Antenna Board

Abstract

To improve antenna characteristics in an antenna substrate having a hollow structure.SOLUTION: An antenna substrate is formed by laminating a plurality of lamination units each having a dielectric layer and an element provided on the upper surface of the dielectric layer, the lowest element is a feeding element, the elements other than the feeding element are parasitic elements, a first lamination unit including at least a lamination unit having the feeding element includes an intermediate dielectric layer having square outer peripheral shape and inner peripheral shape when viewed in plan view between a dielectric layer provided in the first lamination unit and a dielectric layer in the second lamination unit adjacent on the first lamination unit, one of a fact that the ratio of the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second lamination unit to the thickness of the intermediate dielectric layer is within the range of 1.1:0.2 to 1.05, and a fact that the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery in the intermediate dielectric layer is within the range of 8.8:2.2 to 8.7 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an antenna substrate. [Background technology]

[0002] Conventionally, there is known an antenna substrate in which a plurality of dielectric layers and a plurality of conductor layers are alternately laminated (see, for example, Patent Document 1). In the antenna substrate described in Patent Document 1, a hollow structure is provided on the conductor layer inside the antenna substrate, thereby suppressing dielectric loss. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-252304 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inventors of the present application have found that, although it is possible to reduce dielectric loss when a hollow structure is provided in an antenna substrate as described above, there is a possibility that sufficient antenna characteristics cannot be obtained depending on the dimensions of the hollow structure. A technology for improving the antenna characteristics of an antenna substrate having a hollow structure is desired. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms. (1) According to one embodiment of the present disclosure, there is provided an antenna substrate, the antenna substrate being formed by stacking a plurality of stacking units, each stacking unit including a flat dielectric layer made of a dielectric material and an element made of a conductive material provided on an upper surface of the dielectric layer, in a stacking direction of the dielectric layer and the elements, the element disposed at the bottom of each of the plurality of stacking units being a feeding element, and the elements other than the feeding element being parasitic elements electromagnetically coupled to the feeding element, and a first stacking unit including at least a stacking unit including the feeding element among the plurality of stacking units being a dielectric layer included in the first stacking unit and a parasitic element adjacent to the top of the first stacking unit. The element is provided with an intermediate dielectric layer between the dielectric layer of a second stacking unit, which is a stacking unit to be arranged, the intermediate dielectric layer being formed of the dielectric and having a frame shape whose outer and inner peripheral shapes are square when viewed in a plane, and arranged to accommodate the element within the frame when viewed in a plane, and at least one of the following is satisfied: a ratio of the sum of a thickness of the intermediate dielectric layer and a thickness of the dielectric layer of the second stacking unit to a thickness of the intermediate dielectric layer is within a range of 1.1:0.2 to 1.05, and a ratio of a length of one side of the outer periphery to a length of one side of the inner periphery of the intermediate dielectric layer is within a range of 8.8:2.2 to 8.7. According to this form of antenna substrate, by satisfying at least one of the two numerical range conditions, namely, "the ratio of the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layers of the second stacking unit to the thickness of the intermediate dielectric layer is within the range of 1.1:0.2 to 1.05" and "the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within the range of 8.8:2.2 to 8.7", it is possible to increase the gain and improve the antenna characteristics. (2) In the antenna substrate of the above embodiment, the dielectric may have a relative dielectric constant of 5.8 to 6.2, and the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery in the intermediate dielectric layer may be within a range of 8.8:2.2 to 4.0. With this configuration, in an antenna substrate including a dielectric having a relative dielectric constant of 5.8 to 6.2, it is possible to increase gain and improve antenna characteristics. (3) In the antenna substrate of the above embodiment, the dielectric may be polytetrafluoroethylene, and the ratio of the thickness of the intermediate dielectric layer to the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit may be within a range of 1.9:1.6 to 1.8. With this configuration, in an antenna substrate having polytetrafluoroethylene as a dielectric, it is possible to increase gain and improve antenna characteristics. (4) In the antenna substrate of the above embodiment, the dielectric material may be polytetrafluoroethylene, and the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery in the intermediate dielectric layer may be within a range of 8.8:3.6 to 8.7. With this configuration, in an antenna substrate having polytetrafluoroethylene as a dielectric material, it is possible to increase gain and improve antenna characteristics. (5) In the antenna substrate of the above embodiment, the dielectric may be a liquid crystal polymer, and the ratio of the thickness of the intermediate dielectric layer to the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layers of the second stacking unit may be within a range of 1.5:1.0 to 1.4. With this configuration, in an antenna substrate having a liquid crystal polymer as a dielectric, it is possible to increase gain and improve antenna characteristics. (6) In the antenna substrate of the above embodiment, the dielectric material is a liquid crystal polymer, and the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery in the intermediate dielectric layer may be within a range of 8.8:3.0 to 7.6. With this configuration, it is possible to increase gain and improve antenna characteristics in an antenna substrate having a liquid crystal polymer as a dielectric material. (7) According to another embodiment of the present disclosure, there is provided an antenna substrate, which is formed by stacking a plurality of lamination units, each lamination unit including a flat dielectric layer made of a dielectric material and an element formed of a conductive material on an upper surface of the dielectric layer, in a lamination direction of the dielectric layer and the elements, the element arranged at the bottom of each of the plurality of lamination units being a feeding element, and the other elements being parasitic elements electromagnetically coupled to the feeding element, and a first lamination unit including at least a lamination unit including the feeding element among the plurality of lamination units includes an intermediate dielectric layer formed of the dielectric material between the dielectric layer of the first lamination unit and the dielectric layer of a second lamination unit, which is a lamination unit arranged adjacent to and above the first lamination unit, the intermediate dielectric layer being formed of the dielectric material and formed into a frame shape having an outer peripheral shape and an inner peripheral shape in a plan view that are square, and arranged to accommodate the element within the frame in a plan view, and satisfies at least one of the following conditions (1) and (2): (1) The ratio of the thickness of the intermediate dielectric layer to the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit is set within a numerical range calculated from a range of thicknesses of the intermediate dielectric layer when the gain of the antenna substrate at the median of the frequency band of signals transmitted and received by the antenna substrate falls within a range from the highest value at the median to a value 1 dBi lower than the highest value when the thickness of the intermediate dielectric layer is changed and the gain of the antenna substrate is calculated using an electromagnetic field simulator using conditions including the length of one side of the outer periphery, the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit, and the length of one side of the inner periphery of the intermediate dielectric layer. (2) A ratio between the length of an outer periphery side and the length of an inner periphery side of the intermediate dielectric layer when viewed in a plane is set within a numerical range calculated from a range of the length of the inner periphery side when the gain of the antenna substrate is calculated by an electromagnetic field simulator while changing the length of the inner periphery side using conditions including the length of the outer periphery side, the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layers of the second stacking unit, and the thickness of the intermediate dielectric layer, such that the gain at the median value of the frequency band of the signal falls within a range from the highest value at the median value to a value 1 dBi lower than the highest value. According to the antenna board of this embodiment, it is possible to increase the gain of the antenna board and improve the antenna characteristics, regardless of the type of dielectric material the antenna board has or the frequency band of the signal transmitted and received by the antenna board. The present disclosure can be realized in various forms other than those described above, for example, in the form of a method for manufacturing an antenna substrate, a method for designing an antenna substrate, or the like. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a cross-sectional view illustrating a schematic configuration of the antenna substrate according to the first embodiment. [Diagram 2] FIG. 2 is a plan view illustrating an appearance of the antenna substrate. [Diagram 3] FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. [Figure 4] FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. [Diagram 5] FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. [Figure 6] FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. [Figure 7] FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. [Figure 8] FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] A. First embodiment: (A-1) Antenna board configuration: FIG. 1 is a cross-sectional view that shows a schematic configuration of the antenna substrate 10 of the first embodiment. FIG. 2 is a plan view that shows a schematic appearance of the antenna substrate 10. In FIG. 2, the position of the cross section of FIG. 1 is shown as a cross section II. In FIG. 1 and FIG. 2, mutually orthogonal XYZ axes are shown to specify the direction. The X-axis, Y-axis, and Z-axis shown in each figure each indicate the same direction. In this specification, the Z-axis indicates the vertical direction and is also called the "lamination direction". The X-axis and Y-axis indicate the horizontal direction. In addition, the vertical direction and the horizontal direction described above are specified for the convenience of explaining the configuration of the antenna substrate 10, and may not coincide with the direction in which the antenna substrate 10 is installed. Note that FIG. 1 and FIG. 2 show the arrangement of each part diagrammatically, and do not accurately show the ratio of the dimensions of each part.

[0008] The antenna substrate 10 of the present embodiment can be used in fields utilizing the 5th Generation Mobile Communication System (5G), such as the communication field of mobile terminals and base stations, factories, offices, medical care, infrastructure, plants, transportation, etc. Specifically, the antenna substrate 10 of the present embodiment can be an antenna substrate compatible with the frequency band n257 (26.5 to 29.5 GHz) in the 28 GHz band.

[0009] The antenna substrate 10 of this embodiment includes a first dielectric layer 30, second dielectric layers 32a, 32b, and 32c, and a third dielectric layer 34, which are formed of a dielectric material in a flat plate shape. The antenna substrate 10 further includes a first intermediate dielectric layer 40 and second intermediate dielectric layers 42a and 42b, which are formed of a dielectric material in a frame shape. The antenna substrate 10 further includes a feed element 20, parasitic elements 22a, 22b, and 22c, a ground conductor layer 23, and a feed circuit 50. In Figs. 1 and 2, the central axis extending in the stacking direction of the antenna substrate 10 is indicated as an axis O.

[0010] The third dielectric layer 34, the first dielectric layer 30, and the second dielectric layers 32a, 32b, and 32c are arranged in this order from bottom to top (in the +Z direction). The first intermediate dielectric layer 40 is laminated between the first dielectric layer 30 and the second dielectric layer 32a. The second intermediate dielectric layer 42a is laminated between the second dielectric layer 32a and the second dielectric layer 32b. Similarly, the second intermediate dielectric layer 42b is laminated between the second dielectric layer 32b and the second dielectric layer 32c. In this embodiment, the second dielectric layers 32a, 32b, and 32c are formed to the same thickness. Moreover, the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 42b are formed to the same thickness.

[0011] As shown in Fig. 2, the antenna substrate 10 of this embodiment has a rectangular outer periphery in plan view. Specifically, the first dielectric layer 30, the second dielectric layers 32a, 32b, and 32c, the third dielectric layer 34, the first intermediate dielectric layer 40, and the second intermediate dielectric layers 42a and 42b have square outer peripheries that overlap and match each other in plan view. In this specification, the term "square" includes a shape having the same length and width, and a difference between the length of the long side and the length of the short side within 10% of the length of the long side.

[0012] As described above, the first intermediate dielectric layer 40 and the second intermediate dielectric layer 42a, 42b are formed in a frame shape, and the inner peripheral shape when viewed in a plane is square and is formed to coincide with the stacking direction. In Fig. 1 and Fig. 2, the inner peripheral surfaces of the first intermediate dielectric layer 40 and the second intermediate dielectric layer 42a, 42b are shown as inner peripheral surfaces 40I, 42aI, 42bI, respectively, and in Fig. 2, the positions of the inner peripheral surfaces 40I, 42aI, 42bI are shown by dashed lines. The center of gravity of the inner peripheral shape when the first intermediate dielectric layer 40 and the second intermediate dielectric layer 42a, 42b are viewed in a plane coincides with the axis O. In the following description, when the first intermediate dielectric layer 40 and the second intermediate dielectric layer 42a, 42b are not distinguished from each other, they are also simply called "intermediate dielectric layers".

[0013] In this embodiment, the first dielectric layer 30, the second dielectric layers 32a, 32b, and 32c, the third dielectric layer 34, and the intermediate dielectric layers 40, 42a, and 42b are made of the same type of dielectric. As the dielectric constituting these dielectric layers, for example, a dielectric having a relative dielectric constant in the range of 2.0 to 10.0 can be used. Specifically, for example, polytetrafluoroethylene (PTFE) having a relative dielectric constant of 2.1 or liquid crystal polymer (LCP) having a dielectric constant of 3.1 can be used. In this specification, the relative dielectric constant of the dielectric refers to the relative dielectric constant at 1 GHz.

[0014] The feeding element 20 is provided on the upper surface (surface on the +Z direction side) of the first dielectric layer 30 so as to be accommodated in the space formed by the inner peripheral surface 40I of the first intermediate dielectric layer 40, i.e., in the frame of the first dielectric layer 40 formed in a frame shape in a plan view. The parasitic element 22a is provided on the upper surface of the second dielectric layer 32a so as to be accommodated in the space formed by the inner peripheral surface 42aI of the second intermediate dielectric layer 42a, i.e., in the frame of the second dielectric layer 42a formed in a frame shape in a plan view. The parasitic element 22b is provided on the upper surface of the second dielectric layer 32b so as to be accommodated in the space formed by the inner peripheral surface 42bI of the second intermediate dielectric layer 42b, i.e., in the frame of the second dielectric layer 42b formed in a frame shape in a plan view. The parasitic element 22c is provided on the upper surface of the second dielectric layer 32c. The feed element 20 and the parasitic elements 22a, 22b, and 22c have a square outer periphery in a plan view, and are arranged so as to overlap each other in a plan view. In this embodiment, the centers of gravity of the feed element 20 and the parasitic elements 22a, 22b, and 22c in a plan view coincide with the axis O. The feed element 20 and the parasitic elements 22a, 22b, and 22c can also be formed into a circular shape in a plan view.

[0015] The feed element 20 is fed with power from a feed circuit 50. The parasitic elements 22a, 22b, and 22c are electromagnetically coupled to the feed element 20 without receiving power when the feed element 20 functions as an antenna element, and radiate radio waves to the upper surface of the antenna substrate 10. The feed element 20 and the parasitic elements 22a, 22b, and 22c are made of a conductive material, for example, a metal material including copper or aluminum. At least a part of the surface of the feed element 20 that is exposed in the space formed by the inner peripheral surface 40I of the first intermediate dielectric layer 40 without contacting the first dielectric layer 30 may be covered with a dielectric. In this way, the antenna characteristics such as the resonant frequency and the gain can be finely adjusted by the thickness of the coating, and the feed element 20 can be physically protected.

[0016] In this embodiment, a structure including a dielectric layer and a conductive element and repeatedly stacked in the Z-axis direction is called a “lamination unit.” Specifically, a structure including a first dielectric layer 30, a feeding element 20, and a first intermediate dielectric layer 40 is called a lamination unit 70, a structure including a second dielectric layer 32a, a parasitic element 22a, and a second intermediate dielectric layer 42a is called a lamination unit 71, a structure including a second dielectric layer 32b, a parasitic element 22b, and a second intermediate dielectric layer 42b is called a lamination unit 72, and a structure including a second dielectric layer 32c and a parasitic element 22c is called a lamination unit 73.

[0017] The ground conductor layer 23 is formed on the lower surface (surface on the -Z direction side) of the first dielectric layer 30. The ground conductor layer 23 is made of a thin metal plate made of, for example, copper or aluminum, and reflects radio waves radiated from the power feeding element 20. A third dielectric layer 34 is laminated on the lower surface of the ground conductor layer 23, and a power feeding circuit 50 that feeds power to the power feeding element 20 is bonded to the lower surface of the third dielectric layer 34.

[0018] The power feed circuit 50 includes three laminated dielectrics, ie, circuit-side dielectrics 46, 47, and 48. Vias 62, 64, and 66 are formed in the circuit-side dielectrics 46 to 48, respectively, penetrating along the Z-axis, which is the thickness direction. To connect the power feed circuit 50 and the power feed element 20, the antenna substrate 10 is provided with a conductor portion (not shown) penetrating the first dielectric layer 30, the ground conductor layer 23, and the third dielectric layer 34.

[0019] 2, the antenna substrate 10 may further have a through hole 15 penetrating the antenna substrate 10 in the stacking direction. The through hole 15 is formed by a through hole provided in each of the second dielectric layers 32a, 32b, 32c at a position that does not overlap with the feed element 20 and the parasitic elements 22a, 22b, 22c. The through hole 15 communicates the space formed by the inner peripheral surface 40I of the first intermediate dielectric layer 40 and the space formed by the inner peripheral surfaces 42aI, 42bI of the second intermediate dielectric layers 42a, 42b with the outside of the antenna substrate 10. However, the through hole 15 is not essential, and the through hole 15 may not be provided.

[0020] (A-2) Manufacturing method of antenna substrate: In the following, as an example of a method for manufacturing the antenna substrate 10, an outline of a method for manufacturing the antenna substrate 10 using dielectric ceramics as a constituent material will be described. When manufacturing the antenna substrate 10, first, a plurality of green sheets for low-temperature firing formed by a doctor blade method are prepared. The thickness and size of the prepared green sheets may be appropriately set according to the desired thickness and size of each dielectric layer of the antenna substrate 10 to be finally obtained.

[0021] Thereafter, holes are formed in the prepared green sheets by punching or laser processing. For example, holes are formed in the green sheets to be the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a, 42b at positions corresponding to the inner circumference of the frame-like shape described above. Here, in the green sheets to be the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a, 42b, the size of the rectangular holes to be formed may be determined so that the "ratio between the length of one side of the dielectric layer and the length of one side of the hollow portion" to be described later satisfies a numerical range to be described later in the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a, 42b of the antenna substrate 10 obtained after the firing process to be described later. Furthermore, in the green sheets that will become the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a, 42b, and the first dielectric layer 30 and the second dielectric layers 32a-32c, the thickness of each green sheet can be set so that the "ratio of the total thickness of the dielectric layers to the thickness of the hollow portion" in the antenna substrate 10 obtained after the firing process described below satisfies the numerical range described below.

[0022] In the green sheets that will become the circuit-side dielectrics 46, 47, 48, holes are formed at positions corresponding to the vias 62, 64, 66. The holes corresponding to the vias 62, 64, 66, etc. are filled with a conductive paste by screen printing or the like to form the vias. Then, a conductive layer that will become the feed element 20 or the parasitic elements 22a, 22b, 22c, etc. is formed on a specific green sheet by screen printing the conductive paste. A laminate is obtained by stacking a plurality of green sheets with the conductive layers formed thereon in a specific order and applying heat and pressure. The obtained laminate is degreased and fired to obtain the antenna substrate 10.

[0023] (A-3) Dimensional ratio of hollow parts: The antenna substrate 10 of this embodiment improves the gain of the antenna substrate 10 by the dimensional ratio of the spaces formed by the inner circumferential surfaces 40I, 42aI, 42bI of the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a, 42b in the antenna substrate 10. The first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a, 42b have the same shape, and the dimensional ratios described below apply to all stacking units.

[0024] In this embodiment, each of the lamination units including the intermediate dielectric layer (the first intermediate dielectric layer 40 or the second intermediate dielectric layer 42a, 42b) formed in a frame shape is also called a "first lamination unit". The lamination unit arranged adjacent to the upper side (the +Z-axis side) of the first lamination unit is also called a "second lamination unit". When the lamination unit 70 is the first lamination unit, the lamination unit 71 is the second lamination unit, when the lamination unit 71 is the first lamination unit, the lamination unit 72 is the second lamination unit, and when the lamination unit 72 is the first lamination unit, the lamination unit 73 is the second lamination unit. In addition, when the first lamination unit is the lamination unit 70, the space formed by the inner peripheral surface of the intermediate dielectric layer of the first lamination unit, that is, the space partitioned by the inner peripheral surface 40I, the first dielectric layer 30, and the second dielectric layer 32a of the second lamination unit, is also called a "space portion".

[0025] In an antenna substrate formed by laminating dielectric layers such as the antenna substrate 10 of this embodiment, the length of one side and the thickness of the dielectric layer are generally determined by the relative dielectric constant of the dielectric and the operating frequency of the antenna substrate (the frequency of the signal transmitted and received by the antenna substrate). For example, when the antenna substrate 10 of this embodiment uses the band n257 of the 28 GHz band, the length of one side and the thickness of the dielectric layer are determined by the frequency of 26.5 to 29.5 GHz and the relative dielectric constant of the dielectric. The length of one side and the thickness of the dielectric layer thus determined can be finely adjusted by, for example, the size of the feed element 20 and the parasitic elements 22a, 22b, and 22c, the number of lamination units included in the antenna substrate 10, the presence or absence of a dielectric covering layer on the surface of the feed element 20, and the like, but are not greatly changed.

[0026] One of the dimensional ratios of the hollow portion defined in this embodiment is the ratio of the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layers of the second stack unit (hereinafter also referred to as the "total thickness of the dielectric layers") to the thickness of the intermediate dielectric layer. In Fig. 1, the sum of the thicknesses of the dielectric layers is shown as thickness T1, and the thickness of the intermediate dielectric layer is shown as thickness T2, and the "ratio of the sum of the thicknesses of the dielectric layers to the thickness of the intermediate dielectric layer" is "T1:T2". Such a dimensional ratio is also referred to as the "ratio of the sum of the thicknesses of the dielectric layers to the thickness of the hollow portion".

[0027] Another dimensional ratio of the hollow portion defined in this embodiment is the ratio between the length of one side of the outer periphery and the length of one side of the inner periphery of the intermediate dielectric layer when the intermediate dielectric layer is viewed in plan. In Fig. 2, the length of the outer periphery is shown as length L1, and the length of the inner periphery is shown as length L2, and the "ratio between the length of one side of the outer periphery and the length of one side of the inner periphery of the intermediate dielectric layer" is "L1:L2". Such a dimensional ratio is also called the "ratio between the length of one side of the dielectric layer and the length of one side of the hollow portion".

[0028] The antenna substrate 10 of this embodiment satisfies at least one of the following: "The ratio of the total thickness of the intermediate dielectric layer and the thickness of the dielectric layers of the second stack unit to the thickness of the intermediate dielectric layer is within a range of 1.1:0.2 to 1.05" and "The ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within a range of 8.8:2.2 to 8.7." The above numerical ranges will be explained in more detail below.

[0029] (A-3-1) Ratio of total dielectric layer thickness to hollow part thickness: The following describes an antenna substrate 10 in which the ratio of the total T1 of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit to the thickness T2 of the intermediate dielectric layer is in the range of 1.1:0.2 to 1.05.

[0030] <Aspect 1> FIG. 3 is an explanatory diagram showing an example of the results of calculating the gain of the antenna substrate 10 by an electromagnetic field simulator by changing the thickness T2 of the intermediate dielectric layer. FIG. 3 shows the analysis results of the antenna substrate 10, which is an antenna substrate for band n257 (26.5 to 29.5 GHz) of the 28 GHz band, and uses a dielectric ceramic with a relative dielectric constant of 6.0 as the dielectric constituting the dielectric layer. Here, the length L1 of one side of the outer periphery of the intermediate dielectric layer is set to 8.8 mm, the total thickness T1 of the dielectric layers is set to 1.1 mm, and the length L2 of one side of the inner periphery of the intermediate dielectric layer is set to 2.6 mm. The length L1 of one side of the outer periphery of the intermediate dielectric layer and the total thickness T1 of the dielectric layers are values ​​determined according to the frequency of the signal transmitted and received by the antenna substrate 10 and the relative dielectric constant of the dielectric.

[0031] In the analysis results shown in FIG. 3, the thickness T2 of the intermediate dielectric layer was changed in 11 steps from 0.1 mm to 1.1 mm in 0.1 mm increments. The electromagnetic field simulator used was the electromagnetic field analysis software Ansys HFSS (manufactured by Ansys Japan, Inc.). The electromagnetic field simulator was used to input information on the shape and dimensions of the dielectric (the outer peripheral side length L1 of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the inner peripheral side length L2 of the intermediate dielectric layer) as well as the side length (2.0 mm in this case) of the feed element 20 and the parasitic elements 22a to 22c, the thickness (0.4 mm in this case) of the first dielectric layer 30, the type of metal (conductivity, conductor loss) used in the antenna substrate 10, the type of dielectric (dielectric constant, dielectric loss), and the power conditions. The thickness T2 of the intermediate dielectric layer was changed in the above 11 steps, and analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In addition, when the thickness T2 of the intermediate dielectric layer is changed in 11 steps as described above, the case where the thickness T2 of the intermediate dielectric layer is 1.1 mm represents a hypothetical state where the thickness T2 of the intermediate dielectric layer is equal to the total thickness T1 of the dielectric layers (the thickness of the dielectric layer of the second stack unit is 0). In Fig. 3, the horizontal axis represents frequency and the vertical axis represents gain.

[0032] The median frequency of the 28 GHz band n257 (26.5 to 29.5 GHz) is 28.0 GHz, and as shown in Figure 3, the gain at the median frequency is highest when the thickness T2 of the intermediate dielectric layer is 0.7 mm. In Figure 3, the value that is 1 dBi lower than the gain value when the thickness T2 of the intermediate dielectric layer is 0.7 mm, which is the highest gain value (hereinafter also referred to as the maximum gain) at the median frequency of 28.0 GHz, is indicated by a white arrow as "-1 dBi." The vertical axis of Figure 3, which shows the gain, represents a relative value when the maximum gain is set to 0.

[0033] As shown in FIG. 3, the greater the difference between the thickness T2 of the intermediate dielectric layer and 0.7 mm, which is the thickness T2 of the intermediate dielectric layer when the gain at the frequency of 28.0 GHz is maximum, the smaller the magnitude of the gain at the frequency of 28.0 GHz tends to be. As shown in FIG. 3, among the results of changing the thickness T2 of the intermediate dielectric layer to the above 11 steps, the range of the thickness T2 of the intermediate dielectric layer when the gain of the antenna substrate 10 at the median frequency of 28.0 GHz is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 0.2 mm to 1.0 mm. Furthermore, even under the hypothetical condition that the thickness T2 of the intermediate dielectric layer is 1.1 mm, the gain of the antenna substrate 10 is a relatively high value close to the reference value 1 dBi lower than the maximum gain. From the results of FIG. 3, the range of the thickness T2 of the intermediate dielectric layer when the gain of the antenna substrate 10 at the median frequency of 28.0 GHz is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is considered to be 0.2 mm to 1.05 mm. In this case, the ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is 1.1:0.2-1.05. From the results shown in Fig. 3, it can be seen that when a dielectric ceramic having a relative dielectric constant of 6.0 is used as the dielectric, the antenna substrate 10 in which the ratio of the total thickness of the dielectric layers to the thickness of the intermediate dielectric layer is within the range of 1.1:0.2-1.05 can achieve high gain.

[0034] <Aspect 2> Fig. 4 is an explanatory diagram showing another example of the results of calculating the gain of the antenna substrate 10 by an electromagnetic field simulator by using a dielectric different from that in the above-mentioned embodiment 1 and changing the thickness T2 of the intermediate dielectric layer. Fig. 4 shows the analysis results of the antenna substrate 10, which is an antenna substrate for band n257 (26.5 to 29.5 GHz) of the 28 GHz band, and uses polytetrafluoroethylene with a relative dielectric constant of 2.1 as the dielectric constituting the dielectric layer. Here, the length L1 of one side of the outer periphery of the intermediate dielectric layer is set to 8.8 mm, the total thickness T1 of the dielectric layers is set to 1.9 mm, and the length L2 of one side of the inner periphery of the intermediate dielectric layer is set to 4.4 mm.

[0035] The thickness T2 of the intermediate dielectric layer was changed in four stages from 1.5 mm to 1.8 mm in 0.1 mm increments. The electromagnetic field simulator used was the electromagnetic field analysis software Ansys HFSS (manufactured by Ansys Japan Co., Ltd.). The electromagnetic field simulator was used to input information on the shape and dimensions of the dielectric (the length L1 of one side of the outer periphery of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the length L2 of one side of the inner periphery of the intermediate dielectric layer) as well as the length of one side of the feed element 20 and the parasitic elements 22a to 22c (3.4 mm in this case), the thickness of the first dielectric layer 30 (0.7 mm in this case), the type of metal (conductivity, conductor loss) used in the antenna substrate 10, the type of dielectric (dielectric constant, dielectric loss), and the power conditions, and the thickness T2 of the intermediate dielectric layer was changed in the above four stages to perform analysis using the electromagnetic field simulator, and the change in gain in the 28 GHz band was obtained. In FIG. 4, the horizontal axis represents frequency, and the vertical axis represents gain.

[0036] The median frequency of the 28GHz band n257 (26.5-29.5GHz) is 28.0GHz, and as shown in FIG. 4, the gain at the median frequency is highest when the thickness T2 of the intermediate dielectric layer is 1.8mm. Note that FIG. 7 does not show the case where the thickness T2 of the intermediate dielectric layer exceeds 1.8mm, but when the thickness T2 of the intermediate dielectric layer exceeds 1.8mm, the thickness (T1-T2) of the dielectric layer of the second stack unit becomes thin, which may cause insufficient strength, so the maximum value of the thickness T2 of the intermediate dielectric layer is set to 1.8mm. Therefore, the maximum gain at the median frequency is specified as when the thickness T2 of the intermediate dielectric layer is 1.8mm. In FIG. 4, the value that is 1dBi lower than the gain value when the thickness T2 of the intermediate dielectric layer is 1.8mm, which is the maximum gain at the median frequency of 28.0GHz, is indicated by a white arrow as "-1dBi". The vertical axis of FIG. 4, which shows the gain, represents a relative value when the maximum gain is set to 0.

[0037] As shown in Fig. 4, the greater the difference between the thickness T2 of the intermediate dielectric layer and the thickness T2 of the intermediate dielectric layer at the frequency of 28.0 GHz, which is 1.8 mm, the smaller the magnitude of the gain at the frequency of 28.0 GHz. Also, as shown in Fig. 4, the range of the thickness T2 of the intermediate dielectric layer at the median frequency of 28.0 GHz when the gain of the antenna substrate 10 is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 1.6 mm to 1.8 mm. Therefore, the "ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer" at this time is "1.9:1.6 to 1.8". In this way, when polytetrafluoroethylene, which has a relative dielectric constant of 2.1, is used as the dielectric, it can be understood that an antenna substrate 10 in which the ratio of the sum of the thicknesses T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is within the range of 1.1:0.2 to 1.05, particularly within the range of 1.9:1.6 to 1.8, i.e., 1.1:0.93 to 1.04, can achieve a particularly high gain.

[0038] <Aspect 3> Fig. 5 is an explanatory diagram showing yet another example of the results of calculating the gain of the antenna substrate 10 by an electromagnetic field simulator by using a dielectric different from those in the above-mentioned embodiment 1 and embodiment 2 and changing the thickness T2 of the intermediate dielectric layer. Fig. 5 shows the analysis results of the antenna substrate 10, which is an antenna substrate for band n257 (26.5 to 29.5 GHz) of the 28 GHz band and uses liquid crystal polymer (LCP) with a relative dielectric constant of 3.1 as the dielectric constituting the dielectric layer. Here, the length L1 of one side of the outer periphery of the intermediate dielectric layer is set to 8.8 mm, the total thickness T1 of the dielectric layers is set to 1.5 mm, and the length L2 of one side of the inner periphery of the intermediate dielectric layer is set to 3.6 mm.

[0039] The thickness T2 of the intermediate dielectric layer was changed in six steps from 0.9 mm to 1.4 mm in 0.1 mm increments. The electromagnetic field simulator used was the electromagnetic field analysis software Ansys HFSS (manufactured by Ansys Japan Co., Ltd.). The electromagnetic field simulator was used with information on the shape and dimensions of the dielectric (the length L1 of one side of the outer periphery of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the length L2 of one side of the inner periphery of the intermediate dielectric layer), as well as the length of one side of the feed element 20 and the parasitic elements 22a to 22c (2.8 mm in this case), the thickness of the first dielectric layer 30 (0.56 mm in this case), the type of metal (conductivity, conductor loss) used in the antenna substrate 10, the type of dielectric (dielectric constant, dielectric loss), and the power conditions. The thickness T2 of the intermediate dielectric layer was changed in the six steps described above, and an analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In FIG. 5, the horizontal axis represents frequency, and the vertical axis represents gain.

[0040] The median of the 28GHz band n257 (26.5-29.5GHz) is 28.0GHz, and as shown in FIG. 5, the gain at the median of this frequency is highest when the thickness T2 of the intermediate dielectric layer is 1.4mm. Note that FIG. 5 does not show the case where the thickness T2 of the intermediate dielectric layer exceeds 1.4mm, but when the thickness T2 of the intermediate dielectric layer exceeds 1.4mm, the thickness (T1-T2) of the dielectric layer of the second stack unit becomes thin, which may cause insufficient strength, so the maximum value of the thickness T2 of the intermediate dielectric layer is set to 1.4mm. Therefore, the maximum gain at the median of the above frequency is specified to be when the thickness T2 of the intermediate dielectric layer is 1.4mm. In FIG. 5, the value 1dBi lower than the gain value when the thickness T2 of the intermediate dielectric layer is 1.4mm, which is the maximum gain at the median frequency of 28.0GHz, is indicated by a white arrow as "-1dBi value". The vertical axis of FIG. 5, which shows the gain, represents a relative value when the maximum gain is set to 0.

[0041] As shown in Fig. 5, the greater the difference between the thickness T2 of the intermediate dielectric layer and the thickness T2 of the intermediate dielectric layer at the frequency of 28.0 GHz, which is 1.4 mm, the smaller the magnitude of the gain at the frequency of 28.0 GHz. Also, as shown in Fig. 5, the range of the thickness T2 of the intermediate dielectric layer at the median frequency of 28.0 GHz when the gain of the antenna substrate 10 is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 1.0 mm to 1.4 mm. Therefore, the "ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer" at this time is "1.5:1.0 to 1.4". In this way, when a liquid crystal polymer with a relative dielectric constant of 3.1 is used as the dielectric, it can be understood that an antenna substrate 10 in which the ratio of the sum of the thicknesses T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is within the range of 1.1:0.2 to 1.05, particularly within the range of 1.5:1.0 to 1.4, i.e., 1.1:0.73 to 1.027, can achieve a particularly high gain.

[0042] (A-3-2) Ratio of the length of one side of the dielectric layer to the length of one side of the hollow part: In the following, an antenna substrate 10 will be described in which "the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within the range of 8.8:2.2 to 8.7".

[0043] <Aspect 4> Fig. 6 is an explanatory diagram showing an example of the results of calculating the gain of the antenna substrate 10 by an electromagnetic field simulator while changing the length L2 of one side of the inner circumference of the intermediate dielectric layer. Fig. 6 shows the analysis results of the antenna substrate 10, which is an antenna substrate for band n257 (26.5 to 29.5 GHz) of the 28 GHz band, and uses a dielectric ceramic having a relative dielectric constant of 6.0 as the dielectric constituting the dielectric layer. Here, the length L1 of one side of the outer circumference of the intermediate dielectric layer is set to 8.8 mm, the total thickness T1 of the dielectric layers is set to 1.1 mm, and the thickness T2 of the intermediate dielectric layer is set to 0.7 mm.

[0044] The length L2 of one side of the inner circumference of the intermediate dielectric layer was changed in seven stages, namely, 2.0 mm, 2.2 mm, 3.2 mm, 3.4 mm, 3.6 mm, 4.0 mm, and 4.2 mm. As an electromagnetic field simulator, electromagnetic field analysis software Ansys HFSS (manufactured by Ansys Japan Co., Ltd.) was used. In the electromagnetic field simulator, information on the shape and dimensions of the dielectric (the outer circumference side length L1 of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the thickness T2 of the intermediate dielectric layer) was input together with the length of one side of the feed element 20 and the parasitic elements 22a to 22c (here, 2.0 mm), the thickness of the first dielectric layer 30 (here, 0.4 mm), the type of metal (conductivity, conductor loss) used in the antenna substrate 10, the type of dielectric (dielectric constant, dielectric loss), and the power conditions were input, and the length L2 of one side of the inner circumference of the intermediate dielectric layer was changed in the seven stages, and an analysis was performed using the electromagnetic field simulator to obtain the change in gain in the 28 GHz band. In FIG. 6, the horizontal axis represents frequency, and the vertical axis represents gain.

[0045] The median value of the 28GHz band, band n257 (26.5~29.5GHz), is 28.0GHz, and as shown in Figure 6, the highest gain at this median frequency occurs when the length of one side of the inner circumference, L2, is 3.4mm. In Figure 6, the maximum gain at the median frequency of 28.0GHz, which is 1dBi lower than the gain value when the length of one side of the inner circumference, L2, is 3.4mm, is indicated by a white arrow as "-1dBi". The vertical axis of Figure 6, which shows the gain, represents a relative value when the maximum gain is set to 0.

[0046] As shown in Fig. 6, the greater the difference between the length L2 of the inner circumference of the intermediate dielectric layer and the length L2 of the inner circumference of 3.4 mm when the gain is maximum at 28.0 GHz, the smaller the magnitude of the gain at 28.0 GHz. As shown in Fig. 6, when the length L2 of the inner circumference of the intermediate dielectric layer is changed to the above seven stages, the range of the length L2 of the inner circumference when the gain of the antenna substrate 10 at the median frequency of 28.0 GHz is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 2.2 mm to 4.0 mm. In this case, the ratio of the length L1 of the outer circumference of the intermediate dielectric layer to the length L2 of the inner circumference is 8.8:2.2 to 4.0. From the results shown in FIG. 6, it can be seen that when a dielectric ceramic having a relative dielectric constant of 6.0 is used as the dielectric, an antenna substrate 10 in which the ratio of the length L1 of the outer periphery of the intermediate dielectric layer to the length L2 of the inner periphery of the intermediate dielectric layer is within the range of 8.8:2.2 to 8.7, and particularly within the range of 8.8:2.2 to 4.0, can achieve a particularly high gain.

[0047] <Aspect 5> Fig. 7 is an explanatory diagram showing an example of the results of calculating the gain of the antenna substrate 10 by an electromagnetic field simulator by using a dielectric different from that in the above-mentioned embodiment 4 and changing the length L2 of one side of the inner circumference of the intermediate dielectric layer. Fig. 7 shows the analysis results of the antenna substrate 10, which is an antenna substrate for band n257 (26.5 to 29.5 GHz) of the 28 GHz band, and uses polytetrafluoroethylene with a relative dielectric constant of 2.1 as the dielectric constituting the dielectric layer. Here, the length L1 of one side of the outer circumference of the intermediate dielectric layer is set to 8.8 mm, the total thickness T1 of the dielectric layers is set to 1.9 mm, and the thickness T2 of the intermediate dielectric layer is set to 1.8 mm.

[0048] The length L2 of one side of the inner circumference of the intermediate dielectric layer was changed in seven stages, 3.4 mm, 3.6 mm, 4.2 mm, 4.4 mm, 4.6 mm, 8.6 mm, and 8.8 mm. The electromagnetic field simulator used was electromagnetic field analysis software Ansys HFSS (manufactured by Ansys Japan Co., Ltd.). The electromagnetic field simulator was used to input information on the shape and dimensions of the dielectric (the outer circumference side length L1 of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the thickness T2 of the intermediate dielectric layer) as well as the length of one side of the feed element 20 and the parasitic elements 22a to 22c (3.4 mm in this case), the thickness of the first dielectric layer 30 (0.7 mm in this case), the type of metal (conductivity, conductor loss) used in the antenna substrate 10, the type of dielectric (dielectric constant, dielectric loss), and the power conditions, and the length L2 of one side of the inner circumference of the intermediate dielectric layer was changed in the seven stages, and analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In addition, when the length L2 of one side of the inner circumference of the intermediate dielectric layer is changed in seven stages as described above, the case where the length L2 of one side of the inner circumference of the intermediate dielectric layer is 8.8 mm represents a hypothetical state in which the length L1 of one side of the outer circumference of the intermediate dielectric layer is equal to the length L2 of one side of the inner circumference (the entire intermediate dielectric layer is a hollow portion). In Fig. 7, the horizontal axis represents frequency and the vertical axis represents gain.

[0049] The median frequency of the 28 GHz band n257 (26.5 to 29.5 GHz) is 28.0 GHz, and as shown in Figure 7, the gain at the median frequency is highest when the length of one side of the inner circumference L2 is 4.4 mm. In Figure 7, the value that is 1 dBi lower than the gain value when the length of one side of the inner circumference L2 is 4.4 mm, which is the maximum gain at the median frequency of 28.0 GHz, is indicated by a white arrow as "-1 dBi." The vertical axis of Figure 7, which shows the gain, represents a relative value when the maximum gain is set to 0.

[0050] As shown in Fig. 7, the greater the difference between the length L2 of one side of the inner circumference of the intermediate dielectric layer and the length L2 of one side of the inner circumference at the frequency of 28.0 GHz, which is 4.4 mm, the smaller the magnitude of the gain at the frequency of 28.0 GHz. As shown in Fig. 7, among the results of changing the length L2 of one side of the inner circumference of the intermediate dielectric layer to the seven stages described above, the range of the length L2 of one side of the inner circumference when the gain of the antenna substrate 10 at the median frequency of 28.0 GHz is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 3.6 mm to 8.6 mm. Even under the hypothetical condition that the length L2 of one side of the inner circumference of the intermediate dielectric layer is 8.8 mm, the gain of the antenna substrate 10 is a relatively high value close to the reference value 1 dBi lower than the maximum gain. From the results shown in FIG. 7, it is considered that the range of the length L2 of one side of the inner circumference of the intermediate dielectric layer when the gain of the antenna substrate 10 at the median frequency of 28.0 GHz is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 3.6 mm to 8.7 mm. In this case, the "ratio of the length L1 of one side of the outer circumference of the intermediate dielectric layer to the length L2 of one side of the inner circumference" is "8.8:3.6 to 8.7". From the results shown in FIG. 7, it is understood that when polytetrafluoroethylene with a relative dielectric constant of 2.1 is used as the dielectric, the antenna substrate 10 having the "ratio of the length L1 of one side of the outer circumference of the intermediate dielectric layer to the length L2 of one side of the inner circumference" in the range of "8.8:2.2 to 8.7", particularly in the range of "8.8:3.6 to 8.7", can realize a particularly high gain.

[0051] <Aspect 6> Fig. 8 is an explanatory diagram showing yet another example of the results of calculating the gain of the antenna substrate 10 by an electromagnetic field simulator by using a dielectric different from those in the above-mentioned embodiment 4 and embodiment 5 and changing the length L2 of one side of the inner circumference of the intermediate dielectric layer. Fig. 8 shows the analysis results of the antenna substrate 10, which is an antenna substrate for band n257 (26.5 to 29.5 GHz) of the 28 GHz band and uses a liquid crystal polymer (LCP) with a relative dielectric constant of 3.1 as the dielectric constituting the dielectric layer. Here, the length L1 of one side of the outer circumference of the intermediate dielectric layer is set to 8.8 mm, the total thickness T1 of the dielectric layers is set to 1.5 mm, and the thickness T2 of the intermediate dielectric layer is set to 1.4 mm.

[0052] The length L2 of one side of the inner circumference of the intermediate dielectric layer was changed in seven stages, namely, 2.8 mm, 3.0 mm, 5.6 mm, 5.8 mm, 6.0 mm, 7.4 mm, and 7.6 mm. The electromagnetic field simulator used was electromagnetic field analysis software Ansys HFSS (manufactured by Ansys Japan Co., Ltd.). The electromagnetic field simulator was used to input information on the shape and dimensions of the dielectric (the outer circumference side length L1 of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the thickness T2 of the intermediate dielectric layer) as well as the side length (2.8 mm here) of the feed element 20 and the parasitic elements 22a to 22c, the thickness (0.56 mm here), the type of metal (conductivity, conductor loss) used in the antenna substrate 10, the type of dielectric (dielectric constant, dielectric loss), and the power conditions, and the length L2 of one side of the inner circumference of the intermediate dielectric layer was changed in the seven stages, and analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In FIG. 8, the horizontal axis represents frequency, and the vertical axis represents gain.

[0053] The median value of the 28GHz band n257 (26.5~29.5GHz) is 28.0GHz, and as shown in Figure 8, the highest gain at this median frequency occurs when the length of one side of the inner circumference L2 is 6.0mm. In Figure 8, the maximum gain at the median frequency of 28.0GHz, which is 1dBi lower than the gain value when the length of one side of the inner circumference L2 is 6.0mm, is indicated by a white arrow as "-1dBi". The vertical axis of Figure 8, which shows the gain, represents a relative value when the maximum gain is set to 0.

[0054] As shown in Fig. 8, the greater the difference between the length L2 of the inner circumference of the intermediate dielectric layer and the length L2 of the inner circumference of 6.0 mm when the gain is maximum at 28.0 GHz, the smaller the magnitude of the gain at 28.0 GHz tends to be. As shown in Fig. 8, the range of the length L2 of the inner circumference when the gain of the antenna substrate 10 at the median frequency of 28.0 GHz is in the range from the maximum gain to a value 1 dBi lower than the maximum gain is 3.0 mm to 7.6 mm. In this case, the ratio of the length L1 of the outer circumference of the intermediate dielectric layer to the length L2 of the inner circumference is 8.8:3.0 to 7.6. From the results shown in Figure 8, it can be seen that when a liquid crystal polymer with a relative dielectric constant of 3.1 is used as the dielectric, an antenna substrate 10 in which the ratio of the length L1 of the outer periphery of the intermediate dielectric layer to the length L2 of the inner periphery of the intermediate dielectric layer is within the range of "8.8:2.2 to 8.7", and in particular within the range of "8.8:3.0 to 7.6", can achieve a particularly high gain.

[0055] According to the antenna substrate 10 of the present embodiment configured as described above, by satisfying at least one of the conditions related to the two numerical ranges, namely, "the ratio of the total T1 of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stack unit to the thickness T2 of the intermediate dielectric layer is within the range of 1.1:0.2 to 1.05" and "the ratio of the length L1 of one side of the outer periphery of the intermediate dielectric layer to the length L2 of one side of the inner periphery is within the range of 8.8:2.2 to 8.7", it is possible to show a high gain in the frequency band used and improve the antenna characteristics. In order to obtain a higher gain, it is desirable to satisfy both of the above two conditions. The antenna characteristics such as the resonant frequency and the gain can be finely adjusted, for example, by the presence or absence of a coating that covers the power supply element 20, the size (length of one side) of the element including the power supply element 20, etc., but even if such fine adjustment is performed, the same effect of ensuring a high gain can be obtained by satisfying at least one of the above two conditions.

[0056] In the antenna substrate 10, for example, when a dielectric ceramic having a relative dielectric constant of 6.0 is used as the dielectric, a higher gain can be realized and the antenna characteristics can be improved by satisfying at least one of the following: "The ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is within the range of 1.1:0.2-1.05" and "The ratio of the length L1 of one side of the intermediate dielectric layer to the length L2 of one side of the inner circumference is within the range of 8.8:2.2-4.0". In addition, for example, when polytetrafluoroethylene having a relative dielectric constant of 2.1 is used as the dielectric, a higher gain can be realized and the antenna characteristics can be improved by satisfying at least one of the following: "The ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is within the range of 1.9:1.6-1.8" and "The ratio of the length L1 of one side of the intermediate dielectric layer to the length L2 of one side of the inner circumference is within the range of 8.8:3.6-8.7". Furthermore, for example, when a liquid crystal polymer (LCP) with a relative dielectric constant of 3.1 is used as the dielectric, by satisfying at least one of the following: "the ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is within the range of 1.5:1.0 to 1.4" and "the ratio of the length L1 of one side of the intermediate dielectric layer to the length L2 of one side of the inner circumference is within the range of 8.8:3.0 to 7.6", a higher gain can be achieved and the antenna characteristics can be improved.

[0057] If the antenna substrate 10 satisfies the conditions relating to the numerical ranges described above, it is believed that even if the frequency of the signal actually transmitted and received by the antenna substrate 10 is a value outside the median frequency of the frequency band described above, an extremely high gain close to the gain at the median frequency can be obtained within the frequency band used.

[0058] B. Other embodiments: In the above embodiment, three lamination units each including a parasitic element are laminated, but a different configuration may be used. The number of lamination units each including a parasitic element to be laminated in lamination unit 70 including feed element 20 may be any number equal to or greater than one.

[0059] In the above embodiment, the second intermediate dielectric layers 42a, 42b formed in a frame shape are disposed on the second dielectric layers 32a, 32b on which the parasitic elements 22a, 22b are formed, respectively, but a different configuration may be used. For example, a solid plate-shaped dielectric without a hollow portion may be laminated on at least some of the parasitic elements, instead of the frame-shaped intermediate dielectric layer. A similar effect of improving gain can be obtained by having one or more laminate units including the laminate unit 70 including the feeding element 20, as the first laminate unit, satisfy at least one of the numerical ranges described above for "the ratio of the total T1 of the thickness of the intermediate dielectric layer and the thickness of the dielectric layers of the second laminate unit to the thickness T2 of the intermediate dielectric layer" and the numerical range for "the ratio of the length L1 of one side of the outer periphery to the length L2 of one side of the inner periphery of the intermediate dielectric layer."

[0060] Although a single antenna substrate 10 is shown in FIG. 1 and FIG. 2, a plurality of antenna substrates 10 may be arranged in a line, or may be arranged two-dimensionally to form an array antenna.

[0061] In the embodiment, the antenna substrate 10 having dielectrics with dielectric constants of 6.0, 2.1, and 3.1 is exemplified, and the antenna substrate 10 in the embodiment is an antenna substrate for the 28 GHz band, but may have a different configuration. Even if the type of dielectric included in the antenna substrate or the frequency band of the signal transmitted and received by the antenna substrate is different, the antenna substrate can obtain the same effect of increasing the antenna gain by satisfying at least one of the following conditions (1) and (2).

[0062] That is, the condition (1) is that, in the antenna substrate, "(1) the ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer is set within a numerical range calculated from the range of the thickness T2 of the intermediate dielectric layer when the gain of the antenna substrate 10 is calculated using an electromagnetic field simulator while changing the thickness T2 of the intermediate dielectric layer using conditions including the length L1 of one side of the outer periphery, the total thickness T1 of the dielectric layers, and the length L2 of one side of the inner periphery of the intermediate dielectric layer, and the gain at the median of the frequency band of the signal transmitted and received by the antenna substrate 10 is in the range from the highest value at the median to a value 1 dBi lower than the highest value."

[0063] In the analysis using the electromagnetic field simulator, the range of "T1:T2" when the gain is in the range from "maximum gain" to "-1 dBi value" at the median frequency of the frequency band can be uniquely obtained by changing the thickness T2 of the intermediate dielectric layer while inputting each of the above-mentioned conditions. Therefore, if the antenna substrate 10 satisfies the above condition (1), it can be said that a high gain close to the optimal gain can be obtained in the entire frequency band of the signal. In the condition (1) related to the "ratio of the total thickness T1 of the dielectric layers to the thickness T2 of the intermediate dielectric layer", the standard of the difference from the maximum gain at the median frequency of the frequency band is set to 1 dBi, but it is more desirable to satisfy the condition with the standard set to 0.9 dBi, and even more desirable to satisfy the condition with the standard set to 0.8 dBi. If the antenna substrate 10 satisfies such a standard, the gain can be further increased in a wide range of frequencies included in the frequency band.

[0064] Moreover, condition (2) is that, in the antenna substrate, "(2) the ratio of the length L1 of the outer periphery of the intermediate dielectric layer to the length L2 of the inner periphery of the intermediate dielectric layer is set within a numerical range calculated from the range of the length L2 of the inner periphery of the intermediate dielectric layer when the gain of the antenna substrate 10 at the median of the frequency band of the signal transmitted and received by the antenna substrate 10 is in the range from the highest value at the median to a value 1 dBi lower than the highest value when the inner periphery of the intermediate dielectric layer is changed and the gain of the antenna substrate 10 is calculated using an electromagnetic field simulator using conditions including the length L1 of the outer periphery of the intermediate dielectric layer, the total thickness T1 of the dielectric layers, and the thickness T2 of the intermediate dielectric layer."

[0065] In the analysis using the electromagnetic field simulator, the range of "L1:L2" when the gain is in the range from "maximum gain" to "-1 dBi value" at the median frequency of the frequency band can be uniquely obtained by changing the length L2 of one side of the inner circumference of the intermediate dielectric layer while inputting each of the above-mentioned conditions. Therefore, if the antenna substrate 10 satisfies the above condition (2), it can be said that a high gain close to the optimal gain can be obtained in the entire frequency band of the signal. In the condition (2) related to the "ratio of the length L1 of one side of the outer circumference of the intermediate dielectric layer to the length L2 of one side of the inner circumference," the standard of the difference from the maximum gain at the median frequency of the frequency band is set to 1 dBi, but it is more desirable to satisfy the condition with the standard set to 0.9 dBi, and even more desirable to satisfy the condition with the standard set to 0.8 dBi. If the antenna substrate 10 satisfies such a standard, the gain can be further increased in a wide range of frequencies included in the frequency band.

[0066] The present disclosure is not limited to the above-mentioned embodiments, etc., and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0067] 10...Antenna board 15...Communication hole 20...Feed element 22a to 22c: Parasitic elements 23...Ground conductor layer 30...First dielectric layer 32a to 32c: second dielectric layer 34...Third dielectric layer 40...First intermediate dielectric layer 40I…Inner surface 42a, 42b...Second intermediate dielectric layer 42aI,42bI…Inner peripheral surface 46...Circuit side dielectric 50...Power supply circuit 62…Beer 70~73…Layer unit O…Axis line

Claims

1. An antenna substrate, a flat dielectric layer formed of a dielectric material; an element formed of a conductive material on an upper surface of the dielectric layer; In the lamination direction of the dielectric layer and the element, a plurality of lamination units each having the above structure are laminated, Among the elements included in each of the plurality of stack units, an element arranged at the bottom is a feed element, and elements other than the feed element are parasitic elements electromagnetically coupled to the feed element, Among the plurality of lamination units, a first lamination unit including at least a lamination unit including the power supply element includes an intermediate dielectric layer between the dielectric layer of the first lamination unit and the dielectric layer of a second lamination unit that is a lamination unit disposed adjacent to and above the first lamination unit, the intermediate dielectric layer being formed of the dielectric and having a frame shape whose outer peripheral shape and inner peripheral shape in a plan view are square, and disposed so as to accommodate the element within the frame in a plan view; the ratio of the thickness of the intermediate dielectric layer to the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stack unit is within a range of 1.1:0.2 to 1.05; and the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within a range of 8.8:2.2 to 8.7; The present invention is characterized in that at least one of the following is satisfied: Antenna board.

2. 2. The antenna substrate according to claim 1, The dielectric has a relative dielectric constant of 5.8 to 6.2, The ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within a range of 8.8:2.2 to 4.

0. Antenna board.

3. 2. The antenna substrate according to claim 1, the dielectric material is polytetrafluoroethylene; The ratio of the thickness of the intermediate dielectric layer to the total thickness of the dielectric layers of the second stack unit is in the range of 1.9:1.6 to 1.

8. Antenna board.

4. 4. The antenna substrate according to claim 1, the dielectric material is polytetrafluoroethylene; The ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within a range of 8.8:3.6 to 8.

7. Antenna board.

5. 2. The antenna substrate according to claim 1, the dielectric is a liquid crystal polymer; The ratio of the thickness of the intermediate dielectric layer to the total thickness of the dielectric layers of the second stack unit is in the range of 1.5:1.0 to 1.

4. Antenna board.

6. The antenna substrate according to claim 1 or 5, the dielectric is a liquid crystal polymer; The ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of the intermediate dielectric layer is within a range of 8.8:3.0 to 7.

6. Antenna board.

7. An antenna substrate, a flat dielectric layer formed of a dielectric material; an element formed of a conductive material on an upper surface of the dielectric layer; In the lamination direction of the dielectric layer and the element, a plurality of lamination units each having the above structure are laminated, Among the elements included in each of the plurality of stack units, an element arranged at the bottom is a feed element, and the other elements are parasitic elements electromagnetically coupled to the feed element, Among the plurality of lamination units, a first lamination unit including at least a lamination unit including the power supply element includes an intermediate dielectric layer between the dielectric layer of the first lamination unit and the dielectric layer of a second lamination unit that is a lamination unit disposed adjacent to and above the first lamination unit, the intermediate dielectric layer being formed of the dielectric and having a frame shape whose outer peripheral shape and inner peripheral shape in a plan view are square, and disposed so as to accommodate the element within the frame in a plan view; The present invention is characterized in that it satisfies at least one of the following conditions (1) and (2): Antenna board. (1) The ratio of the thickness of the intermediate dielectric layer to the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit is set within a numerical range calculated from a range of thicknesses of the intermediate dielectric layer when the gain of the antenna substrate at the median value of the frequency band of a signal transmitted and received by the antenna substrate falls within a range from the highest value at the median value to a value 1 dBi lower than the highest value when the thickness of the intermediate dielectric layer is changed and the gain of the antenna substrate is calculated using an electromagnetic field simulator using conditions including the length of one side of the outer periphery, the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit, and the length of one side of the inner periphery of the intermediate dielectric layer. (2) A ratio between the length of an outer periphery side and the length of an inner periphery side of the intermediate dielectric layer when viewed in a plane is set within a numerical range calculated from a range of the length of the inner periphery side when the gain of the antenna substrate is calculated by an electromagnetic field simulator while changing the length of the inner periphery side using conditions including the length of the outer periphery side, the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking unit, and the thickness of the intermediate dielectric layer, such that the gain at the median value of the frequency band of the signal falls within a range from the highest value at the median value to a value 1 dBi lower than the highest value.

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