antenna

Abstract

This antenna comprises a first plate conductor and a columnar conductor provided so as to protrude on a plate surface of the first plate conductor. The tip end of the columnar conductor has a feed point, and the cross-sectional area of a cross-section of the columnar conductor along the plate surface is greater than the area of the end surface of the tip end.

Description

Technical Field

[0001] The present disclosure relates to an antenna. This application claims priority based on Japanese Application No. 2022-157687 filed on September 30, 2022, and incorporates all the descriptions set forth in the above Japanese application.

Background Art

[0002] Conventionally, as an antenna for a mobile station in a mobile communication system, there is one in which a capacitive loading plate is provided at the tip of a monopole element. A monopole antenna having a capacitive loading plate can be made low-profile, and thus may be used as an in-vehicle antenna (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The antenna according to an embodiment includes a first plate-shaped conductor and a columnar conductor provided to protrude from the plate surface of the first plate-shaped conductor. A tip portion of the columnar conductor has a feeding point, and a cross-sectional area of a cross-section of the columnar conductor along the plate surface is larger than an area of an end surface of the tip portion.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 is a perspective view showing an example of an antenna according to a first embodiment. [Figure 2A] FIG. 2A is a front view of the antenna according to the first embodiment. [Figure 2B] FIG. 2B is a side view of the antenna according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the antenna according to the first embodiment taken along the X-Z plane. [Figure 4] Figure 4 is a graph showing the lateral contour curve of a cross-section of a columnar conductor along a plane containing the axis of rotation. [Figure 5] Figure 5 is a perspective view showing an example of an antenna according to the second embodiment. [Figure 6] Figure 6 is a side view of the antenna according to the second embodiment. [Figure 7] Figure 7 is a cross-sectional view of the antenna according to the second embodiment along the XZ plane. [Figure 8] Figure 8 is a perspective view of the antenna according to the third embodiment. [Figure 9] Figure 9 is a cross-sectional view of the antenna according to the third embodiment, along the XZ plane. [Figure 10] Figure 10 is a cross-sectional view taken along the line AA in Figure 9. [Figure 11] Figure 11 is a perspective view of the antenna according to the fourth embodiment. [Figure 12] Figure 12 is a perspective view of the antenna according to the fifth embodiment. [Figure 13A] Figure 13A is a perspective view of the modified antenna. [Figure 13B] Figure 13B is a front view of the modified antenna. [Figure 14A] Figure 14A is a perspective view of an antenna relating to another modified example. [Figure 14B] Figure 14B is a front view of an antenna relating to another modification. [Figure 15] Figure 15 is a perspective view of an antenna related to a comparative example. [Figure 16] Figure 16 is a cross-sectional view of the antenna in the comparative example along the XZ plane. [Figure 17] Figure 17 shows the frequency characteristics of the return loss for Comparative Example 1. [Figure 18] Figure 18 shows the frequency characteristics of the return loss in Example 1. [Figure 19] Figure 19 shows the frequency characteristics of the return loss in Example 2. [Figure 20]FIG. 20 is a diagram showing the frequency characteristics of the return loss in Example 3. [Figure 21] FIG. 21 is a diagram showing the frequency characteristics of the return loss in Example 4. [Figure 22] FIG. 22 is a diagram showing the frequency characteristics of the return loss in Example 5.

Mode for Carrying Out the Invention

[0006] [Problems to be Solved by the Present Disclosure] In recent years, in mobile communication systems, multi-band operation has been progressing, and wide-band operation is also required for antennas for mobile stations. However, in the monopole antenna having the above-described capacitive loading plate, although it is possible to transmit and receive signals in a relatively low frequency band of 1 GHz or less, for example, it may not be possible to support transmission and reception of signals in a relatively high frequency band of several GHz or more, such as SUB6 in the fifth-generation mobile communication system. As described above, the monopole antenna having a capacitive loading plate has a problem that while it can achieve a low profile, it is difficult to support a wide band.

[0007] Therefore, an object of the present disclosure is to provide an antenna that can support a wide band while achieving a low profile.

[0008] [Effects of the Present Disclosure] According to the present disclosure, it is possible to obtain an antenna that can support a wide band while achieving a low profile.

[0009] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments will be listed and described. [Outline of Embodiment]

[0010] (1) The antenna according to the embodiment includes a first plate-shaped conductor and a columnar conductor provided so as to protrude from the plate surface of the first plate-shaped conductor, and a tip end portion of the columnar conductor has a feeding point, and a cross-sectional area of a cross-section of the columnar conductor along the plate surface is larger than an area of an end surface of the tip end portion.

[0011] With the above configuration, the first plate-shaped conductor functions as a capacitive loading plate, making it possible to achieve a low profile while responding to signals in a relatively low frequency band. Furthermore, by shaping the sides of the columnar conductor connecting the feed point and the first plate-shaped conductor appropriately, the change in the characteristic impedance of the first columnar conductor from the feed point to the first plate-shaped conductor can be made gradual. This reduces the antenna's return loss for signals in relatively high frequency bands.

[0012] (2) More specifically, in the antenna of (1) above, the columnar conductor may have a tapered side surface that narrows from the first plate-shaped conductor side toward the tip side. In this case, the connection between the feed point and the first plate-shaped conductor can be made smooth. As a result, the change in the characteristic impedance of the columnar conductor from the feed point to the first plate-shaped conductor can be made gradual. This reduces the antenna's return loss for signals in relatively high frequency bands. As a result, it is possible to obtain an antenna that can support a wide frequency band while achieving a low profile.

[0013] (3) In addition, in the antenna described in (1) or (2) above, the side surface may be a convex curved surface. In this case, the change in the characteristic impedance of the columnar conductor can be appropriately adjusted.

[0014] (4) In any one of the antennas described in (1) to (3) above, the shape of the side surface is the shape of a rotating body with a straight line perpendicular to the plate surface as the axis of rotation, and the contour curve of the side surface in the cross section of the columnar conductor along the plane containing the axis of rotation may satisfy the following equation when the axis of rotation is the y-axis and the straight line perpendicular to the axis of rotation at the tip is the x-axis. y = ax P However, x≧0, a>0, and P≧1. In this case, the change in the characteristic impedance of the columnar conductor can be adjusted more appropriately.

[0015] (5) In the antenna described in (1) above, the columnar conductor may have a stepped shape with side surfaces that widen in stages from the tip side toward the first plate-shaped conductor side. In this case, the stepped, widening side surfaces allow for a smooth connection between the power supply point and the first plate-shaped conductor, making the change in the characteristic impedance of the columnar conductor more gradual.

[0016] (6) In the antennas described in (1) to (5) above, the first plate-shaped conductor may be in the shape of a strip. In this case, the size of the antenna when viewed from above can be reduced, making it possible to miniaturize the antenna.

[0017] (7) In the antenna described in (6) above, the columnar conductor may be provided on the first end side in the longitudinal direction of the first plate-shaped conductor. In this case, while achieving a more compact design, it is possible to appropriately secure the distance from the second end on the opposite side of the first end to the columnar conductor, making it easier to achieve a lower profile.

[0018] (8) In the antenna described in (6) or (7) above, the width dimension of the first plate-shaped conductor and the width dimension of the cross-section of the columnar conductor along the plate surface may be the same. In this case, the size of the antenna when viewed from above can be made smaller.

[0019] (9) In the antenna described in (8) above, the short side of the first end of the first plate-shaped conductor in the longitudinal direction may have a shape that conforms to the contour shape of the cross section of the columnar conductor along the plate surface. In this case, the size of the antenna when viewed from above can be further reduced.

[0020] (10) In any one of the antennas described in (1) to (9) above, the columnar conductor may be provided at a position on the plate surface that is offset from the center of the first plate conductor. In this case, the distance on the first plate-shaped conductor from the columnar conductor to the other edge of the first plate-shaped conductor, with the center of the first plate-shaped conductor in between, can be secured as needed, making it suitable for responding to signals in a relatively low frequency band.

[0021] (11) In the antenna described in (10) above, the center of the first plate-shaped conductor may be the centroid of the contour shape when the first plate-shaped conductor is viewed in plan, or the center of the circumscribed circle of the contour shape. The centroid and the center of the circumscribed circle of these contour shapes are suitable as the center of the first plate-shaped conductor.

[0022] (12) Any one of the antennas described in (1) to (11) above may further include a short-circuit conductor that protrudes from the plate surface and grounds the first plate-shaped conductor. In this case, the input impedance of the antenna can be appropriately adjusted by the short-circuit conductor, allowing the antenna to operate across a wider frequency band.

[0023] (13) In the antenna described in (12) above, the short-circuit conductor may have a plate shape curved in accordance with the side surface of the columnar conductor and may be positioned opposite to the side surface of the columnar conductor at a predetermined distance. In this case, it is possible to broaden the bandwidth for the relatively lower frequency bands among the available frequency bands.

[0024] (14) In any one of the antennas described in (1) to (13) above, a second plate-shaped conductor may be provided protruding from the side surface of the columnar conductor and positioned opposite to the first plate-shaped conductor on the plate surface side of the first plate-shaped conductor. In this case, the antenna can be made into a two-element design, and the bandwidth can be increased by increasing the resonant frequency.

[0025] [Details of the embodiment] Preferred embodiments will be described below with reference to the drawings. Furthermore, at least some of the embodiments described below may be combined in any way. [Regarding the overall configuration of the first embodiment] Figure 1 is a perspective view showing an example of an antenna according to the first embodiment. Antenna 1 is a vehicle-mounted antenna, for example, mounted on the roof of a vehicle. Antenna 1 is used in mobile stations of mobile communication systems mounted on vehicles such as passenger cars, buses, and railway cars. Antenna 1 can be used in fifth-generation mobile communication systems.

[0026] In the following explanation, the three mutually orthogonal directions in each figure will be referred to as the X, Y, and Z directions. Furthermore, the direction of the arrow in Figure 1 will be referred to as the X1 direction, and the opposite direction will be referred to as the X2 direction. The direction of the arrow in Figure 1 will be referred to as the Y1 direction, and the opposite direction will be referred to as the Y2 direction. The direction of the arrow in Figure 1 will be referred to as the Z1 direction, and the opposite direction will be referred to as the Z2 direction.

[0027] Antenna 1 is mounted on a ground conductor 10. The ground conductor 10 has a plate shape parallel to the XY plane. The ground conductor 10 is, for example, the roof of a vehicle. Note that Figure 1 shows only a portion of the ground conductor 10. Antenna 1 comprises a first plate-shaped conductor 2, a columnar conductor 4, and a short-circuit conductor 6. The first plate-shaped conductor 2 has a plate shape that aligns with the XY plane. Therefore, the first plate-shaped conductor 2 and the ground conductor 10 are parallel to each other. Furthermore, the first plate-shaped conductor 2 extends in a strip shape along the X direction. The term "strip-shaped" refers to a shape that has a certain width and continues in a long, narrow manner, like a strip or belt. In this specification, it refers to shapes that include a long, narrow rectangular shape, such as the first plate-shaped conductor 2. The columnar conductor 4 and the short-circuit conductor 6 protrude from the first plate-shaped conductor 2 in the Z2 direction. The tips of the columnar conductor 4 and the short-circuit conductor 6 are connected to the ground conductor 10. As a result, the first plate-shaped conductor 2 is positioned facing the ground conductor 10.

[0028] Figure 2A is a front view of the antenna 1 according to the first embodiment, and Figure 2B is a side view of the antenna 1 according to the first embodiment. Figure 3 is a cross-sectional view of the antenna 1 according to the first embodiment along the XZ plane. Note that Figure 3 shows a cross-section passing through the center of the antenna 1 in the Y direction.

[0029] As shown in Figures 2A and 2B, a connector 13 is provided on the first surface 10a of the grounding conductor 10 to which a coaxial cable (not shown) is connected. As shown in Figure 3, the grounding conductor 10 is provided with a hole 11. The connector 13 is inserted into the hole 11. The connector 13 includes a cylindrical insulating member 13a, a pin 12, and a main body portion 13b. The insulating member 13a is inserted into the hole 11. The insulating member 13a has a through hole 13a1 that penetrates in the Z direction.

[0030] Pin 12 is inserted into the through hole 13a1. Therefore, pin 12 is insulated from the ground conductor 10 by the insulating member 13a. Pin 12 protrudes from the second surface 10b and the end face 13a2 of the insulating member 13a. The second surface 10b is the surface facing the Z1 direction side of the ground conductor 10. Pin 12 is connected to the internal conductor (not shown) of the coaxial cable. The main body 13b connects the outer conductor (not shown) of the coaxial cable to the ground conductor 10.

[0031] The columnar conductor 4 is a columnar member formed of a conductor such as copper. The columnar conductor 4 is provided protruding from the plate surface 2a of the first plate-shaped conductor 2. The plate surface 2a is the plate surface of the first plate-shaped conductor 2 facing in the Z2 direction. The columnar conductor 4 has a tip portion 16, a base end surface 18, and a side surface 20. The tip portion 16 has an end face 19. The end face 19 is the end face of the columnar conductor 4 facing in the Z2 direction. The base end face 18 is the end face facing in the Z1 direction, which is the opposite direction to the end face 19. The side surface 20 is the surface connecting the end face 19 and the base end face 18. The side surface 20 has a shape that tapers from the base end surface 18 (first plate-shaped conductor 2) side towards the tip end 16 side.

[0032] The base end surface 18 is in contact with the plate surface 2a of the first plate-shaped conductor 2. Therefore, the columnar conductor 4 and the first plate-shaped conductor 2 are electrically connected. The first plate-shaped conductor 2 and the columnar conductor 4 are fixed together in contact with each other by a plurality of screws (not shown).

[0033] Furthermore, the statement that the columnar conductor 4 and the first plate-shaped conductor 2 are electrically connected includes not only cases where the columnar conductor 4 and the first plate-shaped conductor 2 are in direct contact with each other or conduct through other conductors, but also cases where the columnar conductor 4 and the first plate-shaped conductor 2 are connected at high frequencies by capacitive coupling. The same applies to the connections between conductors in the following explanation.

[0034] The end face 19 is in contact with the end face 13a2 of the insulating member 13a. Therefore, the columnar conductor 4 and the ground conductor 10 are not electrically connected. As shown in Figure 3, a tip hole 17 is opened in the end face 19. The tip hole 17 is a cylindrical hole provided along the Z direction. A pin 12 is inserted into the tip hole 17. The inner surface of the tip hole 17 and the outer surface of the pin 12 are in contact. Therefore, the columnar conductor 4 and the pin 12 are electrically connected. Pin 12 is electrically connected to the internal conductor of the coaxial cable. Therefore, the open end edge 19a of the tip hole 17 on the end face 19 is the power supply point.

[0035] The columnar conductor 4 has a hole 21. The hole 21 is a cylindrical hole provided along the Z direction. The hole 21 opens to the base end face 18. The hole 21 has a small diameter portion 21a and a large diameter portion 21b. The small diameter portion 21a and the large diameter portion 21b are concentrically connected to each other. The small diameter portion 21a is located on the tip portion 16 side. The large diameter portion 21b is located on the base end surface 18 side. The hole 21 and the tip hole 17 are concentric and connected to each other. In other words, the tip hole 17 and the hole 21 penetrate the columnar conductor 4 along the Z direction.

[0036] As shown in Figure 3, the pin 12 inserted into the tip hole 17 protrudes into the hole 21. The pin 12 and the columnar conductor 4 are joined by a welded member (not shown) formed by, for example, soldering or brazing. The shape of the hole 21 in the columnar conductor 4 is not particularly limited. However, the hole 21 in the columnar conductor 4 may be used as a workspace when forming a welded member that joins the pin 12 and the columnar conductor 4. In this case, from the viewpoint of workability, it is preferable that the inner diameter of the hole 21 be as large as possible. In order to make the inner diameter of the hole 21 as large as possible, it is conceivable to form the inner circumferential surface of the hole 21 so as to gradually expand in diameter from the tip portion 16 side toward the base end surface 18 side, following the shape of the side surface 20. However, in this case, the cost required to form the hole 21 may increase. Therefore, in this embodiment, the hole 21 is composed of a small-diameter portion 21a and a large-diameter portion 21b. This makes it possible to secure a relatively large inner diameter of the hole 21 with the large-diameter portion 21b while suppressing the cost required to form the hole 21.

[0037] The columnar conductor 4 has a revolving shape. The axis of rotation S of the revolving shape of the columnar conductor 4 is a straight line perpendicular to the plate surface 2a and is aligned in the Z direction. Furthermore, the axis of rotation S passes through the center of the tip hole 17. Therefore, the contour shape of the cross-section of the columnar conductor 4 along the XY plane is circular. Therefore, the side surface 20 of the columnar conductor 4 has the same side shape as the rotating body. The shape of the side surface 20 will be described in detail later.

[0038] As described above, the first plate-shaped conductor 2 extends in a strip-like shape along the X direction. The columnar conductor 4 is provided on the first end 2b side in the longitudinal direction of the first plate-shaped conductor 2 (on the X2 direction side of the first plate-shaped conductor 2). In other words, the first end 2b side of the first plate-shaped conductor 2 is electrically connected to the columnar conductor 4 which has a power supply point. Therefore, the second end 2c side of the first plate-shaped conductor 2 becomes an open end. The second end 2c is the end of the first plate-shaped conductor 2 opposite to the first end 2b in the longitudinal direction. Furthermore, the longitudinal direction of the first plate-shaped conductor 2 is the direction of extension of the strip-shaped first plate-shaped member 2, and is the direction along the X direction.

[0039] As shown in Figure 1, the short side portion 2c1 on the second end 2c side of the first plate-shaped conductor 2 is an end face along the Y direction and is a plane parallel to the YZ plane. On the other hand, the short side portion 2b1 on the first end 2b side in the longitudinal direction of the first plate-shaped conductor 2 has a curved surface that is continuous with the side surface 20 without any steps. The short side portion 2b1 may also be a curved surface that is parallel to the Z direction while following the side surface 20 in the XY plane. In this case, it is advantageous in terms of ease of manufacture and cost. In this case, the short side portion 2b1 may protrude or recess slightly with respect to the side surface 20. However, these protrusions and recesses are very slight and have little effect on the effect of gradualizing the change in characteristic impedance, which will be described later.

[0040] Furthermore, the pair of long sides 2d1 of the first plate-shaped conductor 2 are end faces aligned with the X direction and are planes parallel to the XZ plane. The width dimension of the first plate-shaped conductor 2 along the Y direction is approximately the same as the width dimension of the base end face 18 along the Y direction. The base end face 18 is also the cross-section along the plate surface 2a of the columnar conductor 4.

[0041] The first plate-shaped conductor 2 functions as a capacitive loading plate for the columnar conductor 4. Therefore, instead of a strip-shaped member as in this embodiment, a plate-shaped member with a larger area can also be used. However, as in this embodiment, by making the first plate-shaped conductor 2 into a strip shape, it is possible to reduce the size of the antenna 1 when viewed from above while maintaining the characteristics of the antenna 1, thereby miniaturizing the antenna 1. Furthermore, by making the width dimension of the first plate-shaped conductor 2 the same as the width dimension of the base end face 18 of the columnar conductor 4, the size of the antenna 1 when viewed from above can be made smaller. Furthermore, in this embodiment, since the short side portion 2b1 on the first end 2b side of the first plate-shaped conductor 2 has a shape that follows the contour shape of the base end surface 18, the size of the antenna 1 when viewed from above can be further reduced.

[0042] The short-circuit conductor 6 is a cylindrical member that protrudes from the plate surface 2a of the first plate-shaped conductor 2. As shown in Figure 3, the short-circuit conductor 6 is provided at a predetermined distance from the columnar conductor 4. The short-circuit conductor 6 has a conductor body 6a and a spacer 6b. The conductor body 6a is a long screw made of a conductor such as copper, structural steel, or alloy steel. The spacer 6b is a cylindrical member made of an insulator such as resin or a conductor. The spacer 6b is placed between the first plate-shaped conductor 2 and the ground conductor 10. The first plate-shaped conductor 2 and the grounding conductor 10 are provided with holes 2e and 10d for attaching the short-circuit conductor 6. The spacer 6b is positioned along the Z direction. In this configuration, the inner circumference hole of the spacer 6b coincides with the hole 2e of the first plate-shaped conductor 2 and the hole 10d of the ground conductor 10. The length of the spacer 6b is set to be approximately the same as the length of the columnar conductor 4 in the Z direction. Both end faces of the spacer 6b are in contact with the first plate-shaped conductor 2 and the ground conductor 10. This positions the spacer 6b at the distance between the first plate-shaped conductor 2 and the ground conductor 10.

[0043] The conductor body 6a is inserted through the hole 2e, the spacer 6b, and the hole 10d. A nut 7 is attached to the threaded end of the conductor body 6a. By tightening the nut 7, the first plate-shaped conductor 2, the spacer 6b, and the ground conductor 10 are tightened between the screw head 6a1 of the conductor body 6a and the nut 7. This reduces the load acting on the tip 16 of the columnar conductor 4 connected to the ground conductor 10, and the antenna 1 is held firmly in place. Note that the screw head 6a1 is omitted in Figure 2B. A washer 8 made of a conductor is interposed between the screw head 6a1 and the first plate-shaped conductor 2. A washer 9, also made of a conductor, is interposed between the nut 7 and the grounding conductor 10. As a result, the short-circuit conductor 6 electrically connects the first plate-shaped conductor 2 and the grounding conductor 10, and grounds the first plate-shaped conductor 2. In this case, the short-circuit conductor 6 can appropriately adjust the input impedance of the antenna 1, allowing the antenna 1 to support a wider frequency band.

[0044] [Regarding the side surface 20 of the columnar conductor 4] As described above, the side surface 20 of the columnar conductor 4 is tapered, narrowing from the first plate-shaped conductor 2 side towards the tip 16 side. In this embodiment, "tapered" means that the side surface 20, as a whole, tapers towards the tip 16 from the first plate-shaped conductor 2 side. Even if there are partial protrusions or indentations, if the side surface 20 as a whole tapers from the first plate-shaped conductor 2 side to the tip 16 side, then the shape is tapered.

[0045] Furthermore, the side surface 20 is a smooth convex curved surface. Figure 4 is a graph showing the contour curve of the side surface 20 in the cross-section of the columnar conductor 4 along the plane containing the axis of rotation S. Figure 4 shows the contour curve C when the rotation axis S is the y-axis and the line perpendicular to the rotation axis S at the end face 19 is the x-axis. The contour curve C shown in Figure 4 satisfies the following equation (1). y = ax P ...(1) However, x≧0, a>0, and P≧1.

[0046] The columnar conductor 4 of this embodiment has a side surface 20 having a contour curve that satisfies the above formula (1). Therefore, the area of ​​the base end surface 18 (the cross-sectional area of ​​the columnar conductor 4 along the plate surface 2a) is larger than the area of ​​the end surface 19 of the tip portion 16. In this case, the profile length of the base end face 18 and the profile length of the end face 19 are different from each other. In contrast, the side surface 20 tapers towards the tip 16 from the first plate-shaped conductor 2 side.

[0047] In other words, the columnar conductor 4 of this embodiment has a side surface 20 having a contour curve that satisfies the above formula (1), so that the cross-sectional area of ​​the columnar conductor 4 along a plane parallel to the plate surface 2a gradually decreases from the first plate conductor 2 side toward the tip 16 side.

[0048] With this configuration, the first plate-shaped conductor 2 functions as a capacitive loading plate, making it possible to achieve a low profile while responding to signals in a relatively low frequency band of, for example, 1 GHz or less. Furthermore, since the columnar conductor 4 has a tapered side surface 20 that narrows from the first plate-shaped conductor 2 side towards the tip 16 side, the contours of the base end surface 18 and the end surface 19, which are of different lengths, can be smoothly connected. As a result, the change in the characteristic impedance of the columnar conductor 4 from the tip 16, which has the feed point, to the first plate-shaped conductor 2 can be made gradual. This makes it possible to reduce the return loss of the antenna 1 for signals in a relatively high frequency band of several GHz or more, such as SUB6. As a result, an antenna 1 can be obtained that is low to the ground while supporting a wide frequency band.

[0049] Furthermore, it is preferable that the height of antenna 1 be approximately 0.07 times the wavelength in the relatively low frequency band of 1 GHz or less within the frequency band that antenna 1 supports. For example, if the frequency band of antenna 1 includes 800 MHz, the wavelength is approximately 380 mm, so the height of antenna 1 is preferably approximately 27 mm.

[0050] Furthermore, since the side surface 20 is a convex curved surface, and the contour curve of the side surface 20 satisfies the above equation, the change in the characteristic impedance of the columnar conductor 4 can be adjusted more appropriately. The contour curve of the side surface 20 is a curve that represents the overall shape of the side surface 20. Therefore, even if there are partial protrusions or indentations on the side surface 20, if the contour curve that represents the overall shape of the side surface 20 satisfies the above formula, the contour curve of the side surface 20 is considered to satisfy the above formula.

[0051] Furthermore, in this embodiment, by providing the columnar conductor 4 on the first end 2b side of the first plate-shaped conductor 2, it is possible to achieve a compact design while appropriately securing the distance from the second end 2c of the first plate-shaped conductor 2 to the columnar conductor 4, thereby making it easier to achieve a low-profile design.

[0052] In this embodiment, an example was given in which the antenna 1 is obtained by assembling the first plate-shaped conductor 2 and the columnar conductor 4. However, the antenna 1 may also be constructed using the first plate-shaped conductor 2 and the columnar conductor 4 which are integrally formed. Furthermore, although the first embodiment described above illustrates a case where the columnar conductor 4 is formed integrally, the columnar conductor 4 may also be constructed by combining multiple divided parts, as shown in the second embodiment described later.

[0053] [Regarding the second embodiment] Figure 5 is a perspective view of the antenna 1 according to the second embodiment, and Figure 6 is a side view of the antenna 1 according to the second embodiment. Note that the screw head 6a1 is omitted in Figure 6. This embodiment differs from the first embodiment in that the antenna 1 has a second plate-shaped conductor 30. The second plate-shaped conductor 30 is provided protruding from the side surface 20 of the columnar conductor 4 and is positioned opposite the first plate-shaped conductor 2. The second plate-shaped conductor 30 is positioned between the first plate-shaped conductor 2 and the ground conductor 10.

[0054] The second plate-shaped conductor 30 has a plate shape that aligns with the XY plane. Therefore, the second plate-shaped conductor 30 and the ground conductor 10 are parallel to each other. Furthermore, the second plate-shaped conductor 30 extends in a strip shape along the X direction.

[0055] As shown in Figure 5, the third end 30b in the longitudinal direction of the second plate-shaped conductor 30 is connected to the side surface 20 of the columnar conductor 4. On the other hand, the short side portion 30c1 on the fourth end 30c side of the second plate-shaped conductor 30 is an end face along the Y direction and is a plane parallel to the YZ plane. Furthermore, the pair of long sides 30d1 of the second plate-shaped conductor 30 are end faces aligned with the X direction and are planes parallel to the XZ plane. The position of the short side portion 30c1 of the second plate-shaped conductor 30 in the X direction is the same as the position of the short side portion 2c1 of the first plate-shaped conductor 2 in the X direction. Furthermore, the positions of the pair of long sides 30d1 of the second plate-shaped conductor 30 in the Y direction are the same as the positions of the pair of long sides 2d1 of the first plate-shaped conductor 2 in the Y direction. Therefore, the width dimension of the second plate-shaped conductor 30 along the Y direction is the same as the width dimension of the first plate-shaped conductor 2 along the Y direction. Therefore, the projected shapes of the pair of long sides 30d1 and short sides 30c1 of the second plate-shaped conductor 30 in the XY plane are the same as the projected shapes of the pair of long sides 2d1 and short sides 2c1 of the first plate-shaped conductor 2 in the XY plane.

[0056] The pair of long sides 30d1 of the second plate-shaped conductor 30 extend to the position of the axis of rotation S in the X direction. The diameter of the columnar conductor 4 at the Z-direction position where the second plate-shaped conductor 30 is located is smaller than the diameter of the base end face 18. Therefore, the X2-direction side edge 30d2 of the long side portion 30d1 protrudes relative to the side surface 20. As a result, the third end portion 30b of the second plate-shaped conductor 30 has a pair of end flat portions 33 on both sides of the columnar conductor 4. As shown in Figures 5 and 6, the pair of end planes 33 are faces oriented in the X2 direction. The pair of end planes 33 are planes parallel to the YZ plane.

[0057] Figure 7 is a cross-sectional view of the antenna 1 according to the second embodiment, along the XZ plane. Note that Figure 7 shows a cross-section passing through the center of the antenna 1 in the Y direction. As shown in Figure 7, the columnar conductor 4 includes a first divided body 22 and a second divided body 24. The first segmented body 22 is a component formed from a conductor such as copper. The first divided body 22 includes the tip portion 16 described above. The first divided body 22 also includes the hole portion 21. The hole 21 opens to the contact surface 22a. The contact surface 22a is a surface of the first divided body 22 that is opposite to the end face 19.

[0058] The second divided body 24 is a component formed from a conductor such as copper. The second segment 24 includes a base end face 18. The contact surface 24a of the second segment 24 is provided with a projection 24a1 that fits into the hole 21. The contact surface 24a is a surface of the second segment 24 that is opposite to the base end face 18. This projection 24a1 is used to position the first segment 22 and the second segment 24.

[0059] As shown in Figure 7, a plate member 40 is sandwiched and fixed between the first divided body 22 and the second divided body 24. The plate member 40 includes the second plate-shaped conductor 30 described above and an intervening portion 42. The intervening portion 42 is a portion interposed between the first divided body 22 and the second divided body 24. The intervening portion 42 constitutes a part of the columnar conductor 4. When the plate member 40 is fixed between the first divided body 22 and the second divided body 24, the portion of the plate member 40 that protrudes from the columnar conductor 4 becomes the second plate-shaped conductor 30. In other words, in the plate member 40, the portion on the X1 direction side of the boundary portion 32 in Figure 7 is the second plate-shaped conductor 30. In the plate member 40, the portion on the X2 direction side of the boundary portion 32 is the intervening portion 42.

[0060] Thus, the columnar conductor 4 of this embodiment is composed of a first divided body 22, a second divided body 24, and an intervening portion 42. The plate-shaped intervening portion 42 is sandwiched between the contact surface 22a and the contact surface 24a. As a result, the first divided body 22 and the intervening portion 42 come into contact with each other. Also, the intervening portion 42 and the second divided body 24 come into contact with each other. Therefore, the first divided body 22, the second divided body 24, and the intervening portion 42 are electrically connected to each other. As a result, the second plate-shaped conductor 30 and the columnar conductor 4 are electrically connected to each other.

[0061] The end face of the intervening portion 42 facing in the X2 direction has a curved surface that is continuous with respect to the side surface 20 without any step. The end face of the intervening portion 42 facing in the X2 direction may also be a curved surface that is parallel to the Z direction while following the side surface 20 in the XY plane, similar to the short side portion 2b1 of the first plate-shaped conductor 2. The intervening portion 42 is provided with a hole 42a. A projection 24a1 is inserted into the hole 42a. This positions the intervening portion 42 (plate member 40) relative to the first divided body 22 and the second divided body 24.

[0062] The first divided body 22, the second divided body 24, and the intervening part 42 are combined with each other and fixed together with the first plate-shaped conductor 2 by screws (not shown) or the like. The first segment 22 and the second segment 24 are fixed together after the pin 12 is joined to the first segment 22. The reason for this is that the hole 21 in the first divided body 22 can be used as a workspace when forming a welding member that joins the pin 12 and the first divided body 22, as described above.

[0063] The second plate-shaped conductor 30 is provided with a hole 30e through which the conductor body 6a of the short-circuit conductor 6 is inserted. The conductor body 6a is inserted through the holes 2e, 30e, spacer 6b, and 10d. The spacer 6b includes a first main body portion 36 and a second main body portion 38. The first main body portion 36 and the second main body portion 38 are cylindrical members made of an insulator such as resin. The second main body portion 38 is positioned between the grounding conductor 10 and the second plate-shaped conductor 30. Both end faces of the second main body portion 38 are in contact with the second plate-shaped conductor 30 and the grounding conductor 10. In this way, the second main body portion 38 positions the distance between the second plate-shaped conductor 30 and the grounding conductor 10.

[0064] The first main body 36 is positioned between the first plate-shaped conductor 2 and the second plate-shaped conductor 30. The first main body portion 36 has a large diameter portion 36a and a small diameter portion 36b. The small diameter portion 36b is provided protruding from one end face of the large diameter portion 36a. The small-diameter portion 36b is inserted into the hole 30e of the second plate-shaped conductor 30. The small-diameter portion 36b is interposed between the conductor body 6a and the second plate-shaped conductor 30. Therefore, the conductor body 6a and the second plate-shaped conductor 30 are insulated from each other. Both end faces of the large-diameter portion 36a are in contact with the first plate-shaped conductor 2 and the second plate-shaped conductor 30. This allows the large-diameter portion 36a to position the distance between the first plate-shaped conductor 2 and the second plate-shaped conductor 30.

[0065] As described above, the antenna 1 of this embodiment includes a second plate-shaped conductor 30 that is provided protruding from the side surface 20 of the columnar conductor 4 and is positioned opposite to the first plate-shaped conductor 2 on the plate surface 2a side of the first plate-shaped conductor 2. This allows antenna 1 to be made into a two-element antenna, and by increasing the resonant frequency, a wider bandwidth becomes possible.

[0066] In this embodiment, an example is given in which the antenna 1 is obtained by assembling the first plate-shaped conductor 2, the plate member 40, the first divided body 22, and the second divided body 24. However, the antenna 1 may also be constructed using a first plate-shaped conductor 2, the second plate-shaped conductor 30, and the columnar conductor 4 that are integrally formed.

[0067] Furthermore, this embodiment shows a case where the projected shape of the second plate-shaped conductor 30 in the XY plane matches the projected shape of the first plate-shaped conductor 2 in the XY plane. However, the projected shape of the second plate-shaped conductor 30 in the XY plane does not have to be the same as the projected shape of the first plate-shaped conductor 2 in the XY plane. Furthermore, in addition to the first plate-shaped conductor 2 and the second plate-shaped conductor 30, other plate-shaped conductors may be provided. In this case, the other plate-shaped conductors are provided protruding from the side surface 20 of the columnar conductor 4. In this case, the other plate-shaped conductors are provided at a predetermined distance in the Z direction from the first plate-shaped conductor 2 and the second plate-shaped conductor 30.

[0068] Furthermore, the first plate-shaped conductor 2 and the plate member 40 may have exactly the same shape. In this case, the first plate-shaped conductor 2 can be used not only as the first plate-shaped conductor 2 but also as the plate member 40. Therefore, cost reduction through economies of scale becomes possible. When the first plate-shaped conductor 2 is used as a plate member 40, the edge of the plate member 40 (the edge of the first end 2b of the first plate-shaped conductor 2 when used as a plate member 40) protrudes from the side surface 20 of the columnar conductor 4. However, the side surface 20 as a whole tapers from the first plate-shaped conductor 2 side towards the tip 16 side, so this does not cause any significant effect.

[0069] [Regarding the third embodiment] Figure 8 is a perspective view of the antenna 1 according to the third embodiment, and Figure 9 is a cross-sectional view of the antenna 1 according to the third embodiment along the XZ plane. In Figure 8, the first plate-shaped conductor 2 is shown as a dashed line (two-dotted line) for ease of understanding. Figure 9 shows a cross-section passing through the center of the antenna 1 in the Y direction. This embodiment differs from the second embodiment in that the short-circuit conductor 6 has a plate shape.

[0070] The short-circuit conductor 6 of this embodiment has a main body member 6c formed from a conductor such as copper in a plate shape. The fifth end portion 6c1 of the main body member 6c is fixed in contact with the first plate-shaped conductor 2. This electrically connects the main body member 6c and the first plate-shaped conductor 2. The sixth end portion 6c2 of the main body member 6c is fixed in contact with the grounding conductor 10. This electrically connects the main body member 6c and the grounding conductor 10. Therefore, the main body component 6c is grounded to the first plate-shaped conductor 2.

[0071] The main body member 6c has a plate shape that is curved in accordance with the side surface 20 of the columnar conductor 4, and is positioned opposite the side surface 20 of the columnar conductor 4 at a predetermined distance. As shown in Figure 8, the hole 30e of the second plate-shaped conductor 30 has a curved shape that conforms to the shape of the main body member 6c. A gap is provided between the main body member 6c and the hole 30e. Therefore, the main body member 6c and the second plate-shaped conductor 30 are insulated from each other.

[0072] As shown in Figure 9, the radial distance D between the first surface 6c3 of the main body member 6c and the side surface 20 of the columnar conductor 4 in a cross-section including the diameter of the columnar conductor 4 is constant in the Z direction. In other words, the main body member 6c has a curved shape that follows the side surface when the radius of the columnar conductor 4 is increased by D.

[0073] Figure 10 is a cross-sectional view taken along the line AA in Figure 9. In Figure 10, the radial distance between contour line 19b and edge 6c4 is D1, and the radial distance between contour line 20a and contour line 6c5 is D2. The contour line 19b is the contour line of the end face 19. The edge 6c4 is the edge of the sixth end 6c2 of the main body member 6c. The edge 6c4 is an arc centered on the axis of rotation S. The edge 6c4 and the contour line 19b are at the same position in the Z direction. In this embodiment, if the insulating member 13a protrudes slightly from the second surface 10b of the grounding conductor 10, the position of the edge 6c4 in the Z direction and the position of the contour line 19b in the Z direction may be slightly misaligned. In such cases, the positions of the main body member 6c and the columnar conductor 4 are adjusted so that the position of the edge 6c4 in the Z direction and the position of the contour line 19b in the Z direction coincide. For the sake of clarity, we will assume that the position of edge 6c4 in the Z direction is the same as the position of contour line 19b in the Z direction.

[0074] The contour line 20a is the contour line of the side surface 20 in the cross-section of the columnar conductor 4 in Figure 10. The contour line 6c5 is the contour line of the first surface 6c3 in the cross-section of the main body member 6c in Figure 10. The contour line 6c5 is an arc centered on the axis of rotation S.

[0075] In Figure 10, intervals D1 and D2 have the same value D. Thus, the radial distance D between the main body member 6c and the columnar conductor 4 is the same regardless of the position in the Z direction and the position in the circumferential direction around the rotation axis S. Thus, the main body member 6c has a curved shape that follows the side surface when the radius of the columnar conductor 4 is increased by D.

[0076] In this embodiment, by arranging the curved short-circuit conductor 6, which conforms to the side surface 20 of the columnar conductor 4, opposite the side surface 20 with a gap D between them, it is possible to broaden the bandwidth for relatively low frequency bands among the available frequency bands.

[0077] [Regarding the fourth embodiment] Figure 11 is a perspective view of the antenna 1 according to the fourth embodiment. In Figure 11, the first plate-shaped conductor 2 is shown as a dashed line (two-dotted line) for ease of understanding. This embodiment differs from the second and third embodiments in that the first plate-shaped conductor 2 and the second plate-shaped conductor 30 are circular in shape, and the main body member 6c of the short-circuit conductor 6 is rectangular in shape.

[0078] As shown in Figure 11, the first plate-shaped conductor 2 and the second plate-shaped conductor 30 have a circular shape centered on the axis of rotation S. Therefore, the columnar conductor 4 is located at the center of the first plate-shaped conductor 2 and the second plate-shaped conductor 30.

[0079] The main body member 6c of the short-circuit conductor 6 is formed in a plate shape along the YZ plane. The main body member 6c extends along the Z direction. The hole 30e of the second plate-shaped conductor 30 through which the main body member 6c is inserted is formed in a rectangular shape according to the shape of the main body member 6c. In this embodiment as well, a gap is provided between the main body member 6c and the hole 30e. Therefore, the main body member 6c and the second plate-shaped conductor 30 are insulated from each other.

[0080] [Regarding the fifth embodiment] Figure 12 is a perspective view of the antenna 1 according to the fifth embodiment. In Figure 12, for ease of understanding, the first plate-shaped conductor 2 is shown as a dashed line (two-dotted line). This embodiment differs from the fourth embodiment in that the axis of rotation S of the columnar conductor 4 and the central axis T of the first plate-shaped conductor 2 and the second plate-shaped conductor 30 do not coincide.

[0081] As shown in Figure 12, the columnar conductor 4 in this embodiment is positioned at a location offset from the central axis T in the X2 direction. The edge 18a of the base end face 18 of the columnar conductor 4 coincides with the edge 2f1 of the first plate-shaped conductor 2. In other words, the columnar conductor 4 is provided at the outermost end of the first plate-shaped conductor 2.

[0082] Thus, since the columnar conductor 4 is positioned offset from the central axis T of the first plate-shaped conductor 2, the distance on the first plate-shaped conductor 2 from the columnar conductor 4 to the other edge 2f2 on either side of the central axis T can be secured as needed, making it suitable for responding to signals in a relatively low frequency band. In the first to third embodiments, the columnar conductor 4 is also provided between the center of the first plate-shaped conductor 2 and the edge of the first plate-shaped conductor 2. In this case, the center is, for example, the centroid of the contour shape of the first plate-shaped conductor 2.

[0083] [Regarding variations] In the embodiments described above, examples were given in which the side surface 20 of the columnar conductor 4 is a smooth curved surface. However, the side surface 20 may be stepped, widening in stages from the end surface 19 side toward the first plate-shaped conductor 2 side, as shown in Figures 13A and 13B. Furthermore, as shown in Figures 14A and 14B, the side surface 20 may be a conical surface. In these cases as well, the change in the characteristic impedance of the columnar conductor 4 can be made gradual, similar to the case where a smooth curved surface is used.

[0084] Furthermore, in each of the above embodiments, examples were given in which the side surface 20 of the columnar conductor 4 has a revolutionary shape and the cross-sectional contour shape of the columnar conductor 4 along the XY plane is circular. However, the cross-sectional contour shape of the columnar conductor 4 along the XY plane may be oval, elliptical, or polygonal. Furthermore, in each of the above embodiments, examples were given in which the columnar conductor 4 (first divided body 22 and second divided body 24) is formed of a conductor. However, the columnar conductor 4 may also be configured to include, for example, a main body made of resin or the like, and a conductive coating formed on the surface of the main body.

[0085] In the embodiments described above, examples were given where the first plate-shaped conductor 2 is strip-shaped or circular. However, the first plate-shaped conductor 2 may also be polygonal, such as triangular or pentagonal, or it may be oval or elliptical. Furthermore, in each of the above embodiments, the center of the first plate-shaped conductor 2 is defined as the centroid of the contour shape when the first plate-shaped conductor 2 is viewed from above, and the position of the columnar conductor 4 is determined based on the center of the first plate-shaped conductor 2, which is the centroid. In contrast, if the first plate-shaped conductor 2 has a polygonal shape, the center of the first plate-shaped conductor 2 may be defined as the center of the circumscribed circle of the contour shape of the first plate-shaped conductor 2, and the position of the columnar conductor 4 may be determined based on this center. The centroid of the first plate-shaped conductor 2, or the center of the circumscribed circle of the contour shape of the first plate-shaped conductor 2, can be suitably used as the center of the first plate-shaped conductor 2.

[0086] Furthermore, in each of the above embodiments, the case in which one short-circuit conductor 6 is provided is illustrated. However, multiple short-circuit conductors 6 may be provided. In this case, the load acting on the tip 16 of the columnar conductor 4 connected to the ground conductor 10 can be further reduced, and the antenna 1 is held more firmly.

[0087] [Regarding Verification Test 1] Next, we will explain Verification Test 1, which was conducted to assess the effects of Antenna 1. The test method involved constructing a model of antenna 1 and using that model to determine the frequency characteristics of the reflection loss (return loss) of antenna 1 (frequency characteristics of S-parameter S11) through computer simulation. In Verification Test 1, the effectiveness of Antenna 1 was verified by comparing the frequency characteristics of the return loss obtained from one comparative example and five examples shown below.

[0088] • Example 1 The antenna 1 shown in the first embodiment was constructed as the model for Example 1. The dimensions of each part of the first plate-shaped conductor 2 were set as follows. Width dimension (Y-direction dimension): 30 mm Length dimension (X-direction dimension): 95 mm Plate thickness: 1mm Furthermore, the dimensions of each part of the columnar conductor 4 were set as follows. Height dimension (Z-direction dimension): 26 mm Diameter of base end face 18: 30 mm In equation (1) above, a=1, P=1.7 The width dimension (Y-direction dimension) of antenna 1 is 30 mm, the length dimension (Y-direction dimension) of antenna 1 is 95 mm, and the height dimension (Z-direction dimension) of antenna 1 is 27 mm. Furthermore, the diameter of the conductor body 6a of the short-circuit conductor 6 was set to 2.5 mm. The distance in the X direction between the central axis of the columnar conductor 4 and the central axis of the short-circuit conductor 6 was set to 30 mm.

[0089] • Example 2 The antenna 1 shown in the second embodiment was constructed as the model for Example 2. In other words, in Example 2, we examined an antenna 1 that had a second plate-shaped conductor 30 added to the one in Example 1. The width dimension of the second plate-shaped conductor 30 in the Y direction was set to 30 mm. The thickness of the second plate-shaped conductor 30 was set to 1 mm. Other dimensions are the same as in Example 1.

[0090] • Example 3 The antenna 1 shown in the third embodiment was constructed as the model for Example 3. In other words, in Example 3, we verified an antenna 1 in which the short-circuit conductor 6 of the second embodiment was in the shape of a plate. In addition, the short-circuit conductor 6 in Example 3 has a plate shape that is curved in accordance with the side surface 20 of the columnar conductor 4. The width dimension in the Y direction of the fifth end 6c1 of the short-circuit conductor 6 was set to 20 mm. The distance in the X direction between the center of the fifth end portion 6c1 in the X and Y directions and the axis of rotation S was set to 30 mm. Other dimensions are the same as in Example 2.

[0091] • Example 4 The antenna 1 shown in the fourth embodiment was constructed as the model for Example 4. In other words, in Example 4, we examined an antenna 1 in which the first plate-shaped conductor 2 and the second plate-shaped conductor 30 are circular in shape. The diameters of the first plate-shaped conductor 2 and the second plate-shaped conductor 30 were set to 70 mm. The width dimension in the Y direction of the rectangular plate-shaped short-circuit conductor 6 was set to 10 mm. The distance in the X direction between the short-circuit conductor 6 and the rotating shaft S was set to 30 mm. Other dimensions are the same as in Example 2.

[0092] • Example 5 The antenna 1 shown in the fifth embodiment was constructed as the model for Example 5. Example 5 examined an antenna 1 in which the rotation axis S of the columnar conductor 4 and the central axes T of the first plate-shaped conductor 2 and the second plate-shaped conductor 30 did not coincide, as in Example 4. Antenna 1 in Example 5 is the same as antenna 1 in Example 4, except that the edge 18a of the base end face 18 of the columnar conductor 4 coincides with the edge 2f1 of the first plate-shaped conductor 2.

[0093] • Comparative Example 1 The antenna 101 shown below was constructed as the model for Comparative Example 1. Figure 15 is a perspective view of antenna 101 according to Comparative Example 1, and Figure 16 is a cross-sectional view of antenna 101 along the XZ plane. In Figure 15, the first plate-shaped conductor 102 is shown as a dashed line (two-dotted line) for ease of understanding. Figure 16 shows a cross-section passing through the center of antenna 101 in the Y direction.

[0094] As shown in Figures 15 and 16, the antenna 101 of Comparative Example 1 is provided on the ground conductor 100. The antenna 101 comprises a first plate-shaped conductor 102, a second plate-shaped conductor 130, a columnar conductor 104, and a short-circuit conductor 106. The first plate-shaped conductor 102, the second plate-shaped conductor 130, the hole 130e, the columnar conductor 104, and the short-circuit conductor 106 correspond, respectively, to the first plate-shaped conductor 2, the second plate-shaped conductor 30, the hole 30e, the columnar conductor 4, and the short-circuit conductor 6 in the fourth embodiment.

[0095] In Comparative Example 1, the columnar conductor 104 is a rod-shaped member with a diameter of 1.3 mm. Furthermore, the width dimension of the short-circuit conductor 106 in the Y direction in Comparative Example 1 was set to 20 mm. Other dimensions were the same as those of the first plate-shaped conductor 2, the second plate-shaped conductor 30, the columnar conductor 4, and the short-circuit conductor 6 in the fourth embodiment.

[0096] Figure 17 shows the frequency characteristics of the return loss for Comparative Example 1. As shown in Figure 17, in Comparative Example 1, the return loss is -5dB or less in the range of approximately 700 to 900MHz. However, the return loss in other frequency bands is greater than -5dB. The frequency band in which the return loss is -5dB or less can be considered to be within the frequency band that the antenna can handle. Thus, Comparative Example 1 is only capable of handling relatively low frequency bands below 1 GHz.

[0097] Figure 18 shows the frequency characteristics of the return loss in Example 1. As shown in Figure 18, in Example 1, the return loss is -5dB or less in the range of approximately 750 to 900MHz. Furthermore, the return loss in the frequency band above 1.6GHz is -5dB or less. Note that in Figure 17, the return loss in the frequency band from 1.6GHz to at least 6GHz is -5dB or less. Thus, Example 1 is capable of handling both relatively low frequency bands of 1 GHz or less and frequency bands of 1.6 GHz or more. From these results, it can be seen that in Example 1, an antenna 1 that supports a wider frequency band than in Comparative Example 1 can be obtained.

[0098] Figure 19 shows the frequency characteristics of the return loss in Example 2. As shown in Figure 19, in Example 2, the return loss is -5dB or less in the range of approximately 750 to 950MHz. Furthermore, the return loss in the frequency band above 1.5GHz is also -5dB or less. In Example 2, the frequency band below 1 GHz among the available frequency bands is wider compared to Example 1. From these results, it can be seen that in Example 2, the addition of the second plate-shaped conductor 30 broadens the bandwidth of the relatively lower frequency bands among the available frequency bands.

[0099] Figure 20 shows the frequency characteristics of the return loss in Example 3. As shown in Figure 20, in Example 3, the return loss is -5dB or less in the range of approximately 700 to 950 MHz. Furthermore, the return loss in the frequency band of 1.5 to 2.3 GHz is -5dB or less. In addition, the return loss in the frequency band of 2.4 GHz or higher is -5dB or less. In Example 3, the frequency band below 1 GHz among the available frequency bands is wider compared to Example 2. From these results, it can be seen that in Example 3, by arranging the curved short-circuit conductor 6, which conforms to the side surface 20 of the columnar conductor 4, opposite the side surface 20 with a spacing D between them, the bandwidth of the relatively lower frequency band among the available frequency bands can be broadened.

[0100] Figure 21 shows the frequency characteristics of the return loss in Example 4. As shown in Figure 21, in Example 4, the return loss is -5dB or less in the range of approximately 800 to 900 MHz. Furthermore, the return loss in the 2.4 to 3.7 GHz frequency band is -5dB or less. Additionally, the return loss in the frequency band above 5.2 GHz is -5dB or less. In Example 4, the frequency band above 1 GHz is narrower compared to Examples 1-3, but it is still possible to operate in some frequency bands. These results show that Example 4 can handle relatively low frequency bands below 1 GHz and some frequency bands above 2.4 GHz, and that an antenna 1 that can handle a wider frequency band can be obtained compared to Comparative Example 1.

[0101] Figure 22 shows the frequency characteristics of the return loss in Example 5. As shown in Figure 22, in Example 5, the return loss is -5dB or less in the range of approximately 800 to 950MHz. Furthermore, the return loss in the frequency band above 1.3GHz is also -5dB or less. Thus, Example 5 is capable of handling both relatively low frequency bands of 1 GHz or less and frequency bands of 1.3 GHz or more. From these results, it can be seen that in Example 5, an antenna 1 that supports a wider frequency band can be obtained compared to Comparative Example 1.

[0102] 〔others〕 It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, not in the sense described above, and is intended to include the meaning and scope of equivalents of the claims, and all modifications within that scope. [Explanation of symbols]

[0103] 1 Antenna 2. First plate-shaped conductor 2a plate surface 2b 1st end 2b1 Short side 2c Second end 2c1 Short side 2d1 Long side 2e Hole 2f1 edge 2f2 edge 4 Columnar conductors 6 Short-circuit conductor 6a Conductor body 6a1 Screw head 6b Spacer 6c Main body components 6c1 5th end 6c2 6th end 6c3, Page 1 6c4 edge 6c5 Outline 7 nuts 8 washers 9 Washers 10 Grounding conductor 10a 1st page 10b 2nd side 10d hole 11 Hole 12 pins 13 Connectors 13a Insulating material 13a1 Through hole 13a2 End face 13b Main body 16 Tip 17 Tip hole 18 Proximal surface 18a edge 19 End face 19a Opening edge 19b Outline 20 Side view 20a Outline 21 Hole 21a Small diameter section 21b Large diameter section 22 1st division body 22a Contact surface 24 Second division body 24a Contact surface 24a1 protrusion 30. Second plate-shaped conductor 30b 3rd end 30b1 Short side 30c 4th end 30c1 Short side 30d1 Long side 30d2 edge 30e hole 32 Boundary 33 End flat part 36. First main body 36a Large diameter section 36b Small diameter section 38. Second Main Body 40 Plate members 42 Interposition part 42a hole 100 Grounding conductor 101 Antenna 102 First plate-shaped conductor 104 Columnar conductor 106 Short-circuit conductor 130 Second plate-shaped conductor 130e Hole C contour curve D interval D1 Interval D2 interval S rotation axis T center axis

Claims

1. A first plate-shaped conductor and, The first plate-shaped conductor comprises a columnar conductor that protrudes from the plate surface of the plate-shaped conductor, The tip of the columnar conductor has a power supply point, The cross-sectional area of ​​the columnar conductor along the plate surface is larger than the area of ​​the end face of the tip portion. The columnar conductor has a tapered side surface that narrows from the first plate-shaped conductor side towards the tip side, The shape of the side surface is the side shape of a rotating body whose axis of rotation is a straight line perpendicular to the plate surface. The generatrix of the body of revolution includes an outwardly convex curve, The contour curve of the side surface in the cross-section of the columnar conductor along the plane containing the rotation axis satisfies the following equation when the rotation axis is the y-axis and the straight line perpendicular to the rotation axis at the tip is the x-axis. antenna. y = ax P However, x ≥ 0, a > 0, and P > 1.

2. The columnar conductor has a stepped shape with side surfaces that widen gradually from the tip side toward the first plate-shaped conductor side. The antenna according to claim 1.

3. The first plate-shaped conductor is strip-shaped. The antenna according to claim 1.

4. The columnar conductor is provided on the first end side in the longitudinal direction of the first plate-shaped conductor. The antenna according to claim 3.

5. A first plate-shaped conductor, The first plate-shaped conductor comprises a columnar conductor that protrudes from the plate surface of the plate-shaped conductor, The tip of the columnar conductor has a power supply point, The cross-sectional area of ​​the columnar conductor along the plate surface is larger than the area of ​​the end face of the tip portion. The columnar conductor has a tapered side surface that narrows from the first plate-shaped conductor side towards the tip side, The shape of the side surface is the side shape of a rotating body whose axis of rotation is a straight line perpendicular to the plate surface. The generatrix of the body of revolution includes an outwardly convex curve, The first plate-shaped conductor is strip-shaped, The width dimension of the first plate-shaped conductor is the same as the width dimension of the cross-section of the columnar conductor along the plate surface. antenna.

6. The short side of the first plate-shaped conductor on the first end side in the longitudinal direction has a shape that follows the contour shape of the cross-section along the plate surface of the columnar conductor. The antenna according to claim 5.

7. The columnar conductor is provided on the plate surface at a position offset from the center of the first plate-shaped conductor. The antenna according to claim 1.

8. The center of the first plate-shaped conductor is the centroid of the contour shape when the first plate-shaped conductor is viewed from above, or the center of the circumscribed circle of the contour shape. The antenna according to claim 7.

9. The board surface is further provided with a short-circuit conductor that protrudes from the board surface and grounds the first board-shaped conductor. The antenna according to claim 1.

10. A first plate-shaped conductor, The first plate-shaped conductor comprises a columnar conductor that protrudes from the plate surface of the plate-shaped conductor, The tip of the columnar conductor has a power supply point, The cross-sectional area of ​​the columnar conductor along the plate surface is larger than the area of ​​the end face of the tip portion. The columnar conductor has a tapered side surface that narrows from the first plate-shaped conductor side towards the tip side, The shape of the side surface is the side shape of a rotating body whose axis of rotation is a straight line perpendicular to the plate surface. The generatrix of the body of revolution includes an outwardly convex curve, The board surface is further provided with a short-circuit conductor that protrudes from the board surface and grounds the first board-shaped conductor, The short-circuit conductor has a curved plate shape such that the distance between the short-circuit conductor and the columnar conductor along the radial direction of the columnar conductor is the same regardless of the position along the rotation axis and the position in the circumferential direction around the rotation axis. antenna.

11. A first plate-shaped conductor, The first plate-shaped conductor comprises a columnar conductor that protrudes from the plate surface of the plate-shaped conductor, The tip of the columnar conductor has a power supply point, The cross-sectional area of ​​the columnar conductor along the plate surface is larger than the area of ​​the end face of the tip portion. The columnar conductor has a tapered side surface that narrows from the first plate-shaped conductor side towards the tip side, The shape of the side surface is the side shape of a rotating body whose axis of rotation is a straight line perpendicular to the plate surface. The generatrix of the body of revolution includes an outwardly convex curve, The columnar conductor is further provided with a second plate conductor that protrudes from the side surface of the first plate conductor and is positioned opposite to the first plate conductor on the plate surface side of the first plate conductor. antenna.

Images