Antenna element and antenna device

Abstract

To provide an antenna element that is suitable for transmitting and receiving circularly polarized radio waves while suppressing material costs.SOLUTION: An antenna element 30 comprises an upper conductor 40 having a line symmetrical outer circumferential chape, and at least a pair of legs 50. Recesses 44 corresponding to the legs 50 are provided to the upper conductor 40. Each of the legs 50 projects toward a first or second bearing, the first and second bearings being opposite to each other as seen from the center of the upper conductor 40 when the upper conductor 40 is seen along a vertical direction and extends downward in the vertical direction. Meanwhile, each of the recesses 44 is juxtaposed with the legs 50 corresponding in a direction orthogonal to a direction defined by the first and second bearings and is recessed in the second or first bearing. Thus, according to the present invention, it is possible to obtain an antenna element suitable for transmitting and receiving circularly polarized radio waves, and to obtain an antenna device having a good axial ratio characteristic.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an antenna element and an antenna device using the same. [Background technology]

[0002] As shown in Fig. 11, an antenna device 90 of Patent Document 1 includes a substrate 94 having a ground conductor 92, and an antenna element 98 made of a conductor fixed onto the substrate 94 via a support 96. The ground conductor 92 and the antenna element 98 are physically spaced apart. The antenna element 98 has rotational symmetry in order to transmit and receive circularly polarized radio waves, and is formed by bending a metal plate 99 shown in Fig. 12. As can be seen from Fig. 10, the antenna element 98 has a four-fold symmetric unfolded shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-150365 A Summary of the Invention [Problem to be solved by the invention]

[0004] When an antenna element has a four-fold symmetrical deployed shape, a lot of wasted material is generated in the base metal sheet, making it difficult to reduce material costs with the deployed shape of a conventional circularly polarized antenna element.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an antenna element suitable for transmitting and receiving circularly polarized radio waves while keeping material costs down. [Means for solving the problem]

[0006] In order to reduce material costs, it is desirable to make the deployed shape of the antenna element (particularly its outer peripheral shape) line-symmetric. However, if the deployed shape of the antenna element is simply line-symmetric, the rotational symmetry of the antenna element is lost, and the axial ratio characteristic of the antenna device using the antenna element deteriorates. As a result of verification, the inventor of the present invention found that by providing a recess near the leg, the lost rotational symmetry of the antenna element can be corrected and the axial ratio characteristic of the antenna device can be improved. In this way, by providing a recess at a predetermined position, an antenna element suitable for transmitting and receiving circularly polarized radio waves can be obtained while reducing material costs.

[0007] Providing a recess in the antenna element to improve the axial ratio characteristic of the antenna device can also be applied to antenna elements other than antenna elements made of sheet metal. If rotational symmetry is not required for the antenna element itself, the degree of freedom in designing the antenna element is somewhat increased. In other words, by providing a recess in a predetermined position, it is possible to obtain an antenna element suitable for transmitting and receiving circularly polarized radio waves while increasing the degree of freedom in design. The present invention has been made based on such findings, and specifically provides the following antenna elements.

[0008] The present invention provides a first antenna element, An antenna element that is fixed onto a substrate having a ground conductor to constitute an antenna device, The antenna element includes an upper conductor and at least a pair of legs; the upper conductor has an outer periphery that is symmetrical with respect to a line passing through a center of the upper conductor when viewed in a vertical direction; the pair of legs respectively protrude in a first direction and a second direction which are opposite directions as viewed from the center of the upper conductor when the upper conductor is viewed along the vertical direction, and each extends downward in the vertical direction, The upper conductor is provided with at least a pair of recesses, The pair of recesses correspond one-to-one to the pair of legs, the pair of recesses are recessed in the second direction and the first direction, respectively, when the upper conductor is viewed along the up-down direction; Each of the recesses is juxtaposed with the corresponding leg in a direction intersecting a direction defined by the first orientation and the second orientation. An antenna element is provided.

[0009] The present invention provides a first antenna element as a second antenna element, Each of the recesses has a wide shape. An antenna element is provided.

[0010] The present invention provides a third antenna element, which is a first antenna element, Each of the recesses is disposed adjacent to the corresponding leg in a direction perpendicular to a direction defined by the first orientation and the second orientation. An antenna element is provided.

[0011] The present invention provides a fourth antenna element, which is a first antenna element, the upper conductor extends in a predetermined plane perpendicular to the up-down direction, When a specific rectangle is assumed to be a rectangle that exists on the predetermined plane and has four sides that are imaginary lines and has a minimum area that includes the upper conductor, the corresponding legs and recesses are located on the same sides. An antenna element is provided.

[0012] The present invention provides a fifth antenna element, which is the fourth antenna element, The at least one pair of legs includes two pairs of legs, The at least one pair of recesses includes two pairs of recesses, Each of the legs is located on one of two sides of the specific rectangle that are located in the first direction and the second direction when viewed from the center of the upper conductor. An antenna element is provided.

[0013] The present invention provides a sixth antenna element, which is a first antenna element, The antenna element further comprises at least a pair of stubs; a direction defined by a third orientation and a fourth orientation, which are opposite orientations as viewed from the center of the upper conductor, is perpendicular to a direction defined by the first orientation and the second orientation; the pair of stubs extend from the outer periphery of the upper conductor in the third and fourth directions, respectively; Each of the stubs does not overlap with the upper conductor when the upper conductor is viewed in the up-down direction. An antenna element is provided.

[0014] The present invention provides a seventh antenna element, which is the sixth antenna element, Each of the stubs has a wide shape. An antenna element is provided.

[0015] The present invention provides an eighth antenna element, which is a first antenna element, a lower conductor extending at least partially from each of the legs in a direction parallel to the top surface of the substrate, the lower conductor being spaced apart from the upper conductor in the vertical direction; An antenna element is provided.

[0016] The present invention provides a ninth antenna element, which is a first antenna element, At least one pair of additional legs each extending downward in the up-down direction from a position closer to the center of the upper conductor than each of the legs, and an additional lower conductor extending at least partially from each of the additional legs in a direction parallel to the top surface of the substrate and spaced apart from the upper conductor in the vertical direction. An antenna element is provided.

[0017] The present invention provides a tenth antenna element, which is any one of the first to ninth antenna elements, The antenna element is made of a single metal plate. An antenna element is provided.

[0018] The present invention provides an eleventh antenna element, which is the tenth antenna element, The antenna element has a deployed shape in which the outer periphery is symmetrical. An antenna element is provided.

[0019] Furthermore, the present invention provides an antenna device comprising a first antenna element and a substrate, The substrate includes a ground conductor, The antenna element is fixed onto the substrate. An antenna device is provided. Effect of the Invention

[0020] As described above, each of the legs protrudes in the first or second direction, which are opposite directions when viewed from the center of the upper conductor when the upper conductor is viewed in the up-down direction, and extends downward in the up-down direction. Meanwhile, each of the recesses is juxtaposed with the leg corresponding to the recess in a direction perpendicular to the direction defined by the first and second directions, and is recessed in the second or first direction. As a result, according to the present invention, an antenna element suitable for transmitting and receiving circularly polarized radio waves can be obtained, and an antenna device having good axial ratio characteristics can be obtained. [Brief description of the drawings]

[0021] [Figure 1] 1 is a perspective view showing an antenna device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view showing the antenna device of FIG. [Diagram 3] 3 is a bottom perspective view showing an antenna element included in the antenna device of FIG. 2. [Figure 4] FIG. 4 is a top view showing the antenna element of FIG. [Diagram 5] FIG. 5 is a top view showing the deployed shape of the antenna element in FIG. [Figure 6] FIG. 11 is a perspective view showing an antenna device according to a second embodiment of the present invention. [Figure 7] 7 is a perspective view showing an antenna element and an auxiliary element included in the antenna device of FIG. 6. [Figure 8] FIG. 8 is a bottom perspective view showing the antenna element of FIG. [Figure 9] FIG. 9 is a top view showing the antenna element of FIG. 8. [Figure 10] 10 is a top view showing the deployed shape of the antenna element in FIG. [Figure 11] FIG. 1 is an exploded perspective view showing the antenna device of Patent Document 1. [Figure 12] FIG. 1 is a top view showing the deployed shape of the antenna element of Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (First embodiment) 1 and 2, an antenna device 10 according to a first embodiment of the present invention includes a substrate 20 and an antenna element 30. The substrate 20 includes a ground conductor 22. More specifically, as shown in FIG. 2, the substrate 20 includes a ground conductor 22, fixing pads 24 and 26, and a power supply pad 28 formed on a dielectric substrate. The ground conductor 22, the fixing pads 24 and 26, and the power supply pad 28 are separated from each other. In this embodiment, the fixing pads 24 and 26 are floating pads that are not electrically connected to anything. In contrast, the power supply pad 28 is electrically led out to the outside of the antenna device 10 by a means not shown. However, the substrate 20 is not limited to the above. The size, shape, and the like of the substrate 20 are not particularly limited as long as the substrate 20 includes the ground conductor 22. The substrate 20 may also include an additional ground conductor or other conductors.

[0023] 1 and 2, the antenna element 30 is fixed onto the substrate 20. A specific fixing method will be described later.

[0024] As shown in Fig. 1 to Fig. 4, the antenna element 30 includes an upper conductor 40, legs 50, a lower conductor 60, a power supply portion 70, and a stub 75. The antenna element 30 of this embodiment is made of a single sheet metal. As will be described in detail later, the antenna element 30 of this embodiment is integrally formed by punching and bending a sheet metal as a base material. However, the present invention is not limited to this. The antenna element 30 may be formed by laser direct structuring (LDS).

[0025] As can be seen from FIG. 4, the upper conductor 40 according to the present embodiment extends in a predetermined plane perpendicular to the vertical direction, and has an outer periphery that is symmetrical with respect to a line passing through the center of the upper conductor 40 when viewed along the vertical direction. In the present embodiment, the vertical direction is the Z direction. The +Z direction is upward, and the -Z direction is downward. The predetermined plane is a horizontal plane, that is, an XY plane. With reference to FIGS. 1 and 4, in the present embodiment, the predetermined plane is a plane parallel to the upper surface of the substrate 20. The upper conductor 40 according to the present embodiment extends parallel to the upper surface of the substrate 20. However, the upper conductor 40 is not limited thereto, and may extend at least partially in a direction parallel to the upper surface of the substrate 20.

[0026] Here, the specific rectangle is assumed to be a rectangle that exists on a predetermined plane and has four sides that are imaginary lines, and has the smallest area that includes the upper conductor 40. As can be seen from Figs. 4 and 5, the specific rectangle 42 in this embodiment is a square. That is, the specific rectangle 42 has four-fold symmetry. The antenna element 30 that includes the upper conductor 40 that forms such a specific rectangle 42 is basically suitable for circularly polarized communication. However, the specific rectangle 42 is not limited to a square, and in some cases, the rotational symmetry that has been broken as a rectangle may be corrected.

[0027] As shown in Fig. 2 and Fig. 3, there are two power supply units 70 according to this embodiment. As can be seen from Fig. 1 and Fig. 2, the power supply units 70 are each connected to a power supply pad 28. As can be seen from Fig. 2 and Fig. 4, each of the power supply units 70 is formed by bending a part of the upper conductor 40, and as a result of forming the power supply units 70, a slot 46 is also formed in the upper conductor 40. As can be seen from Fig. 4, when the upper conductor 40 is viewed in the up-down direction, imaginary lines connecting the center of the upper conductor 40 and each of the two power supply units 70 form an angle of 90 degrees. This makes it possible to realize circularly polarized communication using a two-point feeding method.

[0028] 1 to 4, the antenna element 30 according to the present embodiment includes four legs 50. As can be seen from FIG. 4, the legs 50 extend in pairs from each of two sides of the specific rectangle 42 that are perpendicular to the Y direction. That is, the antenna element 30 according to the present embodiment includes two pairs of legs 50. Each of the legs 50 is located on one of two sides of the specific rectangle 42 that are located in the first and second orientations when viewed from the center of the upper conductor 40. In this embodiment, the +Y side (right side in FIG. 4) is the first orientation, and the -Y side (left side in FIG. 4) is the second orientation.

[0029] Each pair of legs 50 protrudes in a first direction and a second direction which are opposite directions as viewed from the center of the upper conductor 40 when the upper conductor 40 is viewed in the up-down direction, and each extends downward in the up-down direction. That is, in this embodiment, two legs 50 protrude from the upper conductor 40 to the +Y side and extend to the -Z side, and the other two legs 50 protrude from the upper conductor 40 to the -Y side and extend to the -Z side.

[0030] As described above, in this embodiment, when the upper conductor 40 is viewed in the up-down direction, two legs 50 extend from the side on the +Y side of the specific rectangle 42, and two legs 50 extend from the side on the -Y side of the specific rectangle 42. However, the present invention is not limited to this. For example, when the upper conductor 40 is viewed in the up-down direction, one leg 50 may extend from the side on the +Y side of the specific rectangle 42, and one leg 50 may extend from the side on the -Y side of the specific rectangle 42. In other words, it is sufficient that the antenna element 30 is provided with at least one pair of legs 50.

[0031] 1 to 4, the upper conductor 40 is provided with four recesses 44. The recesses 44 correspond one-to-one to the leg portions 50. That is, in the present embodiment, the number of recesses 44 is equal to the number of legs 50. As shown in FIG. 4, the leg portions 50 and the recesses 44 corresponding to each other are located on the same one of the four sides of the specific quadrilateral 42.

[0032] 4, two recesses 44 are provided on each of two sides perpendicular to the Y direction among the four sides of the specific quadrangle 42. That is, two pairs of recesses 44 are provided in the upper conductor 40 according to the present embodiment.

[0033] These recesses 44 are intended to correct the rotational symmetry of the antenna element 30 that is lost due to the line-symmetric arrangement of the legs 50. For this purpose, each of the recesses 44 is juxtaposed to the leg 50 corresponding to the recess 44 in a direction intersecting the Y direction (i.e., the direction defined by the first and second azimuths). In this embodiment, it is essential to juxtapose the recesses 44 to the legs 50, which significantly improves the possibility of supporting circularly polarized communication. Particularly in this embodiment, in order to obtain better correction results, each of the recesses 44 is adjacently arranged to the leg 50 corresponding to the recess 44 in a direction perpendicular to the Y direction.

[0034] In this embodiment, the recesses 44 are provided in the same manner as the legs 50. That is, two recesses 44 are provided on the side of the +Y side of the specific rectangle 42, and two recesses 44 are provided on the side of the -Y side of the specific rectangle 42. However, the present invention is not limited to this. For example, in the case where the legs 50 are a pair as described above, when the upper conductor 40 is viewed in the up-down direction, one recess 44 may be provided on the side of the +Y side of the specific rectangle 42, and one recess 44 may be provided on the side of the -Y side of the specific rectangle 42. In other words, it is sufficient that at least a pair of recesses 44 is provided in the upper conductor 40 in accordance with the legs 50.

[0035] 4, the recess 44 provided on the side on the +Y side of the specific rectangle 42 is recessed toward the -Y direction, and the recess 44 provided on the side on the -Y side of the specific rectangle 42 is recessed toward the +Y direction. That is, when the upper conductor 40 is viewed in the up-down direction, the former recess 44 is recessed in the second direction, and the latter recess 44 is recessed in the first direction. In other words, the former recess 44 and the latter recess 44 are recessed toward opposite directions.

[0036] As is clear from FIG. 4, each of the recesses 44 has a wide shape. That is, the size of the recesses 44 in the X direction is larger than the size of the recesses 44 in the Y direction. More specifically, the Y direction is the direction in which the recesses 44 are recessed, and the X direction is the direction perpendicular to the direction in which the recesses 44 are recessed, and the size of the recesses 44 in the latter direction is larger than the size of the recesses 44 in the former direction. Furthermore, as can be seen from FIG. 4, in this embodiment, the width of the recesses 44 is larger than the width of the corresponding leg portion 50. Here, the width is the size in the X direction. When the recesses 44 have a wide shape in this way, a good correction result can be obtained most effectively. However, the recesses 44 are not limited to this shape. For example, the size of the recesses 44 in the X direction may be a narrow shape smaller than the size of the recesses 44 in the Y direction. In addition, the recesses 44 are not necessarily limited to a rectangular shape, and may be a shape including a curve such as a semicircular shape or a semielliptical shape.

[0037] As can be seen from Figs. 2 and 3, the lower conductor 60 according to this embodiment extends from each of the legs 50 in a direction parallel to the upper surface of the substrate 20, and is separated from the upper conductor 40 in the vertical direction. That is, the lower conductor 60 according to this embodiment extends parallel to the upper conductor 40. As a result, the lower conductor 60 and the upper conductor 40 form a capacitor. The shape and arrangement of the lower conductor 60 are not particularly limited as long as the lower conductor 60 and the upper conductor 40 form a capacitor. However, in order to suppress fluctuations in capacitance due to variations in dimensional tolerances, it is desirable for the lower conductor 60 to at least partially extend in a direction parallel to the upper surface of the substrate 20.

[0038] In this embodiment, a fixed portion 62 extends further downward from the lower conductor 60, and is soldered and fixed to a fixing pad 24 on the substrate 20, as can be seen from Figures 1 and 2. In this way, the lower conductor 60 and the ground conductor 22 form an additional capacitor.

[0039] 1 to 4, the antenna element 30 according to the present embodiment has four stubs 75. Two stubs 75 extend from each of two sides of the specific rectangle 42 that are perpendicular to the X direction. That is, the antenna element 30 according to the present embodiment has two pairs of stubs 75. Each of the stubs 75 is located on one of two sides of the specific rectangle 42 that are located in the third and fourth directions that are opposite directions when viewed from the center of the upper conductor 40. In this embodiment, the +X side (lower side in FIG. 4) is the third direction, and the -X side (lower side in FIG. 4) is the fourth direction. That is, the direction defined by the third and fourth directions is the X direction, which is perpendicular to the Y direction defined by the first and second directions.

[0040] 4, each of the stubs 75 extends from the outer periphery of the upper conductor 40 in the third or fourth direction, and does not overlap with the upper conductor 40 when the upper conductor 40 is viewed in the up-down direction. That is, each of the stubs 75 extends outward from the upper conductor 40 when the upper conductor 40 is viewed in the up-down direction. Note that, like the upper conductor 40, the stubs 75 according to the present embodiment extend in a horizontal plane, but may extend in a direction that intersects the horizontal plane slightly as long as they do not overlap with the upper conductor 40 when viewed in the up-down direction.

[0041] Each of the stubs 75 supplementarily corrects the lost rotational symmetry of the antenna element 30. For this purpose, it is desirable that the stubs 75 are disposed near the legs 50. As described above, since the recesses 44 mainly correct the lost rotational symmetry of the antenna element 30, the stubs 75 are not essential to the antenna element 30, but providing the stubs 75 further improves the possibility of supporting circularly polarized communication. In particular, the stubs 75 of this embodiment have a wide shape. That is, the size of the stubs 75 in the Y direction is larger than the size of the stubs 75 in the X direction. In detail, the X direction is the direction in which the stubs 75 extend, the Y direction is the direction perpendicular to the direction in which the stubs 75 extend, and the size of the stubs 75 in the latter direction is larger than the size of the stubs 75 in the former direction. Note that the stubs 75 of this embodiment correspond to the legs 50, respectively, but the present invention is not limited thereto. For example, in the case where two pairs of legs 50 are provided on the antenna element 30 as in this embodiment, only one pair of stubs long in the Y direction may be provided, while each end of the stub 75 may be extended to the vicinity of the legs 50. Note that, if the correction by the recess 44 is sufficient, the stub 75 may not be provided.

[0042] 2 and 3, the antenna element 30 according to this embodiment further has an additional leg 55, an additional lower conductor 65, and a fixed portion 67. The additional leg 55, the additional lower conductor 65, and the fixed portion 67 are formed by processing a part of the upper conductor 40, and do not affect the shape of the outer periphery of the upper conductor 40 in this embodiment.

[0043] The additional leg 55 extends downward from a position close to the center of the upper conductor 40. The additional lower conductor 65 extends from the additional leg 55 in a direction parallel to the upper surface of the substrate 20 and is separated from the upper conductor 40 in the vertical direction. That is, the additional lower conductor 65 of this embodiment extends parallel to the upper conductor 40. As a result, the additional lower conductor 65 and the upper conductor 40 form a capacitor. The shape and arrangement of the additional lower conductor 65 are not particularly limited as long as the additional lower conductor 65 and the upper conductor 40 form a capacitor. However, in order to suppress fluctuations in capacitance due to variations in dimensional tolerances, it is desirable for the additional lower conductor 65 to at least partially extend in a direction parallel to the upper surface of the substrate 20.

[0044] In this embodiment, a fixed portion 67 extends further downward from the additional lower conductor 65, and is soldered and fixed to the fixing pad 26 on the substrate 20, as can be seen from Figures 1 and 2. As a result, the additional lower conductor 65 and the ground conductor 22 form an additional capacitor.

[0045] As described above, the lower conductor 60 and the upper conductor 40 form a capacitor, and the additional lower conductor 65 and the upper conductor 40 form a capacitor. The lower conductor 60 and the ground conductor 22 form a capacitor, and the additional lower conductor 65 and the ground conductor 22 form a capacitor. The capacitor formed by the lower conductor 60 mainly contributes to miniaturization of the antenna element 30 having a predetermined resonance frequency. The capacitor formed by the additional lower conductor 65 mainly contributes to adjustment of the resonance frequency. However, the present invention is not limited to this, and instead of these capacitors, a capacitor element such as a chip capacitor may be connected between the leg 50 or the additional leg 55 and the ground conductor.

[0046] The antenna element 30 having the above-mentioned configuration is obtained by bending a metal plate 32 as shown in Fig. 5. In other words, the antenna element 30 of this embodiment has a developed shape in which the outer periphery is symmetrical with respect to an axis, as shown in Fig. 5.

[0047] The illustrated sheet metal 32 is a blank obtained by punching a sheet metal as a base material, and has a first portion 34, a second portion 36, and a third portion 38 in addition to an upper conductor 40 and a stub 75. With reference to FIG. 4 and FIG. 5, the first portion 34 is a portion that is bent to form a leg portion 50 and a lower conductor 60. Two first portions 34 extend from the upper conductor 40 in a first direction (+Y direction) and a second direction (-Y direction). The second portion 36 is a portion that is bent to form an additional leg portion 55 and an additional lower conductor 65. The third portion 38 is a portion that is bent to form a power supply portion 70. Two third portions 38 are provided on a line extending from the center of the specific rectangle 42 (i.e., the center of the upper conductor 40) toward a vertex of the specific rectangle 42. If necessary, in order to enhance the rotational symmetry of the antenna element 30, a dummy slot corresponding to the slot 46 may be provided on a line extending from the center of the specific rectangle 42 (i.e., the center of the upper conductor 40) to a vertex of the specific rectangle 42, on a line on which the third portion 38 is not provided.

[0048] In this manner, the antenna element 30 of this embodiment has a deployed shape in which the outer periphery is line symmetric. Compared to a case in which the outer periphery of the deployed shape of the antenna element is rotationally symmetric, if the outer periphery of the deployed shape of the antenna element 30 is line symmetric, waste is less likely to occur when cutting out multiple antenna elements from the base metal sheet. Therefore, according to this embodiment, material costs can be reduced. Also, according to this embodiment, the outer periphery of the deployed shape of the antenna element 30 does not need to be rotationally symmetric, so the degree of freedom in designing the antenna element 30 can be increased.

[0049] If the antenna element 30 is simply protruded only in the first azimuth (+Y side) or the second azimuth (-Y side) of the leg 50 in order to make the deployed shape of the antenna element 30 symmetrical, the rotational symmetry of the antenna element 30 is destroyed, and the antenna device 10 having good axial ratio characteristics cannot be realized. In contrast, in this embodiment, the recesses 44 recessed in the second azimuth or the first azimuth are juxtaposed to the leg 50, respectively, to correct the destroyed rotational symmetry of the antenna element 30, and further, the stub 75 is used to perform auxiliary correction. As a result, the antenna element 30 of this embodiment is suitable for circularly polarized communication, and the antenna device 10 using it can obtain good axial ratio characteristics. The size and shape of the recesses 44 and the size and shape of the stub 75 described above are not particularly limited other than those described above, and may be appropriately adjusted so that good axial ratio characteristics can be realized in the assumed frequency band for the assumed antenna device 10.

[0050] (Second embodiment) 6, an antenna device 10A according to the second embodiment of the present invention includes an auxiliary element 80A in addition to a substrate 20A and an antenna element 30A. The substrate 20A includes a ground conductor 22A. Specifically, the substrate 20A includes the ground conductor 22A formed on a dielectric substrate. The size, shape, and other structures of the substrate 20A are not particularly limited as long as the substrate 20A includes the ground conductor 22A.

[0051] In this embodiment, the antenna element 30A is fixed on the substrate 20A via the auxiliary element 80A. The antenna element 30A of this embodiment has a structure almost similar to that of the antenna element 30 of the first embodiment shown in Figs. 1 to 4. The parts of the antenna element 30A of this embodiment that are similar to those of the antenna element 30 of the first embodiment are given reference symbols with "A" added to the reference symbols of the parts of the antenna element 30 of the first embodiment. For example, the upper conductor of the antenna element 30A of this embodiment is given "40A", which is the reference symbol "40" of the upper conductor of the antenna element 30 of the first embodiment with "A" added. In this way, the description of the parts that are understood to be the same as those described in the first embodiment by the reference symbols will be omitted or simplified below.

[0052] The antenna element 30A of this embodiment differs from the antenna element 30 of the first embodiment described above in that it does not include a lower conductor and an additional lower conductor. Since the antenna element 30A does not include a lower conductor and an additional lower conductor, the fixed parts 52A and 57A extend directly from the leg 50A and the additional leg 55A.

[0053] As can be seen from FIG. 6, the auxiliary element 80A of this embodiment is a sub-substrate on which the antenna element 30A is mounted and which is fixed to the substrate 20A. As shown in FIG. 7, the auxiliary element 80A has a first auxiliary lower electrode 82A, a second auxiliary lower electrode 84A, and a power supply pad 86A formed on a dielectric substrate. The first auxiliary lower electrode 82A, the second auxiliary lower electrode 84A, and the power supply pad 86A are separated from each other. In this embodiment, the first auxiliary lower electrode 82A and the second auxiliary lower electrode 84A are floating pads that are not electrically connected to anything. In contrast, the power supply pad 86A is electrically drawn out to the outside of the antenna device 10A by a means not shown. In addition to the above-mentioned configuration, the auxiliary element 80A may further include a solid ground pattern on the back surface.

[0054] The auxiliary first lower electrode 82A in Fig. 7 corresponds to the lower electrode 60 in Fig. 2. As can be seen from Fig. 6 and Fig. 7, the auxiliary first lower electrode 82A forms a capacitor with the upper conductor 40A by fixing the fixed portion 52A to the auxiliary first lower electrode 82A. In addition, the auxiliary element 80A is fixed onto the substrate 20A, so that the auxiliary first lower electrode 82A forms another capacitor with the ground conductor 22A.

[0055] The auxiliary second lower electrode 84A in Fig. 7 corresponds to the additional lower electrode 65 in Fig. 2. As can be seen from Fig. 6 and Fig. 7, the auxiliary second lower electrode 84A forms a capacitor with the upper conductor 40A by fixing the fixed part 57A to the auxiliary second lower electrode 84A. In addition, the auxiliary second lower electrode 84A forms another capacitor with the ground conductor 22A by fixing the auxiliary element 80A on the substrate 20A.

[0056] The antenna element 30A according to the present embodiment is obtained by bending a metal plate 32A as shown in Fig. 10. That is, the antenna element 30A according to the present embodiment has a developed shape in which the outer periphery is symmetrical about an axis, as shown in Fig. 10.

[0057] The illustrated sheet metal 32A is a blank obtained by punching a base metal, and has a first portion 34A, a second portion 36A, and a third portion 38A in addition to an upper conductor 40A and a stub 75A. With reference to Figs. 9 and 10, the first portion 34A is a portion that is bent to form a leg portion 50A. The second portion 36A is a portion that is bent to form an additional leg portion 55A. The third portion 38A is a portion that is bent to form a power supply portion 70A. In this embodiment, a dummy slot corresponding to the slot 46A may be further provided in the upper conductor 40A.

[0058] As in the first embodiment described above, the antenna element 30A according to this embodiment does not waste the base metal sheet and allows for greater design freedom. In addition, the rotational symmetry lost by making the antenna element 30A symmetrical about the axis can be appropriately corrected by the recess 44A and the stub 75A, and the antenna device 10A using the antenna element 30A can obtain good axial ratio characteristics.

[0059] The present invention has been described above by way of examples, but the present invention is not limited to the above-described examples, and various modifications and changes are possible without departing from the spirit and scope of the present invention.

[0060] For example, the upper conductors 40 and 40A in the above-described embodiment have an approximately rectangular outer periphery, but the present invention is not limited thereto, and may have other shapes as long as they are symmetrical with respect to a line passing through the center of the upper conductor when viewed in a plan view. For example, the approximate outer periphery of the upper conductor may be a circle, an ellipse, or another polygon. In that case, the above-described specific rectangles 42 and 42A are to be matched to the approximate outer periphery of the upper conductor. For example, when the approximate outer periphery of the upper conductor is a circle, a circle with the minimum area that contains the upper conductor may be assumed as the specific circle.

[0061] In the above-described embodiment, the protruding direction of the legs 50, 50A and the recessed direction of the corresponding recesses 44, 44A are parallel and opposite to each other, but as long as they are generally opposite, they may not be parallel and may intersect each other slightly. For example, if the upper conductor has a generally circular outer circumferential shape, the legs may protrude radially outward and the corresponding recesses may be recessed radially inward. [Explanation of symbols]

[0062] 10,10A Antenna device 20,20A board 22,22A Ground Conductor 24,26 Fixed pad 28 Power Pad 30,30A Antenna Element 32, 32A Sheet metal 34,34A 1st part 36,36A 2nd part 38,38A 3rd part 40,40A Upper conductor 42,42A Specific rectangle 44,44A Recess 46,46A Slot 50,50A Legs 52A Fixed part 55,55A Additional legs 57A Fixed part 60 Lower Conductor 62 Fixed part 65 Additional Lower Conductor 67 Fixed part 70,70A power supply 75,75A stub 80A Auxiliary Element 82A Auxiliary 1st lower electrode 84A Auxiliary 2nd lower electrode 86A Power Pad

Claims

1. An antenna element that is fixed onto a substrate having a ground conductor to constitute an antenna device, The antenna element includes an upper conductor and at least a pair of legs; the upper conductor has an outer periphery that is symmetrical with respect to a line passing through a center of the upper conductor when viewed in a vertical direction; the pair of legs respectively protrude in a first direction and a second direction which are opposite directions as viewed from the center of the upper conductor when the upper conductor is viewed along the vertical direction, and each extends downward in the vertical direction, The upper conductor is provided with at least a pair of recesses, The pair of recesses correspond one-to-one to the pair of legs, the pair of recesses are recessed in the second direction and the first direction, respectively, when the upper conductor is viewed along the up-down direction; Each of the recesses is juxtaposed with the corresponding leg in a direction intersecting a direction defined by the first orientation and the second orientation. Antenna element.

2. 2. The antenna element according to claim 1, Each of the recesses has a wide shape. Antenna element.

3. 2. The antenna element according to claim 1, Each of the recesses is disposed adjacent to the corresponding leg portion in a direction perpendicular to a direction defined by the first orientation and the second orientation. Antenna element.

4. 2. The antenna element according to claim 1, the upper conductor extends in a predetermined plane perpendicular to the up-down direction, When a specific rectangle is assumed to be a rectangle that exists on the predetermined plane and has four sides that are imaginary lines and has a minimum area that includes the upper conductor, the corresponding legs and recesses are located on the same sides. Antenna element.

5. 5. The antenna element according to claim 4, The at least one pair of legs includes two pairs of legs, The at least one pair of recesses includes two pairs of recesses, Each of the legs is located on one of two sides of the specific rectangle that are located in the first direction and the second direction when viewed from the center of the upper conductor. Antenna element.

6. 2. The antenna element according to claim 1, The antenna element further comprises at least a pair of stubs; a direction defined by a third orientation and a fourth orientation, which are opposite orientations as viewed from the center of the upper conductor, is perpendicular to a direction defined by the first orientation and the second orientation; the pair of stubs extend from the outer periphery of the upper conductor in the third and fourth directions, respectively; Each of the stubs does not overlap with the upper conductor when the upper conductor is viewed in the up-down direction. Antenna element.

7. The antenna element according to claim 6 . Each of the stubs has a wide shape. Antenna element.

8. 2. The antenna element according to claim 1, a lower conductor extending at least partially from each of the legs in a direction parallel to the top surface of the substrate, the lower conductor being spaced apart from the upper conductor in the vertical direction; Antenna element.

9. 2. The antenna element according to claim 1, At least one pair of additional legs each extending downward in the up-down direction from a position closer to the center of the upper conductor than each of the legs, and an additional lower conductor extending at least partially from each of the additional legs in a direction parallel to the top surface of the substrate and spaced apart from the upper conductor in the vertical direction. Antenna element.

10. An antenna element according to any one of claims 1 to 9, The antenna element is made of a single metal plate. Antenna element.

11. 11. The antenna element of claim 10, The antenna element has a deployed shape in which the outer periphery is symmetrical. Antenna element.

12. An antenna device comprising the antenna element according to claim 1 and a substrate, The substrate includes a ground conductor, The antenna element is fixed onto the substrate. Antenna device.

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