JP7436183B2 - antenna device - Google Patents

Description

The present invention relates to an antenna device configured using a dielectric substrate.

In wireless communication using high frequency signals, there is a demand for a wideband antenna device that can transmit and receive electromagnetic waves in as wide a frequency band as possible. As a method for expanding the frequency band, for example, a bowtie antenna using a metal electrode having a triangular planar shape is known (see, for example, Patent Documents 1 and 2). In such a bowtie antenna, a plurality of current paths are formed by feeding power from the apex of the triangle, so that the overall combined frequency band can be widened. For example, when power is supplied from the power feeding point 5 to the sheet metal 10 shown in FIG. A current flows through the antenna, and each path having a different length has a different resonant frequency, so that the entire antenna device including the metal plate 10 has a wide band.

Japanese Patent Application Publication No. 2018-050209 Japanese Patent Application Publication No. 2012-109652

In recent years, from the viewpoint of reducing the size and weight of antenna devices, an antenna structure has been proposed in which the antenna device is configured using a dielectric substrate and power is fed to an antenna element made of a conductor pattern formed on the dielectric substrate. When realizing the above-mentioned bowtie antenna structure in order to widen the band of an antenna device using such a dielectric substrate, it is assumed that a pattern of triangular planar electrodes is formed on a predetermined conductive layer as an antenna element. However, in order to sufficiently widen the frequency band, it is necessary to expand the area allocated to the planar electrode. Therefore, the planar size of the dielectric substrate on which the antenna element is disposed becomes large, making it difficult to miniaturize the entire antenna device.

The present invention has been made in order to solve the above-mentioned problems, and realizes an antenna device in which an antenna element is configured using a planar electrode and a via conductor on a dielectric substrate, and can realize a wide band while maintaining a small size. It is something to do.

In order to solve the above problems, an antenna device of the present invention includes a dielectric substrate (10), a first planar electrode (20) formed on the dielectric substrate, and a first planar electrode (20) formed on the dielectric substrate, a second plane electrode (22) disposed opposite to the first plane electrode in a first direction (Z) that is the thickness direction of the body substrate; and a second plane electrode (22) formed on the dielectric substrate and arranged to face the first plane electrode. and the second planar electrode, one or more via conductors (30) are formed on the dielectric substrate, and the first planar electrode is formed on the dielectric substrate and is connected to the first planar electrode when viewed from the first direction. and a ground conductor (12) arranged in a region that does not overlap with the second plane electrode, and the antenna element (11) is formed by the first plane electrode, the second plane electrode, and the one or more via conductors. ), and one end of the antenna element is electrically connected to a feed point (24) via a feed line (23, 32).

According to the antenna device of the present invention, the antenna element and the ground conductor are formed on the dielectric substrate, and the antenna element is configured by the first plane electrode, the second plane electrode, and one or more via conductors. When power is supplied to one end of the antenna element via the feed line, the current flows through various paths within a range including the length direction of the plane electrode and the height direction of the via conductor. Resonant frequency characteristics are synthesized along the path and the frequency band can be expanded. In this case, since there is no need to increase the area of the planar electrode, the dielectric substrate can be made smaller.

The antenna element of the present invention further includes one or more third plane electrodes formed on a dielectric substrate and arranged between the first plane electrode and the second plane electrode, and one or more third plane electrodes. Each of the plane electrodes may be electrically connected to the first plane electrode and the second plane electrode via one or more via conductors. As a result, by increasing the number of planar electrodes, the number of current paths further increases, making it possible to further widen the frequency band.

The ground conductor of the present invention can be arranged on the same conductor layer as at least each of the first plane electrode, the second plane electrode, and one or more third plane electrodes. Here, the "same conductor layer" refers to a conductor layer formed at the same lamination position on a dielectric substrate, and includes different conductor patterns such as signal and ground. In this case, the ground conductor includes a first plane electrode, a second plane electrode, one or more third plane electrodes, a plurality of plane electrodes arranged symmetrically with one or more via conductors, and one or more via conductors. It is also possible to have a structure having a component consisting of. By ensuring a sufficient area for the ground conductor, it is possible to strengthen the ground of the antenna device and improve antenna characteristics, and by arranging the ground conductor symmetrically with the antenna element, the antenna gain can be improved. You can expect it.

In the present invention, a plurality of via conductors arranged at predetermined intervals along the longitudinal direction of the first plane electrode and the second plane electrode may be used as the one or more via conductors. In this case, if all the predetermined intervals of the plurality of via conductors are set to λ0/4 or less with respect to the wavelength λ0 used by the antenna device, the plurality of via conductors all function as one conductor wall. However, the predetermined interval between at least two of the plurality of via conductors may be set to λ0/4 or less.

The antenna element of the present invention can function as one or both of a horizontal polarization element and a vertical polarization element. In this case, the first plane electrode and the second plane electrode mainly function as elements for horizontal polarization, and one or more via conductors mainly function as elements for vertical polarization. Note that depending on the dimensional parameters of the antenna element (the length of each planar electrode or the height of each via conductor), it is determined whether the antenna element mainly operates as a horizontally polarized wave element or a vertical polarized wave element. Determined.

According to the present invention, since the antenna element including the first and second planar electrodes and one or more via conductors is constructed using a dielectric substrate, when power is supplied to the antenna element, Since various current paths are formed within the range including be.

FIG. 3 is a cross-sectional view (AA cross section in FIG. 3(B)) of the antenna device of the present embodiment viewed from the X direction. FIG. 3 is a cross-sectional view of the antenna device of FIG. 1 viewed from the left side of FIG. 1 along the Y direction (BB cross section of FIG. 3(B)). FIG. 2 is a plan view of conductor layers 40a, 40b, and 40c included in the antenna device of FIG. 1, viewed from above in the Z direction. FIG. 2 is a plan view of conductor layers 40d, 40e, and 40f included in the antenna device of FIG. 1, viewed from above in the Z direction. FIG. 2 is a perspective view showing an enlarged portion of the antenna element 11 in the antenna device of the present embodiment. This is a modification example in which the number of planar electrodes 20 to 22 constituting the antenna element 11 is increased. This is a modification example in which the sizes of the planar electrodes 20 to 22 constituting the antenna element 11 are changed. This is a modification example in which the antenna element 11 is changed to operate mainly as a vertically polarized wave element. FIG. 1 is a first diagram illustrating an overview of a method for manufacturing an antenna device according to the present embodiment. FIG. 2 is a second diagram illustrating an overview of the method for manufacturing the antenna device of the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below is an example of a form to which the technical idea of the present invention is applied, and the present invention is not limited by the content of the present embodiment.

The structure of an antenna device according to an embodiment to which the present invention is applied will be explained using FIGS. 1 to 5. In FIGS. 1 to 5, for convenience of explanation, arrows indicate the X direction, Y direction, and Z direction (first direction of the present invention), which are orthogonal to each other. FIG. 1 is a sectional view of the antenna device of this embodiment viewed from the X direction (AA cross section of FIG. 3(B)), and FIG. 2 is a sectional view of the antenna device of FIG. 3 is a sectional view (BB cross section in FIG. 3(B)) viewed from the left side, and FIGS. 3 and 4 are views of the six conductor layers included in the antenna device in FIG. This is a plan view.

The antenna device of this embodiment is configured using a multilayer dielectric substrate 10 made of a dielectric material such as ceramic. The dielectric substrate 10 is provided with an antenna element 11 consisting of three layers of planar electrodes 20, 21, 22 and a plurality of via conductors 30, and a multilayered ground conductor 12. Six conductor layers 40a, 40b, 40c, 40d, 40e, and 40f are formed on the dielectric substrate 10, and various conductor patterns of the respective conductor layers 40a to 40f are used to form planar electrodes 20 to 22 and ground conductors. 12 are formed. In addition to the plurality of via conductors 30 described above, the plurality of via conductors extending in the Z direction between the respective conductor layers 40a to 40f include a plurality of via conductors 31 that are part of the ground conductor 12, 34, a via conductor 32 for power supply, etc. are formed.

The dielectric substrate 10 is a rectangular plate member having a long side along the Y direction, a short side along the X direction, and a predetermined thickness along the Z direction, and includes a dielectric layer having a predetermined dielectric constant. , and the aforementioned conductor layers 40a to 40f made of a conductive material are alternately laminated. 3 and 4, planar structures of conductor layers 40a, 40b, 40c, 40d, 40e, and 40f are shown in order from above in the Z direction. Among these, the conductor layers 40a and 40f are exposed on a pair of surfaces of the dielectric substrate 10 facing each other in the Z direction, and the conductor layers 40b, 40c, 40d, and 40e constitute the inner layer of the dielectric substrate 10. do. Furthermore, a feed terminal 24 (feed point of the present invention) electrically connected to the antenna element 11 is provided on the lowest conductor layer 40f.

The antenna element 11 includes a planar electrode 20 (a first planar electrode of the present invention) of a conductor layer 40b, a planar electrode 21 (a third planar electrode of the present invention) of a conductor layer 40c, and a planar electrode 22 (a first planar electrode of the present invention) of a conductor layer 40d. It has a three-dimensional structure composed of a second planar electrode of the invention) and four via conductors 30 that connect between each of the planar electrodes 20 to 22. The three planar electrodes 20, 21, and 22 all have a rectangular shape with the Y direction as the longitudinal direction. The four via conductors 30 are arranged at predetermined intervals along the Y direction within the rectangular range of the three planar electrodes 20 to 22. This predetermined interval is desirably set to λ0/4 or less with respect to the wavelength λ0 used by the antenna device.

As shown in FIG. 3(B), one end 20a of the upper plane electrode 20 is connected to a conductive pattern 23 for power feeding. This conductor pattern 23 is connected to the upper end of the power supply via conductor 32, and as shown in FIG. 4(C), the lower end of the power supply via conductor 32 is connected to the power supply terminal 24 of the conductor layer 40f. There is. That is, power is supplied from the power supply terminal 24 to one end 20a of the planar electrode 20 via the via conductor 32 and the conductor pattern 23. Therefore, the via conductor 32 and the conductor pattern 23 constitute a feed line between the feed terminal 24 and the antenna element 11. The power supply terminal 24 has a shape extending in the X direction by a predetermined length within a region surrounded by the ground conductor 12 .

Here, FIG. 5 is a perspective view showing an enlarged portion of the antenna element 11 of the antenna device of this embodiment. As shown in FIG. 5, the three planar electrodes 20 to 22 are formed to have the same shape and size, and are arranged in regions that overlap with each other when viewed from the top in the Z direction. A pair of plane electrodes 20 and 21 face each other at a distance H1 in the Z direction, and similarly a pair of plane electrodes 21 and 22 face each other at a distance H2 in the Z direction. Note that in the example of FIG. 5, H1=H2 is set. On the other hand, the four via conductors 30 have the same diameter when viewed from above in the Z direction, and are arranged side by side along the Y direction at the aforementioned predetermined intervals. Note that the upper via conductor 30 that connects between the planar electrodes 20 and 21 and the lower via conductor 30 that connects between the planar electrodes 21 and 22 are manufactured separately, but here, from the Z direction The explanation will be made assuming that it is one via conductor 30 as long as it is at the same position in plan view.

In FIG. 5, a conductive pattern 23 for power feeding connected to one end 20a of the plane electrode 20 extends in the X direction. Then, an input signal of a predetermined frequency supplied from the power supply terminal 24 via the via conductor 32 and the conductor pattern 23 excites the antenna element 11 consisting of the three planar electrodes 20 to 22 and the four via conductors 30, Electromagnetic waves are radiated to the outside. In this embodiment, by setting the length L (FIG. 1) in the Y direction of each of the planar electrodes 20 to 22 to an appropriate value that can resonate with the frequency used, the antenna element 11 is mainly used as a horizontally polarized wave element. Assuming that it operates as In this case, as shown in FIG. 5, horizontally polarized electromagnetic waves are radiated from the side surfaces 20b, 21b, 22b of the respective planar electrodes 20, 21, 22 in the X direction. Such a radiation direction facilitates making the antenna device thinner when it is placed inside a mobile terminal or the like.

Here, in the antenna element 11 having the structure shown in FIG. 5, attention will be paid to the path through which current flows when an input signal is fed. First, regarding the upper planar electrode 20, the path length from one end 20a along the Y direction is a maximum length L. On the other hand, the path length of the planar electrodes 21 and 22 needs to take into consideration the length of the via conductor 30. Therefore, for the planar electrode 21 immediately below, the maximum path length including the Y and Z directions from one end 20a is L+H1, and for the bottom planar electrode 22, the maximum path length including the Y and Z directions from one end 20a. So L+H1+H2. In this way, the antenna element 11 has a structure suitable for widening the antenna characteristics since there are various different path lengths for the input signal. Note that the structure shown in FIG. 5 is an example, and various structures can be applied when configuring the antenna element 11 according to the present invention, but the details will be described later.

As shown in FIGS. 3 and 4, the ground conductor 12 is disposed over the entire six conductor layers 40a to 40f, and the ground portion of each conductor layer 40a to 40f is electrically connected via a plurality of via conductors 31 and 34. It has a multilayer structure that is connected to each other. Of these, only the ground conductor 12 is disposed on the conductor layer 40a on one surface of the dielectric substrate 10. Furthermore, five via conductors 34 are connected to the ground conductor 12 of the conductor layer 40a, and corresponding locations of the lower conductor layers 40b to 40f are electrically connected via each via conductor 34. The areas of the ground conductors 12 of the six conductor layers 40a to 40f are arranged generally facing each other in the Z direction, but depending on the arrangement of the antenna element 11, the areas inside the center of the ground conductors 12 of the conductor layers 40b and 40c It has a cutout shape.

Now, focusing on the conductor layers 40b, 40c, and 40d, the ground conductor 12 in these portions is arranged symmetrically with the antenna element 11. Specifically, the ground conductor 12 has a three-layer planar shape in which the three-layer planar electrodes 20, 21, 22 and four via conductors 30 are moved to the right side in FIGS. 3 and 4 along the Y direction. The conductor pattern includes a conductor pattern and four via conductors 31. Among these, the ground conductor 12 of the conductor layer 40d is connected to a component symmetrical to the plane electrode 22 via a conductor pattern extending in the X direction. Arranging the ground conductor 12 symmetrically with the antenna element 11 in this manner has the effect of increasing the gain of the antenna device to some extent.

The entire ground conductor 12 formed on the dielectric substrate 10 functions as a reflector of the antenna device. That is, since a mirror image of the antenna element 11 is formed on the entire ground conductor 12, it is necessary to ensure a sufficient area of the entire ground in order to improve antenna characteristics. However, it is desirable to arrange the ground conductor 12 so that it does not overlap the antenna element 11 in plan view from the Z direction. Further, it is desirable to ensure a certain distance in the X direction between the plane electrodes 20, 21, 22 and the ground conductor 12 in the conductor layers 40b, 40c, 40d. Note that the arrangement, shape, and area of the ground conductor 12 can be varied in various ways without being limited to the structures shown in FIGS. 3 and 4 as long as the antenna characteristics necessary for the antenna device can be obtained.

Although the dimensional conditions of the antenna element 11 are various, as a specific example of the dimensional conditions in the Z direction, in FIG. 15 mm, 0.3 mm up to the conductor layer 40d, 0.8 mm up to the conductor layer 40c, 1.3 mm up to the conductor layer 40b, and 1.5 mm up to the topmost conductor layer 40a. Under these dimensional conditions, the height of the antenna element 11 in the Z direction is approximately 1.0 mm. If the antenna element 11 were to be configured in a plane as in a conventional structure (for example, FIG. 1 of Patent Document 1), a width of at least 1 mm in the X direction would be required, but in this embodiment, the antenna element 11 is Since it expands in the X direction, the width in the X direction can be small. Therefore, if the structure of the antenna element 11 of this embodiment is adopted, the planar size of the dielectric substrate 10 can be reduced, which is suitable for miniaturizing the antenna device.

In this embodiment, the structure of the antenna element 11 is not limited to the above description, and various changes can be made. Modifications of the antenna element 11 will be described below with reference to FIGS. 6 to 8. FIG. 6 shows a modification in which the number of planar electrodes 20 to 22 constituting the antenna element 11 is increased. That is, in FIG. 6, from the top, the planar electrode 20 (the first planar electrode of the present invention), the planar electrodes 21 and 22 (both are the third planar electrode of the present invention), and the planar electrode 25 (the second planar electrode of the present invention). The lower end of each of the four via conductors 30 is connected to the plane electrode 25. In this way, the number of planar electrodes of the antenna element 11 can be increased as necessary.

Although four via conductors 30 are provided in the modified example of FIG. 6, the number of via conductors 30 may be increased in addition to the number of planar electrodes. For example, when extending the length L (FIG. 1) of the planar electrodes 20 to 23, 25, five or more via conductors 30 may be arranged in line along the Y direction. To configure the antenna element 11, it is sufficient to provide at least two planar electrodes (a first planar electrode and a second planar electrode) and one or more via conductors 30, depending on the structure and antenna characteristics of the antenna device. Appropriate selection is possible. Note that the minimum configuration of the antenna element 11 of the present invention is two planar electrodes and one via conductor. However, in order to increase the number of current paths in the antenna element 11 and widen the band, it is desirable to increase the number of planar electrodes and the number of via conductors to some extent.

Next, FIG. 7 shows a modification in which the sizes of the planar electrodes 20 to 22 forming the antenna element 11 are changed. That is, in the modified example of FIG. 7, the planar electrodes 20 and 21 have the same size as in FIG. 5, but the length of the lower planar electrode 22 in the Y direction is approximately half that of FIG. . Therefore, only two via conductors 30 are connected to the lower plane electrode 22, and the height of the other two via conductors 30 in the Z direction is reduced. Although the antenna element 11 having such a structure also has a different path length distribution from that in FIG. 4, it is possible to obtain the effect of widening the antenna characteristics due to the existence of various paths. Broadly considering the structure of FIG. 7, regardless of the number of planar electrodes constituting the antenna element 11, as long as the arrangement partially overlaps in the Z direction, the length of only the arbitrary planar electrodes in the Y direction is changed (shortened). Even if the length of the antenna is increased (or longer), it is possible to widen the antenna characteristics.

Next, FIG. 8 shows a modified example in which the antenna element 11 is changed to operate mainly as a vertically polarized wave element. That is, in the modified example of FIG. 8, the conductor pattern 23 of FIG. 5 is separated from the upper plane electrode 20, a conductor pattern 26 is provided above the plane electrode 20, and a via conductor is connected from one end 26a of the conductor pattern 26. It has a structure connected to the planar electrode 20 via 30a. Thereby, by increasing the height of the via conductors 30a, 30 extending in the Z direction from one end 26a of the conductor pattern 26 and setting the height to an appropriate value that can resonate at the frequency used, the antenna element 11 can be used for vertically polarized waves. It can be operated as an element. Note that the length L of the planar electrodes 20, 21, 22, and 25 is slightly shorter than that in FIG.

In this embodiment, the antenna element 11 not only operates as either a horizontally polarized wave element or a vertically polarized wave element as described above, but also operates as a horizontally polarized wave element by appropriately setting dimension parameters. It can be operated both as an element and as a vertical polarization element. For example, in FIG. 5, if the length L of the planar electrodes 20, 21, 22 of the antenna element 11 and the height H1+H2 of the four via conductors 30 are both set to values that can resonate at the operating frequency, the planar electrode 20, , 21 and 22 function as elements for horizontal polarization, and the via conductor 30 mainly functions as an element for vertical polarization. Therefore, it is desirable to determine desired dimensional parameters so that the antenna element 11 functions as one or both of a horizontally polarized wave element and a vertically polarized wave element, depending on the intended use of the antenna device.

Next, an overview of the method for manufacturing the antenna device of this embodiment will be described with reference to FIGS. 9 and 10. First, as a plurality of dielectric layers constituting the dielectric substrate 10, a plurality of ceramic green sheets 50 for low-temperature firing formed by, for example, a doctor blade method are prepared. Then, as shown in FIG. 9A, a plurality of via holes 51 are formed by punching each ceramic green sheet 50 at a predetermined position. Note that the position and number of each via hole 51 in each ceramic green sheet 50 are set corresponding to the arrangement of the plurality of via conductors 30, 31, 32, and 34 in FIGS. 1 and 2.

Next, as shown in FIG. 9B, a plurality of via conductors are formed by filling each of the plurality of via holes 51 opened in each ceramic green sheet 50 with a conductive paste containing Cu by screen printing. 30, 31, etc. are formed. Subsequently, as shown in FIG. 10(A), a conductive paste containing Cu is applied to the front or back surface of each ceramic green sheet 50 by screen printing to form each conductor pattern of the conductor layers 40a to 40f. form. The conductor pattern formed at this time and the via conductors 30, 31, etc. described above define a basic structure including the antenna element 11 and the ground conductor 13 in the antenna device.

Then, as shown in FIG. 10(B), a plurality of ceramic green sheets 50 are sequentially laminated and then heated and pressurized to form a laminate. Thereafter, the obtained laminate is degreased and fired to complete the antenna device configured on the dielectric substrate 10 as described in this embodiment.

Although the content of the present invention has been specifically explained based on the present embodiment, the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist thereof. That is, the structural examples shown in FIGS. 1 to 5 of this embodiment are just one example, and the present invention can be widely applied to various antenna devices using other structures and materials as long as the effects of the present invention can be obtained. The invention can be applied. Furthermore, the contents of the present invention are not limited to the above embodiments in other respects, and modifications may be made as appropriate without being limited to the contents disclosed in the above embodiments as long as the effects of the present invention can be obtained. It is possible.

10... Dielectric substrate 11... Antenna element 12... Ground conductor 20, 21, 22, 25... Planar electrode 23... Conductor pattern 24... Power supply terminal 30, 31, 32, 34... Via conductor 40a, 40b, 40c, 40d, 40e , 40f...conductor layer

Claims (6)

a dielectric substrate;
a first planar electrode formed on the dielectric substrate;
a second planar electrode formed on the dielectric substrate and disposed opposite to the first planar electrode in a first direction that is the thickness direction of the dielectric substrate;
one or more via conductors formed on the dielectric substrate and electrically connecting between the first plane electrode and the second plane electrode;
a ground conductor formed on the dielectric substrate and disposed in a region that does not overlap with the first planar electrode and the second planar electrode when viewed from the first direction;
Equipped with
An antenna element is configured by the first plane electrode, the second plane electrode, and the one or more via conductors, and one end of the antenna element is electrically connected to a feeding point via a feeding line ,
The antenna element further includes one or more third planar electrodes formed on the dielectric substrate and arranged between the first planar electrode and the second planar electrode,
Each of the one or more third plane electrodes is electrically connected to the first plane electrode and the second plane electrode via the one or more via conductors,
The ground conductor is arranged on the same conductor layer as at least each of the first plane electrode, the second plane electrode, and the one or more third plane electrodes,
An antenna device characterized by: The ground conductor includes the first plane electrode, the second plane electrode, the one or more third plane electrodes, a plurality of plane electrodes arranged symmetrically with the one or more via conductors, and one or more plane electrodes. The antenna device according to claim 1 , further comprising a component made of a via conductor. 2. The one or more via conductors are a plurality of via conductors arranged in line at predetermined intervals along the longitudinal direction of the first plane electrode and the second plane electrode. The antenna device described. The antenna device according to claim 1, wherein the antenna element functions as one or both of a horizontal polarization element and a vertical polarization element. The antenna device according to claim 4, wherein the first plane electrode and the second plane electrode function as the horizontally polarized wave element. The antenna device according to claim 4 , wherein the one or more via conductors function as the vertically polarized wave element.

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