JP5006820B2 - Antenna device - Google Patents

Description

  The present invention relates to a sheet-like structure having a high surface impedance, an antenna device using the same, and an RFID (Radio Frequency Identification) tag.

  With recent miniaturization of devices, for example, the distance between a metal surface such as a ground plane and an antenna is shortened, and there is a concern about deterioration of antenna characteristics due to this. It is also known that when an RFID tag is attached to a metal surface, the characteristics of an antenna included in the RFID tag are remarkably deteriorated and the RFID tag does not function properly. These problems are all due to the low surface impedance of the metal surface. On the metal surface, due to the low surface impedance, the phase of the incident electric field and the phase of the reflected electric field differ by 180 degrees or nearly 180 degrees. That is, the reflected wave on the metal surface is in reverse phase or almost in reverse phase of the incident wave. Therefore, in the vicinity of the metal, the combined electric field is reduced, and the performance of the near-metal antenna and the tag is significantly deteriorated. On the contrary, it is known that if an object having a high surface impedance can be arranged in the vicinity of the antenna, the electromagnetic wave incident on the impedance surface is reflected in the same phase by the high surface impedance and the antenna characteristics are improved.

  As a sheet-like structure having a high surface impedance, one having a so-called mushroom-like conductor having a via is conventionally known (see, for example, Patent Document 1). On the other hand, a left-handed medium that is not limited to an antenna use and that does not require a via and has scalability exceeding the limit of via density (for example, see Patent Document 2) has been proposed.

US Pat. No. 6,538,621 JP 2006-245984 A

  When the antenna is downsized, or when it is desired to obtain the sensitivity of the antenna with respect to two orthogonal directions of polarization, the antenna may be bent.

  However, when a sheet-like structure having a rectangular shape such as a card shape is formed by arranging a plurality of unit cells, there is a problem that sufficient antenna characteristics or polarization characteristics cannot be obtained. It was.

  Therefore, the present invention can obtain good antenna characteristics or polarization characteristics even when a bent antenna is mounted on a rectangular sheet-like structure having a high surface impedance. An object of the present invention is to provide an antenna device that can be used.

  When an attempt is made to construct a rectangular sheet-like structure using a plurality of symmetrical square cells with respect to a diagonal line, the number of cells differs vertically and horizontally in the sheet-like structure.

  However, the inventors have found that when the number of cells is small, the in-phase reflection frequencies in the electric field directions are different from each other if the number of cells in each electric field direction is different. This is presumably because when the number of cells is finite, the in-phase reflection frequency shifts due to the influence of the external boundary. Therefore, when a high surface impedance sheet consisting of a small number of cells with different number of cells in the vertical and horizontal directions is formed using isotropic cells, that is, unit cells having a line-symmetric structure with respect to the diagonal of the cells, The in-phase reflection frequency varies with the transverse electric field.

  The fact that the in-phase reflection frequency is different between the longitudinal direction and the lateral direction of the sheet-like structure means that the in-phase reflection effect can be obtained only in one of the longitudinal direction and the lateral direction for a certain frequency. It is. In other words, in order to obtain an in-phase reflection effect over the entire antenna even when a non-linear antenna such as a bent antenna is used, the in-phase reflection frequency is the same in the longitudinal direction and the lateral direction of the sheet-like structure. You can do it.

  Of the things that can be assumed as means for adjusting the common-mode reflection frequency in the vertical and horizontal directions of the sheet-like structure, it may be difficult to greatly change the outer shape of the sheet-like structure due to the specifications of the antenna device. There are no such restrictions on changes to the unit structure of.

  Therefore, in the present invention, the unit structure having a quadrangular shape is configured to be asymmetrical with respect to the diagonal line of the quadrilateral shape, and the in-phase reflection frequencies in the vertical and horizontal directions of the sheet-like structure are thereby determined. It was decided that it could be adjusted individually.

  The present invention has been made on the basis of the above-described knowledge, and specifically includes the following configurations.

  That is, according to the present invention, as a first antenna device, a sheet-like structure having a principal surface parallel to a surface defined by a first direction and a second direction orthogonal to the first direction; An antenna device comprising an antenna layer having an antenna conductor pattern and an antenna support layer made of a dielectric formed on the sheet-like structure, wherein the sheet-like structure has a unit structure as the first structure. The unit structure is configured to increase the surface impedance with respect to a specific frequency band by a periodic structure that is repeatedly arranged in the direction and the second direction, thereby reflecting the incident wave having a frequency belonging to the specific frequency band in-phase. Has a quadrangular shape when viewed from a third direction orthogonal to the first direction and the second direction, and has a non-symmetrical structure with respect to a diagonal line of the quadrangle. In which the antenna device is obtained.

  Furthermore, according to the present invention, as the second antenna device, in the first antenna device, the unit structure is connected to the ground layer by a ground layer, a via extending perpendicularly from the ground layer, and the via. A top layer, a dielectric layer filled between the top layer and the ground layer, and a floating capacitor layer held in a floating state in the dielectric layer, the ground layer, the via Thus, an antenna device in which the top layer and the floating capacitor layer are made of a conductor can be obtained.

Furthermore, according to the present invention, as the third antenna device, in the second antenna device, the dielectric layer has a LTCC (Low
Ceramics such as Temperature Co-fired Ceramics), FR-4 (Flame
Glass epoxy base materials such as retardant-4), Teflon (registered trademark) base materials, BT (Bismaleimide Triazine) resin base materials, polyether ether ketone (PEEK) thermoplastic resin films, or PET (Polyethylene terephthalate) ) Or a resin such as PET-G (Polyethylene terephthalate Glycol), a fiber such as linen, or a composite thereof.

  Furthermore, according to the present invention, as the fourth antenna device, in the second or third antenna device, at least one of the top layer and the floating capacitor layer has a non-symmetrical outer shape with respect to the diagonal line. An antenna device having the same is obtained.

  Furthermore, according to the present invention, as the fifth antenna device, in any one of the second to fourth antenna devices, at least one of the top layer and the floating capacitor layer includes a plurality of parts, and the parts The antenna device located at a position that is axisymmetric with respect to the diagonal line is obtained.

  Further, according to the present invention, as the sixth antenna device, in any one of the first to fifth antenna devices, the capacitive conductor portion has a slit extending from one side of the capacitive conductor portion toward the inner surface. An antenna device in which is formed is obtained.

  Furthermore, according to the present invention, as the seventh antenna device, in the sixth antenna device, an antenna device can be obtained in which each of the slits has a linear shape, a curved shape, or a combination thereof.

  Furthermore, according to the present invention, as the eighth antenna device, in any one of the first to seventh antenna devices, an antenna device in which the outer shape of the unit structure is axisymmetric with respect to the diagonal line can be obtained.

  Furthermore, according to the present invention, as the ninth antenna device, in any of the first to eighth antenna devices, the sheet-like structure has a rectangular outer shape when viewed from the third direction. An antenna device can be obtained.

  Furthermore, according to the present invention, as the tenth antenna device, in any one of the first to ninth antenna devices, the antenna device having the same frequency in the first direction and the second direction can be obtained. .

  Furthermore, according to the present invention, as the eleventh antenna device, in any one of the first to tenth antenna devices, the antenna support layer includes a hole, an air bubble, and an air layer. A device is obtained.

  Furthermore, according to the present invention, as the twelfth antenna device, in any one of the first to eleventh antenna devices, the antenna support layer is made of foamed material such as foamed polyethylene, acrylic foam or urethane, Teflon (registered trademark). ), PET (Polyethylene terephthalate) or PET-G (Polyethylene terephthalate Glycol), an antenna device made of fiber such as linen, or a combination thereof.

  Furthermore, according to the present invention, as the thirteenth antenna device, any one of the second to twelfth sheet-like structures, and the antenna support layer provided on the sheet-like structures, the sheet-like structures. An antenna device including an antenna support layer made of the same material as the dielectric body is obtained.

  Furthermore, according to the present invention, in any one of the first to thirteenth antenna devices, a sheet in which the antenna layer is omitted can be obtained.

  Furthermore, according to the present invention, the antenna device includes any one of the first to thirteenth antenna devices and an IC connected to the antenna conductor pattern on the antenna support layer, and the sheet-like structure is a part of the tag base. An RFID (Radio Frequency Identification) tag is obtained.

  Furthermore, according to the present invention, as a first antenna device design method, a sheet-like structure having a main surface parallel to a surface defined by a first direction and a second direction orthogonal to the first direction. Body, an antenna layer having an antenna conductor pattern, and an antenna support layer made of a dielectric formed on the sheet-like structure, wherein the sheet-like structure has a unit structure as the first structure. The periodic structure that is repeatedly arranged in the direction of 1 and the second direction increases the surface impedance for a specific frequency band, thereby in-phase reflecting an incident wave having a frequency belonging to the specific frequency band, When viewed from a third direction orthogonal to each of the first direction and the second direction, it has a rectangular outer shape, and the unit structure is viewed from the third direction. In the case of having a square shape, in order to make the frequencies in the first direction and the second direction equal, the unit structure has a non-symmetric structure with respect to the rectangular diagonal line A device design method is obtained.

  Furthermore, according to the present invention, as a second antenna device design method, in the first antenna device design method, the unit structure includes a ground layer, a via extending perpendicularly from the ground layer, and the via. The ground layer includes a top layer connected to the ground layer, a dielectric layer filled between the top layer and the ground layer, and a floating capacitor layer held in a floating state in the dielectric layer. , The via, the top layer, and the floating capacitor layer, in order to make the unit structure non-symmetrical, at least one of the top layer and the floating capacitor layer is the diagonal line. And at least one of the top layer and the floating capacitor layer is made up of a plurality of parts. And the site and be positioned to a non-axisymmetric positions with respect to the diagonal line, or the outer shape of the unit structure and a non-axisymmetric with respect to the diagonal line, or combination of these, method of designing the antenna device is obtained.

  According to the present invention, even when a non-linear antenna such as a bent antenna is used, antenna characteristics can be improved by performing in-phase reflection with respect to polarized waves in two orthogonal directions. A device is obtained.

(First embodiment)
As shown in FIGS. 1 and 2, an RFID tag to which the antenna device according to the first embodiment of the present invention is applied includes a sheet-like structure 1 and an antenna support layer 2 formed on the sheet-like structure 1. And an antenna element 3 having a predetermined antenna conductor pattern 3a on the upper surface of the antenna support layer 2, and an IC 4 connected to the antenna conductor pattern 3a.

  As can be understood from FIG. 2, the antenna element 3 in the RFID tag according to the embodiment of the present invention is a non-linear bent antenna, which has a substantially U-shape and is symmetrical with respect to the IC 4. The antenna conductor pattern 3a is arranged.

  In the antenna element 3 in the present embodiment, a beam portion conductor 3b for connecting the antenna conductor pattern 3a is further provided for impedance matching. In FIG. 1 and FIG. 2, the actual dielectric material may be a relatively transparent material (at least the inside can be seen through), but for the sake of simplicity, it is depicted as not transmitting.

  As a material for the antenna support layer 2, a dielectric material such as PET (Polyethylene terephthalate), PET-G (Polyethylene terephthalate Glycol), and Teflon (registered trademark) can be used, but the dielectric constant is as low as possible. Resin, foam material containing air, sponge, urethane, foamed polyethylene, acrylic foam, fiber such as linen, and the like are preferable. In particular, regarding the plastic, more specifically, it may be a thermoplastic such as vinyl chloride, polyethylene, polypropylene, polycarbonate, polystyrene, or ABS resin, or a thermosetting plastic such as melamine resin, polyurethane, phenol resin, or unsaturated polyester resin. Air layers and holes concentrate the electric field in the air and lower the electric field in the material, which is effective in reducing loss. A low dielectric constant also reduces the correlation between the antenna and the sheet-like structure and reduces the degradation of the antenna characteristics, so materials containing air layers and holes are particularly effective. Furthermore, the antenna support layer 2 may be made of the same material as that of the dielectric layer 40 (described later) of the sheet-like structure 1. Thereby, the sheet-like structure 1, the antenna support layer 2, and the antenna element 3 can be formed integrally, and the antenna device can be manufactured at low cost.

  The sheet-like structure 1 according to the present embodiment generally has a surface for a specific frequency band by a periodic structure in which unit structures 5 as shown in FIG. 3 are repeatedly arranged in the X direction and the Y direction as shown in FIG. Impedance is increased, whereby an incident wave having a frequency belonging to the specific frequency band is reflected in phase.

  Specifically, the sheet-like structure 1 according to the present embodiment includes a ground layer 10 having a solid conductor pattern and vias 20 made of a conductor extending vertically from the ground layer 10, as can be understood from FIGS. 5 to 7. A top layer 30 having a predetermined conductor pattern electrically connected to the ground layer by the via 20, a dielectric layer 40 filled between the top layer 30 and the ground layer 10, and a dielectric for increasing the capacitance. A floating capacitor layer 50 including a predetermined number of capacitive conductor portions 51 held in a floating state in the layer 40 is provided. 5 and 6, the dielectric layer 40 is omitted in order to clarify the relationship among the constituent elements.

  As a material of the dielectric layer 40 in the present embodiment, a substrate material such as FR-4 may be used, but a material having a small dielectric loss (tan δ) is desirable, such as ceramics such as LTCC, PET, PET-G, and Teflon (registered). It is preferable to use a general resin such as a trademark), a plastic, a low-loss substrate material such as BT resin, or a polyether ether ketone (PEEK) thermoplastic resin film. Further, a fiber such as linen may be used. More specifically, the plastic may be a thermoplastic plastic such as vinyl chloride, polyethylene, polypropylene, polycarbonate, polystyrene, or ABS resin, or a thermosetting plastic such as melamine resin, polyurethane, phenol resin, or unsaturated polyester resin.

  As shown in FIG. 6, the unit structure 5 and the top layer 30 in the present embodiment are each rectangular, that is, have a non-axisymmetric outer shape with respect to each diagonal line. Further, as shown in FIG. 7, the floating capacitor layer 50 also has a non-symmetrical outer shape with respect to the diagonal of the unit structure 5. The sheet-like structure 1 in the present embodiment has a structure in which the unit structures 5 are continuously arranged in the X direction and the Y direction. Thereby, the outer shape of the unit structure 5 is non-axisymmetric with respect to the diagonal line.

  As shown in FIG. 8, in the sheet-like structure 1 according to the present embodiment, the impedance Zs of the sheet-like structure viewed from the surface can be approximately expressed by an equivalent circuit of an LC parallel circuit. At the time of resonance of this parallel resonant circuit, the surface impedance Zs becomes very high and in-phase reflection occurs. Therefore, in the equivalent circuit in each of the X direction and the Y direction, in-phase reflection frequencies in the X direction and the Y direction can be adjusted separately, particularly by changing the structure of the capacitance component c.

Thereby, even in the case where the number of unit structures 5 in the X direction and the Y direction is different in the sheet-like structure 1, in particular, the capacitance c is separately adjusted independently in the X direction and the Y direction. The in-phase reflection frequency in the direction can be the same.

  As shown in FIG. 9, the slit 52 may be formed so as to extend from one side of the capacitive conductor portion 51 toward the inner surface. Thereby, an inductance can be increased, a common mode reflection frequency can be lowered, and the sheet-like structure 1 can be reduced in size.

(Second Embodiment)
As shown in FIG. 10, the antenna device according to the second embodiment of the present invention has the above-described first configuration except that the shape of the capacitive conductor portion 51a constituting the unit structure 5a and the floating capacitor layer 50a is different. The structure is almost the same as that of the embodiment. Accordingly, the same components as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  The floating capacitor layer 50a according to the present embodiment is composed of four capacitive conductor portions 51a each having a substantially triangular shape. The bottom portion of the substantially triangular shape is arranged on the side of the unit structure 5a, while the apex is the unit structure. It arrange | positions so that it may face the via | veer 20a arrange | positioned in the center of 5a. In the present embodiment, the set of capacitive conductor portions 51a arranged to face each other in the X direction has a height Ha with respect to the bottom side. On the other hand, the capacitive conductor portion 51a arranged so as to face each other in the Y direction has a height Hb with respect to the bottom side. In the present embodiment, the height Ha is larger than the height Hb (Ha> Hb). The four capacitive conductor portions 51a in the present embodiment correspond to a straight line passing through the center of the unit structure 5a in the X direction (hereinafter referred to as the X direction straight line) and a straight line extending in the Y direction (hereinafter referred to as the Y direction straight line). Is located in a line-symmetric position, but is located in an asymmetric position with respect to the diagonal of the unit structure 5a. Therefore, the unit structure 5a has a non-axisymmetric structure with respect to the diagonal of the unit structure 5a.

  Thereby, even in the case where the number of unit structures 5a in the X direction and the Y direction is different in the sheet-like structure 1a, in particular, the capacitance c is separately adjusted independently in the X direction and the Y direction. The in-phase reflection frequency in the direction can be the same.

  As in the first embodiment, in this embodiment, as shown in FIG. 11, the slit 52a may be formed so as to extend from one side of the capacitive conductor portion 51a toward the inner surface. Thereby, an inductance can be increased, an in-phase reflection frequency can be lowered, and the sheet-like structure 1a can be reduced in size.

(Third embodiment)
The antenna device according to the third embodiment of the present invention has a structure substantially similar to that of the first embodiment described above. Accordingly, the same components as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  As shown in FIG. 12, in the antenna device according to the present embodiment, the distance Hc between the top layers 30b adjacent in the X direction and the distance Hd between the top layers 30b adjacent in the Y direction are different. By changing the distance between the top layers 30b in the X direction and the Y direction, the capacitance c in each direction can be changed independently and independently. Thereby, an in-phase reflection frequency can be adjusted independently in each direction, and it can be set as the same frequency. The outer shape of the unit structure 5b in the present embodiment is a square, but the top layer 30b is a rectangle. For this reason, the unit structure 5b has a non-axisymmetric structure with respect to the diagonal of the unit structure 5b.

  Thereby, even in the case where the number of unit structures 5b in the X direction and the Y direction is different in the sheet-like structure 1b, the capacitance c is adjusted separately and independently in the X direction and the Y direction, respectively. The in-phase reflection frequency in the direction can be the same.

  As seen from the Z direction, the unit structure is made non-linearly symmetric with respect to the diagonal by the various methods described above, and a plurality of unit structures having non-symmetrical structures are arranged to form a sheet-like structure. Even if the outer shape of the sheet-like structure in the case is rectangular, the sheet-like structure can be adjusted to have the same in-phase reflection frequency in the X direction and the Y direction. Thereby, even when a non-linear antenna such as a bent antenna is used, an in-phase reflection effect can be obtained over the entire antenna.

  In the above-described embodiments, 1) the outer shape of the unit structure itself is rectangular, 2) the shape of the floating capacitor layer is configured to be axisymmetric with respect to the diagonal of the unit structure, and 3) The unit structure has a non-symmetrical structure with respect to at least one of the two diagonal lines by three methods of changing the interval between adjacent top layers in the X direction and the Y direction, respectively. 4) The shape and / or arrangement of the top layer is configured to be axisymmetric with respect to at least one of the two diagonal lines of the unit structure, or 5) the floating capacitor layer By arranging the arrangement so that it is non-symmetrical with respect to at least one of the two diagonal lines of the unit structure, the unit structure has a structure that is non-symmetrical with respect to the diagonal line. The unit structure may have a non-symmetrical structure with respect to at least one of the two diagonal lines by the possible combinations of 1) to 5). You may make it become.

It is a figure which shows the example which applied the sheet-like structure by the 1st Embodiment of this invention to the RFID tag. FIG. 2 is a top view of the RFID tag shown in FIG. 1. It is a perspective view which shows roughly the unit structure in the sheet-like structure of FIG. It is a perspective view which shows the structure of the sheet-like structure of FIG. 1 schematically. It is sectional drawing of the sheet-like structure of FIG. FIG. 2 is a top view schematically showing a top layer of the sheet-like structure of FIG. 1. It is a top view which shows roughly the floating capacitor layer of the sheet-like structure of FIG. FIG. 2 is an xz sectional view of the sheet-like structure of FIG. 1 and an equivalent circuit of a surface impedance Zs. It is a top view which shows roughly the modification which put the slit in the floating capacitor layer of the sheet-like structure of FIG. It is a top view which shows roughly the structure of the sheet-like structure by the 2nd Embodiment of this invention, especially the floating capacitor layer. It is a top view which shows roughly the modification which put the slit in the floating capacitor layer of the sheet-like structure of FIG. It is a top view which shows roughly the structure of the sheet-like structure by the 3rd Embodiment of this invention, especially the top layer.

Explanation of symbols

1, 1a, 1b Sheet-like structure 2 Antenna support layer 3 Antenna element 3a Antenna conductor pattern 3b Beam portion conductor 4 IC
5, 5a, 5b Unit structure 10 Ground layer 20, 20a Via 30, 30b Top layer 40 Dielectric layer 50, 50a Floating capacitor layer 51, 51a Capacitance conductor portion 52, 52a Slit

Claims (17)

A sheet-like structure having a main surface parallel to a surface defined by a first direction and a second direction orthogonal to the first direction, an antenna layer having an antenna conductor pattern, and the sheet-like structure An antenna device comprising an antenna support layer made of a dielectric formed on
The sheet-like structure has a periodic structure in which unit structures are repeatedly arranged in the first direction and the second direction, thereby increasing the surface impedance with respect to a specific frequency band, whereby frequencies belonging to the specific frequency band are increased. In-phase reflection of incident waves with
The unit structure has a quadrangular shape when viewed from a third direction orthogonal to the first direction and the second direction, and has a non-symmetrical structure with respect to a diagonal line of the quadrangle. has,
The antenna device , wherein the frequencies in the first direction and the second direction are equal to each other . The unit structure includes a ground layer, a via extending perpendicularly from the ground layer, a top layer connected to the ground layer by the via, and a dielectric layer filled between the top layer and the ground layer. And a floating capacitor layer held in a floating state in the dielectric layer,
The antenna device according to claim 1, wherein the ground layer, the via, and the top layer are made of a conductor. The dielectric layer is made of ceramics such as LTCC (Low Temperature Co-fired Ceramics), glass epoxy substrate materials such as FR-4 (Flame Retardant-4), Teflon (registered trademark) substrate materials, BT (Bismaleimide Triazine). Claim made of resin-based substrate material, polyether ether ketone (PEEK) -based thermoplastic resin film, resin such as PET (Polyethylene terephthalate) or PET-G (Polyethylene terephthalate Glycol), fiber such as linen, or a composite thereof Item 3. The antenna device according to Item 2. 4. The antenna device according to claim 2, wherein at least one of the top layer and the floating capacitor layer has a non-axisymmetric outer shape with respect to the diagonal line. 5. At least one of the top layer and the floating capacitor layer is composed of a plurality of parts,
The antenna device according to any one of claims 2 to 4, wherein the part is located in a position that is non-axisymmetric with respect to the diagonal line. The antenna device according to claim 1, wherein a slit is formed in the part so as to extend from one side of the part toward the inner surface.   The antenna device according to claim 6, wherein each of the slits has a linear shape, a curved shape, or a combination thereof.   The antenna device according to claim 1, wherein an outer shape of the unit structure is axisymmetric with respect to the diagonal line.   The antenna device according to any one of claims 1 to 8, wherein the sheet-like structure has a rectangular outer shape when viewed from the third direction.   The antenna device according to claim 1, wherein the frequency is equal in the first direction and the second direction.   The antenna device according to any one of claims 1 to 10, wherein the antenna support layer includes holes, air bubbles, and an air layer.   The antenna support layer is made of foamed material such as foamed polyethylene, acrylic foam or urethane, resin such as Teflon (registered trademark), PET (Polyethylene terephthalate) or PET-G (Polyethylene terephthalate Glycol), fiber such as linen, or a combination thereof. The antenna device according to claim 1, comprising any one of the above. An antenna made of the same material as the dielectric of the sheet-like structure, the sheet-like structure according to any one of claims 2 to 12, and an antenna support layer provided on the sheet-like structure An antenna device comprising a support layer.   The sheet | seat which abbreviate | omits the said antenna layer in the antenna apparatus in any one of Claims 1 thru | or 13.   An RFID (1) comprising: the antenna device according to any one of claims 1 to 13; and an IC connected to the antenna conductor pattern on the antenna support layer, wherein the sheet-like structure is a part of a tag base. Radio Frequency Identification) tag. A sheet-like structure having a main surface parallel to a surface defined by a first direction and a second direction orthogonal to the first direction; an antenna layer having an antenna conductor pattern; and the sheet-like structure. An antenna device comprising an antenna support layer formed of a dielectric, wherein the sheet-like structure is specified by a periodic structure in which unit structures are repeatedly arranged in the first direction and the second direction. The surface impedance of the first frequency band and the incident wave having a frequency belonging to the specific frequency band is reflected in-phase, and is orthogonal to each of the first direction and the second direction. When viewed from the direction of, and when the unit structure has a rectangular shape when viewed from the third direction,
A method for designing an antenna device, wherein the unit structure has a non-symmetrical structure with respect to a diagonal of the quadrangle in order to equalize the frequencies in the first direction and the second direction. The unit structure includes a ground layer, a via extending perpendicularly from the ground layer, a top layer connected to the ground layer by the via, and a dielectric layer filled between the top layer and the ground layer. , Consisting of a floating capacitor layer held in a floating state in the dielectric layer, and consisting of the ground layer, the via, the top layer, the floating capacitor layer,
In order to make the unit structure a non-symmetrical structure,
At least one of the top layer and the floating capacitor layer has a non-symmetric shape with respect to the diagonal line,
At least one of the top layer and the floating capacitor layer is made up of a plurality of parts, and the part is positioned at a position axisymmetric with respect to the diagonal line, or
17. The antenna device design method according to claim 16, wherein the outer shape of the unit structure is non-axisymmetric with respect to the diagonal, or a combination thereof.

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