Periodic structure forming substrate and method for adjusting periodic structure forming substrate

Abstract

To provide a periodic structure forming substrate and a method for adjusting the periodic structure forming substrate, which are capable of suppressing degradation of characteristics due to collapse of periodicity of a periodic structure.SOLUTION: A periodic structure forming substrate 1 includes: a periodic structure 5 including a plurality of unit cells 51 periodically arranged on an upper surface 2Aa of a first substrate 2A; a conductor 4 provided on a lower surface 2Ab of the first substrate 2A; a first electrode pad 71 provided in the periodic structure 5; an anti-pad 8 formed around the first electrode pad 71; and a via 73 penetrating the upper surface 2Aa and the lower surface 2Ab and connected to the first electrode pad 71. In addition, the anti-pad 8 is located in a gap G between a pair of adjacent unit cells 51 and overlaps with at least one of the unit cells 51, and a capacitance C3 between the first electrode pad 71 and each unit cell 51 is adjusted by the anti-pad 8 to a value that suppresses a decrease in characteristics due to a collapse of periodicity of the periodic structure 5.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a periodic structure forming substrate and a method for adjusting a periodic structure forming substrate. [Background technology]

[0002] As an antenna device 900 having an EBG (electromagnetic band gap), the configuration shown in FIGS. 1 and 2 is known.

[0003] The antenna device 900 includes a dielectric substrate 910, antenna elements 920a and 920b, a ground conductor 930, and an EBG structure 940. The antenna elements 920a and 920b are formed using a conductor pattern on the upper surface of the dielectric substrate 910. The ground conductor 930 is formed using a conductor pattern on the lower surface (the surface opposite to the upper surface) of the dielectric substrate 910.

[0004] The EBG structure 940 is formed on the upper surface of the dielectric substrate 910 between the antenna elements 920a and 920b using a conductor pattern. The EBG structure 940 has a plurality of patches 941 formed on the upper surface of the dielectric substrate 910 and a plurality of vias 942 connecting each patch 941 to the ground conductor 930. In the EBG structure 940, unit cells 943, each consisting of one patch 941 and one via 942 connected thereto, are periodically arranged on the dielectric substrate 910. Such an EBG 940 blocks signals in a specific frequency band and functions to improve the isolation performance between the antenna elements 920a and 920b. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-164149 Summary of the Invention [Problem to be solved by the invention]

[0006] In such an antenna device 900, if the periodic structure is disrupted in a portion of the EBG structure 940, the aforementioned blocking effect is reduced in the portion where the periodic structure is disrupted, increasing the coupling between the antenna elements 920a and 920b and reducing the isolation performance between the antenna elements 920a and 920b. Therefore, for example, as shown in Figures 3 and 4, if a circuit 950 is provided on the lower surface of a dielectric substrate 910 and a pad 960 extending from the circuit 950 is formed on the upper surface of the dielectric substrate 910, the pad 960 disrupts the periodic structure of the EBG structure 940, causing the above-mentioned problem. Therefore, it is difficult to mount the circuit 950 on the antenna device 900, and the circuit 950 must be formed on a substrate separate from the antenna device 900. This makes it difficult to achieve a compact and cost-effective system overall.

[0007] The present invention has been made in consideration of the above points, and aims to provide a periodic structure-forming substrate and a method for adjusting a periodic structure-forming substrate that can suppress deterioration in characteristics due to collapse of the periodicity of the periodic structure, so that circuits can be provided on a substrate on which a periodic structure such as an EBG structure is formed. [Means for solving the problem]

[0008] These objects can be achieved by the present inventions (1) and (2) below.

[0009] (1) a first substrate having a first surface and a second surface that are opposite surfaces; a periodic structure including a plurality of unit cells periodically arranged on the first surface and connected to each other; a conductor provided on the second surface and arranged to face the periodic structure; a first electrode pad provided within the periodic structure; an anti-pad formed around the first electrode pad to prevent contact between the first electrode pad and the periodic structure; a via that penetrates the first surface and the second surface and is connected to the first electrode pad; the anti-pad is located in a gap between a pair of adjacent unit cells and overlaps at least one of the unit cells; a periodic structure forming substrate, characterized in that the capacitance between the first electrode pad and the unit cell adjacent to the first electrode pad is adjusted by the anti-pad to a value that suppresses deterioration in characteristics due to disruption of the periodicity of the periodic structure caused by the formation of the first electrode pad.

[0010] (2) a first substrate having a first surface and a second surface that are opposite surfaces; a periodic structure including a plurality of unit cells periodically arranged on the first surface and connected to each other; a conductor provided on the second surface and arranged to face the periodic structure; a first electrode pad provided within the periodic structure; an anti-pad formed around the first electrode pad to prevent contact between the first electrode pad and the periodic structure; a via that penetrates the first surface and the second surface and is connected to the first electrode pad; The anti-pad is located in a gap between a pair of adjacent unit cells and overlaps with at least one of the unit cells, in a periodic structure forming substrate, a capacitance between the first electrode pad and the unit cell adjacent to the first electrode pad is adjusted by the anti-pad, thereby suppressing deterioration in characteristics caused by the collapse of the periodicity of the periodic structure due to the formation of the first electrode pad. [Effects of the Invention]

[0011] In the periodic structure-forming substrate of the present invention, the anti-pads adjust the capacitance between the first electrode pads and the unit cells to a value that suppresses degradation of characteristics due to the disruption of the periodicity of the periodic structure caused by the formation of the first electrode pads. Therefore, even if the periodicity of the periodic structure is disrupted by forming the first electrode pads within the periodic structure, the periodic structure can still exhibit characteristics equivalent to those of a periodic structure with maintained periodicity. Therefore, for example, a circuit can be disposed on the second surface side of the first substrate, and vias can be used as the circuit's lead wiring. This configuration allows the manufacture of a module in which a circuit is mounted on the periodic structure-forming substrate without impairing the characteristics of the periodic structure. Therefore, compared to conventional configurations in which circuits are formed separately from the periodic structure-forming substrate, the overall system can be made smaller and less expensive.

[0012] In the method for adjusting a periodic structure-forming substrate of the present invention, the capacitance between the first electrode pads and the unit cells is adjusted using anti-pads, thereby suppressing the degradation of characteristics due to the disruption of the periodicity of the periodic structure caused by the formation of the first electrode pads. Therefore, even if the periodicity of the periodic structure is disrupted by forming first electrode pads within the periodic structure, the periodic structure can still exhibit characteristics equivalent to those of a periodic structure with maintained periodicity. Therefore, for example, a circuit can be disposed on the second surface of the first substrate, and vias can be used as the circuit's lead wiring. This configuration allows the manufacture of a module in which a circuit is mounted on the periodic structure-forming substrate without impairing the characteristics of the periodic structure. Therefore, compared to conventional configurations in which circuits are formed separately from the periodic structure-forming substrate, the overall system can be made smaller and less expensive. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a top view showing a conventional antenna device. [Figure 2] FIG. 2 is a cross-sectional view taken along the line F1-F1 in FIG. [Figure 3] FIG. 10 is a top view showing a state in which a circuit is provided on the underside of a conventional antenna device. [Figure 4] FIG. 4 is a cross-sectional view taken along the line F2-F2 in FIG. 3. [Figure 5] 1 is a top view showing an antenna device according to a first embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along the line F3-F3 in FIG. 5. [Figure 7] FIG. 2 is a top view showing the basic shape of a unit cell of the periodic structure. [Figure 8] FIG. 2 is a cross-sectional view of an extraction through electrode. [Figure 9] FIG. 2 is a cross-sectional view of an extraction through electrode. [Figure 10] FIG. 2 is a top view showing first electrode pads formed on the periodic structure. [Figure 11] FIG. 2 is a top view showing a unit cell provided in the reference body. [Figure 12] FIG. 12 is a diagram showing an equivalent circuit of the unit cell shown in FIG. [Figure 13] FIG. 11 is a diagram showing an equivalent circuit of the unit cell shown in FIG. [Figure 14] FIG. 10 is a diagram showing how two capacitors connected in series are combined into one capacitor. [Figure 15] FIG. 14 is a diagram in which the equivalent circuit shown in FIG. 13 is redrawn. [Figure 16] FIG. 16 is a diagram in which the equivalent circuit shown in FIG. 15 is redrawn. [Figure 17] FIG. 10 is a top view for explaining a method for adjusting the capacitance. [Figure 18] FIG. 10 is a diagram showing the results of a plane wave irradiation analysis. [Figure 19] 10A and 10B are diagrams showing the results of verification of radio wave passage through a microstrip line. [Figure 20] FIG. 10 is a top view for explaining a method for verifying passage of radio waves through a microstrip line. [Figure 21] FIG. 10 is a top view showing a modified example of the anti-pad. [Figure 22] FIG. 10 is a top view showing a modified example of the anti-pad. [Figure 23] FIG. 10 is a top view showing a modified example of the anti-pad. [Figure 24] FIG. 10 is a top view showing an antenna device according to a second embodiment. [Figure 25] FIG. 11 is a cross-sectional view showing an extraction through electrode included in the antenna device according to the third embodiment. [Figure 26] 26 is a diagram showing an equivalent circuit of the lead-out through electrode shown in FIG. 25. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A periodic structure forming substrate and a method for adjusting a periodic structure forming substrate according to the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0015] First Embodiment FIG. 5 is a top view showing the antenna device according to the first embodiment. FIG. 6 is a cross-sectional view taken along line F3-F3 in FIG. 5. FIG. 7 is a top view showing the basic shape of a unit cell included in the periodic structure. FIGS. 8 and 9 are cross-sectional views of the lead-out through electrodes, respectively. FIG. 10 is a top view showing a first electrode pad formed on the periodic structure. FIG. 11 is a top view showing a unit cell included in the reference body. FIG. 12 is a diagram showing an equivalent circuit of the unit cell shown in FIG. 11. FIG. 13 is a diagram showing an equivalent circuit of the unit cell shown in FIG. 10. FIG. 14 is a diagram showing how two series-connected capacitances are combined into one capacitance. FIG. 15 is a diagram redrawing the equivalent circuit shown in FIG. 13. FIG. 16 is a diagram redrawing the equivalent circuit shown in FIG. 15. FIG. 17 is a top view for explaining a method for adjusting capacitance. FIG. 18 is a diagram showing the results of a plane wave irradiation analysis. FIG. 19 is a diagram showing the results of a verification of radio wave passage through a microstrip line. Fig. 20 is a top view for explaining a method for verifying passage of radio waves through a microstrip line, and Figs. 21 to 23 are top views showing modified examples of anti-pads.

[0016] For ease of explanation, the X-axis, Y-axis, and Z-axis are shown in certain drawings as being orthogonal to one another. Hereinafter, the direction along the X-axis will be referred to as the "X-axis direction," the direction along the Y-axis as the "Y-axis direction," and the direction along the Z-axis as the "Z-axis direction." The arrowed side of each axis will also be referred to as the "plus side," and the opposite side as the "minus side." The plus side of the Z-axis will also be referred to as the "upper" and the minus side as the "lower."

[0017] 5 and 6 is applied to an antenna device 100. The antenna device 100 has a substrate 2 whose thickness direction is in the Z-axis direction, and a pair of antenna elements 31 and 32, a conductor 4, a periodic structure 5, a circuit 6, and an extraction through electrode 7 provided at predetermined positions on the substrate 2.

[0018] <Board 2> 6, the substrate 2 is a dielectric substrate and is composed of a laminate of a first substrate 2A and a second substrate 2B. The first substrate 2A is located between the periodic structure 5 and the conductor 4, and the second substrate 2B is located between the conductor 4 and the circuit 6.

[0019] The first substrates 2A are opposite sides of each other and have an upper surface 2Aa as a first surface located on the positive side in the Z axis direction and a lower surface 2Ab as a second surface located on the negative side in the Z axis direction. The first substrate 2A is configured by stacking four dielectric layers 21, 22, 23, and 24 in this order from above in the Z axis direction. Meanwhile, the second substrate 2B is provided on the lower surface 2Ab side of the first substrate 2A. The second substrates 2B are opposite sides of each other and have an upper surface 2Ba located on the positive side in the Z axis direction (the first substrate 2A side) and a lower surface 2Bb as a third surface located on the negative side in the Z axis direction (the opposite side from the first substrate 2A). The second substrate 2B is configured by stacking two dielectric layers 25 and 26 in this order from above in the Z axis direction.

[0020] However, the number of dielectric layers included in the first and second substrates 2A and 2B is not particularly limited and can be set appropriately depending on the required characteristics and size. Furthermore, the dielectric layers 21 to 26 are not particularly limited, but examples that can be used include a glass epoxy substrate (a substrate made by weaving glass fibers into a cloth and layering them and impregnating it with epoxy resin), a fluororesin substrate such as PTFE (polytetrafluoroethylene), a glass plate, etc.

[0021] The thickness of the substrate 2 is not particularly limited, but in this embodiment, a standard thickness of 1.6 mm is used.

[0022] <Antenna elements 31 and 32> As shown in FIG. 5, the antenna elements 31 and 32 are formed using a conductor pattern on the upper surface of the substrate 2, i.e., the upper surface 2Aa of the first substrate 2A. The antenna elements 31 and 32 are arranged side by side in the X-axis direction and spaced apart from each other. The first and second antenna elements 31 and 32 each have a rod shape extending in the Y-axis direction. For example, the antenna elements 31 and 32 are each a dipole antenna. In this embodiment, the antenna element 31 is used as a transmitting antenna, and the antenna element 32 is used as a receiving antenna. However, the uses of the antenna elements 31 and 32 are not particularly limited.

[0023] Conductor 4 6, the conductor 4 is formed in a planar shape using a conductor pattern on the lower surface 2Ab of the first substrate 2A, that is, between the dielectric layers 24 and 25. The conductor 4 overlaps with the periodic structure 5 in the Z-axis direction and is disposed opposite the periodic structure 5 and the first substrate 2A interposed therebetween. In the antenna device 100, the thickness of the first substrate 2A, specifically the number of dielectric layers constituting the first substrate 2A and the thickness of each dielectric layer, is appropriately set so that the separation distance D between the conductor 4 and the periodic structure 5 is a predetermined distance.

[0024] ≪Periodic structure 5≫ 5, a periodic structure 5 is provided on the upper surface of the substrate 2, that is, the upper surface 2Aa of the first substrate 2A. The periodic structure 5 is formed using a conductor pattern between the antenna elements 31 and 32. Such a periodic structure 5 is an EBG (electromagnetic band gap) structure, which blocks signals in a specific frequency band and improves the isolation performance between the antenna elements 31 and 32.

[0025] The periodic structure 5 has a plurality of unit cells 51. The plurality of unit cells 51 are periodically arranged in a matrix along the X-axis direction (first direction) and the Y-axis direction (second direction). The plurality of unit cells 51 aligned in the X-axis direction are connected to one another, and similarly, the plurality of unit cells 51 aligned in the Y-axis direction are connected to one another. The size and number of unit cells 51 (the number of repetitions in the X-axis direction and the Y-axis direction) are appropriately set depending on the frequency band of the signal to be blocked, etc. The frequency band of the signal to be blocked is not particularly limited, but is assumed to be approximately 6.5 GHz to 8.0 GHz in this embodiment.

[0026] Fig. 7 shows the shape of a unit cell 51. Fig. 7 shows the original shape before a portion is lost due to an anti-pad 8, which will be described later. In contrast, Fig. 5 shows the state after the anti-pad 8 has been formed.

[0027] The unit cell 51 is formed in a square region S and has a square central portion 511 located in the center of the region S. The unit cell 51 also has four square corners 512a, 512b, 512c, and 512d located at the four corners (respective corners) of the region S. Each of these corners 512a to 512d is larger than the central portion 511. Each of the corners 512a to 512d is connected to the central portion 511 at one corner close to the center of the region S. Furthermore, unit cell 51 has X-axis thin wire portion 513x as a first thin wire portion that extends in the X-axis direction through the center of region S and is arranged between corners 512a, 512b and corners 512c, 512d, and Y-axis thin wire portion 513y as a second thin wire portion that extends in the Y-axis direction through the center of region S and is arranged between corners 512a, 512d and corners 512b, 512c. By configuring unit cell 51 in this way, it is possible to easily connect adjacent unit cells 51 while making the shape of unit cell 51 as simple as possible.

[0028] The "square" mentioned above includes not only a square, but also shapes that are slightly different from a square within a range that can be regarded as the same as a square from the common technical knowledge in the field.

[0029] In addition, in a pair of unit cells 51 adjacent in the X-axis direction, corners 512a, 512d of one unit cell 51 (on the negative side of the X-axis direction) and corners 512b, 512c of the other unit cell 51 (on the positive side of the X-axis direction) are spaced apart by a predetermined gap G, and are connected to each other at the ends of X-axis thin wire portions 513x. In other words, the X-axis thin wire portions 513x function as wiring connecting a pair of unit cells 51 adjacent in the X-axis direction. In addition, in a pair of unit cells 51 adjacent in the Y-axis direction, corners 512c, 512d of one unit cell 51 (on the positive side of the Y-axis direction) and corners 512a, 512b of the other unit cell 51 (on the negative side of the Y-axis direction) are spaced apart by a predetermined gap G, and are connected to each other at the ends of Y-axis thin wire portions 513y. In other words, the Y-axis thin wire portions 513y function as wiring connecting a pair of unit cells 51 adjacent in the Y-axis direction.

[0030] Although the periodic structure 5 has been described above, the configuration of the periodic structure 5 is not particularly limited. For example, the shape of the unit cell 51 is not particularly limited as long as it can exhibit the effects of the present invention described below. For example, each of the corners 512a to 512d may be smaller than the central portion 511.

[0031] Circuit 6 6, a circuit 6 is provided on the lower surface of the substrate 2, i.e., the lower surface 2Bb of the second substrate 2B. The circuit 6 is a circuit that constitutes the circuit portion of the antenna device 100. Such a circuit 6 includes a transmitter 61, a receiver 62, and a control device 63 that controls the driving of these.

[0032] The transmitter 61 has, for example, an input unit that inputs information to be transmitted via radio waves from the antenna element 31, an oscillator that generates a high-frequency signal that is the basis of the radio waves, a modulation control unit that modulates the high-frequency signal oscillated by the oscillator and superimposes the signal from the input unit on it, and an amplifier unit that amplifies the high-frequency signal modulated by the modulation control unit to a predetermined power. The high-frequency signal amplified by the amplifier unit is input to the antenna element 31, and radio waves based on the input high-frequency signal are radiated from the antenna element 31.

[0033] In contrast, the receiver 62 has, for example, a tuning unit that selects and outputs only the necessary frequency components from the received signal received by the antenna element 32, an amplifier unit that amplifies the received signal output from the tuning unit to the necessary level, a demodulator unit that demodulates the received signal amplified by the amplifier unit and extracts the information carried in the received signal, and an output unit that outputs the information extracted by the demodulator unit in a predetermined format.

[0034] The control device 63 controls the operation of the transmitter 61 and the receiver 62. The control device 63 is configured, for example, as a computer, and has one or more processors for processing information and a memory communicatively connected to the processor. The memory stores programs and data that can be executed by the processor, and the processor reads and executes the left-behind programs and data stored in the memory.

[0035] Although the circuit 6 has been described above, there are no particular limitations on the configuration of the circuit 6. For example, the circuit 6 does not have to constitute the circuit portion of the antenna device 100.

[0036] ≪Drawer through electrode 7≫ 6, a plurality of lead-out through electrodes 7 are formed on the substrate 2. Each of these lead-out through electrodes 7 is used as wiring for electrically routing the circuit 6 provided on the lower surface of the substrate 2 to the upper surface of the substrate 2. With this configuration, the circuit 6 can be electrically connected to an external device from the upper surface side of the substrate 2. This facilitates electrical connection between the antenna device 100 and an external device.

[0037] As shown in FIG. 8 , the lead-out through electrode 7 includes a first electrode pad 71 provided on the upper surface of the substrate 2, i.e., the upper surface 2Aa of the first substrate 2A; a second electrode pad 72 provided on the lower surface of the substrate 2, i.e., the lower surface 2Bb of the second substrate 2B; and a via 73 that penetrates the substrate 2 in the thickness direction (Z-axis direction) and is connected to the first and second electrode pads 71 and 72 at both ends. The first electrode pad 71, the second electrode pad 72, and the via 73 are concentrically arranged in a plan view of the substrate 2 (plan view from the Z-axis direction). In this embodiment, the first electrode pad 71, the second electrode pad 72, and the via 73 are each circular in a plan view of the substrate 2 (plan view from the Z-axis direction). However, the shapes of the first electrode pad 71, the second electrode pad 72, and the via 73 are not particularly limited. The term "circular" includes not only a circle, but also shapes that are slightly deviated from a circle within a range that can be considered the same as a circle according to common technical knowledge in the relevant field.

[0038] Moreover, the second electrode pad 72 is electrically connected to the circuit 6. Therefore, the circuit 6 and the lead-out through electrode 7 are electrically connected at the second electrode pad 72. With this configuration, the circuit 6 and the lead-out through electrode 7 can be easily electrically connected.

[0039] Here, the width W1 of the via 73 (diameter in this embodiment) is not particularly limited, but is preferably 0.3 mm or less, for example. By setting the width W1 to such a size, the via 73 can be formed sufficiently thin, and the inductance component of the via 73 can be sufficiently large. Note that the through-hole for forming the via 73 can be formed by a drill if the width W1 is up to about 0.3 mm, and can be formed by a laser if the width W1 is smaller than that. Particularly in this embodiment, the width W1 is set to about 0.3 mm in order to reduce the cost of the antenna device 100 by using an inexpensive substrate 2 in which the through-hole is formed by a drill.

[0040] Furthermore, the length L of the via 73 is not particularly limited, but is preferably 1.6 mm or more, for example. By setting the length L to such a size, the inductance component of the via 73 can be sufficiently increased. Furthermore, the distance between the first electrode pad 71 and the second electrode pad 72 can be sufficiently increased, and the capacitance formed between them can be kept sufficiently small.

[0041] The above has described the configuration of the lead-out through electrode 7. The uses of such lead-out through electrodes 7 are not particularly limited, and examples include a GND electrode that connects the circuit 6 to ground, a VDD electrode that supplies power to the circuit 6, an IN electrode that inputs information to an input section of the circuit 6, and an OUT electrode that outputs information from an output section of the circuit 6, and one or more types can be selected and used from these. Hereinafter, for convenience of explanation, of the lead-out through electrodes 7, those used as GND electrodes will be referred to as lead-out through electrodes 7a, and those used for other purposes (VDD electrodes, IN electrodes, OUT electrodes, etc.) will be collectively referred to as lead-out through electrodes 7b.

[0042] In this embodiment, a plurality of lead-out through electrodes 7a, 7b are formed on the substrate 2. As shown in FIG. 8, each lead-out through electrode 7a contacts the conductor 4 along the way. Therefore, during use of the antenna device 100, the conductor 4 is connected to ground by the lead-out through electrode 7a. On the other hand, as shown in FIG. 9, each lead-out through electrode 7b does not contact the conductor 4. This prevents short-circuiting between the lead-out through electrodes 7a, 7b via the conductor 4. An opening is formed in the conductor 4 at a portion where the lead-out through electrode 7b intersects with the lead-out through electrode 7b, and this opening prevents contact between the lead-out through electrode 7b and the conductor 4.

[0043] However, this is not limited to this, and both of the lead-out through electrodes 7a and 7b may be in non-contact with the conductor 4, or only one type of lead-out through electrode 7b (for example, only the VDD electrode, only the IN electrode, or only the OUT electrode) may be in contact with the conductor 4, with the remaining electrodes and the lead-out through electrode 7a being in non-contact with the conductor 4.

[0044] Next, a description will be given of the arrangement of the first electrode pads 71. As shown in Fig. 10, the plurality of first electrode pads 71 are each arranged within the periodic structure 5. Around each first electrode pad 71, an anti-pad 8 is formed, which is an opening for preventing contact between the first electrode pad 71 and the periodic structure 5.

[0045] The anti-pads 8 are circular in plan view of the substrate 2 (plan view from the Z-axis direction), similar to the first electrode pads 71. However, the shape of the anti-pads 8 is not particularly limited, and may be a shape different from that of the first electrode pads 71, such as a rectangle or an ellipse. Furthermore, the term "circular" as used above includes not only a circle but also a shape that is slightly deviated from a circle within a range that can be regarded as the same as a circle from the perspective of common technical knowledge in the field.

[0046] The anti-pads 8 are formed in the gap G between a pair of unit cells 51 adjacent to each other in the X-axis or Y-axis direction. The anti-pads 8 are also formed to avoid the connection between the pair of unit cells 51 located on both sides of the anti-pads 8. That is, the anti-pads 8 formed in the gap G between a pair of unit cells 51 adjacent to each other in the X-axis direction are formed to avoid the X-axis thin wire portion 513x so as not to overlap with and cut the X-axis thin wire portion 513x. Similarly, the anti-pads 8 formed in the gap G between a pair of unit cells 51 adjacent to each other in the Y-axis direction are formed to avoid the Y-axis thin wire portion 513y so as not to overlap with and cut the Y-axis thin wire portion 513y.

[0047] In particular, in this embodiment, two anti-pads 8 (8a, 8b) are formed in the gap G between a pair of unit cells 51 adjacent to each other in the X-axis direction, with the X-axis thin line portion 513x sandwiched therebetween, and two anti-pads 8 (8c, 8d) are formed in the gap G between a pair of unit cells 51 adjacent to each other in the Y-axis direction, with the Y-axis thin line portion 513y sandwiched therebetween.

[0048] The anti-pad 8 has a diameter larger than the gap G and overlaps with each of a pair of unit cells 51 located on both sides thereof. Therefore, the anti-pad 8 forms arc-shaped cutouts 515 on the outer peripheries of the corners 512a to 512d. Specifically, the anti-pad 8a is formed so as to overlap both the corner 512a of the unit cell 51 located on the negative side in the X-axis direction and the corner 512b of the unit cell 51 located on the positive side in the X-axis direction, thereby forming the cutouts 515 at these corners 512a and 512b. The anti-pad 8b is formed so as to overlap both the corner 512d of the unit cell 51 located on the negative side in the X-axis direction and the corner 512c of the unit cell 51 located on the positive side in the X-axis direction, thereby forming the cutouts 515 at these corners 512d and 512c.

[0049] Anti-pad 8c is formed to overlap both corner 512c of unit cell 51 located on the positive side in the Y axis direction and corner 512b of unit cell 51 located on the negative side in the Y axis direction, forming cutouts 515 at these corners 512c and 512b. Anti-pad 8d is formed to overlap both corner 512d of unit cell 51 located on the positive side in the Y axis direction and corner 512a of unit cell 51 located on the negative side in the Y axis direction, forming cutouts 515 at these corners 512d and 512a.

[0050] A first electrode pad 71 is formed inside the anti-pad 8 as described above. The width (diameter in this embodiment) of the first electrode pad 71 is smaller than the width of the anti-pad 8, and the first electrode pad 71 is arranged concentrically with the anti-pad 8. This prevents the first electrode pad 71 from contacting the periodic structure 5 by the anti-pad 8. In particular, in this embodiment, the width of the first electrode pad 71 is equal to or larger than the gap G between a pair of adjacent unit cells 51. Therefore, as described above, it becomes necessary to form the anti-pad 8 so as to overlap the unit cells 51 located on both sides of it.

[0051] The above has described the arrangement of the first electrode pads 71. Note that in this embodiment, the plurality of first electrode pads 71 are arranged regularly within the periodic structure 5, that is, eight first electrode pads 71 are arranged around each unit cell 51, but this is not limiting, and for example, the first electrode pads 71 may be arranged irregularly within the periodic structure 5, as in a second embodiment described later.

[0052] In the antenna device 100 configured as described above, the first electrode pads 71 and anti-pads 8 are formed within the periodic structure 5, which causes the periodicity of the periodic structure 5 to be disrupted. It is known that disruption of the periodicity of the periodic structure 5 leads to a deterioration in the characteristics of the periodic structure 5. However, in the antenna device 100, the degradation of the characteristics of the periodic structure 5 caused by the disruption of periodicity is effectively suppressed by devising the configuration of specific parts. This will be described in detail below.

[0053] First, FIG. 11 shows a reference body 500, which is a periodic structure 5 in which the first electrode pads 71 and anti-pads 8 are not formed and periodicity is maintained. FIG. 12 shows an equivalent circuit of a unit cell 51 when a current in the X-axis direction flows through the reference body 500. In FIG. 12, L1 equivalently represents the inductance of the unit cell 51. Furthermore, L2 equivalently represents the inductance of the X-axis thin line portion 513x, which serves as wiring connecting a pair of adjacent unit cells 51. Furthermore, capacitance C1 equivalently represents the capacitance between the unit cell 51 and the conductor 4. Furthermore, capacitance C2 equivalently represents the capacitance between a pair of adjacent unit cells 51.

[0054] Next, FIG. 13 shows an equivalent circuit of a unit cell 51 when a current flows through the periodic structure 5 in the X-axis direction. In FIG. 13, L1 equivalently represents the inductance of the unit cell 51. L2 equivalently represents the inductance of the X-axis thin wire portion 513x, which serves as a wiring connecting a pair of adjacent unit cells 51. C1 equivalently represents the capacitance between the unit cell 51 and the conductor 4. This is the same as for the reference body 500. C3a equivalently represents the capacitance between the unit cell 51 located on the negative side in the X-axis direction and the first electrode pad 71, and C3b equivalently represents the capacitance between the unit cell 51 located on the positive side in the X-axis direction and the first electrode pad 71. L3 equivalently represents the inductance of the via 73. C4 equivalently represents the capacitance between the first electrode pad 71 and the second electrode pad 72.

[0055] That is, the periodic structure 5 has a different portion in region Q in Fig. 13 compared to the reference body 500. Therefore, in the antenna device 100, by adjusting the inductance L3 and capacitances C3a, C3b, and C4 included in region Q, even the periodic structure 5 with its irregular periodicity can exhibit characteristics equivalent to those of the reference body 500. This will be explained in detail below.

[0056] Here, as shown in FIG. 14, when the series-connected capacitances C3a and C3b are combined into capacitance C3, the capacitance C3 is expressed by the following equation (1).

[0057]

number

[0058] Furthermore, the impedance of the via 73 in the operating frequency band (the frequency band of the signal to be blocked), i.e., the impedance Z of the RL series circuit of the resistance R and the inductance L3, is expressed by the following equation (2), and the magnitude |Z| of the impedance Z is expressed by the following equation (3).

[0059]

number

[0060]

number

[0061] In the antenna device 100, the via 73 is formed sufficiently long to ensure a sufficiently large separation distance between the first and second electrode pads 71 and 72. In particular, in this embodiment, the thickness of the substrate 2 is 1.6 mm, so that the capacitance C4 between the first and second electrode pads 71 and 72 can be made sufficiently small to be practically negligible. In particular, in this embodiment, no electrode pads other than the first and second electrode pads 71 and 72 are provided midway through the via 73, i.e., between the first electrode pad 71 and the second electrode pad 72. Furthermore, a conductor 4 connected to GND is located between the first and second electrode pads 71 and 72, and functions as a shield. This further reduces the capacitance C4. Therefore, the equivalent circuit shown in FIG. 13 can be rewritten as the equivalent circuit shown in FIG. 15.

[0062] Furthermore, in the antenna device 100, the via 73 is formed to be sufficiently thin and long. In particular, in this embodiment, the width W1 of the via 73 is 0.3 mm, and the length L of the via 73 is approximately 1.6 mm. Therefore, the impedance Z of the via 73 in the used frequency band can be made sufficiently large. This makes the impedance Z sufficiently large relative to the capacitance C3. By making the impedance Z sufficiently large relative to the capacitance C3 in this way, the inductance L3 becomes virtually invisible in the equivalent circuit, and as a result, the inductance L3 can be ignored. Therefore, the equivalent circuit shown in FIG. 15 can be further re-expressed as the equivalent circuit shown in FIG. 16.

[0063] Therefore, the only substantial difference between the equivalent circuit of the periodic structure 5 and the equivalent circuit of the reference body 500 shown in FIG. 12 is the capacitance C3. Therefore, by adjusting the capacitance C3 of the periodic structure 5 to be equal to the capacitance C2 of the reference body 500, the periodic structure 5 can also exhibit isolation characteristics equivalent to those of the reference body 500. In other words, it is possible to effectively suppress the degradation of characteristics due to the collapse of the periodicity of the periodic structure 5. Note that it is preferable to adjust the capacitance C3 to be 90% to 110% of the capacitance C2, more preferably 95% to 105% of the capacitance C2, and even more preferably to match the capacitance C3 to the capacitance C2. This makes the above-mentioned effects more pronounced.

[0064] 17, the capacitances C3a and C3b can be adjusted by the size of the anti-pad 8. Specifically, the capacitance C3a can be adjusted by adjusting the distance d1 between the unit cell 51 located on the negative side in the X-axis direction and the first electrode pad 71, and the capacitance C3a can be adjusted by adjusting the distance d2 between the unit cell 51 located on the positive side in the X-axis direction and the first electrode pad 71. The capacitances C3a and C3b may be equal to or different from each other.

[0065] In this way, the antenna device 100 is configured so that the capacitance C4 and inductance L3 can be ignored in advance by designing the vias 73 to be thin and long. Therefore, simply by adjusting the capacitances C3a and C3b, the periodic structure 5 can exhibit characteristics equivalent to those of the reference body 500. Therefore, according to the antenna device 100, it is easy to adjust the periodic structure 5 to exhibit characteristics equivalent to those of the reference body 500.

[0066] Hereinafter, it will be shown that the periodic structure 5 can also exhibit isolation characteristics equivalent to those of the reference body 500 based on two types of verification.

[0067] 18 is a diagram showing the results of a plane wave irradiation analysis, that is, a diagram showing the reflection phase of the periodic structure 5 when a plane wave in which a current flows toward the negative X-axis direction is perpendicularly incident on the periodic structure 5. In the figure, the dashed line indicates the reflection phase of the reference body 500, and the solid line indicates the reflection phase of the periodic structure 5.

[0068] In the reference body 500, the periodicity of the unit cells 51 is maintained, resulting in the desired reflection characteristics, and the phase is 0° at frequencies around 7.5 GHz. Therefore, the reference body 500 functions to block signals in the frequency band around 7.5 GHz. In contrast, the periodic structure 5 also exhibits isolation characteristics equivalent to those of the conventional periodic structure 5 by adjusting the capacitances C3a and C3b to sufficiently minimize (preferably equalize) the difference between the capacitances C3 and C2. This result demonstrates that even if the periodicity of the periodic structure 5 is disrupted by the formation of the first electrode pads 71, adjusting the capacitances C3a and C3b can achieve isolation characteristics equivalent to those of the reference body 500. Note that in FIG. 18, the solid line is slightly shifted from the dashed line for ease of explanation in order to distinguish between the dashed line and the solid line. However, in practice, the solid line can be substantially aligned with the dashed line.

[0069] 19 is a diagram showing the results of verification of radio wave passage through a microstrip line, that is, a diagram showing the radio wave blocking characteristics of the periodic structure 5. In the figure, the dashed line indicates the blocking characteristics of the reference body 500, and the solid line indicates the blocking characteristics of the periodic structure 5. Note that verification of radio wave passage through the microstrip line was performed by forming a microstrip line MS (microstrip wiring) on the upper layer of the periodic structure 5 and transmitting a signal from port P1 to port P2 via the microstrip line MS, as shown in FIG.

[0070] In the reference body 500, the periodicity of the unit cells 51 is maintained, so that the desired blocking characteristics are obtained, and signals in the frequency band of 6.5 GHz to 7.3 GHz are blocked. In contrast, in the periodic structure 5, by adjusting the capacitances C3a and C3b to sufficiently reduce the difference between the capacitances C3 and C2 (preferably making them equal), it is possible to exhibit isolation characteristics equivalent to those of the reference body 500. In FIG. 19, for the sake of convenience in order to distinguish between the dashed line and the solid line, the solid line is drawn slightly shifted from the dashed line, but in reality, the solid line can be made to substantially coincide with the dashed line.

[0071] In this way, even if the periodicity of the periodic structure 5 is disrupted by forming the first electrode pads 71 within the periodic structure 5, it is possible to exhibit characteristics equivalent to those of the reference body 500 in which the periodicity is maintained. Therefore, as in this embodiment, the circuit 6 can be disposed on the lower surface 2Bb of the second substrate 2B, and the vias 73 can be used as lead wiring for the circuit 6. With this configuration, it is possible to manufacture a module in which the circuit 6 is mounted on the periodic structure forming substrate 1, that is, the antenna device 100 of this embodiment, without impairing the characteristics of the periodic structure 5. Therefore, it is possible to reduce the size and cost of the entire system compared to a conventional configuration in which the circuit 6 is formed separately from the periodic structure forming substrate 1.

[0072] The periodic structure forming substrate 1 and the method for adjusting the periodic structure forming substrate 1 have been described above.

[0073] As described above, such a periodic structure forming substrate 1 has a first substrate 2A having an upper surface 2Aa as a first surface and a lower surface 2Ab as a second surface which are opposite surfaces, a periodic structure 5 having a plurality of unit cells 51 arranged periodically on the upper surface 2Aa and connected to each other adjacent to each other, a conductor 4 provided on the lower surface 2Ab and arranged opposite the periodic structure 5, a first electrode pad 71 provided within the periodic structure 5, an anti-pad 8 formed around the first electrode pad 71 to prevent contact between the first electrode pad 71 and the periodic structure 5, and a via 73 which penetrates the upper surface 2Aa and the lower surface 2Ab and is connected to the first electrode pad 71. Furthermore, the anti-pad 8 is located in the gap G between a pair of adjacent unit cells 51 and is formed to overlap at least one (both in this embodiment) of the unit cells 51. The anti-pad 8 adjusts the capacitance C3 between the first electrode pad 71 and the unit cell 51 adjacent to the first electrode pad 71 to a value that suppresses deterioration in characteristics due to disruption of the periodicity of the periodic structure 5 caused by the formation of the first electrode pad 71. With this configuration, even if the periodicity of the periodic structure 5 is disrupted by forming the first electrode pad 71 within the periodic structure 5, it is possible to exhibit characteristics equivalent to those of the reference body 500 in which periodicity is maintained. Therefore, as in this embodiment, the circuit 6 can be disposed on the lower surface 2Bb of the second substrate 2B, and the vias 73 can be used as lead wiring for the circuit 6. With this configuration, a module in which the circuit 6 is mounted on the periodic structure-forming substrate 1, i.e., the antenna device 100 of this embodiment, can be manufactured without impairing the characteristics of the periodic structure 5. Therefore, compared to a conventional configuration in which the circuit 6 is formed separately from the periodic structure-forming substrate 1, the overall system can be made smaller and less expensive.

[0074] Furthermore, as described above, the capacitance C3 is adjusted to be 90% or more and 110% or less of the capacitance C2 between a pair of adjacent unit cells 51 in the reference body 500 in which the first electrode pads 71 and the anti-pads 8 are not formed in the periodic structure 5 and the periodicity of the periodic structure 5 is maintained. With this configuration, the periodic structure 5 can more reliably exhibit characteristics equivalent to those of the reference body 500. In other words, it is possible to effectively suppress deterioration in characteristics due to the collapse of the periodicity of the periodic structure 5.

[0075] As described above, the periodic structure-forming substrate 1 includes the second substrate 2B stacked on the lower surface 2Ab of the first substrate 2A, and the circuit 6 disposed on the lower surface 2Bb, which serves as the third surface of the second substrate 2B opposite the first substrate 2A. The vias 73 penetrate to the lower surface 2Bb and are electrically connected to the circuit 6. This allows the vias 73 to be used as wiring for electrically routing the circuit 6 to the upper surface 2Aa of the first substrate 2A. This configuration allows the circuit 6 to be electrically connected to an external device from the upper surface 2Aa of the first substrate 2A. This facilitates electrical connection between the periodic structure-forming substrate 1 and an external device.

[0076] As described above, the periodic structure forming substrate 1 has the second electrode pads 72 provided on the lower surface 2Bb and connected to the circuit 6 and the vias 73. With this configuration, the circuit 6 and the vias 73 can be easily electrically connected to each other.

[0077] As described above, no electrode pads other than the first electrode pad 71 and the second electrode pad 72 are provided in the via 73. With this configuration, the capacitance C4 between the first and second electrode pads 71 and 72 can be made sufficiently small.

[0078] As mentioned above, the length L of the via 73 is 1.6 mm or more. With this configuration, the impedance Z of the via 73 in the frequency band used can be made sufficiently large relative to the capacitance C3. Therefore, the inductance L3 is substantially invisible in the equivalent circuit, and as a result, the inductance L3 can be ignored. By designing in this way so that the inductance L3 can be ignored, the periodic structure forming substrate 1 can be easily adjusted.

[0079] As mentioned above, the width W1 of the via 73 is 0.3 mm or less. With this configuration, the impedance Z of the via 73 in the frequency band used can be made sufficiently large relative to the capacitance C3. Therefore, the inductance L3 is virtually invisible in the equivalent circuit, and as a result, the inductance L3 can be ignored. By designing the periodic structure forming substrate 1 so that the inductance L3 can be ignored, the adjustment of the periodic structure forming substrate 1 becomes easy.

[0080] As described above, each unit cell 51 has a central portion 511 located at the center of the square region S, four corner portions 512a-512d located at the four corners of the region S and connected to the central portion 511, an X-axis thin wire portion 513x serving as a first thin wire portion extending in the X-axis direction (a first direction) through the center of the region S and connected to the central portion 511, and a Y-axis thin wire portion 513y serving as a second thin wire portion extending in the Y-axis direction (a second direction perpendicular to the X-axis direction) through the center of the region S and connected to the central portion 511. A pair of adjacent unit cells 51 in the X-axis direction are connected at their X-axis thin wire portions 513x, and a pair of adjacent unit cells 51 in the Y-axis direction are connected at their Y-axis thin wire portions 513y. This configuration allows the unit cells 51 to have as simple a shape as possible while easily connecting adjacent unit cells 51.

[0081] As described above, the method for adjusting the periodic structure forming substrate 1 includes a first substrate 2A having an upper surface 2Aa as a first surface and a lower surface 2Ab as a second surface, which are in a reverse relationship; a periodic structure 5 having a plurality of unit cells 51 periodically arranged on the upper surface 2Aa and connected to each other adjacent to each other; a conductor 4 provided on the lower surface 2Ab and arranged opposite to the periodic structure 5; a first electrode pad 71 provided within the periodic structure 5; anti-pads 8 formed around the first electrode pads 71 to prevent contact between the first electrode pads 71 and the periodic structure 5; For a periodic structure-forming substrate 1 having a via 73 penetrating the lower surface 2Ab of the second substrate 2B and connected to the first electrode pad 71, and an anti-pad 8 positioned in the gap G between a pair of adjacent unit cells 51 and overlapping at least one (both in this embodiment) of the unit cells 51, the anti-pad 8 adjusts the capacitance C3 between the first electrode pad 71 and the unit cell 51 adjacent to the first electrode pad 71, thereby suppressing degradation in characteristics due to disruption of the periodicity of the periodic structure 5 caused by the formation of the first electrode pad 71. According to this adjustment method, even if the periodicity of the periodic structure 5 is disrupted by forming the first electrode pad 71 within the periodic structure 5, the periodic structure 5 can exhibit characteristics equivalent to those of a reference body 500 in which periodicity is maintained. Therefore, as in this embodiment, a circuit 6 can be disposed on the lower surface 2Bb of the second substrate 2B, and the via 73 can be used as an extraction wiring for the circuit 6. With this configuration, a module in which the circuit 6 is mounted on the periodic structure-forming substrate 1, i.e., the antenna device 100 of this embodiment, can be manufactured without impairing the characteristics of the periodic structure 5. Therefore, compared to the conventional configuration in which the circuit 6 is formed separately from the periodic structure forming substrate 1, the overall system can be made smaller and less expensive.

[0082] The antenna device 100 of the first embodiment has been described above. However, the configuration of the antenna device 100 is not particularly limited. For example, in this embodiment, the center of the anti-pad 8 is located at the midpoint between adjacent unit cells 51 (the center of the gap G), and the anti-pad 8 overlaps the pair of adjacent unit cells 51 equally, but this is not limiting. For example, as shown in FIG. 21 , the anti-pad 8 may be formed biased toward one of the unit cells 51, and the overlapping area with the anti-pad 8 (the area of the missing portion 515) may differ between the pair of unit cells 51.

[0083] 22, the anti-pad 8 may be formed so as to overlap only one of a pair of adjacent unit cells 51. In this case, however, it is preferable that the anti-pad 8 faces the outer periphery of the unit cell 51, and it is not preferable that the anti-pad 8 is confined within the unit cell 51, as shown in FIG. 23. In the case of the configuration shown in FIG. 23, depending on the configuration of each part, it may not be possible to achieve substantially the same isolation characteristics as the reference body 500 simply by adjusting the capacitance C3.

[0084] Of course, the anti-pads 8 shown in FIG. 17 and the anti-pads 8 shown in FIGS.

[0085] Second Embodiment FIG. 24 is a top view showing the antenna device according to the second embodiment.

[0086] The antenna device 100 of this embodiment is similar to the antenna device 100 of the first embodiment described above, except for the position where the lead-out through electrode 7 is formed. Therefore, in the following description, the differences between this embodiment and the first embodiment described above will be mainly described, and a description of similar points will be omitted. Furthermore, in the drawings of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0087] In the first embodiment described above, the first electrode pads 71 were regularly formed within the periodic structure 5, but in the antenna device 100 of this embodiment, the first electrode pads 71 are irregularly formed within the periodic structure 5, as shown in Fig. 24. Even with this configuration, by adjusting the capacitance C3, it is possible to exhibit isolation characteristics equivalent to those of the reference body 500, as in the first embodiment described above. Note that in this embodiment, the periodicity of the periodic structure 5 is further disrupted compared to the first embodiment described above, and therefore the effects of the present invention are more pronounced.

[0088] The second embodiment as described above can also achieve the same effects as the first embodiment.

[0089] <Third embodiment> Fig. 25 is a cross-sectional view showing an extraction through electrode included in the antenna device according to the third embodiment, and Fig. 26 is a diagram showing an equivalent circuit of the extraction through electrode shown in Fig. 25.

[0090] The antenna device 100 of this embodiment is similar to the antenna device 100 of the first embodiment described above, except for the configuration of the lead-out through electrode 7. Therefore, in the following description, the differences between this embodiment and the first embodiment will be mainly described, and a description of similar points will be omitted. Furthermore, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0091] In the lead-out through electrode 7 of the first embodiment described above, the first and second electrode pads 71, 72 are provided only at both ends of the via 73, that is, on the upper and lower surfaces of the substrate 2. In contrast to this, in the present embodiment, as shown in Fig. 25 , a plurality of electrode pads 74 are formed not only at both ends of the via 73 but also midway along the via 73, specifically between the dielectric layers 21 to 26. Note that, hereinafter, the electrode pad formed between the dielectric layers 21 and 22 will be referred to as electrode pad 74a, the electrode pad formed between the dielectric layers 22 and 23 as electrode pad 74b, the electrode pad formed between the dielectric layers 23 and 24 as electrode pad 74c, the electrode pad formed between the dielectric layers 24 and 25 as electrode pad 74d, and the electrode pad formed between the dielectric layers 25 and 26 as electrode pad 74e.

[0092] In such a configuration, the equivalent circuit of the unit cell 51 is expressed as shown in Fig. 26. The inductance L3 is formed by connecting in series the inductance L3a between the electrode pads 71 and 74a of the via 73, the inductance L3b between the electrode pads 74a and 74b of the via 73, the inductance L3c between the electrode pads 74b and 74c of the via 73, the inductance L3d between the electrode pads 74c and 74d of the via 73, the inductance L3e between the electrode pads 74d and 74e of the via 73, and the inductance L3f between the electrode pads 74e and 72 of the via 73. In addition, capacitance C4 is formed by serially connecting capacitance C4a between electrode pads 71 and 74a, capacitance C4b between electrode pads 74a and 74b, capacitance C4c between electrode pads 74b and 74c, capacitance C4d between electrode pads 74c and 74d, capacitance C4e between electrode pads 74d and 74e, and capacitance C4f between electrode pads 74e and 72.

[0093] In such a configuration, the capacitance C4 is larger than in the first embodiment described above, but it is still possible to keep the capacitance C4 small enough to be negligible.

[0094] The third embodiment as described above can also achieve the same effects as the first embodiment.

[0095] While the periodic structure forming substrate and the method for adjusting the periodic structure forming substrate of the present invention have been described above based on the illustrated embodiments, the present invention is not limited to these, and the configurations and methods of each part can be replaced with any configurations and methods having similar functions. Furthermore, any other configurations and methods may be added to the present invention.

[0096] Furthermore, for example, when the frequency bands used (the frequency bands of signals to be blocked) differ between the X-axis direction and the Y-axis direction, the distance between the unit cell 51 and the first electrode pad 71 in the X-axis direction and the distance between the unit cell 51 and the first electrode pad 71 in the Y-axis direction may be made different, and the capacitance C3 in the X-axis direction and the capacitance C3 in the Y-axis direction may be adjusted independently.

[0097] Furthermore, in the above-described embodiment, the periodic structure 5 is used as an EBG (electromagnetic band gap) for isolating the antenna elements 31 and 32, but the use of the periodic structure 5 is not particularly limited. For example, in a circuit incorporating digital and analog circuits, the periodic structure 5 may be disposed between the digital and analog circuits to prevent high-frequency noise generated in the digital circuit from being mixed into the analog circuit. Furthermore, the periodic structure 5 may also be used for purposes other than EBG (electromagnetic band gap), particularly as an AMC (artificial magnetic conductor), FSS (frequency selective surface), etc. [Explanation of symbols]

[0098] 1...periodic structure forming substrate, 100...antenna device, 2...substrate, 2A...first substrate, 2Aa...upper surface, 2Ab...lower surface, 2B...second substrate, 2Ba...upper surface, 2Bb...lower surface, 21...dielectric layer, 22...dielectric layer, 23...dielectric layer, 24...dielectric layer, 25...dielectric layer, 26...dielectric layer, 31...antenna element, 32...antenna element, 4...conductor, 5...periodic structure, 500...reference body, 51...unit cell, 511...central portion, 512a...corner portion, 512b...corner portion, 51 2c...corner portion, 512d...corner portion, 513x...X-axis thin line portion, 513y...Y-axis thin line portion, 515...missing portion, 6...circuit, 61...transmitter, 62...receiver, 63...control device, 7...drawing through electrode, 7a...drawing through electrode, 7b...drawing through electrode, 8...anti-pad, 8a...anti-pad, 8b...anti-pad, 8c...anti-pad, 8d...anti-pad, 71...first electrode pad, 72...second electrode pad, 73...via, 74...electrode pad, 74a...electrode pad , 74b...electrode pad, 74c...electrode pad, 74d...electrode pad, 74e...electrode pad, 900...antenna device, 910...dielectric substrate, 920a...antenna element, 920b...antenna element, 930...ground conductor, 940...EBG structure, 941...patch, 942...via, 943...unit cell, 950...circuit, 960...pad, C1...capacitance, C2...capacitance, C3...capacitance, C3a...capacitance, C3b...capacitance, C4...capacitance, C4a...capacitance, C4b...capacitance Quantity, C4c...capacitance, C4d...capacitance, C4e...capacitance, C4f...capacitance, G...gap, L...length, L1...inductance, L2...inductance, L3...inductance, L3a...inductance, L3b...inductance, L3c...inductance, L3d...inductance, L3e...inductance, L3f...inductance, P1...port, P2...port, Q...area, S...area, D...separation, d1...separation, d2...separation, W1...width

Claims

1. a first substrate having a first surface and a second surface that are opposite surfaces; a periodic structure including a plurality of unit cells periodically arranged on the first surface and connected to each other; a conductor provided on the second surface and arranged to face the periodic structure; a first electrode pad provided within the periodic structure; an anti-pad formed around the first electrode pad to prevent contact between the first electrode pad and the periodic structure; a via that penetrates the first surface and the second surface and is connected to the first electrode pad; the anti-pad is located in a gap between a pair of adjacent unit cells and overlaps at least one of the unit cells; a periodic structure forming substrate, characterized in that the capacitance between the first electrode pad and the unit cell adjacent to the first electrode pad is adjusted by the anti-pad to a value that suppresses deterioration in characteristics due to collapse of the periodicity of the periodic structure caused by the formation of the first electrode pad.

2. 2. The periodic structure forming substrate according to claim 1, wherein the capacitance is adjusted to be 90% or more and 110% or less of the capacitance between a pair of adjacent unit cells in a reference body in which the first electrode pads and the anti-pads are not formed in the periodic structure and the periodicity of the periodic structure is maintained.

3. a second substrate stacked on the second surface side of the first substrate; a circuit disposed on a third surface of the second substrate opposite to the first substrate; The periodic structure forming substrate according to claim 1 , wherein the via penetrates to the third surface and is electrically connected to the circuit.

4. The periodic structure formed substrate according to claim 3 , further comprising a second electrode pad provided on the third surface and connected to the circuit and the via.

5. 5. The periodic structure forming substrate according to claim 4, wherein no electrode pads other than the first electrode pad and the second electrode pad are provided midway through the via.

6. 6. The periodic structure forming substrate according to claim 5, wherein the via has a length of 1.6 mm or more.

7. 7. The periodic structure forming substrate according to claim 6, wherein the via has a width of 0.3 mm or less.

8. each unit cell has a central portion provided at the center of a square region, four corner portions provided at four corners of the region and connected to the central portion, a first thin line portion extending in a first direction through the center of the region and connected to the central portion, and a second thin line portion extending in a second direction perpendicular to the first direction through the center of the region and connected to the central portion; a pair of the unit cells adjacent to each other in the first direction have the first thin line portions connected to each other, The periodic structure formed substrate according to claim 1 , wherein the second thin line portions of a pair of the unit cells adjacent to each other in the second direction are connected to each other.

9. a first substrate having a first surface and a second surface that are opposite surfaces; a periodic structure including a plurality of unit cells periodically arranged on the first surface and connected to each other; a conductor provided on the second surface and arranged to face the periodic structure; a first electrode pad provided within the periodic structure; an anti-pad formed around the first electrode pad to prevent contact between the first electrode pad and the periodic structure; a via that penetrates the first surface and the second surface and is connected to the first electrode pad; The anti-pad is located in a gap between a pair of adjacent unit cells and overlaps with at least one of the unit cells, in a periodic structure forming substrate, a capacitance between the first electrode pad and the unit cell adjacent to the first electrode pad is adjusted by the anti-pad, thereby suppressing a deterioration in characteristics caused by the collapse of the periodicity of the periodic structure due to the formation of the first electrode pad.

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