Antenna unit and antenna device

Abstract

This antenna unit comprises: an electric power supply portion; a first helical antenna that has a plurality of first helical elements, of which at least a portion is twisted with respect to a first axis, and corresponds to radio waves in a first frequency band; and a second helical antenna that has a plurality of second helical elements, of which at least a portion is twisted with respect to a second axis, and corresponds to radio waves in a second frequency band different from the first frequency band. The plurality of first helical elements and the plurality of second helical elements are supplied with electric power by the electric power supply portion.

Description

Antenna unit and antenna device

[0001] The present invention relates to an antenna unit and an antenna device.

[0002] Patent Document 1 describes a helical antenna that is compatible with radio waves in a predetermined frequency band.

[0003] JP 2017-108328 A

[0004] In order to support radio waves in multiple frequency bands using a helical antenna such as that described in Patent Document 1, first, a first helical antenna that supports radio waves in a first frequency band and a second helical antenna that supports radio waves in a second frequency band different from the first frequency band are prepared. However, feeding power separately to the first helical antenna and the second helical antenna can result in a complicated configuration.

[0005] One example of an object of the present invention is to use multiple helical antennas to support radio waves in multiple frequency bands with a simple configuration. Other objects of the present invention will become apparent from the description of this specification.

[0006] One aspect of the present invention is an antenna unit comprising: a power supply unit; a first helical antenna having a plurality of first helical elements twisted about a first axis and responsive to radio waves in a first frequency band; and a second helical antenna having a plurality of second helical elements twisted about a second axis and responsive to radio waves in a second frequency band different from the first frequency band, wherein the plurality of first helical elements and the plurality of second helical elements are fed by the power supply unit.

[0007] One aspect of the present invention is an antenna device comprising: a first helical antenna having a plurality of first helical elements twisted about a first axis and responsive to radio waves in a first frequency band; a second helical antenna having a plurality of second helical elements twisted about a second axis and responsive to radio waves in a second frequency band different from the first frequency band; and electronic components connected to the first helical antenna and the second helical antenna and configured to combine or separate signals in the first frequency band and signals in the second frequency band.

[0008] According to the above aspect of the present invention, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0009] 1 is an exploded perspective view of antenna unit 10 of the present embodiment; FIG. 2 is a perspective view of antenna unit 10 with case portion 11 removed; FIG. 3 is a plan view of antenna unit 10 with case portion 11 removed; FIG. 4 is a plan view showing an enlarged portion near power feed portion 12; FIG. 5 is a side view of antenna unit 10 with case portion 11 removed; FIG. 6 is an explanatory diagram illustrating the twist angle of first helical element 131; FIG. 7 is a plan view of first helical antenna 13A; FIG. 8 is a side view of first helical antenna 13A; FIG. 9 is a diagram illustrating an example of frequency characteristics of VSWR of first helical antenna 13A; FIG. 10 is a diagram illustrating an example of frequency characteristics of gain of first helical antenna 13A; FIG. 11 is a diagram illustrating an example of frequency characteristics of axial ratio of first helical antenna 13A; FIG. 12 is a plan view of second helical antenna 14B; FIG. 13 is a side view of second helical antenna 14B; FIG. 14 is a diagram illustrating an example of frequency characteristics of VSWR of second helical antenna 14B; FIG. 15 is a diagram illustrating an example of frequency characteristics of gain of second helical antenna 14B; FIG. 16 is a diagram illustrating an example of frequency characteristics of axial ratio of second helical antenna 14B. 1 is a diagram showing an example of frequency characteristics of VSWR of the antenna unit 10 of this embodiment. FIG. 2 is a diagram showing an example of frequency characteristics of gain of the antenna unit 10 of this embodiment. FIG. 3 is a diagram showing an example of frequency characteristics of axial ratio of the antenna unit 10 of this embodiment. FIG. 4 is an explanatory diagram explaining a direction in which directivity is strong in the antenna unit 10 of this embodiment. FIG. 5 is a plan view showing an enlarged portion near the power feeding part 12C in the first modified example. FIG. 6 is an explanatory diagram explaining a direction in which directivity is strong in the antenna unit 10C in the first modified example. FIG. 7 is a perspective view showing an enlarged view 1 of the vicinity of the first power feeding part 18 and the second power feeding part 19 of the antenna device 100 of the second modified example. FIG. 8 is a plan view showing an enlarged view 1 of the vicinity of the first power feeding part 18 and the second power feeding part 19 of the antenna device 100 of the second modified example.

[0010] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0012] ==Present Embodiment== Fig. 1 is an exploded perspective view of an antenna unit 10 according to this embodiment. Fig. 2 is a perspective view of the antenna unit 10 with the case 11 removed.

[0013] <<Definition of Directions, Etc.>> First, directions, etc. in the antenna unit 10 of this embodiment will be defined with reference to FIGS.

[0014] As shown in FIGS. 1 and 2 , the direction parallel to the torsion axis (first axis A1, described later) of first helical element 131 (described later) is defined as the "+Z direction." Antenna unit 10 of this embodiment is mounted so that the +Z direction is the zenith direction. For this reason, in the following description, the +Z direction may be referred to as the "upper direction" and the -Z direction may be referred to as the "lower direction." Furthermore, the +Z direction side may be referred to as the "upper side" and the -Z direction side may be referred to as the "lower side." Furthermore, two directions that are perpendicular to the +Z direction and are perpendicular to each other are defined as the "+X direction" and the "+Y direction," respectively.

[0015] The +X direction, -X direction, +Y direction, -Y direction, +Z direction, and -Z direction are each directions with a fixed orientation. Rather than being directions with a fixed orientation as described above, both the +X direction and the -X direction may be simply referred to as the "X direction." Similarly, both the +Y direction and the -Y direction may be simply referred to as the "Y direction." Furthermore, both the +Z direction and the -Z direction may be simply referred to as the "Z direction." Furthermore, the Z direction may be referred to as the "vertical direction," and the direction perpendicular to the Z direction may be referred to as the "horizontal direction."

[0016] 1 and 2, the +X direction, +Y direction, and +Z direction are each represented by a line segment with an arrow to facilitate understanding of the directions in the antenna unit 10. Note that the intersection of these line segments with an arrow does not represent the origin of the coordinate system.

[0017] The above definitions of directions and the like are common to other embodiments in this specification unless otherwise specified.

[0018] <<Outline of Antenna Unit 10 >> Next, an outline of the antenna unit 10 of this embodiment will be described with reference again to FIGS. 1 and 2 described above, and also with reference to FIGS. 3A, 3B, and 4. FIG.

[0019] Fig. 3A is a plan view of the antenna unit 10 with the case 11 removed. Fig. 3B is a plan view showing an enlarged portion near the power supply unit 12. Fig. 4 is a side view of the antenna unit 10 with the case 11 removed.

[0020] The antenna unit 10 is an antenna unit having multiple helical antennas. As will be described later, the antenna unit 10 has two helical antennas, a first helical antenna 13 and a second helical antenna 14. However, the antenna unit 10 may have three or more helical antennas.

[0021] Antenna unit 10 has a case 11, a power supply unit 12, a first helical antenna 13, a second helical antenna 14, and a support unit 15. Hereinafter, power supply unit 12, first helical antenna 13, second helical antenna 14, and support unit 15 may be collectively referred to as the "main body of antenna unit 10" or simply the "main body."

[0022] The case 11 is a member that constitutes the exterior of the antenna unit 10. The case 11 is formed of an insulating resin such as ABS resin. However, the case 11 may be formed of a material other than insulating resin that transmits radio waves. Furthermore, the case 11 may be composed of an insulating resin portion and a portion of another material that transmits radio waves, and the members may be freely combined.

[0023] The case 11 has a lid 111 and a storage section 112. The lid 111 is a portion of the case 11 that is located on the +Z direction side, and the storage section 112 is a portion of the case 11 that is located on the −Z direction side. In the case 11 of this embodiment, as shown in Fig. 1 , the storage section 112 forms a storage space that stores substantially the entire main body of the antenna unit 10, and the lid 111 covers the upper surface side (+Z direction side) of the storage space.

[0024] However, the detailed shape of the case 11 is not limited to that shown in FIG. 1. For example, the case 11 may be composed of two members: one covering the +X direction side of the main body, and the other covering the −X direction side of the main body. Furthermore, the case 11 does not have to house the entire main body. For example, the case 11 may cover the +Z direction side of the main body, and the main body covered by the case 11 may be installed on the ground. In the antenna unit 10 of this embodiment, although not shown, the housing 112 has a bottom on the −Z direction side. However, the housing 112 does not have to have a bottom.

[0025] The power supply unit 12 is a component that includes the power supply points of the multiple helical antennas included in the antenna unit 10. The power supply unit 12 is located on the +Z direction side of the main body of the antenna unit 10. As shown in Figures 2, 3A, and 3B, the power supply unit 12 has an inner conductor side power supply unit 121 and an outer conductor side power supply unit 122. As shown in Figure 3B, the inner conductor side power supply unit 121 is the portion of the power supply unit 12 to which the inner conductor 171 (e.g., core wire) of the coaxial cable 17 is connected, and the outer conductor side power supply unit 122 is the portion of the power supply unit 12 to which the outer conductor 172 (e.g., ground wire) of the coaxial cable 17 is connected.

[0026] As shown in FIG. 3B , the inner conductor side feeding portion 121 and the outer conductor side feeding portion 122 are each formed in a substantially arc-shaped configuration. When viewed as a whole, the feeding portion 12, which is composed of the inner conductor side feeding portion 121 and the outer conductor side feeding portion 122, each formed in a substantially arc-shaped configuration, has two separation portions S that separate parts of the annular shape. The two separation portions S are located in a direction between the −X direction and the −Y direction and in a direction between the +X direction and the +Y direction. The two separation portions S are also located symmetrically (point symmetrically in this embodiment) with respect to the center of the annular shape of the feeding portion 12. Because the two separation portions S are located symmetrically with respect to the center of the annular shape of the feeding portion 12, the shape of the inner conductor side feeding portion 121 and the shape of the outer conductor side feeding portion 122 are symmetrical with respect to the center of the annular shape of the feeding portion 12 (point symmetrically in this embodiment). However, the shape and arrangement position of the power supplying portion 12 (the inner conductor side power supplying portion 121 and the outer conductor side power supplying portion 122) are not limited to the examples shown in FIGS. 3A and 3B.

[0027] The first helical antenna 13 is an antenna having a plurality of helical elements each made of a conductor wire, at least a portion of which is twisted. The first helical antenna 13 is a QFH (Quadrifilar Helix Antenna) antenna, and is compatible with circularly polarized radio waves.

[0028] The first helical antenna 13 is compatible with radio waves in a frequency band (hereinafter sometimes referred to as the "first frequency band") for the Global Navigation Satellite System (GNSS). In this embodiment, the first helical antenna 13 is compatible with radio waves in the L2 band and the L5 band (1166 MHz to 1250 MHz band).

[0029] The communication standard and frequency band of radio waves supported by the first helical antenna 13 are not limited to GNSS, and may be other communication standards and frequency bands. For example, the first helical antenna 13 may be compatible with radio waves in a frequency band for Satellite Digital Audio Radio Service (SDARS) or a frequency band for Vehicle-to-Everything (V2X: vehicle-to-vehicle communication, road-to-vehicle communication). In this embodiment, the radio waves in the GNSS frequency band are right-handed circularly polarized waves, and the radio waves in the SDARS frequency band are left-handed circularly polarized waves.

[0030] First helical antenna 13 has a plurality of helical elements. In this embodiment, first helical antenna 13 has two helical elements, first helical element 131 and first helical element 132.

[0031] As shown in FIG. 2 , first helical element 131 and first helical element 132 are each twisted about first axis A1. In this embodiment, first helical element 131 is formed in a loop shape connected by power supply unit 12. One end of the loop of first helical element 131 is connected to inner-conductor-side power supply unit 121 of power supply unit 12, and the other end of the loop of first helical element 131 is connected to outer-conductor-side power supply unit 122 of power supply unit 12. Similarly, in this embodiment, first helical element 132 is also formed in a loop shape connected by power supply unit 12. One end of the loop of first helical element 132 is connected to inner-conductor-side power supply unit 121 of power supply unit 12, and the other end of the loop of first helical element 132 is connected to outer-conductor-side power supply unit 122 of power supply unit 12. In this embodiment, first helical element 131 and first helical element 132 are formed in a loop shape, but as long as they are connected to power supply unit 12 in a twisted state at least in part, they may have other shapes without being limited to a loop shape.

[0032] The second helical antenna 14 is an antenna having a plurality of helical elements each formed by helically winding a loop-shaped conductor wire, similar to the first helical antenna 13. The second helical antenna 14 is also a QFH antenna and is compatible with circularly polarized radio waves.

[0033] Similarly to the above-described first helical antenna 13, the second helical antenna 14 supports radio waves in a frequency band for GNSS (hereinafter, sometimes referred to as the "second frequency band"). The second frequency band is different from the frequency band (first frequency band) of radio waves supported by the above-described first helical antenna 13. Specifically, the second helical antenna 14 supports radio waves in the L1 band (1559 MHz to 1606 MHz).

[0034] The communication standard and frequency band of radio waves supported by the second helical antenna 14 are not limited to GNSS, and may be other communication standards and frequency bands. For example, the second helical antenna 14 may be compatible with radio waves in a frequency band for SDARS or a frequency band for V2X.

[0035] Second helical antenna 14 has a plurality of second helical elements. In this embodiment, second helical antenna 14 has two helical elements, second helical element 141 and second helical element 142.

[0036] As shown in FIG. 2 , second helical element 141 and second helical element 142 are each twisted about second axis A2. In this embodiment, second helical element 141 is formed in a loop shape connected by feed unit 12. One end of the loop of second helical element 141 is connected to inner-conductor-side feed unit 121 of feed unit 12, and the other end of the loop of second helical element 141 is connected to outer-conductor-side feed unit 122 of feed unit 12. Similarly, in this embodiment, second helical element 142 is also formed in a loop shape connected by feed unit 12. One end of the loop of second helical element 142 is connected to inner-conductor-side feed unit 121 of feed unit 12, and the other end of the loop of second helical element 142 is connected to outer-conductor-side feed unit 122 of feed unit 12. In this embodiment, second helical element 141 and second helical element 142 are formed in a loop shape, but they may have other shapes as long as they are connected to power supply unit 12 in a twisted state at least in part.

[0037] As shown in FIG. 1 , support portion 15 is a member that supports the multiple helical elements of first helical antenna 13 (first helical element 131 and first helical element 132) and the multiple helical elements of second helical antenna 14 (second helical element 141 and second helical element 142). Support portion 15 has a first cylindrical portion 151 and a second cylindrical portion 152. First cylindrical portion 151 is a member that supports the multiple helical elements of first helical antenna 13 (first helical element 131 and first helical element 132). Second cylindrical portion 152 is a member that supports the multiple helical elements of second helical antenna 14 (second helical element 141 and second helical element 142).

[0038] <<Details of Antenna Unit 10>> <Features> The antenna unit 10 of this embodiment is capable of handling radio waves in multiple frequency bands by including a first helical antenna 13 that handles radio waves in a first frequency band and a second helical antenna 14 that handles radio waves in a second frequency band different from the first frequency band. The antenna unit 10 is a so-called multi-band antenna.

[0039] Let us assume that the multiple helical elements of first helical antenna 13 and the multiple helical elements of second helical antenna 14 are fed separately by different power feed points. In this case, it may be necessary to arrange electronic components such as coaxial cables and circuit boards at each of the different power feed points, which may result in a complex configuration.

[0040] Antenna unit 10 of the present embodiment has power feeding portion 12, which is a common power feeding portion for first helical antenna 13 and second helical antenna 14. In other words, multiple first helical elements 131 and multiple second helical elements 141 are fed by common power feeding portion 12.

[0041] Since the multiple first helical elements 131 and the multiple second helical elements 141 are fed by a common power supply section 12, the antenna unit 10 of this embodiment reduces the need to place coaxial cables and electronic components for each helical antenna, and can accommodate radio waves in multiple frequency bands with a simple configuration.

[0042] <Position of Twist Axis> In antenna unit 10 of this embodiment, first axis A1 and second axis A2 are at the same position. In other words, each of the multiple helical elements of first helical antenna 13 (first helical element 131 and first helical element 132) and the multiple helical elements of second helical antenna 14 (second helical element 141 and second helical element 142) is formed in a loop shape twisted about a common axis.

[0043] However, in antenna unit 10, first axis A1 and second axis A2 do not have to be in the same position as long as first helical antenna 13 and second helical antenna 14 have a common feeder 12. The multiple helical elements of first helical antenna 13 and the multiple helical elements of second helical antenna 14 may each be formed in a twisted loop shape about an axis that is in a different position from each other.

[0044] <Features in Plan View> In antenna unit 10 of the present embodiment, in the plan view shown in Fig. 3A , first helical element 131 and first helical element 132 are arranged along a first surrounding shape that surrounds first axis A1. The first surrounding shape is a circle, and first tubular portion 151 of support unit 15 is arranged along the first surrounding shape. However, the first surrounding shape is not limited to a circle as long as it surrounds first axis A1, and may be, for example, an ellipse or a polygonal shape such as a quadrilateral.

[0045] 3A , second helical element 141 and second helical element 142 are arranged along a second surrounding shape that surrounds second axis A2. Second surrounding shape is a circle, and second cylindrical portion 152 of support portion 15 is arranged along the second surrounding shape. However, second surrounding shape is not limited to a circle, and may be, for example, an ellipse or a polygonal shape such as a quadrilateral, as long as it surrounds second axis A2.

[0046] In addition, in the antenna unit 10 of this embodiment, in the plan view shown in Fig. 3A, the first surrounding shape (i.e., the shape of the first cylindrical portion 151) is larger than the second surrounding shape (i.e., the shape of the second cylindrical portion 152). In other words, the first surrounding shape is a shape that surrounds the second surrounding shape. However, the first surrounding shape may be smaller than the second surrounding shape, or the first surrounding shape and the second surrounding shape may be the same size.

[0047] The power supply unit 12 is located at the center of the first surrounding shape and the center of the second surrounding shape. The "center" refers to the geometric center of the outer edge shape. However, the power supply unit 12 may be located at either the center of the first surrounding shape or the center of the second surrounding shape, or may not be located at the center of either the first surrounding shape or the second surrounding shape.

[0048] Furthermore, when the center position of the first surrounding shape and the center position of the second surrounding shape substantially coincide with each other, first helical element 131 and first helical element 132 each extend radially in a substantially uniform manner around the center (the position of power supply unit 12 in this embodiment) in the plan view shown in Fig. 3B . Furthermore, when the center position of the first surrounding shape and the center position of the second surrounding shape substantially coincide with each other, second helical element 141 and second helical element 142 each extend radially in a substantially uniform manner around the center (the position of power supply unit 12 in this embodiment) in the plan view shown in Fig. 3B .

[0049] 3B , first helical element 131 and first helical element 132 extend from feed portion 12 with a 90° offset around their center. In this embodiment, with respect to first helical element 131 and first helical element 132 extending from inner conductor side feed portion 121, first helical element 131 extends in the +X direction, and first helical element 132 extends in the −Y direction. Similarly, with respect to first helical element 131 and first helical element 132 extending from outer conductor side feed portion 122, first helical element 131 extends in the −X direction, and first helical element 132 extends in the +Y direction.

[0050] Furthermore, second helical element 141 and second helical element 142 extend from feeding unit 12 at a 90° offset around their center. In this embodiment, with respect to second helical element 141 and second helical element 142 extending from inner conductor side feeding unit 121, second helical element 141 extends in a direction between the +X direction and the −Y direction, and second helical element 142 extends in a direction between the −X direction and the −Y direction. Similarly, with respect to second helical element 141 and second helical element 142 extending from outer conductor side feeding unit 122, second helical element 141 extends in a direction between the −X direction and the +Y direction, and second helical element 142 extends in a direction between the +X direction and the +Y direction.

[0051] The arrangement relationship of the first helical elements (first helical elements 131, 132) and the second helical elements (second helical elements 141, 142) in the portions connected to inner conductor side power supply unit 121 or outer conductor side power supply unit 122 is such that the first helical elements and the second helical elements are arranged alternately around the center.

[0052] However, each of first helical element 131 and first helical element 132 does not have to extend radially from feed unit 12 in a substantially uniform pattern around the center (shifted by 90° around the center). Similarly, each of second helical element 141 and second helical element 142 does not have to extend radially from feed unit 12 in a substantially uniform pattern around the center (shifted by 90° around the center).

[0053] 3A , the multiple helical elements of first helical antenna 13 and the multiple helical elements of second helical antenna 14 are arranged to radiate approximately uniformly around the center. The multiple helical elements of second helical antenna 14 are arranged at 45° angles around the center relative to the multiple helical elements of first helical antenna 13 so as to radiate approximately uniformly around the center.

[0054] 3A , the first helical element 131 is disposed inside the first cylindrical portion 151 of the support part 15, and the first helical element 132 is disposed outside the first cylindrical portion 151 of the support part 15. However, the first helical element 131 may be disposed outside the first cylindrical portion 151 and the first helical element 132 may be disposed inside the first cylindrical portion 151, or both the first helical element 131 and the first helical element 132 may be disposed inside or outside the first cylindrical portion 151.

[0055] However, by arranging one of the two first helical elements of the first helical antenna 13 outside the first cylindrical portion 151 and the other inside the first cylindrical portion 151, physical interference (contact between each other) between the first helical element 131 and the first helical element 132 can be suppressed.

[0056] 3A , second helical element 141 is disposed inside second cylindrical portion 152 of support portion 15, and second helical element 142 is disposed outside second cylindrical portion 152 of support portion 15. However, second helical element 141 may be disposed outside second cylindrical portion 152, and second helical element 142 may be disposed inside second cylindrical portion 152, or both second helical element 141 and second helical element 142 may be disposed inside or outside second cylindrical portion 152.

[0057] However, by arranging one of the two second helical elements of the second helical antenna 14 outside the second cylindrical portion 152 and the other inside the second cylindrical portion 152, physical interference (contact between) between the second helical element 141 and the second helical element 142 can be suppressed.

[0058] <Features in Side View> In antenna unit 10 of this embodiment, in a plan view such as that shown in Fig. 4, feed portion 12 is located at the end (upper end L0 in this embodiment) of first helical element 131 and first helical element 132. Also, feed portion 12 is located at the end (upper end L0 in this embodiment) of second helical element 141 and second helical element 142. However, feed portion 12 may be located at the lower end (L131 in this embodiment) of first helical element 131, the lower end (L132 in this embodiment) of first helical element 132, or the middle in the Z direction. Also, feed portion 12 may be located at the lower end (L141 in this embodiment) of second helical element 141, the lower end (L142 in this embodiment), or the middle in the Z direction.

[0059] First helical element 131 and first helical element 132, and second helical element 141 and second helical element 142 are located on one side (the lower side in this embodiment) of feed portion 12. However, first helical element 131 and first helical element 132 may be located on one side (the lower side in this embodiment) of feed portion 12, and second helical element 141 and second helical element 142 may be located on the other side (the upper side in this embodiment) of feed portion 12. However, by locating first helical element 131 and first helical element 132 and second helical element 141 and second helical element 142 on the same side of feed portion 12, the overall size of antenna unit 10 can be reduced.

[0060] 4 , the −Z direction end (L131) of first helical element 131 is located closer to the +Z direction than the −Z direction end (L132) of first helical element 132. Since the −Z direction end (L131) of first helical element 131 is located closer to the +Z direction than the −Z direction end (L132) of first helical element 132, the electrical length of the loop of first helical element 131 is formed to be slightly shorter than the electrical length of the loop of first helical element 132. Therefore, the peak of the frequency band of radio waves corresponding to first helical element 131 (P1 in FIG. 8 , which will be described later) is located on the higher frequency side than the peak of the frequency band of radio waves corresponding to first helical element 132 (P2 in FIG. 8 , which will be described later).

[0061] 4 , the −Z direction end (L141) of second helical element 141 is located closer to the +Z direction than the −Z direction end (L142) of second helical element 142. Since the −Z direction end (L141) of second helical element 141 is located closer to the +Z direction than the −Z direction end (L142) of second helical element 142, the electrical length of the loop of second helical element 141 is formed to be slightly shorter than the electrical length of the loop of second helical element 142. Therefore, the peak of the frequency band of radio waves corresponding to second helical element 141 (P3 in FIG. 13 , which will be described later) is located on the higher frequency side than the peak of the frequency band of radio waves corresponding to first helical element 132 (P4 in FIG. 13 , which will be described later).

[0062] <Twist Shape> In antenna unit 10 of this embodiment, the shape of the multiple helical elements of first helical antenna 13 is the same as the shape of the multiple helical elements of second helical antenna 14. Specifically, as shown in Fig. 3A , twist angle Θ1 (= 180°) of first helical element 131 is the same as twist angle Θ2 (= 180°) of second helical element 141 (Θ1 = Θ2). Here, the twist angle is the angular displacement of the twist described below in Fig. 5 .

[0063] FIG. 5 is an explanatory diagram illustrating the twist angle of first helical element 131.

[0064] The twist angle will be described below using the first helical element 131 as an example. The following description of the first helical element 131 can also be applied to the other helical elements (first helical element 132, second helical element 141, and second helical element 142).

[0065] As shown in Fig. 5 , when upper end 31 of first helical element 131 is fixed and lower end 32 is twisted, the first helical element 131 of this embodiment takes on a twisted loop shape. The angular displacement Θ shown in Fig. 5 is referred to as the twist angle. Note that, in this embodiment, first helical element 131 is described as being formed in a twisted loop shape, but first helical element 131 is not limited to the loop shape described above and may have other shapes as long as the twist angle (angular displacement) is changed appropriately.

[0066] In the antenna unit 10 of this embodiment, the twist angles of the multiple helical elements of the first helical antenna 13 and the twist angles of the multiple helical elements of the second helical antenna 14 are made the same, thereby achieving the desired directivity.

[0067] As described above, the first helical element 131 in this embodiment is compatible with radio waves in the GNSS frequency band and with right-handed circular polarization. Whether right-handed or left-handed circular polarization is determined by the twist direction (winding direction) of the helical element. Since the first helical element 131 is counterclockwise (right-handed), it is compatible with right-handed circular polarization. If the first helical element 131 is clockwise (left-handed), it is compatible with left-handed circular polarization.

[0068] <<Characteristics of Helical Antennas Alone>> The following describes the characteristics of the antenna unit 10 when the first helical antenna 13 and the second helical antenna 14 are each a single antenna.

[0069] <Structure of First Helical Antenna 13A> Fig. 6 is a plan view of the first helical antenna 13A, and Fig. 7 is a side view of the first helical antenna 13A.

[0070] 6 and 7 has the same configuration as the first helical antenna 13 of the antenna unit 10 of the above-described embodiment. Therefore, the description of the first helical element 131A and the first helical element 132A of the first helical antenna 13A is the same as that of the first helical element 131 and the first helical element 132 of the first helical antenna 13 of the antenna unit 10 of the embodiment.

[0071] <Frequency Characteristics of First Helical Antenna 13A> Fig. 8 is a diagram showing an example of the frequency characteristics of the VSWR of the first helical antenna 13A. Fig. 9 is a diagram showing an example of the frequency characteristics of the gain of the first helical antenna 13A. Fig. 10 is a diagram showing an example of the frequency characteristics of the axial ratio of the first helical antenna 13A.

[0072] In Fig. 8, the horizontal axis represents frequency and the vertical axis represents voltage standing wave ratio (VSWR). In Fig. 9, the horizontal axis represents frequency and the vertical axis represents gain [dBi]. In Fig. 10, the horizontal axis represents frequency and the vertical axis represents axial ratio [dB].

[0073] In FIG. 8 , P1 denotes the peak of the frequency band of radio waves supported by first helical element 131A, and P2 denotes the peak of the frequency band of radio waves supported by first helical element 132A. P1 is on the higher frequency band side than P2. In first helical antenna 13A, the electrical length of the loop of first helical element 131A and the electrical length of the loop of first helical element 132A are set to have a phase difference of 90°. By setting the phase difference to be 90°, two linearly polarized radio waves, the radio waves supported by first helical element 131A and the radio waves supported by first helical element 132A, are added together to generate a desired circularly polarized radio wave. As shown in FIGS. 9 and 10 , high gain and a good axial ratio are achieved in the desired frequency band (here, the L2 band and the L5 band, 1166 MHz to 1250 MHz).

[0074] <Structure of Second Helical Antenna 14B> Fig. 11 is a plan view of second helical antenna 14B. Fig. 12 is a side view of second helical antenna 14B.

[0075] 11 and 12 has the same configuration as second helical antenna 14 of antenna unit 10 of the above-described embodiment. Second helical element 141B and second helical element 142B of second helical antenna 14B are similar to second helical element 141 and second helical element 142 of second helical antenna 14 of antenna unit 10 of the present embodiment.

[0076] <Frequency Characteristics of Second Helical Antenna 14B> Fig. 13 is a diagram showing an example of the VSWR frequency characteristics of second helical antenna 14B. Fig. 14 is a diagram showing an example of the gain frequency characteristics of second helical antenna 14B. Fig. 15 is a diagram showing an example of the axial ratio frequency characteristics of second helical antenna 14B.

[0077] In Fig. 13, the horizontal axis represents frequency and the vertical axis represents voltage standing wave ratio (VSWR). In Fig. 14, the horizontal axis represents frequency and the vertical axis represents gain [dBi]. In Fig. 15, the horizontal axis represents frequency and the vertical axis represents axial ratio [dB].

[0078] 13 , P3 is the peak of the frequency band of radio waves supported by second helical element 141B, and P4 is the peak of the frequency band of radio waves supported by second helical element 142B. P3 is on the higher frequency band side than P4. In second helical antenna 14B, the electrical length of the loop of second helical element 141B and the electrical length of the loop of second helical element 142B are set to have a phase difference of 90°. By setting the electrical length of the loop of second helical element 141B and the electrical length of the loop of second helical element 142B to have a phase difference of 90°, two linearly polarized radio waves, the radio wave supported by second helical element 141B and the radio wave supported by second helical element 142B, are added together to generate a desired circularly polarized radio wave. As shown in FIGS. 13 and 14, in the desired frequency band (here, the L1 band, 1559 MHz to 1606 MHz), the gain is high and the axial ratio is also good.

[0079] <<Frequency Characteristics of Antenna Unit 10>> Fig. 16 is a diagram showing an example of frequency characteristics of VSWR of the antenna unit 10 of this embodiment. Fig. 17 is a diagram showing an example of frequency characteristics of gain of the antenna unit 10 of this embodiment. Fig. 18 is a diagram showing an example of frequency characteristics of axial ratio of the antenna unit 10 of this embodiment.

[0080] In Fig. 16, the horizontal axis represents frequency and the vertical axis represents voltage standing wave ratio (VSWR). In Fig. 17, the horizontal axis represents frequency and the vertical axis represents gain [dBi]. In Fig. 18, the horizontal axis represents frequency and the vertical axis represents axial ratio [dB].

[0081] 16, 17, and 18, antenna unit 10 of this embodiment has a characteristic that is the sum of the frequency characteristics of first helical antenna 13A and second helical antenna 14B. Therefore, antenna unit 10 of this embodiment can handle radio waves in multiple frequency bands with a simple configuration using multiple helical antennas (in this embodiment, first helical antenna 13 and second helical antenna 14).

[0082] <<Directivity>> FIG. 19 is an explanatory diagram illustrating directions in which the antenna unit 10 of this embodiment has strong directivity.

[0083] As described above, the helical elements (first helical element 131, first helical element 132, second helical element 141, and second helical element 142) of antenna unit 10 of this embodiment are compatible with radio waves in the GNSS frequency band and with right-hand circularly polarized waves. When compatible with right-hand circularly polarized waves, antenna unit 10 has directivity in the direction of the arrow shown in FIG. 19 (+Z direction).

[0084] 19 , when the antenna has directivity in the direction of the arrow (+Z direction), the electronic components 16 (for example, an LNA or a diplexer) are arranged on the opposite side to the direction of the directivity (−Z direction side), i.e., inside the antenna unit 10, as shown in Fig. 19 . By arranging the electronic components 16 inside the antenna unit 10, it is possible to suppress an increase in the size of the antenna unit 10 while suppressing an effect on the characteristics of the antenna unit 10, compared to when the electronic components 16 are arranged outside the antenna unit 10.

[0085] <<First Modification>> Fig. 20 is a plan view showing an enlarged portion near a power supply portion 12C in a first modification. Fig. 21 is an explanatory diagram illustrating directions in which the directivity of an antenna unit 10C in the first modification is strong.

[0086] The antenna unit 10C of the first modified example is compatible with radio waves in the GNSS frequency band and with right-hand circularly polarized waves, similar to the antenna unit 10 of the present embodiment. When compatible with right-hand circularly polarized waves, the direction of directivity can be made different from that of the antenna unit 10 of the present embodiment by changing the direction of connection between the power supply portion 12C and the helical element of the antenna unit 10C, as shown in Fig. 20. In the first modified example, the antenna unit 10C has directivity in the direction of the arrow shown in Fig. 21 (-Z direction).

[0087] In antenna unit 10C of the first modified example, the twist direction of the multiple helical elements of first helical antenna 13 and the twist direction of the multiple helical elements of second helical antenna 14 are the same as those in antenna unit 10 of the present embodiment. In the first modified example, the twist direction of the multiple helical elements of first helical antenna 13 and the twist direction of the multiple helical elements of second helical antenna 14 are counterclockwise as shown in Fig. 5. Because the twist directions are the same, antenna unit 10C of the first modified example can support right-handed circularly polarized waves, as with antenna unit 10 of the present embodiment.

[0088] However, in antenna unit 10C of the first modified example, the direction of connection between power feed portion 12C and the helical element of antenna unit 10C is different from that of antenna unit 10 of the present embodiment. In the first modified example, the positions of inner conductor side feed portion 121C and outer conductor side feed portion 122C of power feed portion 12C are different from those of power feed portion 12 in antenna unit 10 of the present embodiment. As shown in Fig. 20 , each of inner conductor side feed portion 121C and outer conductor side feed portion 122C is formed in a substantially arc shape like power feed portion 12 of the present embodiment, but two annular separation portions S of power feed portion 12C are located in a direction between the +X direction and the -Y direction and a direction between the -X direction and the +Y direction. Since the two annular separated portions S of the power supply section 12C are located in a direction between the +X direction and the −Y direction, and in a direction between the −X direction and the +Y direction, in the antenna unit 10C of the first modified example, the positions of the inner conductor side power supply section 121C and the outer conductor side power supply section 122C are different from those of the power supply section 12 in the antenna unit 10 of the present embodiment, and the direction of the directivity can be made different from that of the antenna unit 10 of the present embodiment.

[0089] When the direction of the directivity is made different from that of the antenna unit 10 of this embodiment, the electronic components 16 (for example, an LNA or a diplexer) are arranged on the opposite side to the direction of the directivity (the +Z direction side), i.e., on the outside of the antenna unit 10C, as shown in Fig. 21. By arranging the electronic components 16 on the outside of the antenna unit 10C, the antenna unit 10C can be manufactured (assembled) more easily than when the electronic components 16 are arranged inside the antenna unit 10.

[0090] <<Second Modification>> Fig. 22 is a perspective view showing an enlarged view 1 of the vicinity of the first power feeding portion 18 and the second power feeding portion 19 of the antenna device 100 of the second modification. Fig. 23 is a plan view showing an enlarged view of the vicinity of the first power feeding portion 18 and the second power feeding portion 19 of the antenna device 100 of the second modification.

[0091] In antenna unit 10 of the above-described embodiment, first helical antenna 13 and second helical antenna 14 are fed by common power feeder 12, thereby enabling a simple configuration to handle radio waves in multiple frequency bands. However, common power feeder 12 may not be provided (separate power feeders may be provided for the first helical antenna and the second helical antenna), and electronic components may be provided to combine or separate signals in the first frequency band of the first helical antenna and signals in the second frequency band of the second helical antenna.

[0092] The antenna device 100 in the second modified example includes a first helical antenna 13D, a second helical antenna 14D, and an electronic component 16D.

[0093] 22 and 23 , first helical antenna 13D is fed by first feeding section 18, and second helical antenna 14D is fed by second feeding section 19. First feeding section 18 has an inner conductor side first feeding section 181 and an outer conductor side first feeding section 182, and second feeding section 19 has an inner conductor side second feeding section 191 and an outer conductor side second feeding section 192. Internal conductor side first feeding section 181, external conductor side first feeding section 182, internal conductor side second feeding section 191, and outer conductor side second feeding section 192 are connected to electronic component 16D.

[0094] The electronic component 16D is an electronic component that combines or separates signals in a first frequency band supported by the first helical antenna 13D and signals in a second frequency band supported by the second helical antenna 14D. The electronic component 16D is, for example, a diplexer. However, the electronic component 16D may also be a diplexer circuit configured by a group of electronic components that combine inductance (L) and capacitance (C).

[0095] The antenna device 100 of the second modified example can also support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0096] Summary According to the present specification, there is provided an antenna unit having the following aspects.

[0097] (Aspect 1) Aspect 1 is an antenna unit including a power supply unit, a first helical antenna having a plurality of first helical elements at least partially twisted about a first axis and responsive to radio waves in a first frequency band, and a second helical antenna having a plurality of second helical elements at least partially twisted about a second axis and responsive to radio waves in a second frequency band different from the first frequency band, wherein the plurality of first helical elements and the plurality of second helical elements are fed by the power supply unit.

[0098] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0099] (Aspect 2) In aspect 2, the first axis and the second axis are at the same position.

[0100] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0101] (Aspect 3) In aspect 3, the twist angle of each of the plurality of first helical elements is the same as the twist angle of each of the plurality of second helical elements.

[0102] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0103] (Aspect 4) In aspect 4, in a planar view, the plurality of first helical elements are arranged along a first surrounding shape surrounding the first axis, the plurality of second helical elements are arranged along a second surrounding shape surrounding the second axis, and the power supply portion is located at the center of at least one of the first surrounding shape and the second surrounding shape.

[0104] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0105] (Aspect 5) In aspect 5, the first surrounding shape is a shape that surrounds the second surrounding shape.

[0106] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0107] (Aspect 6) In aspect 6, the position of the center of the first surrounding shape and the position of the center of the second surrounding shape are approximately the same, and each helical element of the plurality of first helical elements and each helical element of the plurality of second helical elements extend radially and approximately uniformly around the center.

[0108] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0109] (Aspect 7) In aspect 7, the two first helical elements extend from the feed portion at 90° offsets around the center, and the two second helical elements extend from the feed portion at 90° offsets around the center.

[0110] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0111] (Aspect 8) In aspect 8, a support portion is provided that supports at least two of the first helical elements and the second helical elements.

[0112] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0113] (Aspect 9) In aspect 9, the support portion has a first cylindrical portion formed in a cylindrical shape that has the first surrounding shape when viewed in a plane and that supports the plurality of first helical elements, and a second cylindrical portion formed in a cylindrical shape that has the second surrounding shape when viewed in a plane and that supports the plurality of second helical elements.

[0114] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0115] (Aspect 10) In aspect 10, of the plurality of first helical elements, one of the first helical elements is arranged outside the first cylindrical portion and the other first helical elements are arranged inside the first cylindrical portion, and of the plurality of second helical elements, one of the second helical elements is arranged outside the second cylindrical portion and the other second helical elements are arranged inside the second cylindrical portion.

[0116] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0117] (Aspect 11) In aspect 11, the power supply portion is located at the end of the plurality of first helical elements in side view.

[0118] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0119] (Aspect 12) In aspect 12, the feeding portion is located at an end of the plurality of second helical elements.

[0120] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0121] (Aspect 13) In aspect 13, the plurality of first helical elements and the plurality of second helical elements are located on one side of the power supply portion in a side view.

[0122] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0123] According to the present specification, there is provided an antenna device having the following aspects.

[0124] (Aspect 14) Aspect 14 is an antenna device comprising: a first helical antenna having a plurality of first helical elements at least partially twisted about a first axis and responsive to radio waves in a first frequency band; a second helical antenna having a plurality of second helical elements at least partially twisted about a second axis and responsive to radio waves in a second frequency band different from the first frequency band; and an electronic component connected to the first helical antenna and the second helical antenna and configured to combine or separate signals in the first frequency band and signals in the second frequency band.

[0125] According to the above-described aspect, it is possible to support radio waves in a plurality of frequency bands with a simple configuration using a plurality of helical antennas.

[0126] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof.

[0127] A1 First axis A2 Second axis 10, 10C Antenna unit 12, 12A, 12B, 12C Power supply section 13, 13A, 13D First helical antenna 14, 14B, 14D Second helical antenna 15 Support section 16, 16C, 16D Electronic component 131, 131A, 131D, 132, 132A, 132D First helical element 141, 141B, 141D, 142, 142B, 142D Second helical element 151 First cylindrical section 152 Second cylindrical section 100 Antenna device

Claims

1. An antenna unit comprising: a power supply unit; a first helical antenna having a plurality of first helical elements at least partially twisted about a first axis and responsive to radio waves in a first frequency band; and a second helical antenna having a plurality of second helical elements at least partially twisted about a second axis and responsive to radio waves in a second frequency band different from the first frequency band, wherein the plurality of first helical elements and the plurality of second helical elements are fed by the power supply unit.

2. The antenna unit according to claim 1, wherein the first axis and the second axis are in the same position.

3. The antenna unit according to claim 1, wherein the twist angle of each of said plurality of first helical elements is the same as the twist angle of each of said plurality of second helical elements.

4. The antenna unit described in claim 1, wherein, in a plan view, the plurality of first helical elements are arranged along a first surrounding shape surrounding the first axis, the plurality of second helical elements are arranged along a second surrounding shape surrounding the second axis, and the power supply portion is located at the center of at least one of the first surrounding shape and the second surrounding shape.

5. The antenna unit according to claim 4, wherein the first surrounding shape is a shape that surrounds the second surrounding shape.

6. The antenna unit as described in claim 5, wherein the center position of the first surrounding shape and the center position of the second surrounding shape are approximately coincident, and each helical element of the plurality of first helical elements and each helical element of the plurality of second helical elements extend in a substantially uniform radial pattern around the center.

7. The antenna unit according to claim 6, wherein each of the two first helical elements extends from the feeding portion with an offset of 90° around the center, and each of the two second helical elements extends from the feeding portion with an offset of 90° around the center.

8. The antenna unit according to claim 5, further comprising a support portion that supports at least two of each of the plurality of first helical elements and each of the plurality of second helical elements.

9. The antenna unit described in claim 8, wherein the support portion comprises: a first cylindrical portion formed in a cylindrical shape having the first surrounding shape in a planar view and supporting the plurality of first helical elements; and a second cylindrical portion formed in a cylindrical shape having the second surrounding shape in a planar view and supporting the plurality of second helical elements.

10. The antenna unit described in claim 9, wherein, among the plurality of first helical elements, one of the first helical elements is arranged outside the first cylindrical portion and the other first helical elements are arranged inside the first cylindrical portion, and, among the plurality of second helical elements, one of the second helical elements is arranged outside the second cylindrical portion and the other second helical elements are arranged inside the second cylindrical portion.

11. The antenna unit according to claim 5, wherein, in a side view, the power supply portion is located at an end of the plurality of first helical elements.

12. The antenna unit according to claim 11, wherein the feed portion is located at an end of the plurality of second helical elements.

13. The antenna unit according to claim 12, wherein, in a side view, the plurality of first helical elements and the plurality of second helical elements are located on one side of the power supply portion.

14. An antenna device comprising: a first helical antenna having a plurality of first helical elements at least partially twisted about a first axis and responsive to radio waves in a first frequency band; a second helical antenna having a plurality of second helical elements at least partially twisted about a second axis and responsive to radio waves in a second frequency band different from the first frequency band; and an electronic component connected to the first helical antenna and the second helical antenna and configured to combine or separate signals in the first frequency band and signals in the second frequency band.

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