Antenna and adjustment method

Abstract

This antenna includes: a radiation element; and an adjustment part which is electrically connected to the radiation element and changes an electric length of an outer peripheral part determined together with the radiation element.

Description

Antenna and adjustment method

[0001] The present invention relates to an antenna and an adjustment method.

[0002] Patent Document 1 describes an antenna device in which an antenna having a radiating element formed from a metal plate and a capacitor are arranged on a substrate.

[0003] Japanese Patent Application Laid-Open No. 2018-191111

[0004] However, the antenna described in Patent Document 1 is adjusted to have desired characteristics when it is placed on a substrate (i.e., when it is assembled as an antenna device), which makes it difficult to adjust the antenna characteristics independently.

[0005] One example of an object of the present invention is to easily adjust the characteristics of an antenna by itself. 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 comprising a radiating element and an adjustment section electrically connected to the radiating element and adapted to change the electrical length of an outer periphery defined together with the radiating element.

[0007] One aspect of the present invention is a method for adjusting the frequency band of radio waves that an antenna supports, wherein the antenna comprises a radiating element and an adjustment unit electrically connected to the radiating element and changing the electrical length of an outer periphery that is determined together with the radiating element, and the adjustment method includes a step of applying power to the adjustment unit and a step of the adjustment unit changing the electrical length of the outer periphery using the power.

[0008] According to the above aspect of the present invention, the characteristics of the antenna can be easily adjusted by the antenna alone.

[0009] 1 is a perspective view of the antenna 10 of the present embodiment; FIG. 2 is an exploded perspective view of the antenna 10; FIG. 3 is a side view of the antenna 10 showing the state of the adjustment section 14 at multiple stages; FIG. 4 is an explanatory diagram of the outer circumferential portion 60 when the position of the conductor portion 23 moves from P1 to P2; FIG. 5 is a diagram showing the VSWR frequency characteristics of the antenna 10 at multiple stages of the adjustment section 14; FIG. 6 is a perspective view of the antenna 10A of a first modified example; FIG. 7 is a perspective view of the antenna 10A with the pressing member 26 removed; FIG. 8 is a plan view of the antenna 10B of a second modified example; FIG. 9 is a plan view of the antenna 10C of a third modified example; and FIG. 10 is a side view of the antenna 10C of the third 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 a perspective view of an antenna 10 of this embodiment. Fig. 2 is an exploded perspective view of the antenna 10. Fig. 3 is a side view of the antenna 10 showing the state of the adjustment unit 14 at several stages.

[0013] <<Definition of Directions, Etc.>> First, directions, etc. in the antenna 10 of this embodiment will be defined with reference to FIGS. 1, 2, and 3. FIG.

[0014] As shown in Figures 1, 2, and 3, the direction from the ground plate 13 (described later) toward the radiating element 11 (described later) is defined as the "+Z direction." The antenna 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." The side in the +Z direction may also be referred to as the "upper side" and the side in the -Z direction may also be referred to as the "lower side."

[0015] The directions parallel to the +Z direction surface of the main body 111 (described later) of the radiating element 11 and perpendicular to each other are defined as the "+X direction" and the "+Y direction." In the antenna 10 of this embodiment, as shown in Fig. 2, the +X direction and the +Y direction are also directions from the center of the main body 111 toward the power feeder 112 (described later). Here, the "center" refers to the geometric center of the outer edge shape (for example, the outer edge shape of the main body 111).

[0016] 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."

[0017] 1, 2, and 3, the +X direction, +Y direction, and +Z direction are each represented by an arrowed line segment to facilitate understanding of the directions, etc., of the antenna 10. Note that the intersection of these arrowed line segments does not represent the origin of the coordinate system.

[0018] The above definitions of directions and the like are common to other embodiments in this specification unless otherwise specified.

[0019] <<Outline of Antenna 10 >> Next, an outline of the antenna 10 of this embodiment will be described with reference again to the above-mentioned FIGS. 1, 2, and 3. FIG.

[0020] The antenna 10 is a patch antenna and is compatible with radio waves in the frequency band for the Global Navigation Satellite System (GNSS). The antenna 10 of this embodiment is compatible with radio waves in the L1 band (1559 MHz to 1610 MHz).

[0021] However, the antenna 10 may be a so-called multi-band antenna that supports radio waves in multiple frequency bands. For example, the antenna 10 of this embodiment may support radio waves in two frequency bands, the L2 band (1212 MHz to 1254 MHz) and the L5 band (1164 MHz to 1214 MHz).

[0022] However, the frequency band of radio waves supported by the antenna 10 may be other than the combination of the two frequency bands, the L2 band and the L5 band. For example, the frequency band of radio waves supported by the antenna 10 may be a combination of the two frequency bands, the L1 band and the L2 band, or a combination of the three frequency bands, the L1 band, the L2 band, and the L5 band.

[0023] Furthermore, the frequency bands of radio waves supported by the antenna 10 may include the L6 band (1273 MHz to 1284 MHz band) and the L band (1525 MHz to 1559 MHz band), which are combinations of the L1 band, the L2 band, and the L5 band with correction satellite signals. Furthermore, the frequency bands of radio waves supported by the antenna 10 are not limited to the combination of the specific multiple frequency bands described above, and may be any combination of multiple frequency bands.

[0024] Furthermore, the communication standard and frequency band of radio waves supported by the antenna 10 are not limited to the above-mentioned GNSS, and may be other communication standards and frequency bands. For example, the antenna 10 may be compatible with radio waves in a frequency band for the Satellite Digital Audio Radio Service (SDARS) or a frequency band for V2X (Vehicle to Everything: vehicle-to-vehicle communication, road-to-vehicle communication).

[0025] The antenna 10 of this embodiment is an antenna for use in a vehicle, and is attached to a predetermined location of the vehicle, such as the roof or trunk, with the +Z direction facing the zenith. The antenna 10 may be attached to the interior of a plastic roof or a plastic trunk. However, the location and direction of the antenna 10 can be appropriately changed depending on the desired directivity, etc. In addition to the roof or trunk, the antenna 10 may be attached to various locations, such as the vehicle's windshield, rear window, inside the instrument panel, above the dashboard, overhead console, bumper, license plate mounting portion, pillar, spoiler, etc. The antenna 10 may also be attached so that its main radiation direction faces left or right as viewed from the driver's seat. Furthermore, the antenna 10 may also be attached so that its main radiation direction faces forward or backward as viewed from the driver's seat.

[0026] Here, the antenna 10 is not limited to being attached to a vehicle, but may also be brought into the vehicle and used within the vehicle. While the antenna 10 of this embodiment is described as being used in a "vehicle," which is a wheeled vehicle, the present invention is not limited to this, and may also be used in other mobile objects, such as drones and other flying objects, probes, construction machinery without wheels, agricultural machinery, and ships. Furthermore, the antenna 10 may also be used as an antenna for surveying, a reference station antenna, a transmitting antenna and a reference antenna in an anechoic chamber, or other objects other than mobile objects.

[0027] The antenna 10 includes a radiating element 11 , a support portion 12 , a base plate 13 , and an adjustment portion 14 .

[0028] The radiating element 11, together with a conductor portion 23 (described later) of the adjustment portion 14, is a conductive member that corresponds to the frequency band of radio waves that the antenna 10 supports. The radiating element 11 is located on the +Z direction side of the ground plate 13. The radiating element 11 faces the ground plate 13 so that the surface on the -Z direction side of a main body portion 111 (described later) of the radiating element 11 and the surface on the +Z direction side of the ground plate 13 are approximately parallel.

[0029] The radiating element 11 has a main body portion 111 , a feeding portion 112 , a bent portion 113 , and an opposing portion 114 .

[0030] The main body 111 is the main body portion of the radiating element 11, and is positioned so as to face the ground plate 13. The outer edge shape of the main body 111 in a plan view (when viewed in the -Z direction) is an approximately quadrilateral. In the following description, "approximately quadrilateral" refers to a shape consisting of four sides, including, for example, a square or a rectangle, and for example, at least some of the corners may be cut out obliquely relative to the sides, or at least some of the corners may be rounded.

[0031] Furthermore, the "approximately quadrilateral" shape may have a notch (recess) or a protrusion (convex portion) formed on one of the sides. In the radiating element 11 of this embodiment, a slit 115, which is a notch, is formed approximately in the center of each side of the approximately quadrilateral outer edge shape of the main body 111. By forming the slit 115 in the radiating element 11, the inductance of the antenna 10 is increased compared to a case in which the slit 115 is not formed in the radiating element 11, and the frequency band of radio waves that the antenna 10 supports can be lowered.

[0032] 1 and 2, a plurality of (four in this embodiment) slits 115 are formed in the main body 111, and each slit 115 is formed in a linear shape extending from approximately the center of each side of the approximately quadrilateral outer edge shape of the main body 111 toward the center of the main body 111. In addition, in a plan view (when viewed in the −Z direction), the four slits 115 are arranged so as to be line-symmetric (or point-symmetric with respect to the center of the main body 111).

[0033] As described above, in the main body 111 of this embodiment, a plurality of slits 115 are arranged, the plurality of slits 115 are line-symmetric (or point-symmetric with respect to the center of the main body 111), and each of the plurality of slits 115 is arranged from approximately the center of each side of a substantially quadrilateral. This makes it possible for the antenna 10 to correspond to a desired polarization, compared to a case where only one slit 115 is arranged in the main body 111, a case where multiple slits 115 are formed but are not line-symmetric (or point-symmetric with respect to the center of the main body 111), or a case where the slits are arranged from other than approximately the center of each side of a substantially quadrilateral.

[0034] 1 and 2. When the tolerance for the desired polarization is large, only one slit 115 may be formed in the main body 111, or a plurality of slits 115 other than four may be formed in the main body 111. Even if the number of slits 115 is more than four, the antenna 10 can be made compatible with the desired polarization as long as the plurality of slits 115 are line-symmetric (or point-symmetric with respect to the center of the main body 111).

[0035] The slits 115 may be formed at a position other than the approximate center of each side of the above-described approximate quadrilateral, or may be shaped to point toward a position other than the center of the main body 111. Furthermore, the slits 115 may not be linear, but may have at least a bent or curved portion. The slits 115 may not be formed in the radiating element 11 including the main body 111.

[0036] The outer edge shape of the main body 111 in a plan view (when viewed in the -Z direction) may be circular or elliptical, or may be a polygon other than a substantially quadrilateral. In other words, the main body 111, together with the bent portion 113 and the facing portion 114 described below, may have any shape that can accommodate radio waves in a desired frequency band as the radiating element 11.

[0037] A hole 116 is formed in the center of the main body 111. The hole 116 is an opening through which a rotating member 21 (described later) of the adjustment unit 14 is inserted. In the antenna 10 of this embodiment, the rotating member 21 is a conductive (specifically, metallic) screw, and the radiating element 11 and the ground plate 13 are electrically connected via the rotating member 21.

[0038] The power supply section 112 is a member that includes a power supply point of the antenna 10. The power supply section 112 is branched from the main body section 111, bent toward the −Z direction, and formed so as to extend in the Z direction. However, the extending direction of the bent power supply section 112 is not limited to the Z direction, and may be in a direction inclined at a predetermined angle from the Z direction.

[0039] The antenna 10 of this embodiment employs a feeding method in which two feeding sections 112 are arranged to feed power to the radiating element 11, i.e., a dual-feed method. Compared with a single-feed method described below, the dual-feed antenna 10 can accommodate a wider frequency band of radio waves. However, the feeding method employed by the antenna 10 is not limited to the dual-feed method. For example, the antenna 10 may employ a four-feed method. An antenna 10 employing the four-feed method has four feeding sections 112. Furthermore, the antenna 10 may employ a single-feed method, for example. An antenna 10 employing the single-feed method has one feeding section 112.

[0040] Here, as a method of feeding power to the radiating element 11 having the power feeder 112, for example, the power feeder 112 is connected to a coaxial cable (not shown), and power is fed to the radiating element 11 via the feeder line of the coaxial cable. However, the method of feeding power to the radiating element 11 is not limited to this, and a substrate having a hole (a hole communicating with the hole 132 of the ground plate 13) through which the power feeder 112 is inserted may be disposed on the -Z direction side of the ground plate 13 described below. A conductor portion for wiring may be disposed on the surface of the substrate opposite the ground plate 13, and power may be fed to the radiating element 11 by soldering this conductor portion to the power feeder 112. Furthermore, if the antenna 10 does not have a ground plate 13, a ground (ground pattern) may be printed on the surface of the substrate facing the support portion 12.

[0041] The bent portions 113 are portions extending from the main body portion 111. In the antenna 10 of this embodiment, as shown in FIG. 2, two bent portions 113 are formed on each side of the approximately quadrilateral outer edge shape of the main body portion 111, so as to sandwich a slit 115. Therefore, a total of eight bent portions 113 are formed in the antenna 10 of this embodiment. However, in FIG. 2, some of the eight bent portions 113 are hidden by other parts of the radiating element 11 and are not shown. Each of the eight bent portions 113 is bent from an end of the main body portion 111 toward the −Z direction and is formed to extend in the Z direction. However, the extending direction of the bent portions 113 is not limited to the Z direction, and may be a direction inclined at a predetermined angle from the Z direction.

[0042] The total number of bent portions 113 that the radiating element 11 has is not limited to eight, and may be any number other than eight. Furthermore, the number of bent portions 113 that the radiating element 11 has may be one, or the radiating element 11 may not have any bent portions 113. If the radiating element 11 does not have any bent portions 113, the radiating element 11 is formed only by the main body portion 111 and the feeding portion 112.

[0043] The radiating element 11 has a bent portion 113 extending in the −Z direction (the side of the radiating element 11 where the ground plate 13 is located), so that the radiating element 11 has a portion close to the ground plate 13. The bent portion 113 is not in physical contact with the ground plate 13. This increases the capacitance formed between the radiating element 11 and the ground plate 13 (ground portion) compared to when the radiating element 11 does not have the bent portion 113 extending in the −Z direction, and the frequency band of radio waves that the antenna 10 supports can be lowered.

[0044] The facing portion 114 is a portion that extends from the bent portion 113 and has a facing surface that faces the ground plate 13. The facing portion 114 is formed by bending from the end of the bent portion 113 on the -Z direction side and extending in the horizontal direction (a direction parallel to the surface of the ground plate 13 on the +Z direction side). Therefore, the surface of the facing portion 114 on the -Z direction side becomes the facing surface that faces the surface of the ground plate 13 on the +Z direction side. However, the radiating element 11 does not have to have the facing portion 114. If the radiating element 11 does not have the facing portion 114, the radiating element 11 is formed only by the main body portion 111, the feeding portion 112, and the bent portion 113. Furthermore, among the multiple bent portions 113, there may be a mixture of bent portions 113 that have the facing portion 114 and bent portions 113 that do not have the facing portion 114.

[0045] In the radiating element 11 of this embodiment, the facing portion 114 is located inside the approximate quadrilateral that is the outer edge shape of the main body portion 111 in a plan view. Here, the "inside" of the approximate quadrilateral refers to the side closer to the center of the approximate quadrilateral. Conversely, the "outside" refers to the side away from the center of the approximate quadrilateral. That is, the facing portion 114 extends from the end of the bent portion 113 on the -Z direction side in a direction approaching the center of the above-mentioned approximate quadrilateral. However, the facing portion 114 may also be located outside the above-mentioned approximate quadrilateral. That is, the facing portion 114 may extend in a direction away from the center of the above-mentioned approximate quadrilateral. Furthermore, among the multiple facing portions 114, facing portions 114 extending in a direction closer to the center of the above-mentioned approximate quadrilateral and facing portions 114 extending in a direction away from the center of the above-mentioned approximate quadrilateral may be mixed.

[0046] As described above, the facing portion 114 is formed so as to extend in a direction parallel to the surface on the +Z direction side of the base plate 13. However, the facing portion 114 may be formed so as to extend in a direction other than parallel to the surface on the +Z direction side of the base plate 13, as long as it has an opposing surface.

[0047] Since the radiating element 11 has an opposing portion 114 on which an opposing surface facing the ground plate 13 is formed, the capacitance formed between the radiating element 11 and the ground plate 13 (ground portion) is larger than when the radiating element 11 does not have the opposing portion 114 (i.e., when the radiating element 11 is formed only by the main body portion 111, the power supply portion 112, and the bending portion 113), and the frequency band of radio waves that the antenna 10 supports can be lowered.

[0048] The radiating element 11 in this embodiment is formed from sheet metal. Therefore, in the radiating element 11 in this embodiment, the main body 111, the power supply portion 112, the bent portion 113, and the facing portion 114 are integrally formed, as shown in Fig. 2. That is, the above-mentioned power supply portion 112, the bent portion 113, and the facing portion 114 are formed by bending a portion of the radiating element 11 and extending from the main body 111. However, the radiating element 11 does not have to be formed from sheet metal, and may be formed by printing on the support portion 12 or a substrate. Furthermore, the main body 111, the power supply portion 112, the bent portion 113, and the facing portion 114 do not have to be integrally formed.

[0049] The support portion 12 is a member that supports the radiating element 11. By supporting the radiating element 11, the radiating element 11 (specifically, the opposing portion 114 of the radiating element 11) and the ground plate 13 are physically separated, thereby forming capacitance in the antenna 10. The support portion 12 is formed, for example, from a resin. By forming the support portion 12 from a resin, the weight can be reduced compared to when the support portion 12 is formed from ceramic, and the manufacturing costs and carbon dioxide emissions can be reduced. Furthermore, by positioning the support portion 12 between the radiating element 11 and the ground plate 13, the capacitance formed between the radiating element 11 and the ground plate 13 is increased, thereby enabling the antenna 10 to support a lower frequency band of radio waves. However, the support portion 12 may be formed from a dielectric material such as ceramic. Furthermore, the radiating element 11 may be supported by a member (not shown) other than the support portion 12 (e.g., a case of the antenna 10, etc.), so that the antenna 10 does not need to have the support portion 12.

[0050] In this embodiment, the support portion 12 is formed larger than the outer edge shape of the radiating element 11 (main body portion 111) in a plan view, and supports the entire radiating element 11 including the bent portion 113 and the facing portion 114. However, the support portion 12 may be formed smaller than the outer edge shape of the radiating element 11 (main body portion 111) in a plan view. The support portion 12 may be formed so as to support only the center portion of the main body portion 111, for example.

[0051] 2, holes 121, 122, 123, and a groove 124 are formed in the support part 12. The hole 121 is an opening through which the rotating member 21 of the adjustment part 14 is inserted, and is connected to the hole 116 formed in the main body part 111 of the radiating element 11. The hole 122 is an opening through which the power supply part 112 of the radiating element 11 is inserted. The hole 123 is an opening through which the bent part 113 of the radiating element 11 is inserted. The groove 124 is a recess in which the protrusion part 24 (described later) of the adjustment part 14 can be slidably positioned.

[0052] In the antenna 10 of this embodiment, the radiating element 11 and supporting portion 12 described above are manufactured by insert molding. In insert molding, for example, the radiating element 11, which is an insert product, is set in a mold (not shown), and resin that will become the supporting portion 12 is filled around the radiating element 11, thereby making it possible to manufacture the radiating element 11 and supporting portion 12 as an integrated unit, as shown in Figures 1 and 3.

[0053] However, the radiating element 11 and the supporting portion 12 may be manufactured by a method other than insert molding. For example, if the radiating element 11 does not have the facing portion 114, the supporting portion 12 can be manufactured in advance, and the folded portion 113 of the radiating element 11 can be inserted from above the supporting portion 12 to assemble it. Furthermore, when assembling an antenna 10 in which the folded portion 113 of the radiating element 11 is not covered by the supporting portion 12 (for example, when the supporting portion 12 is formed smaller than the outer edge shape of the main body portion 111), assembly can also be performed by connecting the folded portion 113 and the facing portion 114 to the supporting portion 12 from the outside by snap-fitting.

[0054] The ground plate 13 is a conductive member used as a ground portion of the antenna 10. In this embodiment, the ground plate 13 is a substantially quadrilateral plate-like member. However, the ground plate 13 may be, for example, a circular, elliptical, or polygonal plate-like member other than a substantially quadrilateral. Furthermore, the ground plate 13 may have a shape other than a plate-like shape as long as it is a conductive member that functions as a ground portion.

[0055] 3, the ground plane 13 is placed on, for example, a conductive base 70. However, the antenna 10 may not have the ground plane 13, and the radiating element 11, the support portion 12, and the adjustment portion 14 may be disposed directly on the base 70. In this case, the base 70 may be used as a ground portion. Therefore, the member used as the ground portion, including the ground plane 13, may be referred to as a "ground portion."

[0056] 2 , holes 131 and 132 are formed in the base plate 13. Hole 131 is an opening through which the rotating member 21 of the adjustment unit 14 is inserted, and communicates with hole 116 formed in the main body 111 of the radiating element 11 and hole 121 formed in the support unit 12. Hole 132 is an opening through which the power supply unit 112 of the radiating element 11 is inserted, and communicates with hole 122 formed in the support unit 12.

[0057] The adjustment unit 14 is a member that changes the electrical length of the outer periphery of the element of the antenna 10. The adjustment unit 14 is located on the +Z direction side of the radiating element 11. A detailed configuration of the adjustment unit 14 will be described later, but the adjustment unit 14 in this embodiment has a conductor portion 23 that electrically connects both ends of the slit 115 in the width direction, as shown in FIG. 1 . Furthermore, the adjustment unit 14 changes the position of the conductor portion 23 in the length direction of the slit 115, thereby changing the electrical length of the slit 115 and changing the electrical length of the outer periphery of the element of the antenna 10.

[0058] <<Outer periphery of element>> Before describing the detailed configuration and operation of the adjustment unit 14, the outer periphery of the element of the antenna 10 and an overview of the adjustment unit 14 will be described below, with reference again to Figures 1, 2, and 3 described above, and also with reference to Figure 4.

[0059] FIG. 4 is an explanatory diagram of the outer peripheral portion 60 when the position of the conductor portion 23 moves from P1 to P2.

[0060] Incidentally, the frequency band of radio waves that the antenna 10 supports may vary greatly from the desired characteristics depending on the configuration of the radiating element 11 and the support portion 12. Specifically, when a ceramic with a high dielectric constant, for example, is used for the support portion 12, the frequency band of radio waves that the antenna 10 supports often has high accuracy and little variation from the desired characteristics. Furthermore, even if there is variation from the desired characteristics, it is possible to obtain the desired characteristics by fine-tuning the size of the radiating element 11, for example.

[0061] Here, when a resin having a lower dielectric constant than ceramic is used for the support portion 12, it may be necessary to lower the frequency band of radio waves that the antenna 10 can accommodate. In this case, in the antenna 10 of this embodiment, as described above, the radiating element 11 is formed from sheet metal, and thereby the slits 115, the bent portions 113, and the facing portions 114 are formed, making it possible to lower the frequency band of radio waves that the antenna 10 can accommodate. However, as the shape of the radiating element 11 becomes more complex, there is a possibility that the variation in the desired characteristics, i.e., the variation in the frequency band of radio waves that the antenna 10 can accommodate, increases.

[0062] Until now, it has been difficult to adjust the antenna alone to achieve the desired characteristics before it is configured as an antenna device, rather than when the antenna is placed on a substrate (i.e., assembled as an antenna device).

[0063] Generally, the frequency band of radio waves that an antenna can handle is affected by the inductance and capacitance of the antenna. The inductance of the antenna is determined by the outer periphery of the antenna element. Meanwhile, the capacitance of the antenna, in this embodiment, is determined by the distance between the radiating element 11 (specifically, the end of the bent portion 113) and the ground plate 13 (ground portion) and the area of ​​the surface of the radiating element 11 facing the ground plate 13 (specifically, the surface facing the facing portion 114).

[0064] In the antenna 10 of this embodiment, the adjustment unit 14 can change the inductance of the antenna 10 by changing the electrical length of the outer periphery of the element of the antenna 10. This allows the characteristics of the antenna 10 to be easily adjusted by the antenna 10 alone.

[0065] Furthermore, the location where an antenna device having the antenna 10 is installed may be changed from the planned location. When the location where the antenna device is installed is changed, the characteristics of the antenna 10 may change depending on the conditions of the new installation location. For example, if the antenna device was originally planned to be installed on the roof of a vehicle and the desired characteristics of the antenna 10 were adjusted, the installation location of the antenna device may be changed to above the dashboard. This may change the frequency band of radio waves that the antenna 10 supports. With the antenna 10 of this embodiment, even if the installation location of the antenna 10 is changed, the characteristics of the antenna 10 can be easily adjusted after the fact.

[0066] As described above, the conductor portion 23 of the adjustment portion 14 in this embodiment electrically connects both ends in the width direction of the slit 115. Therefore, when the conductor portion 23 is located at position P1 in the length direction of the slit 115 as shown in Fig. 4, the radiating element 11 and the conductor portion 23 define an outer periphery 60 as an element of the antenna 10, as shown by the thick dashed line in Fig. 4.

[0067] Furthermore, when the conductor portion 23 is located at position P2, which is outside P1 in the longitudinal direction of the slit 115, the radiating element 11 and the conductor portion 23 define an outer periphery 60, as shown by the thick solid line in Figure 4, as an element of the antenna 10.

[0068] Since the electrical length of the outer circumferential portion 60 when the conductor portion 23 is located at position P1 is different from the electrical length of the outer circumferential portion 60 when the conductor portion 23 is located at position P2, the inductance of the antenna 10 when the conductor portion 23 is located at position P1 is different from the inductance of the antenna 10 when the conductor portion 23 is located at position P2. As a result, when the position of the slit 115 of the conductor portion 23 in the length direction changes, the electrical length of the slit 115 changes, and the electrical length of the outer circumferential portion 60 changes. Therefore, when the position of the slit 115 of the conductor portion 23 in the length direction changes, the frequency band of radio waves that the antenna 10 supports also changes.

[0069] In this embodiment, as shown in FIG. 4 , the electrical length of the outer circumferential portion 60 (thick dashed line) when the conductor portion 23 is located at position P1 is longer than the electrical length of the outer circumferential portion 60 (thick solid line) when the conductor portion 23 is located at position P2. As a result, when the conductor portion 23 is located at position P1, the frequency of the radio waves that the antenna 10 can respond to is lower than when the conductor portion 23 is located at position P2. Conversely, the electrical length of the outer circumferential portion 60 (thick solid line) when the conductor portion 23 is located at position P2 is shorter than the electrical length of the outer circumferential portion 60 (thick dashed line) when the conductor portion 23 is located at position P1. As a result, when the conductor portion 23 is located at position P2, the frequency of the radio waves that the antenna 10 can respond to is higher than when the conductor portion 23 is located at position P1.

[0070] The adjustment unit 14 in this embodiment changes the electrical length of the outer circumferential portion 60 by changing the electrical length of the slit 115. Only the position of the slit 115 in the conductor portion 23 in the longitudinal direction changes, and the overall size of the antenna 10 does not change. The adjustment unit 14 in this embodiment can adjust the antenna characteristics without changing the overall size of the antenna 10. However, the adjustment unit 14 may change the electrical length of the outer circumferential portion 60 using a method other than the method of changing the electrical length of the slit 115, as in an antenna 10C of a third modified example shown in Figures 9 and 10 described below.

[0071] <<Detailed Configuration and Operation of Adjustment Unit 14>> Hereinafter, the detailed configuration and operation of the adjustment unit 14 will be described with reference again to FIGS. 1, 2, and 3 described above.

[0072] The adjustment unit 14 has a rotating member 21, an elastic member 22, a conductor 23, and a protrusion 24. However, in the adjustment unit 14 of this embodiment, the elastic member 22 (a head 221 and an arm 222 described later), the conductor 23, and the protrusion 24 are integrally formed. For this reason, in the following description, the conductor 23 and the protrusion 24 may be described as parts of the elastic member 22.

[0073] The rotating member 21 is a member to which power is applied when changing the position of the conductor portion 23 of the elastic member 22, and is also a member for fixing the adjustment unit 14 to an external member. The rotating member 21 is, for example, a conductive (specifically, metal) screw, as shown in FIG. 2 . However, the rotating member 21 may also be a screw made of a material other than conductive, such as a resin. Instead of the rotating member 21, a non-rotating member, such as a nail that fixes the adjustment unit 14 to an external member by pressure, may be used, as long as it is a member to which power is applied and can fix the adjustment unit 14 to an external member. By rotating the rotating member 21, the head 221 of the elastic member 22 can be moved up and down, and the conductor portion 23 can be moved laterally via the arm portion 222, as shown in FIG. 3 .

[0074] As shown in Fig. 2, the rotating member 21 has a fixed portion 211. The fixed portion 211 is a portion of the rotating member 21 that fixes the adjustment portion 14 to the radiating element 11 and the ground plate 13. As described above, the rotating member 21 in this embodiment is a conductive screw, and therefore the radiating element 11 and the ground plate 13 are electrically connected via the fixed portion 211 of the rotating member 21. However, at least one of the fixed portion 211 and the radiating element 11 and the fixed portion 211 and the ground plate 13 may be insulated. In this case, the radiating element 11 and the ground plate 13 may not be electrically connected.

[0075] In this embodiment, the fixed portion 211 is connected to the central region of the radiating element 11, which is a region where voltage is low, in a plan view. Therefore, by using a metal screw, the adjustment portion 14 can be firmly fixed to the radiating element 11 and the ground plate 13, and the effect on the characteristics of the antenna 10 can be suppressed. However, as described above, if the rotating member 21 is a non-conductive screw, or if at least one of the fixed portion 211 and the radiating element 11 and the ground plate 13 is insulated, the fixed portion 211 may be connected to a region of the radiating element 11 other than the central region.

[0076] The fixed portion 211 of the rotating member 21 is inserted into the hole 121 of the support portion 12 described above. Although not shown, the fixed portion 211 may have a protrusion extending outward, and the hole 121 may be formed with a recess into which the protrusion fits. By fitting the protrusion of the fixed portion 211 into the recess of the hole 121, the rotational position of the rotating member 21 can be easily fixed.

[0077] The elastic member 22 is a member that can be deformed by the transmission of force from the fixed portion 211. In the antenna 10 of this embodiment, the elastic member 22 is a leaf spring. The elastic member 22 has a head portion 221 and an arm portion 222.

[0078] The head 221 is the end of the elastic member 22 on the +Z direction side. As shown in FIG. 2 , a hole 25 is formed in the head 221. The rotating member 21 is inserted into the hole 25, and the rotating member 21 comes into contact with the head 221 at the edge of the hole 25. As shown in FIG. 3 , when the rotating member 21, which is a screw, is tightened and the rotating member 21 moves downward, the head 221 also moves downward. Also, as shown in FIG. 3 , when the rotating member 21 is loosened and the rotating member 21 moves upward, the elastic force (restoring force) of the arm portion 222 causes the head 221 to move upward.

[0079] The arm portion 222 is a portion extending from the head portion 221 and has elastic force. The elastic member 22 has four arm portions 222 around the head portion 221. Each of the four arm portions 222 corresponds to one of the four slits 115 formed in the radiating element 11. As shown in FIG. 3 , the end portion of the arm portion 222 on the +Z direction side is connected to the head portion 221, and the end portion of the arm portion 222 on the −Z direction side (the conductor portion 23 in this embodiment) is in physical contact with both ends of the slit 115 of the radiating element 11 in the width direction. However, the end portion of the arm portion 222 on the −Z direction side (the conductor portion 23 in this embodiment) does not have to be in physical contact with both ends of the slit 115 of the radiating element 11 in the width direction, as long as they are electrically connected by capacitive coupling or the like.

[0080] When the rotating member 21 moves downward, the arm 222 moves from the inside to the outside (from the position D=0 to the position D=3.0) via the head 221, as shown in Figure 3. When the rotating member 21 moves upward, the arm 222 moves from the outside to the inside (from the position D=3.0 to the position D=0) and returns to its original position. The elasticity of the arm 222 allows the arm 222 to move easily in response to the up and down movement of the rotating member 21.

[0081] As described above, the conductor portion 23 is a member that electrically connects both ends of the slit 115 in the width direction. The conductor portion 23 is formed by bending the end of the arm portion 222 on the −Z direction side toward the +Z direction. This allows the conductor portion 23 to move in response to the movement of the arm portion 222. In other words, the position of the conductor portion 23 in the length direction of the slit 115 changes. As shown in FIG. 3 , the conductor portion 23 is formed by bending the end of the arm portion 222, and the surface (curved portion) on the −Z direction side of this bent portion electrically connects both ends of the slit 115 in the width direction. This allows the conductor portion 23 to move smoothly in the length direction of the slit 115.

[0082] In the antenna 10 of this embodiment, the four conductor portions 23 are all moved by the same amount, but the four conductor portions 23 may be moved by different amounts. When the conductor portions 23 move and the electrical length of the outer circumferential portion 60 changes, the relative position of the feed point of the antenna 10 with respect to the outer circumferential portion 60 may fluctuate, resulting in a deviation in the impedance of the antenna 10. Even in such a case, the amount of movement of the four conductor portions 23 can be adjusted to eliminate the deviation in the impedance of the antenna 10.

[0083] The protrusion 24 is a portion that guides the movement of the conductor 23 in the length direction of the slit 115. As shown in FIG. 1 , the protrusion 24 is disposed at the end of the arm 222 on the −Z direction side. The protrusion 24 is also positioned slidably in the groove 124 of the support part 12. This restricts the movement direction of the protrusion 24 to the sliding direction in the groove 124 (i.e., the length direction of the slit 115). Therefore, the conductor 23 is also restricted to movement in the length direction of the slit 115, rather than movement in the rotation direction due to friction from the rotating member 21. This allows the conductor 23 to move smoothly in the length direction of the slit 115.

[0084] <<Method for Adjusting the Frequency Band of Radio Waves Supported by Antenna 10>> In a method for adjusting the frequency band of radio waves supported by antenna 10 of this embodiment, for example, a frequency band measuring device is used to apply power to adjustment unit 14 while observing the characteristics of antenna 10. This power causes adjustment unit 14 to change the electrical length of outer circumferential portion 60. Specifically, by moving rotating member 21 in the vertical direction while rotating it, conductor portion 23 moves outward. The movement of rotating member 21 may be performed manually or automatically by connecting a control device (not shown).

[0085] <<Characteristics of Antenna 10 at Each Adjustment Stage>> FIG. 5 is a diagram showing the VSWR frequency characteristics of the antenna 10 at multiple stages of the adjustment unit 14. As shown in FIG.

[0086] 5, the horizontal axis represents frequency and the vertical axis represents voltage standing wave ratio (VSWR). In addition, in FIG. 5, the calculation results when the position D of the conductor 23 of the antenna 10 is changed to 0 mm, 1.0 mm, 2.0 mm, 2.5 mm, and 3.0 mm are shown by a thick solid line, a thick dashed line, a thin dotted line, a thin solid line, and a thin dashed line, respectively.

[0087] As shown in Figure 5, by changing the position D of the conductor 23 of the antenna 10 to 0 mm, 1.0 mm, 2.0 mm, 2.5 mm, and 3.0 mm, it can be seen that the VSWR peak shifts to the higher frequency side. Therefore, in this embodiment, the frequency band of radio waves that the antenna 10 supports can be easily adjusted by the antenna 10 alone. Furthermore, in the antenna 10 of this embodiment, the amount of movement of the conductor 23 can be controlled by controlling the rotation angle of the rotating member 21, making it possible to quantitatively adjust the characteristics of the antenna 10.

[0088] <<First Modification>> Fig. 6 is a perspective view of an antenna 10A according to a first modification, and Fig. 7 is a perspective view of the antenna 10A with the pressing member 26 removed.

[0089] The antenna 10A of the first modified example may have an adjustment unit 14A that is different from the adjustment unit 14 of the antenna 10 of the present embodiment described above. The adjustment unit 14A of the antenna 10A has an elastic member 22A that is different from the elastic member 22 of the present embodiment. Specifically, as shown in Fig. 7, the elastic member 22A has an arm portion 222A that is bent multiple times. Furthermore, the adjustment unit 14A of the antenna 10A has a pressing member 26 that presses the arm portion 222A from above.

[0090] 6 and 7, in the antenna 10A of the first modification, by rotating the rotary member 21, the arm 222A can be moved laterally via the pressing member 26, and the conductor 23 can also be moved laterally via the arm 222A. This makes it possible to easily adjust the characteristics of the antenna 10A by itself.

[0091] As shown in Figures 6 and 7 , in the first modified example, as in the antenna 10 of the present embodiment described above, the antenna 10A has a protrusion 24 that guides movement of the conductor 23 in the length direction of the slit 115. In Figures 6 and 7 , the slit 115 has the same shape as the slit 115 in the antenna 10 of the present embodiment. However, steps, protrusions, etc. may be formed inside the slit 115 so that the protrusion 24 can fit into them. By fitting the protrusion 24 into these steps, protrusions, etc., the position of the conductor 23 can be more easily fixed.

[0092] <<Second Modification>> FIG. 8 is a plan view of an antenna 10B according to a second modification.

[0093] In the antenna 10 of the present embodiment described above, the electrical length of the outer circumferential portion 60 is changed by physically moving the conductor portion 23. However, as in the antenna 10B of the second modified example, the electrical length of the outer circumferential portion 60 may be changed electrically.

[0094] The adjustment unit 14B of the antenna 10B has an adjustment element 27, an adjustment element 28, and an adjustment element 29. The adjustment elements 27, 28, and 29 may be, for example, relay elements or transistors that switch on and off when a voltage is applied. However, the adjustment elements 27, 28, and 29 may also be variable resistors. The adjustment elements 27, 28, and 29 are each arranged so as to straddle both ends of the slit 115 in the width direction and at different positions in the length direction of the slit 115.

[0095] In the antenna 10B of the second modification, the electrical length of the outer periphery of the element can be changed by switching each of the adjustment elements 27, 28, and 29 between conductive and non-conductive states. For example, the electrical length of the outer periphery of the element can be made different when the adjustment element 27 is conductive and the adjustment elements 28 and 29 are non-conductive, compared to when the adjustment element 28 is conductive and the adjustment elements 27 and 29 are non-conductive. This also changes the frequency band of radio waves that the antenna 10B can support. Therefore, the characteristics of the antenna 10B can be easily adjusted by the antenna 10B alone.

[0096] 8, in the antenna 10B of the second modification, four sets of adjustment elements 27, 28, and 29 (hereinafter sometimes referred to as "adjustment element sets") are arranged, and each of the four adjustment element sets corresponds to one of the four slits 115 formed in the radiating element 11. However, the adjustment section 14B of the antenna 10B may have adjustment element sets that correspond to only some of the four slits 115. For example, among the four slits 115, an adjustment element set may be arranged only in the slit 115 on the +X direction side.

[0097] Furthermore, the four adjustment element sets do not all need to have the same configuration. For example, there may be a mixture of an adjustment element set having only adjustment element 27 and adjustment element 28 and an adjustment element set having only adjustment element 28 and adjustment element 29. Furthermore, the positions of the adjustment elements constituting an adjustment element set in the longitudinal direction of slit 115 may differ for each of the four adjustment element sets.

[0098] <<Third Modification>> Fig. 9 is a plan view of an antenna 10C according to a third modification, and Fig. 10 is a side view of the antenna 10C according to the third modification.

[0099] In the antenna 10 of the present embodiment described above, the electrical length of the outer circumferential portion 60 is changed by changing the longitudinal position of the slit 115 in the conductor portion 23. However, the electrical length of the outer circumferential portion 60 may be changed in a manner other than by changing the longitudinal position of the slit 115 in the conductor portion 23. No slits are formed in the radiating element 11C of the antenna 10C of the third modified example. Furthermore, the adjustment unit 14C of the antenna 10C has an adjustment unit 14C that is different from the adjustment unit 14 of the antenna 10 of the present embodiment described above.

[0100] The adjustment unit 14C in the third modification has a rotational member 21 and an elastic member 22C. In the antenna 10C, the rotational member 21 is a screw, similar to the antenna 10 in this embodiment, and changes the position of the tip of the elastic member 22C, as shown in Figures 9 and 10. The elastic member 22C is formed to extend outward in all directions from the rotational member 21.

[0101] In antenna 10C, when rotating member 21, which is a screw, is tightened and moves downward, the position of the tip of elastic member 22C moves outward. Also, when rotating member 21 is loosened and moves upward, the position of the tip moves inward due to the elastic force (restoring force) of elastic member 22C. In this way, the amount of elastic member 22C protruding from the outer edge of radiating element 11C changes, thereby changing the electrical length of the outer periphery defined by radiating element 11C and the position of the tip of elastic member 22C. This allows the characteristics of antenna 10C to be easily adjusted independently of antenna 10C.

[0102] Summary According to the present specification, there is provided an antenna having the following aspects.

[0103] (Aspect 1) Aspect 1 is an antenna including a radiating element and an adjustment section electrically connected to the radiating element and adapted to change the electrical length of a periphery defined together with the radiating element.

[0104] According to the above-described aspect, the characteristics of the antenna can be easily adjusted by the antenna alone.

[0105] (Aspect 2) In aspect 2, a slit is formed in the radiating element, and the adjustment section changes the electrical length of the slit.

[0106] According to the above-described aspect, it is possible to adjust the characteristics of the antenna without changing the size of the entire antenna.

[0107] (Aspect 3) In aspect 3, the adjustment unit has a conductor that electrically connects both ends of the slit in the width direction, and a mechanism that changes the position of the conductor in the length direction of the slit.

[0108] The "mechanism" corresponds to "at least one of the rotating member and the elastic member" in the above-mentioned embodiment.

[0109] According to the above-described aspect, it is possible to quantitatively adjust the characteristics of the antenna by controlling the amount of movement of the mechanism portion.

[0110] (Aspect 4) In aspect 4, at least one of the radiating element and the adjustment section has a guide section that guides movement of the conductor section in the length direction of the slit.

[0111] The "guide portion" corresponds to the "protrusion portion" in the above-mentioned embodiment.

[0112] According to the above-described aspect, the conductor portion can be smoothly moved in the length direction of the slit.

[0113] (Aspect 5) In aspect 5, a ground portion is provided, and the mechanism portion has a fixing portion that electrically connects the radiating element and the ground portion, and the fixing portion is connected to a central region of the radiating element in a planar view of the radiating element.

[0114] The "ground portion" corresponds to the "base plate" in the above-mentioned embodiment.

[0115] According to the above-described aspect, the adjustment section can be firmly fixed and the influence on the characteristics of the antenna can be suppressed.

[0116] According to the present specification, there is provided an adjustment method having the following aspects.

[0117] (Aspect 6) Aspect 6 is a method for adjusting the frequency band of radio waves supported by an antenna, wherein the antenna comprises a radiating element and an adjustment unit electrically connected to the radiating element and changing the electrical length of an outer periphery determined together with the radiating element, and the adjustment method includes a step of applying power to the adjustment unit and a step of causing the adjustment unit to change the electrical length of the outer periphery using the power.

[0118] According to the above-described aspect, the characteristics of the antenna can be easily adjusted by the antenna alone.

[0119] 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.

[0120] 10, 10A, 10B, 10C Antenna 11, 11C Radiating element 13 Ground plate 14, 14A, 14B, 14C Adjustment portion 21 Rotation member 22, 22A, 22C Elastic member 23 Conductor portion 24 Protrusion portion 60 Outer periphery 115 Slit 211 Fixed portion

Claims

1. An antenna comprising: a radiating element; and an adjustment unit electrically connected to the radiating element and adapted to change the electrical length of an outer periphery defined together with the radiating element.

2. The antenna according to claim 1, wherein the radiating element is formed with a slit, and the adjustment section changes the electrical length of the slit.

3. An antenna as described in claim 2, wherein the adjustment section has a conductor section that electrically connects both ends of the slit in the width direction, and a mechanism section that changes the position of the conductor section in the length direction of the slit.

4. The antenna according to claim 3, wherein at least one of said radiating element and said adjustment section has a guide section that guides movement of said conductor section in the longitudinal direction of said slit.

5. An antenna as described in claim 3 or 4, comprising a ground portion, the mechanism portion having a fixing portion that electrically connects the radiating element and the ground portion, the fixing portion being connected to a central region of the radiating element when viewed in a plane.

6. A method for adjusting the frequency band of radio waves supported by an antenna, the antenna comprising a radiating element and an adjustment unit electrically connected to the radiating element and changing the electrical length of an outer periphery determined together with the radiating element, the method comprising the steps of: applying power to the adjustment unit; and causing the adjustment unit to change the electrical length of the outer periphery by the power.

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