a cavity (12) having a shape surrounding the switch antenna, and the predetermined A ground conductor (21, 22, 23) is disposed opposite the dielectric layer with the conductor layer in between. The present invention is configured to include the following.

[0007] The antenna device of the present invention uses a dielectric substrate, and has a pad of a predetermined conductor layer. The patch antenna and the ground conductor directly below it are formed, and the layered structure is placed above the patch antenna. A cavity is formed in the dielectric layer, and the cavity has a shape as shown in a plan view from a first direction. The patch antenna is surrounded by a feed structure. The radio waves radiated from the patch antenna are reflected by the electromagnetic waves on the dielectric surface of the upper cavity side. The radiation direction spreads due to the effect of the field distribution, and the radiation directivity becomes wider. Therefore, when multiple antennas are used, The space required to arrange the sensors in an array is increased, and complex phase control during beamforming is required. 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 a patch antenna and a cavity having a circular shape. The height of the cavity in the first direction is determined by the dielectric constant. 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 a patch antenna. It is desirable to set the distance from the outer edge of the nozzle to a value within the range of 0.03 λ to 0.07 λ. I wish.

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

[0010] In the present invention, the ground conductors are interconnected through a plurality of via conductors extending in a first direction. The ground conductor can be formed 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 either or both of horizontally polarized waves and vertically polarized waves. This allows a single patch antenna to be fed with a smaller 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. Effect of the Invention

[0012] According to the present invention, a single patch antenna is arranged on a dielectric substrate, and a cavity is provided above the patch antenna. By arranging the antennas in an array, it is possible to avoid the increase in size and cost involved in forming an antenna device into an array. Furthermore, the wide angle of radiation directivity makes it possible to realize an antenna device that is easy to use. [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 view of the antenna device 1 of FIG. 1 taken along the line 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. In the embodiment, an antenna device embodying the present invention will be described. The embodiment described above is merely an example of the application of the present invention, and the present invention is not limited by the content of the 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. FIG. 1 is a perspective view of the antenna device 1 as seen obliquely from above. FIG. 3 is a cross-sectional view of the antenna device 1 taken along the line AA of the device 1. 4 is a plan view of the antenna device 1. FIG. 4 is a diagram illustrating the conductor structure of the lower part of the antenna device 1. 1 to 4, for convenience of explanation, the X direction, the Y direction, and the Z direction (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 circuit board has a laminated structure of a lower dielectric layer 10 and an upper dielectric layer 11. A patch antenna 20 is formed at the center of the surface of the dielectric layer 10, and A cavity 12 is formed in the dielectric layer 11. The rectangular hollow portion where the material is removed is the cavity 12. The layer 10 includes three-layered ground conductors 21 and 22 on the lower side 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 the same rectangular planar shape, 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 shape similar to that of a patch antenna in plan view. Since the patch antenna 20 is arranged to surround the cavity 12, 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 in the Z direction are The height Z2 in the direction (height Z2 of the cavity 12) is shown. Z2 is larger than Z1. In addition, in FIG. 3, the X of the upper and lower dielectric layers 10 and 11 is set to be large. 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 of X1, X2, Y1, Y2, Z1, Z2, etc. The conditions must be appropriately determined according to the frequency band used, antenna characteristics, etc. For example, Assuming a frequency of 28 GHz, one 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 mentioned. 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. 1 shows only the area of ​​the lower dielectric layer 10 with the dielectric layer 11 at the bottom removed, In addition to the tenon 20 and the 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 layers of 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 side. Each of the ground conductors 21, 22, and 23 covers almost the entire rectangular area of ​​the dielectric layer 10. The three ground conductors 21, 22, and 23 are formed so as to extend over the entire surface of the board. The ground conductor 21 is electrically connected to the ground conductor 30. , 22, 23 and the patch antenna 20 above are disposed opposite each other, so that the antenna device 1 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. A vertically polarized high-frequency signal is fed to the other via conductor 32. The tenna 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 top end 32a is shown, and extends 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 pair of power supply lines are connected to a pair of pads (not shown) on the bottom surface of the MOSFET. With this structure, the antenna device 1 receives horizontally polarized waves via a feeding structure. It is possible to radiate either or both of the vertically polarized and the vertically polarized waves.

[0022] When a high-frequency signal is externally supplied to the antenna device 1 of this embodiment, the antenna device 1 basically In this case, the conventional structure emits radio waves upward 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 is different in that a cavity 12 is present above the patch antenna 20. In the embodiment, the role of the cavity 12 is to make the radiation directivity of the antenna device 1 wide-angle. Conventionally, a single patch antenna 20 alone cannot provide a wide-angle radiation directivity. According to the antenna device 1 of the present embodiment, the cavity 1 The effect of providing 2 is to obtain a wide angle of radiation directivity, but verification of this point is required. 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. The results are explained below. Here, for comparison with the antenna device 1 of the present 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 corresponding parts are generally common to the antenna device 1 of the embodiment.

[0024] 5 and 6 show the radiation characteristics of the antenna device 1 of the present 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. In both cases, a signal with a frequency of 28 GHz is input, and the The results are shown in Fig. 5 and Fig. 6. 1 shows the radiation directivity of this embodiment (solid line) and the radiation directivity of the comparative example (dashed line) superimposed. do.

[0025] As shown in Figures 5 and 6, the radiation directivity has a peak gain 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 Fig. 5 and Fig. 6, the range of angles where the gain is half the value from the peak is When the half-width is calculated as the half-width, the half-width is about 90° in the comparative example, whereas 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 FIG. 5 and FIG. 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 degrees 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) was obtained by simulation. In FIG. 7, the VSWR (solid line) of this embodiment and the VSWR (dashed line) of the comparative example are overlapped. This is expressed as follows.

[0027] As shown in Fig. 7, the reflection characteristics are such 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 relatively wide. The wave number range is relatively narrow. Specifically, in this embodiment, the VSWR is 2 or less. The frequency range covered by this embodiment is more than four times that of the comparative example. It has been verified that the antenna device 1 has 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 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 above. 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. 8 and 9 are plan views of the tenna device 1 as viewed from above. Here, FIGS. 8 and 9 correspond to FIGS. 1 and 3. 2 and 4 are omitted because they are generally common to this modified example. 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 the patch antenna 20a and the cavity 12a are both planar when viewed from the Z direction. The cavity 12a has a circular planar shape in plan view. A 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 the figure, the upper and lower dielectric layers 10 and 11 each have a rectangular planar shape, similar to that of FIGS. 2, the lower dielectric layer 10 includes a ground conductor 21 having a three-layer structure. , 22, 23 are arranged. Similarly, the feed structure shown in FIG. The arrangement of the upper end 31a and the lower end 32a (FIG. 9) of each of the via conductors 31 and 32 for the wave This is similar to 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. The above is the same as in the case of FIG. 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 according to the frequency band to be 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 are shown in Fig. 10 and Fig. 11. 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 Fig. 10 and Fig. 11 is roughly the same as that in Fig. 5 and Fig. 6. Even when the structure of this modified example is adopted, a wide angle radiation directivity can be obtained. It was verified that the reflection characteristics of this modified example were Regardless of the method used, the results are generally similar to 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 realize good antenna characteristics including wide-angle radiation directivity. In the 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-mentioned modified example (hereinafter referred to as the present embodiment), The cavity 12 in the dielectric layer 11 laminated on the top of the dielectric layer 10 improves radiation directivity. The electric field emitted from the patch antenna 20 in the upward direction in the Z direction can be increased. The waves generate electromagnetic field distributions 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 emits radiation. It is expected that the radiation directionality will become wider.

[0033] In the conventional configuration, in order to achieve a wide-angle radiation directivity, multiple antennas were 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 radiation directivity can be obtained with only one patch antenna 20 without configuring an antenna. This eliminates the need for space for multiple antennas, and each antenna can be There is no need for a complex 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 antenna device 1 by reducing the size of the substrate, and therefore the manufacturing cost of the dielectric substrate is reduced. Dimensional tolerances can also be relaxed, and component costs and mounting costs can be reduced, making it possible to reduce 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 of the dielectric material. This wavelength takes into consideration the wavelength shortening effect in the substrate. The height along the line is the height of the upper dielectric layer 11 relative to the wavelength λ of the frequency used in the dielectric substrate. The height (height of 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 to 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 a desirable setting.

[0035] In this embodiment, as shown in FIG. 3, a patch antenna 20 and a 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 21 may have a different planar shape. 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. In the above description, 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 if the arrangement is asymmetric with respect to the center.

[0036] The present invention has been described in detail above based on the present embodiment. The present invention is not limited to the above embodiment, 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 supply method, size, etc. of the patch antenna 20 can be Various modifications can be made to the above 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 patch antenna formed on a predetermined conductor layer of the dielectric substrate; A dielectric layer is formed on the dielectric substrate, the dielectric layer being disposed above the predetermined conductor layer. A shape surrounding the patch antenna in a plan view seen from a first direction which is a thickness direction of the substrate. a cavity having a A ground electrode is disposed opposite the dielectric layer with the predetermined conductor layer interposed therebetween in the first direction. A conductor and An antenna device comprising:

2. The patch antenna and the cavity are each, when viewed in a plan view from the first direction, 2. The antenna device according to claim 1, characterized in that it has a rectangular shape.

3. The patch antenna and the cavity are each, when viewed in a plan view from the first direction, 2. An antenna device as claimed in claim 1, characterized in that it has a circular shape.

4. The height of the cavity in the first direction is determined based on the frequency of the dielectric substrate.

2. The wavelength λ of the optical fiber is set within a range of 0.7 λ to 0.8 λ. The antenna device according to claim 1 .

5. In a plan view seen from the first direction, an outer edge of the cavity is The distance is set to be larger than the outer edge by a distance within a range of 0.03 λ to 0.07 λ.

2. The antenna device according to claim 1 .

6. In a plan view seen from the first direction, the patch antenna and the cavity are 2. The antenna device according to claim 1, wherein the antenna device is arranged symmetrically with respect to the center of the electric circuit board. Place.

7. The ground conductors are connected to each other through a plurality of via conductors extending in the first direction.

2. The antenna device according to claim 1, wherein the first and second conductor layers are arranged in a first direction and a second direction.

8. The patch antenna is provided with a power supply structure for supplying one or both of horizontally polarized waves and vertically polarized waves.

2. The antenna device according to claim 1, further comprising a structure.

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