JP7621165B2 - Antenna Board - Google Patents

Description

This disclosure relates to an antenna substrate.

Conventionally, antenna substrates in which multiple dielectric layers and multiple conductor layers are alternately stacked are known (see, for example, Patent Document 1). In the antenna substrate described in Patent Document 1, dielectric loss is suppressed by providing a hollow structure on the conductor layer inside the antenna substrate.

Japanese Patent Application Publication No. 2-252304

However, the inventors of the present application have found that although providing a hollow structure in the antenna substrate as described above makes it possible to reduce dielectric loss, sufficient antenna characteristics may not be obtained depending on the dimensions of the hollow structure. There is a demand for technology that improves the antenna characteristics of antenna substrates with hollow structures.

The present disclosure can be realized in the following forms.
(1) According to one aspect 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 formed of a conductive material 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. and an intermediate dielectric layer is provided 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 formed into a frame shape whose outer periphery and inner periphery are square in plan view, and the intermediate dielectric layer is arranged so as to accommodate the element within the frame in plan view, 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 the antenna substrate of this embodiment, by satisfying at least one of the two conditions relating to numerical ranges, namely, "the ratio of the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer of the second stacking 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 in the intermediate dielectric layer is within a 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, it is possible to increase the gain and improve the antenna characteristics in an antenna substrate having a dielectric with a relative dielectric constant of 5.8 to 6.2.
(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 stack 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, it is possible to increase the gain and improve the antenna characteristics in an antenna substrate having polytetrafluoroethylene as a dielectric material.
(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 layer 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 may be 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 the gain and improve the antenna characteristics in an antenna substrate having a liquid crystal polymer as a dielectric material.
(7) According to another aspect of the present disclosure, there is provided an antenna substrate, the antenna substrate being 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 disposed 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, 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 disposed 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 disposed so as to accommodate the element within the frame in a plan view, and satisfying 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 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.
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 manufacturing method for an antenna substrate, a design method for an antenna substrate, or the like.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of the antenna substrate according to the first embodiment. FIG. 2 is a plan view illustrating an appearance of the antenna substrate. FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator. FIG. 11 is an explanatory diagram showing an example of the gain of an antenna substrate calculated by an electromagnetic field simulator.

A. First embodiment:
(A-1) Configuration of antenna substrate:
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 taken along line 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 "stacking direction". The X-axis and Y-axis indicate the horizontal direction. The vertical direction and 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 layout of each part in a schematic manner, and do not accurately show the ratio of the dimensions of each part.

The antenna board 10 of this embodiment can be used in the fields of communication such as mobile terminals and base stations, factories, offices, medical care, infrastructure, plants, transportation, and other fields that utilize the 5th generation mobile communication system (5G: 5th Generation Mobile Communication System). Specifically, the antenna board 10 of this embodiment can be an antenna board that supports the 28 GHz frequency band n257 (26.5 to 29.5 GHz).

The antenna substrate 10 of this embodiment includes a first dielectric layer 30, second dielectric layers 32a, 32b, 32c, and a third dielectric layer 34, which are flat and made of a dielectric. The antenna substrate 10 further includes a first intermediate dielectric layer 40 and second intermediate dielectric layers 42a, 42b, which are frame-shaped and made of a dielectric. The antenna substrate 10 further includes a feed element 20, parasitic elements 22a, 22b, 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 shown as axis O.

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. Also, the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 42b are formed to the same thickness.

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, a "square" includes a shape that has the same length and width, and in which the difference between the length of the long side and the length of the short side is within 10% of the length of the long side.

As described above, the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 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 Figs. 1 and 2, the inner peripheral surfaces of the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 42b are shown as inner peripheral surfaces 40I, 42aI, and 42bI, respectively, and in Fig. 2, the positions of the inner peripheral surfaces 40I, 42aI, and 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 layers 42a and 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 layers 42a and 42b are not distinguished from each other, they are also simply called "intermediate dielectric layers".

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 formed of the same type of dielectric. The dielectrics constituting these dielectric layers may be, for example, dielectrics having a relative dielectric constant in the range of 2.0 to 10.0. Specifically, for example, polytetrafluoroethylene (PTFE) with a relative dielectric constant of 2.1 or liquid crystal polymer (LCP) with a dielectric constant of 3.1 may be used. In this specification, the relative dielectric constant of the dielectric refers to the relative dielectric constant at 1 GHz.

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

The power feed element 20 is fed from the power feed circuit 50. The parasitic elements 22a, 22b, and 22c are electromagnetically coupled to the power feed element 20 without receiving power when the power feed element 20 functions as an antenna element, and radiate radio waves to the upper surface of the antenna substrate 10. The power feed element 20 and the parasitic elements 22a, 22b, and 22c are formed of a conductive material, for example, a metal material containing copper or aluminum. At least a part of the surface of the power feed element 20 that is exposed in the space formed by the inner 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 gain can be fine-tuned by the thickness of the coating, and the power feed element 20 can be physically protected.

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 power supply 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.

The ground conductor layer 23 is formed on the lower surface (the 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 emitted from the power supply element 20. A third dielectric layer 34 is laminated on the lower surface of the ground conductor layer 23, and a power supply circuit 50 that supplies power to the power supply element 20 is bonded to the lower surface of the third dielectric layer 34.

The power supply circuit 50 has three laminated dielectrics, ie, circuit-side dielectrics 46, 47, and 48. Vias 62, 64, and 66 are formed in each of the circuit-side dielectrics 46 to 48, penetrating along the Z-axis, which is the thickness direction. To connect the power supply circuit 50 and the power supply element 20, the antenna substrate 10 has a conductor portion (not shown) that penetrates the first dielectric layer 30, the ground conductor layer 23, and the third dielectric layer 34.

The antenna substrate 10 may further have a through hole 15 penetrating the antenna substrate 10 in the stacking direction, as shown in FIG. 2. 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 connects the space formed by the inner surface 40I of the first intermediate dielectric layer 40 and the space formed by the inner 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.

(A-2) Manufacturing method of antenna substrate:
In the following, as an example of the 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.

Then, holes are formed in the prepared green sheets by punching or laser processing. For example, holes are formed in the green sheets that will become the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 42b at positions corresponding to the inner circumference of the frame-like shape described above. Here, in the green sheets that will become the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 42b, the size of the rectangular holes to be formed can be determined so that the "ratio of the length of one side of the dielectric layer to the length of one side of the hollow portion" in the first intermediate dielectric layer 40 and the second intermediate dielectric layers 42a and 42b of the antenna substrate 10 obtained after the firing process described below satisfies the numerical range described below. In addition, for the green sheets that will become the first intermediate dielectric layer 40 and the second intermediate dielectric layer 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.

Holes are formed in the green sheets that will become the circuit-side dielectrics 46, 47, 48 at positions corresponding to the vias 62, 64, 66. The holes that correspond 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 multiple green sheets with the conductive layers formed in a specific order and applying heat and pressure. The resulting laminate is degreased and fired to obtain the antenna substrate 10.

(A-3) Dimensional ratio of hollow part:
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.

In this embodiment, each of the lamination units including the intermediate dielectric layer (first intermediate dielectric layer 40 or 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 (+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".

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 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 determined in this manner can be finely adjusted, for example, by the size of the feed element 20 and the parasitic elements 22a, 22b, and 22c, the number of stacking units provided in the antenna substrate 10, and the presence or absence of a dielectric coating layer on the surface of the feed element 20, but are not greatly changed.

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 , 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".

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".

The antenna substrate 10 of this embodiment satisfies at least one of the following: "The ratio of the sum of the thickness of the intermediate dielectric layer and the thickness of the dielectric layer 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 in the intermediate dielectric layer is within a range of 8.8:2.2 to 8.7." The above numerical ranges are explained in more detail below.

(A-3-1) Ratio of the total thickness of the dielectric layers to the thickness of the hollow portion:
The following describes an antenna substrate 10 in which the ratio of the sum _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.

<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 for the band n257 (26.5 to 29.5 GHz) of the 28 GHz band, in which a dielectric ceramic having a relative dielectric constant of 6.0 is used 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.

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. As the 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 above-mentioned 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) was input, along with the length of one side of the feed element 20 and the parasitic elements 22a to 22c (2.0 mm in this case), the thickness of the first dielectric layer 30 (0.4 mm in this case), the type of metal used in the antenna substrate 10 (conductivity, conductor loss), the type of dielectric (dielectric constant, dielectric loss), and the power conditions were input, and the thickness _T2 of the intermediate dielectric layer was changed in the above-mentioned 11 steps to perform analysis using the electromagnetic field simulator, and the change in gain in the 28 GHz band was obtained. 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 layers of the second stack unit is 0). In Fig. 3, the horizontal axis represents frequency and the vertical axis represents gain.

The median frequency of band n257 (26.5 to 29.5 GHz) of the 28 GHz band is 28.0 GHz, and as shown in Fig. 3, the gain at the median frequency is highest when the thickness _T2 of the intermediate dielectric layer is 0.7 mm. In Fig. 3, the value 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 Fig. 3, which represents the gain, indicates a relative value when the maximum gain is set to 0.

As shown in Fig. 3, the greater the difference between the thickness _T2 of the intermediate dielectric layer and the thickness _T2 of the intermediate dielectric layer of 0.7 mm 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-mentioned 11 stages, 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 shown in Fig. 3, it is considered that 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 1.05 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 to 1.05". From the results shown in Fig. 3, it is understood 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 in the range of 1.1:0.2 to 1.05 can realize a high gain.

<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 of 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 for the band n257 (26.5 to 29.5 GHz) of the 28 GHz band, in which polytetrafluoroethylene with a relative dielectric constant of 2.1 is used 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.

The thickness _T2 of the intermediate dielectric layer was changed in four stages at intervals of 0.1 mm from 1.5 mm to 1.8 mm. As the 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 above-mentioned 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) was input, along with 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 used in the antenna substrate 10 (conductivity, conductor loss), the type of dielectric (dielectric constant, dielectric loss), and the power conditions were input, and the thickness _T2 of the intermediate dielectric layer was changed in the above four stages, and analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In FIG. 4, the horizontal axis represents frequency, and the vertical axis represents gain.

The median frequency of the band n257 (26.5 to 29.5 GHz) of the 28 GHz band is 28.0 GHz, and as shown in FIG. 4, the gain at the median frequency is highest when the thickness T ₂ of the intermediate dielectric layer is 1.8 mm. Note that FIG. 7 does not show the case where the thickness T ₂ of the intermediate dielectric layer exceeds 1.8 mm, but when the thickness T ₂ of the intermediate dielectric layer exceeds 1.8 mm, the thickness (T ₁ -T ₂ ) of the dielectric layer of the second stack unit becomes thin, which may cause insufficient strength, so the maximum value of the thickness T ₂ of the intermediate dielectric layer is set to 1.8 mm. Therefore, the maximum gain at the median frequency is specified as being when the thickness T ₂ of the intermediate dielectric layer is 1.8 mm. In FIG. 4, a value 1 dBi lower than the gain value when the thickness T ₂ of the intermediate dielectric layer is 1.8 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 FIG. 4, which represents the gain, indicates a relative value when the maximum gain is set to 0.

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 tends to be. Also, as shown in Fig. 4, 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 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 having a relative dielectric constant of 2.1 is used as the dielectric, it is understood that an antenna substrate 10 in which 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, particularly within the range of 1.9:1.6-1.8, i.e., 1.1:0.93-1.04, can realize a particularly high gain.

<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 changing the thickness _T2 of the intermediate dielectric layer using a dielectric different from that of the above-mentioned mode 1 and mode 2. Fig. 5 shows the analysis results of the antenna substrate 10 for band n257 (26.5 to 29.5 GHz) of the 28 GHz band, which uses a liquid crystal polymer (LCP) having 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.

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. As the 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 above-mentioned 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) was input, along with 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 used in the antenna substrate 10 (conductivity, conductor loss), the type of dielectric (dielectric constant, dielectric loss), and the power conditions were input, and the thickness _T2 of the intermediate dielectric layer was changed in the above-mentioned six steps, and analysis was performed using the electromagnetic field simulator to obtain the change in gain in the 28 GHz band. In FIG. 5, the horizontal axis represents frequency, and the vertical axis represents gain.

The median of the band n257 (26.5 to 29.5 GHz) of the 28 GHz band is 28.0 GHz, 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 1.4 mm. Note that Fig. 5 does not show the case where the thickness _T2 of the intermediate dielectric layer exceeds 1.4 mm, but if the thickness _T2 of the intermediate dielectric layer exceeds 1.4 mm, the thickness ( _T1 - _T2 ) of the dielectric layer of the second lamination unit becomes thin, which may result in insufficient strength, so the maximum value of the thickness _T2 of the intermediate dielectric layer is set to 1.4 mm. 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 1.4 mm. In FIG. 5, a value that is 1 dBi lower than the gain value when the thickness _T2 of the intermediate dielectric layer is 1.4 mm, which is the maximum gain at the median frequency of 28.0 GHz, is indicated by a white arrow as a "-1 dBi value. The vertical axis of FIG. 5, which represents the gain, indicates a relative value when the maximum gain is set to 0.

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 tends to be. Also, as shown in Fig. 5, 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 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 having a relative dielectric constant of 3.1 is used as the dielectric, it is understood that an antenna substrate 10 in which 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, particularly within the range of 1.5:1.0-1.4, i.e., 1.1:0.73-1.027, can realize a particularly high gain.

(A-3-2) Ratio of the length of one side of the dielectric layer to the length of one side of the hollow portion:
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."

<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 by 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.

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 the 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 length _L1 of one side of the outer circumference 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 (2.0 mm in this case), the thickness of the first dielectric layer 30 (0.4 mm in this case), the type of metal (conductivity, conductor loss), 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 analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In FIG. 6, the horizontal axis represents frequency, and the vertical axis represents gain.

The median of the 28 GHz band n257 (26.5-29.5 GHz) is 28.0 GHz, and as shown in Fig. 6, the gain at the median of this frequency is highest when the length _L2 of one side of the inner circumference is 3.4 mm. In Fig. 6, the value 1 dBi lower than the gain value when the length _L2 of one side of the inner circumference is 3.4 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 Fig. 6, which shows the gain, represents a relative value when the maximum gain is set to 0.

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 a frequency of 28.0 GHz, the smaller the magnitude of the gain at a frequency of 28.0 GHz tends to be. As shown in Fig. 6, among the results of changing the length _L2 of the inner circumference of the intermediate dielectric layer to the seven stages described above, 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 understood 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 realize a particularly high gain.

<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 changing the length _L2 of one side of the inner circumference of the intermediate dielectric layer by using a dielectric different from that of the above-mentioned embodiment 4. Fig. 7 shows the analysis results of the antenna substrate 10 for the band n257 (26.5 to 29.5 GHz) of the 28 GHz band, in which polytetrafluoroethylene with a relative dielectric constant of 2.1 is used 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.

The length _L2 of one side of the inner circumference of the intermediate dielectric layer was changed in seven stages, namely, 3.4 mm, 3.6 mm, 4.2 mm, 4.4 mm, 4.6 mm, 8.6 mm, and 8.8 mm. As the 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 length _L1 of one side of the outer circumference 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 (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), 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 analysis was performed using the electromagnetic field simulator to determine the change in gain in the 28 GHz band. In addition, among the seven stages in which the length _L2 of one side of the inner periphery of the intermediate dielectric layer is changed as described above, the case in which the length _L2 of one side of the inner periphery of the intermediate dielectric layer is 8.8 mm represents a hypothetical state in which the length _L1 of one side of the outer periphery of the intermediate dielectric layer is equal to the length _L2 of one side of the inner periphery of the intermediate dielectric layer (the entire intermediate dielectric layer is a hollow portion). In Fig. 7, the horizontal axis represents frequency and the vertical axis represents gain.

The median frequency of band n257 (26.5-29.5 GHz) in the 28 GHz band is 28.0 GHz, and as shown in Fig. 7, the gain at the median frequency is highest when the length _L2 of one side of the inner circumference is 4.4 mm. In Fig. 7, the value 1 dBi lower than the gain value when the length _L2 of one side of the inner circumference 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 Fig. 7, which shows the gain, represents a relative value when the maximum gain is set to 0.

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 of 4.4 mm when the gain is maximum at a frequency of 28.0 GHz, the smaller the magnitude of the gain at the frequency of 28.0 GHz tends to be. 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 of 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 of 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 in which 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 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.

<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 changing the length _L2 of one side of the inner circumference of the intermediate dielectric layer using a dielectric different from that of the above-mentioned embodiment 4 and embodiment 5. Fig. 8 shows the analysis results of the antenna substrate 10 for band n257 (26.5 to 29.5 GHz) of the 28 GHz band, which 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.

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. As the 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 length _L1 of one side of the outer circumference 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 (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), 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 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.

The median of the 28 GHz band n257 (26.5 to 29.5 GHz) is 28.0 GHz, and as shown in Fig. 8, the gain at the median of this frequency is highest when the length _L2 of one side of the inner circumference is 6.0 mm. In Fig. 8, the value 1 dBi lower than the gain value when the length _L2 of one side of the inner circumference is 6.0 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 Fig. 8, which shows the gain, represents a relative value when the maximum gain is set to 0.

As shown in Fig. 8, the greater the difference between the length _L2 of the inner periphery of the intermediate dielectric layer and the length _L2 of the inner periphery of 6.0 mm when the gain is maximum at a frequency of 28.0 GHz, the smaller the magnitude of the gain at the frequency of 28.0 GHz tends to be. As shown in Fig. 8, the range of the length _L2 of the inner periphery 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 periphery of the intermediate dielectric layer to the length _L2 of the inner periphery" is "8.8:3.0 to 7.6". From the results shown in FIG. 8, it can be seen that when a liquid crystal polymer having a relative dielectric constant of 3.1 is used as a dielectric, an antenna substrate 10 in which the ratio of the length _L1 of one side of the outer periphery to the length _L2 of one side of the inner periphery in the intermediate dielectric layer is within the range of 8.8:2.2 to 8.7, and particularly within the range of 8.8:3.0 to 7.6, can realize a particularly high gain.

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-mentioned 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-mentioned two conditions.

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 to 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 to _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 to 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 to 8.7". Furthermore, for example, when a liquid crystal polymer (LCP) having 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 a 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 a range of 8.8:3.0 to 7.6", a higher gain can be realized and the antenna characteristics can be improved.

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

B. Other embodiments:
In the embodiment described above, 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 the lamination unit 70 including the feed element 20 may be any number equal to or greater than one.

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. When 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", a similar effect of improving the gain can be obtained.

Although a single antenna substrate 10 is shown in Figs. 1 and 2, multiple antenna substrates 10 may be arranged in a line, or may be arranged two-dimensionally to form an array antenna.

In the embodiment, the antenna substrate 10 is illustrated as having a dielectric with a dielectric constant of 6.0, 2.1, and 3.1, 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 achieve the same effect of increasing the antenna gain by satisfying at least one of the following conditions (1) and (2).

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, when the thickness _T2 of the intermediate dielectric layer is changed 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, the gain of the antenna substrate 10 is calculated using an electromagnetic field simulator while the thickness _T2 of the intermediate dielectric layer is changed, the gain at the median value of the frequency band of the signal transmitted and received by the antenna substrate 10 falls within a range from the highest value at the median value to a value 1 dBi lower than the highest value."

In the analysis using an electromagnetic field simulator, by inputting each of the above-mentioned conditions and changing the thickness _T2 of the intermediate dielectric layer, 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. Therefore, if the above condition (1) is satisfied in the antenna substrate 10, 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 preferable to satisfy the condition with the standard set to 0.9 dBi, and even more preferable 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.

Moreover, the condition (2) is that, in the antenna substrate, "(2) 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 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 value of the frequency band of the signal transmitted and received by the antenna substrate 10 falls within the range from the highest value at the median value to a value _{1 dBi} lower than the highest value when the length _L2 of the inner periphery of the intermediate dielectric layer is changed and the gain of the antenna substrate 10 is calculated by an electromagnetic field simulator using conditions including 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 thickness T2 of the intermediate dielectric layer."

In the analysis using an electromagnetic field simulator, the range of "L 1 :L ₂ " 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 L ₂ 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 L ₁ of one side of the outer circumference of the intermediate dielectric layer to the length L ₂ 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 preferable to satisfy the condition with the standard set to 0.9 dBi, and even more preferable 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.

The present disclosure is not limited to the above-mentioned embodiments, 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 replaced or combined as appropriate 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 deleted as appropriate.

REFERENCE SIGNS LIST 10...antenna substrate 15...communicating hole 20...feeding element 22a to 22c...parasitic element 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 circumferential surface 42a, 42b...second intermediate dielectric layer 42aI, 42bI...inner circumferential surface 46...circuit-side dielectric 50...feeding circuit 62...via 70 to 73...laminated unit O...axis

Claims (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 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;
An antenna substrate, comprising: 2. The antenna substrate according to claim 1,
The dielectric has a relative dielectric constant of 5.8 to 6.2,
The antenna substrate according to claim 1, wherein 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. 2. The antenna substrate according to claim 1,
the dielectric material is polytetrafluoroethylene;
The antenna substrate, wherein a ratio of a thickness of the intermediate dielectric layer to a sum of a thickness of the intermediate dielectric layer and a thickness of the dielectric layer of the second stack unit is within a range of 1.9:1.6 to 1.8. 4. The antenna substrate according to claim 1,
the dielectric material is polytetrafluoroethylene;
The antenna substrate according to claim 1, wherein the ratio of the length of one side of the outer periphery to the length of one side of the inner periphery of said intermediate dielectric layer is within a range of 8.8:3.6 to 8.7. 2. The antenna substrate according to claim 1,
the dielectric is a liquid crystal polymer;
The antenna substrate, wherein a ratio of a thickness of the intermediate dielectric layer to a sum of a thickness of the intermediate dielectric layer and a thickness of the dielectric layer of the second stack unit is within a range of 1.5:1.0 to 1.4. The antenna substrate according to claim 1 or 5,
the dielectric is a liquid crystal polymer;
An antenna substrate, wherein 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. 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;
An antenna substrate, characterized by satisfying 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 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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