JP2022102706A - Array antenna - Google Patents

Abstract

To achieve an array antenna capable of improving the antenna gain in the horizontal direction of a substrate on the basis of an arrangement of a plurality of antenna elements.SOLUTION: An array antenna 10 includes antenna elements 20 to 23 embedded in a dielectric substrate 11. The antenna elements 20, 23 are arranged at a location Z1 in the Z-direction. The antenna elements 21, 22 are arranged at a location Z2, which is different from the location Z1 in the Z direction. The dielectric substrate 11 has surfaces 11a, 11b opposing each other in the Z-direction and a side surface 11c between them. Radio waves from the antenna elements 20 to 23 are radiated to the outside through the side surface 11c.SELECTED DRAWING: Figure 1

Description

The present invention relates to an array antenna in which a plurality of antenna elements are configured by using a dielectric substrate.

Conventionally, an array antenna in which a plurality of antenna elements are arranged side by side in an array is known. For example, Patent Document 1 describes an array antenna structure capable of achieving wide directivity by arranging a plurality of loop-shaped antenna elements on the same plane or parallel planes on the surface of a dielectric substrate. It has been disclosed. Further, for example, Patent Document 2 discloses a structure of an array antenna capable of controlling the radiation direction of an antenna beam by arranging a plurality of helical antenna elements and non-feeding helical antenna elements on the same plane of the substrate surface. ing.

Japanese Unexamined Patent Publication No. 2007-288537 Japanese Patent No. 3417682

In recent years, when an array antenna composed of a plurality of antenna elements is configured, a structure using a dielectric substrate has been widely used from the viewpoint of compactness and weight reduction. For an array antenna using a dielectric substrate, it is particularly required to enhance the horizontal radiation directivity of the dielectric substrate. However, according to the structure of the conventional array antenna, since a plurality of antenna elements are arranged on the surface of the dielectric substrate, the arrangement of the plurality of antenna elements is in the thickness direction with respect to the region where the dielectric constant is high. It is a biased arrangement. As a result of the verification by the inventors, it was found that the radiation direction of the radio wave becomes the radiation directivity diagonally upward or diagonally downward from the horizontal direction of the substrate due to the difference in the dielectric constant in the vicinity of the plurality of antenna elements. As a result, there is a problem that the antenna gain in the horizontal direction of the substrate of the array antenna is lowered.

The present invention has been made to solve the above-mentioned problems, and a plurality of antenna elements are arranged by effectively utilizing the space in the substrate, and the antenna gain of the plurality of antenna elements in the horizontal direction of the substrate is improved. It is intended to realize an array antenna that can achieve the above.

In order to solve the above problems, the array antenna of the present invention is an array antenna using a dielectric substrate formed by laminating a dielectric layer and a conductor layer, and is embedded in the dielectric substrate and is embedded in the conductor layer. The 2N (N is a natural number) antenna elements configured by using the formed conductor pattern are provided, and the 2N antenna elements are N arranged at the first position in the thickness direction of the dielectric substrate. It consists of a first antenna element and N second antenna elements arranged at a second position different from the first position in the thickness direction of the dielectric substrate. The dielectric substrate has a first surface and a second surface facing each other in the thickness direction, and a first side surface arranged between the first surface and the second surface. , The radio waves from the N antenna elements are radiated to the outside through the first side surface.

According to the array antenna of the present invention, the plurality of antenna elements embedded in the dielectric substrate are arranged in the same number at the first position and the second position, which are different in the thickness direction. Therefore, each antenna element has two radiation directions inclined up and down from the horizontal direction of the substrate due to the difference in the wavelength shortening effect depending on the position, but the combined radiation directivity of all the antenna elements is the desired radiation direction. Can be properly controlled to have a peak at.

In the present invention, regarding the center position in the thickness direction of the dielectric substrate, the first position is set between the first surface and the center position, and the second position is set between the second surface and the center position. It is desirable to set to. In this case, the first position and the second position can be set to positions symmetrical to each other with respect to the central position. As a result, it is possible to cancel the vertical inclination of the antenna elements at the two positions with respect to the horizontal direction of the substrate, and it is possible to control the combined radiation directivity so as to be substantially oriented in the horizontal direction of the substrate.

In the present invention, 2N antenna elements are arranged side by side in the first direction parallel to the first side surface in a plan view seen from the thickness direction of the dielectric substrate, and are arranged in the thickness direction on the dielectric substrate. In a plan view from the viewpoint, the first side surface and the first region where 2N antenna elements are arranged and the second region where one layer or a plurality of layers of ground conductors are arranged are divided into a first region. The region and the second region can be arranged so as to face each other in the thickness direction and the second direction orthogonal to the first direction. As a result, the radial direction of the 2N antenna elements in the first region is affected by the presence of the ground conductor in the second region, and therefore can be controlled so as to face the first side surface on the opposite side thereof. ..

In the above structure, when four or more antenna elements are provided, at least two first antenna elements can be arranged adjacent to each other in the central portion in the first direction in the first region. Alternatively, when four or more antenna elements are provided, at least two second antenna elements can be arranged adjacent to each other in the central portion in the first direction in the first region. With such an arrangement, it is possible to effectively utilize the desired electronic component or the like by placing it in the space directly above or directly below the central portion in the first direction.

In the present invention, the 2N antenna elements can be configured to have the same planar shape in a plan view from the thickness direction. This makes it possible to easily control the radiation directivity according to two positions that differ in the thickness direction. In this case, each of the 2N antenna elements can use a horizontally polarized wave antenna element.

According to the present invention, by arranging a plurality of antenna elements embedded in a dielectric substrate at two positions different in the thickness direction, a relatively simple structure can be used to appropriately control the radiation directivity in the horizontal direction of the substrate. It is possible to realize an array antenna that can be used.

It is a perspective view which shows the whole structure of the array antenna 10 of this embodiment. It is a schematic side view which looked at the array antenna 10 of FIG. 1 from the direction of arrow A along the X direction. It is a schematic side view which looked at the array antenna 10 of FIG. 1 from the arrow B direction along the Y direction. FIG. 3 is a plan view of a portion of the antenna element 20 included in the array antenna 10 of FIG. 1 as viewed from above in the Z direction. It is a figure which shows the 1st comparative example which arranged all 4 antenna elements 20 to 23 at the position Z1 in the Z direction. It is a figure which shows the 2nd comparative example in the case where all four antenna elements 20 to 23 are arranged at the position Z2 in the Z direction. It is a figure which shows the structure which arranged the four antenna elements 20 to 23 at two different positions Z1 and Z2 described in this embodiment. It is a side view which shows the structure of the 1st modification. It is a side view which shows the structure of the 2nd modification.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In this embodiment, an array antenna that embodies the present invention will be described. However, the embodiments described below are examples of embodiments to which the present invention is applied, and the present invention is not limited to the contents of the present embodiment.

Hereinafter, structural examples of the array antenna to which the present invention is applied will be described with reference to FIGS. 1 to 4. FIG. 1 is a perspective view showing the overall structure of the array antenna 10 of the present embodiment. In FIG. 1, for convenience of explanation, the X direction, the Y direction, and the Z direction orthogonal to each other are indicated by arrows, and the same applies to FIGS. 2 to 4 below. FIG. 2 is a schematic side view of the array antenna 10 of FIG. 1 as viewed from the direction of arrow A along the X direction, and FIG. 3 is a side view of the array antenna 10 of FIG. 1 from the direction of arrow B along the direction of Y. It is a schematic side view as seen. Further, FIG. 4 is a plan view of a portion of the antenna element 20 included in the array antenna 10 of FIG. 1 as viewed from above in the Z direction.

The array antenna 10 of the present embodiment is configured by using a dielectric substrate 11 made of a dielectric material having a predetermined dielectric constant. The dielectric substrate 11 has a multilayer structure in which a dielectric layer and a conductor layer L (FIGS. 2 and 3) are laminated, and has a short side along the X direction (the second direction of the present invention) and the Y direction (the second direction). It is a rectangular parallelepiped plate-like member having a long side along the first direction of the present invention) and a predetermined thickness along the Z direction (thickness direction of the present invention). Four antenna elements 20, 21, 22, and 23 are embedded inside the dielectric substrate 11. These four antenna elements 20 to 23 are configured by using the conductor pattern of each conductor layer L, and are arranged side by side at substantially equal intervals in the Y direction. Each of the four antenna elements 20 to 23 radiates a horizontally polarized radio wave to the outside via the side surface 11c (first side surface of the present invention) of the dielectric substrate 11.

As shown in FIGS. 2 and 3, the dielectric substrate 11 has a lower surface 11a (first surface of the present invention) and an upper surface 11b (second surface of the present invention) in the Z direction. A plurality of conductor layers L are formed along the surfaces 11a and 11b, and various conductor patterns are formed on the respective conductor layers L. In the dielectric substrate 11, the plurality of conductor layers L are connected to each other via a plurality of via conductors (not shown) penetrating the dielectric layer in the Z direction. Further, as shown in FIG. 3, the dielectric substrate 11 has an antenna region A1 (first region of the present invention) and an RF region A2 (the present invention) facing each other in the X direction with the boundary position XB in the X direction as a boundary. It is divided into the second area). Four antenna elements 20 to 23 are mainly formed in the antenna region A1, and an RF circuit (not shown) mainly including a multi-layered ground conductor 12 and a feeding path is configured in the RF region A2.

Further, as shown in FIGS. 2 and 3, two different positions Z1 (first position of the present invention) and position Z2 (first position of the present invention) and positions Z2 (first position of the present invention) are used as positions of the four antenna elements 20 to 23 in the Z direction. There is a position of 2). Then, in order from the left side of FIG. 2, the antenna element 20 is arranged at the position Z1, the antenna element 21 is arranged at the position Z2, the antenna element 22 is arranged at the position Z2, and the antenna element 23 is arranged at the position Z1. In the present embodiment, these two positions Z1 and Z2 are set to positions symmetrical to each other with respect to the central position in the Z direction. In other words, the distance from the lower surface 11a to the antenna elements 20 and 23 at position Z1 (the first antenna element of the present invention) and the antenna elements 21 and 22 at the position Z2 from the upper surface 11b (the second of the present invention). The distance to the antenna element) is set to be equal. Such an arrangement is effective for proper control of the overall radiation directivity of the array antenna 11, which will be described in detail later.

Here, the structure of the antenna element 20 will be described with reference to FIG. The basic structure of the other antenna elements 21 to 23 is the same as that of the antenna element 20. As shown in FIG. 4, the antenna element 20 includes a signal-side connecting conductor 30, a ground-side connecting conductor 31, a signal-side radiating element 32, and a ground-side radiating element 33. FIG. 4 shows the above-mentioned boundary position XB (FIG. 3), and shows only the planar shape of the antenna element 20 in the antenna region A1. As described above, in the antenna element 20 of the present embodiment, particularly the signal side radiating element 32 and the ground side radiating element 33 have a so-called dipole antenna structure.

In FIG. 4, a pair of signal-side connecting conductors 30 and ground-side connecting conductors 31 arranged in parallel extend in the X direction from their respective ends 30a and 31a, respectively. A signal-side radiating element 32 is connected to the tip of the signal-side connecting conductor 30, and a ground-side radiating element 33 is connected to the tip of the ground-side connecting conductor 31. The pair of signal-side radiating elements 32 and ground-side radiating elements 33 extend in opposite directions in the Y direction. The antenna element 20 radiates a horizontally polarized radio wave having a symmetrical planar shape on the signal side and the ground side and having an electric field component in the Y direction. On the other hand, the end portion 30a of the signal-side connecting conductor 30 is connected to the feeding path 13 formed in the conductor layer L, and the end portion 31a of the ground-side connecting conductor 31 is connected to the predetermined ground conductor 12. Although not shown in FIGS. 1 to 3, a feeding structure including a feeding path 13 is formed in the plurality of conductor layers L, and high-frequency signals from electronic components inside the dielectric substrate 11 and connection pads exposed to the outside are transmitted. It is input to each end portion 30a via the feeding path 13.

The ground conductor 12 can be provided in all the conductor layers L, but it is desirable that the ground conductor 12 is provided in at least two conductor layers L in which the antenna elements 20 to 23 are arranged. Increasing the area of the ground conductor 12 in the dielectric substrate 11 contributes to the improvement of the antenna performance of the array antenna 10. Further, the antenna elements 20 to 23 mainly radiate radio waves through the side surface 11c, and the radiation level from the opposite side surface facing in the X direction is suppressed, which is affected by the presence of the multi-layered ground conductor 12. To receive.

Next, the relationship between the arrangement and the radiation directivity in the array antenna 10 of the present embodiment will be described with reference to FIGS. 5 to 7. Here, as two types of comparative examples to be compared with the array antenna 10 of the present embodiment, FIG. 5 shows a first comparative example in which all four antenna elements 20 to 23 are arranged at the position Z1 in the Z direction. FIG. 6 shows a second comparative example in which all four antenna elements 20 to 23 are arranged at the position Z2 in the Z direction. Further, FIG. 7 shows a structure in which the four antenna elements 20 to 23 are arranged at the two different positions Z1 and Z2 described in the present embodiment. 5 (A), 6 (A), and 7 (A) are simplified side views corresponding to FIG. 2, and FIGS. 5 (B), 6 (B), and 7 (B). ) Is a simplified side view corresponding to FIG.

First, in the first comparative example, as shown in FIG. 5A, all of the four antenna elements 20 to 23 are arranged at the lower position Z1, and the other positional relationships in the X and Y directions are It is assumed that it is common with this embodiment. In this case, according to the verification by the inventors, as shown in FIG. 5B, the radiation directivity of the antenna elements 20 to 23 faces the radiation direction D1 diagonally upward with respect to the direction along the X direction. Further, the combined radiation directivity of the four antenna elements 20 to 23 also faces the same radiation direction D1. This is because when the antenna elements 20 to 23 are arranged at the lower position Z1 in the dielectric substrate 11, the surrounding dielectric material becomes thicker on the upper side than on the lower side, and as a result, the upper and lower wavelength shortening effect is obtained. It is assumed that the radial direction D1 is tilted upward due to the difference between the two.

Next, in the second comparative example, as shown in FIG. 6A, all of the four antenna elements 20 to 23 are arranged at the upper position Z2, and the other positions in the X direction and the Y direction. It is assumed that the relationship is common to this embodiment. In this case, according to the verification by the inventors, as shown in FIG. 6B, the radiation directivity of the antenna elements 20 to 23 faces the radiation direction D2 diagonally downward with respect to the direction along the X direction. Further, the combined radiation directivity of the four antenna elements 20 to 23 also faces the same radiation direction D2. This is because, as described in the first comparative example, when the antenna elements 20 to 23 are arranged at the upper position Z2 in the dielectric substrate 11, the surrounding dielectric material is thicker on the lower side than on the upper side. As a result, it is assumed that the radiation direction D2 is tilted downward due to the difference in the upper and lower wavelength shortening effects.

On the other hand, in the array antenna 10 of the present embodiment, as shown in FIG. 7A, the two antenna elements 20 and 23 are arranged at the lower position Z1 and the two antenna elements 21 and 22 are arranged. It is located at the upper position Z2. Therefore, as shown in FIG. 7B, among the antenna elements 20 to 23 having the same structure, the radiation directivity of each of the antenna elements 20 to 23 faces the radiation directions D1 and D2, respectively, and the radiation directivity obtained by synthesizing them. The property is directed to the radial direction D3 along the X direction, and the gain in the horizontal direction of the substrate can be improved. Even when all the antenna elements 20 to 23 are arranged at the center position in the Z direction, the radiation directivity D3 along the X direction can be obtained, but in the configuration of the present embodiment, the antenna elements 20 to 23 are arranged in the Z direction. Since it is not restricted by the center position of, the degree of freedom of arrangement can be increased.

The array antenna 10 to which the present invention is applied is not limited to the structures shown in FIGS. 1 to 4, and has various modifications as described below. FIG. 8 is a configuration of the first modification, and shows a side view seen from the same direction as in FIG. 2. In the first modification, the positions Z1 and Z2 in the Z direction are alternately arranged in the order of arrangement in the antenna elements 20 to 23. Even in this case, the positions Z1 and Z2 in the antenna elements 20 to 23 are two each, and the combined directivity faces the radiation direction D3 similar to that in FIG. 7B. Comparing FIGS. 2 and 8, two antenna elements 21 and 22 are arranged adjacent to each other in the center of FIG. 2 in the Y direction, and a relatively large space is formed directly under the antenna elements 21 and 22 in the dielectric substrate 11. exist. Therefore, it is possible to effectively use the space by forming an opening and placing an electronic component such as an IC chip in the opening. On the other hand, if space for mounting electronic components is not required, the first modification may be adopted.

Further, FIG. 9 is a configuration of the second modification, and shows a side view seen from the same direction as in FIG. In the second modification, the two positions Z1 and Z2'of the antenna elements 20 to 23 are asymmetric in the Z direction. That is, the distance between the upper position Z2'and the surface 11b is longer than the distance between the lower position Z1 and the surface 11a. Therefore, it is assumed that the radiation directivity synthesized in the second modification is in the radiation direction slightly upward from the X direction as compared with the radiation direction D3 in FIG. 7 (b), but the peak at this time. As long as the radiation direction of is within the allowable range of radiation directivity, the second modification may be adopted.

The second modification shown in FIG. 9 can be more generalized, and the present invention can be applied as long as the two positions Z1 and Z2 of the antenna elements 20 to 23 have different relationships in the Z direction. For example, in FIG. 2, the two different positions Z1 and Z2 may both be set below the center in the Z direction, or both may be set above the center in the Z direction. Any configuration can be adopted if the combined radiation directivity is within the allowable radiation direction. For example, from the viewpoint of component placement in the dielectric substrate 11, when the antenna elements 20 to 23 are subject to placement restrictions, the configuration is adopted to appropriately control the radiation direction.

Further, the number of antenna elements 20 to 23 is not limited to four, and if the same number of antenna elements are arranged at the two positions Z1 and Z2, 2N (N is a natural number) antenna elements can be arranged. can. That is, of the 2N antenna elements, N antenna elements may be arranged at position Z1 and the remaining N antenna elements may be arranged at position Z2. Further, the distance between the antenna elements arranged in the Y direction is not limited to equal intervals, and the antenna elements can be arranged side by side at unequal intervals.

Further, each of the antenna elements 20 to 23 is not limited to the antenna shape having the dipole configuration shown in FIG. 4, and various antenna shapes can be adopted. For example, as an applicable antenna shape, an antenna shape such as a meander antenna, a bow tie antenna, or a log-periodic antenna can be adopted. Further, the applicable antenna shape is not limited to the flat antenna shape, and an antenna shape having a three-dimensional structure may be adopted. That is, a three-dimensional antenna shape can be formed by combining a plurality of conductor patterns and a plurality of via conductors. If there is a thickness of the antenna element having a three-dimensional structure, the positions Z1 and Z2 can be determined by the center position in the Z direction in the thickness of the antenna element.

When manufacturing the array antenna 10 of the present embodiment, for example, a plurality of ceramic green sheets for low-temperature firing formed by the doctor blade method are prepared, and a plurality of via holes are formed in each ceramic green sheet by punching. do. Then, each via hole is filled with the conductive paste by screen printing to form a plurality of via conductors, and the surface of each ceramic green sheet is coated with the conductive paste by screen printing to form a plurality of via conductors. Form a conductor pattern. The plurality of conductor patterns and the plurality of via conductors thus formed can form a basic structure such as a plurality of antenna elements and a ground conductor. Next, a plurality of ceramic green sheets are laminated in order, heated and pressed, and the obtained laminate is degreased and fired to complete the array antenna 10 configured on the dielectric substrate 11 as described in the present embodiment. do.

Although the content of the present invention has been specifically described above based on the present embodiment, the present invention is not limited to the above-described embodiment, and changes can be made without departing from the gist thereof. That is, the basic structure of the array antenna 10 described with reference to FIGS. 1 to 4 widely applies the present invention to various array antennas using other structures and materials as long as the effects of the present invention can be obtained. can do. For example, the type of antenna element, the planar shape or the three-dimensional shape, the feeding method, the size, and the like can be variously changed as long as the effects of the present invention can be obtained.

10 ... Array antenna 11 ... Dielectric substrate 11a, 11b ... Surface 11c ... Side surface 12 ... Ground conductor 13 ... Feeding path 20, 21, 22, 23 ... Antenna element 30 ... Signal side connecting conductor 31 ... Ground side connecting conductor 32 ... Signal Side radiation element 33 ... Ground side radiation element L ... Conductor layer A1 ... Antenna region A2 ... RF region

Claims (8)

An array antenna using a dielectric substrate made by laminating a dielectric layer and a conductor layer.
It is provided with 2N (N is a natural number) antenna elements embedded in the dielectric substrate and configured by using a conductor pattern formed in the conductor layer.
The 2N antenna elements are
N first antenna elements arranged at the first position in the thickness direction of the dielectric substrate, and
N second antenna elements arranged at a second position different from the first position in the thickness direction of the dielectric substrate, and
Consists of
The dielectric substrate is
The first surface and the second surface facing each other in the thickness direction,
A first side surface disposed between the first surface and the second surface,
The radio waves from the N antenna elements are radiated to the outside through the first side surface.
An array antenna that features that. With respect to the center position of the dielectric substrate in the thickness direction, the first position is set between the first surface and the center position, and the second position is the second surface and the center. Set between the position,
The array antenna according to claim 1. The array antenna according to claim 2, wherein the first position and the second position are set to positions symmetrical with respect to the central position. The 2N antenna elements are arranged side by side in the first direction parallel to the first side surface in a plan view seen from the thickness direction of the dielectric substrate.
On the dielectric substrate, a first region in which the first side surface and the 2N antenna elements are arranged and a one-layer or a plurality of layers of ground conductors are arranged in a plan view from the thickness direction. It is divided into the second area, which is divided into two areas.
The first region and the second region are arranged so as to face each other in the thickness direction and the second direction orthogonal to the first direction.
The array antenna according to any one of claims 1 to 3, wherein the array antenna is characterized by the above. The fourth aspect of the present invention is characterized in that the N is 2 or more, and at least two first antenna elements are arranged adjacent to each other in the central portion of the first region in the first direction. The array antenna described. The fourth aspect of the present invention is characterized in that the number of N is 2 or more, and at least two of the second antenna elements are adjacent to each other in the central portion of the first region in the first direction. The array antenna described. The array antenna according to any one of claims 1 to 6, wherein the 2N antenna elements have the same planar shape in a plan view when viewed from the thickness direction. The array antenna according to claim 7, wherein each of the 2N antenna elements is a horizontally polarized wave antenna element.

Images