JP7653767B2 - Antenna Device - Google Patents

Description

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

In recent years, in wireless communication using high frequency signals, antenna devices are known in which antenna elements and ground conductors are formed using a dielectric substrate so that they can be built into devices such as mobile terminals. In general, the ground conductor functions as a reflector for the antenna element, so that the radiation direction of the electromagnetic waves emitted from the antenna device is determined depending on the positional relationship between the antenna element and the ground conductor. For example, Patent Document 1 discloses an antenna device in which a group of multiple antenna elements is arranged above the longitudinal direction of two parallel reflectors made of metal plates, and in such an arrangement, it is assumed that the directivity of the electromagnetic waves faces upward from the reflectors to the antenna element side. On the other hand, an antenna device using a dielectric substrate can adopt an arrangement in which the antenna elements and the ground conductors are arranged side by side on each plane of multiple conductor layers. When designing this type of antenna device, it is desirable to realize antenna characteristics in which the radiation directivity of the electromagnetic waves faces the side direction of the dielectric substrate, taking into account beamforming and the like of the 5G standard.

JP 2017-139575 A

However, as a result of verification by the inventors, it was confirmed that an antenna device in which antenna elements and ground conductors are configured on multiple conductor layers of a dielectric substrate as described above has a radiation directivity that is tilted downward at a certain depression angle with respect to the side direction of the dielectric substrate. Therefore, there was a problem that the directional gain is reduced in the side direction of the dielectric substrate in the antenna device, making it difficult to achieve optimal antenna characteristics.

The present invention has been made to solve the above problems, and realizes an antenna device that can improve the radiation directivity in the lateral direction of a dielectric substrate based on the arrangement of an antenna element and multiple ground conductors that are configured on multiple conductor layers of a dielectric substrate.

The present invention has been made to solve the above-mentioned problems, and can be realized in the following form: An antenna device including an antenna element electrically connected to a power supply section, the antenna device including a dielectric substrate, a plurality of conductor layers formed on the dielectric substrate, the plurality of conductor layers being at least a first conductor layer, a second conductor layer, and a third conductor layer arranged in this order from top to bottom in a first direction which is a thickness direction of the dielectric substrate, a first planar electrode formed on the first conductor layer, a second planar electrode formed on the second conductor layer and arranged opposite to the first planar electrode in the first direction, one or more via conductors formed on the dielectric substrate and electrically connecting between the first planar electrode and the second planar electrode, and at least one via conductor formed on each of the first, second, and third conductor layers and arranged such that the first planar electrode is located at a position opposite to the first planar electrode in the first direction. and a plurality of ground conductors arranged in an area not overlapping with first and second planar electrodes, wherein the first planar electrode, the second planar electrode, and the one or more via conductors constitute the antenna element, and a first ground conductor of the third conductor layer among the plurality of ground conductors is located in an area not overlapping with the first planar electrode and the second planar electrode in a plan view seen from a direction perpendicular to the first direction and below the first planar electrode and the second planar electrode in the first direction, and a distance between the first ground conductor and the antenna element is smaller than that between the first ground conductor and the antenna element in the plan view seen from the first direction, as compared with the ground conductors of the first and second conductor layers.
In order to solve the above problem, the antenna device of the present invention is an antenna device including an antenna element (11) electrically connected to a power supply section (25), comprising: a dielectric substrate (10); a plurality of conductor layers (50a to 50f) formed on the dielectric substrate and arranged in a first direction (Z) that is a thickness direction of the dielectric substrate, in that order from top to bottom in the first direction (Z), at least a first conductor layer (50b), a second conductor layer (50d), and a third conductor layer (50f); a first planar electrode (20) formed on the first conductor layer; a second planar electrode (22) formed on the second conductor layer and arranged opposite the first planar electrode in the first direction; and a second planar electrode (23) formed on the dielectric substrate and arranged opposite the first planar electrode in the first direction. and a plurality of ground conductors (12a to 12f, 30 to 32) formed in at least the first, second, and third conductor layers, respectively, and arranged in areas not overlapping with the first and second planar electrodes in a planar view seen from the first direction, wherein the first planar electrode, the second planar electrode, and the one or more via conductors constitute the antenna element, and among the plurality of ground conductors, a first ground conductor (12f) of the third conductor layer has a smaller distance from it to the antenna element in a planar view seen from the first direction, compared to the ground conductors (12b, 12d) of the first and second conductor layers.

According to the antenna device of the present invention, an antenna element and multiple ground conductors are formed on a dielectric substrate, and the antenna element has a so-called bowtie antenna structure due to a group of planar electrodes with a multi-layer structure, and the multiple ground conductor layers are arranged in an area that does not overlap with the antenna element in a planar view from a first direction, while the first ground conductor of the lower third conductor layer is arranged closer to the antenna element than the other ground conductors. Therefore, when the multiple ground conductors and the antenna element are equidistant in a planar view from the first direction, the radiation direction of the electromagnetic wave tends to tilt downward at a certain depression angle from the side direction of the dielectric substrate, but the structure in which the first ground conductor protrudes toward the antenna element can increase the directional gain in the side direction of the dielectric substrate.

In the present invention, the multiple conductor layers are configured to further include one or more fourth conductor layers between the first conductor layer and the second conductor layer, the antenna element is configured to further include one or more third planar electrodes formed in the one or more fourth conductor layers and electrically connected to the first and second planar electrodes through one or more via conductors, and the first ground conductor can be arranged such that the distance between the first ground conductor and the antenna element is smaller than that of the ground conductor of the fourth conductor layer in a planar view seen from the first direction. In this way, by increasing the number of planar electrodes that make up the antenna element, the number of current paths increases, making it possible to widen the frequency band.

Each planar electrode constituting the antenna element of the present invention can be configured in a variety of planar shapes. For example, the first planar electrode, the second planar electrode, and one or more third planar electrodes may each be configured in a rectangular planar shape when viewed from a first direction. In this case, the distance between the first ground conductor and the antenna element when viewed from a first direction can be set to 1/2 the distance between the ground conductors of the first and second conductor layers and the antenna element.

For example, each of the first planar electrode, the second planar electrode, and the one or more third planar electrodes may be configured with a crank shape in which one end of the rectangular longitudinal direction protrudes in a direction perpendicular to the longitudinal direction when viewed from a first direction. In this case, when viewed from a first direction, the end of the first ground conductor can be set at the same position as the tip of the crank shape along the longitudinal direction of each planar electrode.

In the present invention, the ground conductor may be configured to include a component part consisting of a first planar electrode, a second planar electrode, one or more third planar electrodes, and one or more via conductors arranged symmetrically with the first planar electrode, the second planar electrode, one or more third planar electrodes, and one or more via conductors. This allows each antenna element to function as a dipole antenna including the symmetrical ground conductor part, and by ensuring a sufficient area of the ground conductor, it is possible to improve the antenna characteristics.

The antenna element of the present invention can function as a horizontally polarized element. In this case, the polarization direction of the antenna element basically coincides with the longitudinal direction of the dielectric substrate, so that a structure suitable for incorporating the antenna device into a mobile terminal or the like can be easily realized. Note that in order to be able to transmit and receive two different polarized waves, a vertically polarized element may be provided in addition to the horizontally polarized element.

According to the present invention, it is possible to optimize the radiation directivity of electromagnetic waves and sufficiently increase the directional gain in the lateral direction of the dielectric substrate depending on the arrangement of the antenna element constructed using a dielectric substrate and multiple ground conductors. Therefore, it is possible to realize an antenna device that can reliably comply with various standards for radiation directivity and is optimal for being built into mobile terminals, etc.

3B is a cross-sectional view of the antenna device of the present embodiment as viewed from the X direction (cross-section AA in FIG. 3B). 3B is a cross-sectional view of the antenna device of FIG. 1 as viewed from the left side of FIG. 1 along the Y direction (cross-section B-B of FIG. 3B). 2A to 2C are plan views of conductor layers 50a, 50b, and 50c included in the antenna device of FIG. 1, as viewed from above in the Z direction. 2A and 2B are plan views of conductor layers 50d, 50e, and 50f included in the antenna device of FIG. 1, as viewed from above in the Z direction. FIG. 2 is an enlarged perspective view of an antenna element 11 of the antenna device of the present embodiment. 3B is a cross-sectional view of the antenna device of the present embodiment, taken along the Y direction in the same direction as FIG. 2, but taken along a cross section different from FIG. 2 (cross section CC in FIG. 3B). 11A and 11B are diagrams showing verification results of radiation patterns in the XZ plane obtained by simulation for the antenna device of the present embodiment. This is a modified example in which the planar shapes of the planar electrodes 20 to 22 that constitute the antenna element 11 are changed. 9 is a cross-sectional view of an antenna device according to a modified example of FIG. 8, and corresponds to FIG. 6; 1A to 1C are first diagrams illustrating an overview of a method for manufacturing an antenna device according to an embodiment of the present invention. 11 is a second diagram illustrating an outline of the method for manufacturing the antenna device according to the present embodiment. FIG.

Below, a preferred embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below is one example of a form in which the technical concept of the present invention is applied, and the present invention is not limited to the content of this embodiment.

The structure of an antenna device according to an embodiment of the present invention will be described with reference to Figs. 1 to 5. For ease of explanation, the mutually orthogonal X, Y, and Z directions (first directions of the present invention) are indicated by arrows in Figs. 1 to 5. Fig. 1 is a cross-sectional view of the antenna device of this embodiment as viewed from the X direction (cross-section A-A in Fig. 3(B)), Fig. 2 is a cross-sectional view of the antenna device of Fig. 1 as viewed from the left side of Fig. 1 along the Y direction (cross-section B-B in Fig. 3(B)), and Figs. 3 and 4 are plan views of the six conductor layers included in the antenna device of Fig. 1 as viewed from above in the Z direction.

The antenna device of this embodiment is configured using a multi-layered 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, and 22 and a plurality of via conductors 40, a plurality of ground conductors 12a, 12b, 12c, 12d, 12e, and 12f (hereinafter, collectively referred to as ground conductors 12) and three layers of ground conductors 30, 31, and 32. Six conductor layers 50a, 50b, 50c, 50d, 50e, and 50f are formed on the dielectric substrate 10. Using various conductor patterns, planar electrodes 20 to 22 are formed on the conductor layers 50b, 50c, and 50d, and a plurality of ground conductors 12a to 12f, 30 to 32 having a six-layered structure are formed on all of the conductor layers 50a to 50f. In addition to the aforementioned multiple via conductors 40 that are part of the antenna element 11, multiple via conductors 43, 41 that connect the ground conductors 12a-12f, 30-32, and a via conductor 42 for power supply are formed between the conductor layers 50a-50f, each extending in the Z direction.

The dielectric substrate 10 is a rectangular plate-shaped 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 is formed by alternately stacking a dielectric layer having a predetermined dielectric constant and the aforementioned conductor layers 50a to 50f made of a conductive material. In Figs. 3 and 4, the planar structures of the conductor layers 50a, 50b, 50c, 50d, 50e, and 50f are shown in order from the top in the Z direction. Of these, the topmost conductor layer 50a shown in Fig. 3(A) and the bottommost conductor layer 50f shown in Fig. 4(C) are exposed on a pair of surfaces of the dielectric substrate 10 facing each other in the Z direction, and the conductor layers 50b, 50c, 50d, and 50e constitute the inner layers of the dielectric substrate 10. In addition, the bottommost conductor layer 50f is provided with a power supply terminal 25 (power supply point of the present invention) electrically connected to the antenna element 11.

The antenna element 11 has a three-dimensional structure composed of a planar electrode 20 (first planar electrode of the present invention) on the conductor layer 50b, a planar electrode 21 (third planar electrode of the present invention) on the conductor layer 50c, a planar electrode 22 (second planar electrode of the present invention) on the conductor layer 50d, and four via conductors 40 connecting the planar electrodes 20 to 22. All three planar electrodes 20, 21, and 22 have a rectangular planar shape with the Y direction as the longitudinal direction. The four via conductors 40 are arranged side by side at a predetermined interval along the Y direction within the rectangular range of the three planar electrodes 20 to 22. It is desirable to set this predetermined interval to λ0/4 or less, where λ0 is the wavelength used by the antenna device.

As shown in FIG. 3B, one end 20a of the upper planar electrode 20 is connected to a conductor pattern 23 for power supply. This conductor pattern 23 is connected to the upper end of a via conductor 42 for power supply and extends in the X direction, and as shown in FIG. 4C, the lower end of the via conductor 42 for power supply is connected to a power supply terminal 25 of the conductor layer 50f. That is, power is supplied from the power supply terminal 25 to the one end 20a of the planar electrode 20 via the via conductor 42 and the conductor pattern 23. Thus, the via conductor 42 and the conductor pattern 23 form a power supply line between the power supply terminal 25 and the antenna element 11. The power supply terminal 25 has a shape that extends in the X direction by a predetermined length within the area surrounded by the ground conductor 12.

Figure 5 is an enlarged perspective view of the antenna element 11 of the antenna device of this embodiment. As shown in Figure 5, the three planar electrodes 20 to 22 are formed to have the same shape and size, and are arranged in an overlapping area in a plan view from the Z direction. A pair of planar electrodes 20, 21 face each other at a distance H1 in the Z direction, and similarly a pair of planar electrodes 21, 22 face each other at a distance H2 in the Z direction. In the example of Figure 5, H1 = H2 is set. On the other hand, the four via conductors 40 have the same diameter as each other in a plan view from the Z direction, and are arranged side by side at the above-mentioned predetermined intervals along the Y direction. Note that the upper via conductor 40 connecting the planar electrodes 20, 21 and the lower via conductor 40 connecting the planar electrodes 21, 22 are fabricated separately from each other, but here, as long as they are in the same position in a plan view from the Z direction, they are considered to be one via conductor 40.

In FIG. 5, an input signal of a predetermined frequency fed from the power supply terminal 25 through the via conductor 42 and the conductor pattern 23 excites the antenna element 11 consisting of three planar electrodes 20-22 and four via conductors 40, and electromagnetic waves are emitted to the outside. In this embodiment, the length L (FIG. 1) in the Y direction of each of the planar electrodes 20-22 is set to an appropriate value that can resonate with the frequency used, so that the antenna element 11 basically operates as a horizontally polarized element. In this case, as shown in FIG. 5, horizontally polarized electromagnetic waves are radiated from the side surfaces 20b, 21b, and 22b of each of the planar electrodes 20, 21, and 22 toward the X direction. In this case, it is desirable that the radiation direction in which the directivity of the electromagnetic waves is maximized exactly coincides with the X direction when viewed in the XZ plane, and the arrangement of the ground conductor 12 is important for optimizing this. The arrangement of the ground conductor 12 will be described in detail later.

In the antenna element 11 having the structure of FIG. 5, attention is focused on the path through which the current flows when an input signal is supplied. First, for the upper planar electrode 20, the path length from one end 20a along the Y direction is a maximum of length L. On the other hand, the path length of the planar electrodes 21 and 22 must take into account the length of the via conductor 40. Therefore, for the planar electrode 21 directly below, the path length including the Y direction and the Z direction from one end 20a is a maximum of L+H1, and for the lower planar electrode 22, the path length including the Y direction and the Z direction from one end 20a is a maximum of L+H1+H2. In this way, the antenna element 11 has a variety of different path lengths for the input signal, and has a structure suitable for widening the bandwidth of the antenna characteristics.

As shown in Figs. 3 and 4, the ground conductors 12a to 12f are arranged over the six conductor layers 50a to 50f, and have a multi-layer structure in which the ground conductors 12a to 12f are electrically connected to each other through a plurality of via conductors 43. Of these, only the ground conductor 12a is arranged on the conductor layer 50a on one surface of the dielectric substrate 10. The five via conductors 43 connected to this ground conductor 12a extend linearly along the Z direction and are electrically connected to the corresponding locations of the ground conductor layers 12b to 12f. The areas of the six ground conductors 12a to 12f are arranged generally opposite each other in the Z direction. However, depending on the arrangement of the antenna element 11, the ground conductors 12b and 12c have a shape in which the central inner portion is cut out. In addition, from the viewpoint of optimizing the radiation direction of the antenna device, the ground conductor 12f on the bottom layer protrudes toward the antenna element 11 facing in the X direction, but this point will be described later.

Here, when focusing on the conductor layers 50b, 50c, and 50d, the ground conductors 30, 31, and 32 of the three layers are arranged symmetrically with the antenna element 11. Specifically, the ground conductors 30, 31, and 32 of the three layers have a planar shape in which the planar electrodes 20, 21, and 22 of the three layers are moved to the right in the Y direction in Figures 3 and 4. In addition, four via conductors 41 connecting the ground conductors 30, 31, and 32 of the three layers are arranged in positions symmetrical to the four via conductors 40 connecting the planar electrodes 20, 21, and 22 of the three layers. The ground conductor 32 of the lower conductor layer 50d is connected to the ground conductor 12d of the same layer through a conductor pattern 24 extending in the X direction. In this way, the structure in which the planar electrodes 20 to 22 and the ground conductors 30 to 32 of the antenna element 11 are arranged symmetrically functions as a dipole antenna, and has the effect of increasing the gain of the antenna device to a certain extent.

The entire ground conductors 12, 30 to 32 formed on the dielectric substrate 10 function as a reflector for the antenna device of this embodiment. In other words, a mirror image of the antenna element 11 is formed on the entire ground conductors 12, 30 to 32, so it is necessary to ensure a sufficient overall ground area to improve the antenna characteristics. However, it is desirable to arrange the ground conductors 12, 30 to 32 so that they do not overlap with the antenna element 11 in a plan view seen from the Z direction.

Next, the arrangement and effect of the multiple ground conductors 12 included in the antenna device of this embodiment will be described with reference to Figures 6 and 7. Figure 6 is a cross-sectional view of the antenna device of Figure 1 viewed from the same direction as Figure 2 along the Y direction, and is a cross-sectional view viewed from a different cross section (C-C cross section of Figure 3 (B)) from Figure 2. Figure 6 shows the distance in the X direction between each of the ground conductors 12a to 12f and the antenna element 11. First, the five ground conductors 12a to 12e in the range from the conductor layer 50a to the conductor layer 50e are all disposed at the same distance D1 along the X direction between the antenna element 11 and each of the five layers. In contrast, the ground conductor 12f of the bottom conductor layer 50f and the antenna element 11 are disposed at a distance D2, which is smaller than the distance D1, along the X direction, reflecting the planar shape of Figure 4 (C). In the example of Figure 6, the distance D2 is set to approximately 1/2 of the distance D1. Distances D1 and D2 are the distances between the planar electrodes 20-22 of the antenna element 11 facing each other in the X direction and the ground conductor 12, but because the basic shape of each is roughly rectangular when viewed from the Z direction, they are equal to the distance between the long sides parallel to the Y direction.

In this embodiment, only the bottom ground conductor 12f is structured to protrude toward the antenna element 11 along the X direction, thereby improving the directional gain in the XZ plane. FIG. 7 is a diagram showing the verification results of the radiation pattern in the XZ plane obtained by simulation for the antenna device of this embodiment. In FIG. 7, in addition to the radiation pattern P1 of this embodiment, a radiation pattern P2 in which the distance between the ground conductor 12f and the antenna element 11 is set to the same distance D1 as the other ground conductors 12 is superimposed as a comparative example, and a simulation was performed by feeding an input signal with a frequency of 30 GHz to the antenna device.

As is clear from FIG. 7, the radiation pattern P1 of this embodiment has a directional gain of 3.3 dBi in the X direction (90°), which is sufficiently larger than the 1.7 dBi obtained by the radiation pattern P2 of the comparative example. That is, in the comparative example, due to the positional relationship between the antenna element 11 having a so-called bowtie antenna structure and the ground conductor 12 having a six-layer structure, the peak of the directivity tends to point slightly downward in the X direction. In contrast, the ground conductor 12f of the lowest layer of this embodiment is arranged to protrude toward the antenna element 11 side (FIG. 6), so that the function of the ground conductor 12f of the lowest layer as a reflector is enhanced, and the directivity peak is inclined upward in the X direction more than in the comparative example, resulting in an improved directional gain at 90°. In this way, the antenna device of this embodiment has a peak in the radiation direction of the electromagnetic waves in the X direction (side direction of the dielectric substrate 10), so that the antenna device as a whole can be easily made thin when placed inside a mobile terminal, etc., and antenna characteristics that meet the requirements for radiation directivity such as beamforming of the 5G standard can be reliably realized.

The antenna device of this embodiment is not limited to the above-mentioned structure, and various modifications are possible. Figures 8 and 9 show modified examples in which the planar shapes of the planar electrodes 20 to 22 constituting the antenna element 11 are modified. Figure 8 shows the planar structure of the conductor layer 50c in this modified example, similar to that in Figure 3(C), and Figure 9 is a cross-sectional view (cross section D-D in Figure 8) of the antenna device according to this modified example, seen from the same direction as Figure 6 along the Y direction. In this modified example, the planar shape of the antenna element 11 is modified from a rectangular shape to a crank shape. Note that the conductor layers 50a and 50d including the antenna element 11 are not shown, but the same planar shape as in Figure 8 is basically applied.

As shown in FIG. 8, the planar electrode 21 constituting the antenna element 11 has a crank shape with a protrusion 21c protruding in the X direction connected to one end of a rectangle whose long side is the Y direction. The ground conductor 31, which is symmetrical to the planar electrode 21, has a crank shape with a protrusion 31c protruding in the X direction connected to one end of a rectangle, similar to the planar electrode 21. The other planar electrodes 20, 22 and the ground conductors 30, 32 also have a crank shape with similar protrusions. As shown in FIG. 9, the distance D2 between the ground conductors 12b, 12c, 12d and the antenna element 11 is approximately 1/2 the distance D1 in FIG. 1 along the X direction. On the other hand, the ground conductor 12f in the lowest layer and the antenna element 11 are in a positional relationship in which their ends are at the same position X1 in the X direction.

By adopting the structure of this modified example, the planar shape of the antenna element 11 changes from a simple rectangle to a crank shape, and the path length can be relatively increased. Therefore, less space is required on the dielectric substrate 10 when tuning the antenna element 11 to a specific wavelength, which is advantageous for miniaturizing the antenna device. Note that the structures shown in Figures 8 and 9 are just examples, and the antenna element 11 may be configured with a different crank shape, and the ends of the ground conductor 12f and the antenna element 11 may be set at positions that are somewhat separated from each other rather than at the same position X1.

Next, an overview of the method for fabricating the antenna device of this embodiment will be described with reference to Figures 10 and 11. First, a plurality of ceramic green sheets 60 for low-temperature firing formed by, for example, a doctor blade method are prepared as a plurality of dielectric layers constituting the dielectric substrate 10. Then, as shown in Figure 10 (A), a punching process is performed at predetermined positions of each ceramic green sheet 60 to open a plurality of via holes 61. The positions and number of each via hole 61 in each ceramic green sheet 60 are set corresponding to the arrangement of the plurality of via conductors 40, 41, 42, 43 in Figures 1 and 2.

Next, as shown in FIG. 10(B), a conductive paste containing Cu is screen-printed to fill each of the via holes 61 opened in each ceramic green sheet 60, thereby forming a plurality of via conductors 40, 41, etc. Then, as shown in FIG. 11(A), a conductive paste containing Cu is screen-printed to the front or back surface of each ceramic green sheet 60, thereby forming the conductor patterns of the conductor layers 50a to 50f. The conductor patterns formed at this time and the aforementioned via conductors 40, 41, etc. define the basic structure of the antenna device, including the antenna element 11 and ground conductors 12, 30 to 32.

As shown in FIG. 11(B), a plurality of ceramic green sheets 60 are stacked in order and heated and pressurized to form a laminate. The resulting laminate is then degreased and fired to complete the antenna device configured on the dielectric substrate 10 as described in this embodiment.

Although the contents of the present invention have been specifically described above based on the present embodiment, the present invention is not limited to the above embodiment, and can be modified within the scope of the gist of the present invention. In other words, the structure of the antenna device described using Figures 1 to 9 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. For example, the planar shape of the planar electrodes 20 to 22 constituting the antenna element 11 is not limited to a rectangular or crank shape, and various planar shapes can be adopted as long as the effects of the present invention can be obtained. In addition, the antenna element 11 is not limited to the use of three planar electrodes 20 to 22, and can be configured using two planar electrodes or four or more planar electrodes. Furthermore, the number of via conductors 41 connecting the planar electrodes 20 to 22 can be appropriately increased or decreased.

Meanwhile, in this embodiment, a structure is shown in which the ground conductor 12f in the bottom layer protrudes toward the antenna element 11, but the present invention can be applied to any structure in which a specific ground conductor located below the antenna element 11 protrudes toward the antenna element 11. Also, in this embodiment, the ground conductors 30 to 32 are arranged symmetrically with the antenna element 11, and the two function together as a dipole antenna, but as long as only the antenna element 11 and the ground conductor 12 are appropriately arranged, the present invention can be applied even if the symmetrical ground conductors 30 to 32 are not provided. In this case, the antenna element 11 functions as a monopole antenna.

10...Dielectric substrate 11...Antenna element 12, 30, 31, 32...Ground conductor 20, 21, 22...Planar electrode 23, 24...Conductor pattern 25...Power supply terminal 40, 41, 42, 43...Via conductor 50a, 50b, 50c, 50d, 50e, 50f...Conductor layer

Claims (8)

An antenna device including an antenna element electrically connected to a power supply,
A dielectric substrate;
a plurality of conductor layers formed on the dielectric substrate, the conductor layers including at least a first conductor layer, a second conductor layer, and a third conductor layer arranged in this order from top to bottom in a first direction which is a thickness direction of the dielectric substrate;
a first planar electrode formed on the first conductor layer;
a second planar electrode formed on the second conductor layer and disposed opposite the first planar electrode in the first direction;
one or more via conductors formed on the dielectric substrate and electrically connecting the first planar electrode and the second planar electrode;
at least a plurality of ground conductors formed in each of the first, second, and third conductor layers and arranged in areas not overlapping with the first and second planar electrodes in a plan view seen from the first direction;
Equipped with
the first planar electrode, the second planar electrode, and the one or more via conductors constitute the antenna element;
a first ground conductor of the third conductor layer among the plurality of ground conductors is located in a region that does not overlap with the first planar electrode and the second planar electrode in a planar view seen from a direction perpendicular to the first direction and is located below the first planar electrode and the second planar electrode in the first direction, and a distance between the first ground conductor and the antenna element is smaller than that between the first ground conductor and the ground conductors of the first and second conductor layers in the planar view seen from the first direction;
1. An antenna device comprising: the plurality of conductor layers further includes one or more fourth conductor layers between the first conductor layer and the second conductor layer;
the antenna element further includes one or more third planar electrodes formed in the one or more fourth conductor layers and electrically connected to the first and second planar electrodes through the one or more via conductors,
a distance between the first ground conductor and the antenna element is smaller than a distance between the first ground conductor and the antenna element in a plan view seen from the first direction, compared to a distance between the first ground conductor and the antenna element and a ground conductor of the fourth conductor layer;
2. The antenna device according to claim 1 . The antenna device according to claim 2, characterized in that each of the first planar electrode, the second planar electrode, and the one or more third planar electrodes has a rectangular planar shape when viewed from the first direction. The antenna device according to claim 1 or 2, characterized in that, in a plan view seen from the first direction, the distance between the first ground conductor and the antenna element corresponds to 1/2 of the distance between the ground conductors of the first and second conductor layers and the antenna element. The antenna device according to claim 3, characterized in that each of the first planar electrode, the second planar electrode, and the one or more third planar electrodes has a crank shape in which one end of the longitudinal direction of the rectangle protrudes in a direction perpendicular to the longitudinal direction in a plan view seen from the first direction. The antenna device according to claim 5, characterized in that, in a plan view seen from the first direction, the first ground conductor has an end portion along the longitudinal direction at the same position as the tip portion of the crank shape. The antenna device according to claim 2, characterized in that the ground conductor includes components consisting of a first planar electrode, the second planar electrode, the one or more third planar electrodes, a plurality of planar electrodes arranged symmetrically with the one or more via conductors, and one or more via conductors. The antenna device according to claim 1, characterized in that the antenna element functions as a horizontally polarized element.

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