Antenna equipment

Abstract

To provide an antenna device which is for use in an offshore buoy or the like and comprises a grounding plate and has the large maximum gain in a radiation direction of an electric wave in spite of the small diameter of the grounding plate.SOLUTION: An antenna device 210 comprises: a grounding plate 200; and an antenna element 10 which has an electrically conductive column with the one end coming in contact with the grounding plate 200, and which extends to a direction orthogonal to a ground surface of the grounding plate 200. The grounding plate 200 includes: an upper surface conductor 202 coming in contact with the electrically conductive column; a gap Sa without the upper surface conductor 202; a lower surface conductor 204; and a gap Sb without the lower surface conductor 204.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an antenna device used for an offshore buoy or the like.

Background Art

[0002] In recent years, for the purpose of improving the efficiency of fishing using Internet technology and for fixed-point observations such as rising seawater temperature and increasing marine garbage, attention has been paid to an offshore buoy having a communication function, so-called a smart buoy. The radiation characteristics of the antenna mounted on this smart buoy are set so that the maximum gain is obtained in a direction inclined more in the horizontal direction than in the zenith direction, which is directly above the buoy, in consideration of communication with a ground base station. A monopole antenna is known as an antenna having such characteristics (see Patent Document 1). The basic structure of a monopole antenna is a structure in which a linear antenna element having a length of 1 / 4 wavelength is erected at the center of a disc-shaped ground plane. As the diameter of the ground plane, a diameter equivalent to twice the wavelength or more is recommended.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding the antenna element, if a stack structure in which flat elements are stacked is adopted, the length dimension can be shortened. However, regarding the ground plane, miniaturization is difficult because the larger the diameter, the better the characteristics. Therefore, when the frequency of the radio wave to be used is specified and the inner diameter of the buoy that houses the antenna is limited, the outer diameter of the antenna device is regulated, and it may not be possible to obtain the desired characteristics, that is, the required maximum gain.

[0005] Therefore, the present invention aims to provide an antenna device for use on offshore buoys and the like that has a large maximum gain in the direction of radio wave radiation, even if the diameter of the disc-shaped grounding plate is small. [Means for solving the problem]

[0006] An antenna device according to one aspect of the present invention is: Grounding plate and The antenna element comprises a conductive column having one end in contact with the grounding plate and extending in a direction perpendicular to the grounding surface of the grounding plate, The grounding plate has a conductor in contact with the conductor column and an air gap where there is no conductor. death, The antenna element is provided between one end and the other end in the longitudinal direction of the conductor column and has an intermediate conductor to which a feed line can be connected. . [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an antenna device for use on offshore buoys and the like that has a large maximum gain in the direction of radio wave radiation and a small outer diameter. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of the antenna device according to this embodiment. [Figure 2] This is an exploded perspective view of the antenna device according to this embodiment. [Figure 3A] This is a cross-sectional view of the antenna device according to this embodiment. [Figure 3B] Figure 3A is a magnified view of the main components of the antenna device shown. [Figure 4] This is a perspective view of the antenna element according to this embodiment. [Figure 5] This is a cross-sectional view of the antenna element according to this embodiment. [Figure 6A] This is a top view of a ground plate having a gap according to this embodiment. [Figure 6B] This is a bottom view of a ground plate having a gap according to this embodiment. [Figure 7]It is an exploded perspective view of a conventional antenna device. [Figure 8] It is a cross-sectional view of a conventional antenna device. [Figure 9] It is a diagram showing the radiation characteristics of radio waves of a conventional antenna device. [Figure 10] It is a diagram showing the radiation characteristics of radio waves of the antenna device according to the present embodiment. [Figure 11A] It is a perspective view of a ground plane of an antenna device according to a first modification. [Figure 11B] It is a top view of a ground plane of an antenna device according to a first modification. [Figure 12A] It is a perspective view of a ground plane of an antenna device according to a second modification. [Figure 12B] It is a top view of a ground plane of an antenna device according to a second modification.

Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each figure, the scale of each member may be different from the actual one. Also, in each figure, a three-dimensional orthogonal coordinate system in three axial directions (X direction, Y direction, Z direction) is used. The central axis direction (height direction) of the antenna device 210 is the Z direction, and the directions orthogonal to the Z direction are the X direction and the Y direction.

[0010] [Configuration Example of Antenna Device 210] FIG. 1 is a perspective view of an antenna device 210 according to the present embodiment. FIG. 2 is an exploded perspective view of the antenna device 210 according to the present embodiment. FIG. 3A is a cross-sectional view of the antenna device 210 according to the present embodiment, and FIG. 3B is an enlarged view of the main part IIIB of the antenna device 210 shown in FIG. 3A. FIG. 4 is a perspective view of an antenna element 10 according to the present embodiment, and FIG. 5 is a cross-sectional view of the antenna element 10. FIG. 6A is a top view of a ground plane 200 including a gap Sa in the antenna device 210 according to the present embodiment, and FIG. 6B is a bottom view of the ground plane 200 including a gap Sb. In FIGS. 6A and 6B, for the sake of convenience, the cylindrical conductor 201 and the like are omitted.

[0011] The antenna device 210 according to this embodiment is a monopole antenna, and is configured to be storable, for example, in a smart buoy (offshore buoy) having a communication function, and wirelessly communicates ocean data obtained by fixed-point observation of seawater temperature, ocean currents, marine debris, etc. As shown in FIGS. 1 to 3, the antenna device 210 includes an antenna element 10, a bandwidth expansion ring 20, a ring support plate 30, and a ground plate 200.

[0012] As shown in FIGS. 4 and 5, the antenna element 10 has a disk-shaped upper conductor 11, a disk-shaped intermediate conductor 13, a disk-shaped lower conductor 15, and a cylindrical conductor column 16. In this embodiment, the upper conductor 11, the intermediate conductor 13, and the conductor column 16 constitute a monopole antenna element, and the lower conductor 15 has a ground potential and contacts the ground plate 200.

[0013] The upper conductor 11 is formed on the upper surface of a disk-shaped upper dielectric 12. A through hole 121 is provided at the central portion (central axis O) of the upper dielectric 12. The upper conductor 11 faces the lower conductor 15 via the conductor column 16 and extends in a plane in the X-Y direction orthogonal to the longitudinal direction (Z direction) of the conductor column 16. In this embodiment, in order to shorten the dimension in the height direction of the antenna element 10, the upper end of the conductor column 16 is bent in the X-Y direction to shorten the height direction of the conductor column 16, and the upper conductor 11 extending in the plane in the X-Y direction functions as a part of the conductor column 16.

[0014] The intermediate conductor 13 has a feeding point for connecting a feeding line 41 described later. The intermediate conductor 13 is formed on the upper surface of a disk-shaped lower dielectric 14. A through hole 131 is provided at the central portion of the intermediate conductor 13. A through hole 132 is provided at a position displaced in the radial direction from the central portion of the intermediate conductor 13. In this embodiment, the portion including the through hole 132 functions as a feeding point.

[0015] A through hole 141 connected to the through hole 131 is provided at the central portion of the lower dielectric 14. A through hole 142 connected to the through hole 132 is provided at a position displaced in the radial direction from the central portion of the lower dielectric 14.

[0016] The lower conductor 15 is formed on the lower surface of the lower dielectric 14. A through hole 151, connected to a through hole 142, is provided at a position radially offset from the center of the lower conductor 15. The lower conductor 15 is connected to a grounding wire 43 (described later) and becomes ground potential, and is positioned on the upper surface of the grounding plate 200 and in contact with the grounding plate 200.

[0017] The conductor column 16 extends from the center of the upper surface of the lower conductor 15 in a direction perpendicular to the upper surface (Z direction). The lower end (one end in the longitudinal direction) of the conductor column 16 passes through the through hole 141 and abuts against the upper surface of the lower conductor 15. The upper end (the other end in the longitudinal direction) of the conductor column 16 passes through the through hole 121 and abuts against the lower surface of the upper conductor 11. Approximately the middle of the conductor column 16 in the longitudinal direction abuts against the intermediate conductor 13 via the through hole 131.

[0018] One end of a coaxial cable 40 is connected to the antenna device 210. The coaxial cable 40 has a feed line 41, which is an internal conductor, in the center, an insulator 42 outside of that, a ground wire 43, which is an external conductor, and a sheath 44 on the outermost side. The feed line 41 is exposed at the uppermost part of the intermediate conductor 13 in Figure 5, and is electrically connected by contacting and passing through a through hole 132, forming the feed point of the intermediate conductor 13. The insulator 42 is exposed at the lower conductor 15, and passes through through holes 151 and 142 without contact. The ground wire 43 is exposed on the lower surface of the lower conductor 15 and is electrically connected to the lower conductor 15. The entire coaxial cable 40 below that point passes through a coaxial cable through hole 206 provided in the grounding plate 200 without contact. The other end of the coaxial cable 40 is connected to a wireless communication device (not shown). The wireless communication device is housed in an offshore buoy and communicates wirelessly with base stations, information processing terminals, etc. The connection of the antenna device to the coaxial cable is the same for the antenna devices 310 and 410 described later, as well as the conventional antenna device 110.

[0019] As shown in Figures 3A and 3B, the grounding plate 200 has a cylindrical conductor 201, an upper conductor 202, a side conductor 203, and a lower conductor 204. The cylindrical conductor 201, upper conductor 202, side conductor 203, and lower conductor 204 are electrically connected to each other. The side conductor 203 has a cylindrical side conductor 2031 that extends downward from the side portion of the dielectric 205.

[0020] The cylindrical conductor 201 has a diameter slightly larger than the outer diameter of the antenna element 10 and is erected in the center of the upper surface of the upper conductor 202. The height of the cylindrical conductor 201 in the Z direction is at least greater than the height of the antenna element 10. The upper end of the cylindrical conductor 201 is open, and the antenna element 10 can be inserted through this upper end opening.

[0021] As shown in Figures 6A and 6B, the upper conductor 202 has a first conductive portion 2021, a second conductive portion 2022, and a third conductive portion 2023. The first conductive portion 2021 is disc-shaped and constitutes the bottom wall of the cylindrical conductor 201. The second conductive portion 2022 consists of a plurality of linear patterns and extends radially from the first conductive portion 2021. In this embodiment, for example, there are eight second conductive portions 2022, which are arranged at 45-degree intervals in the circumferential direction. The third conductive portion 2023 consists of, for example, a ring-shaped pattern and is arranged concentrically with respect to the first conductive portion 2021 so as to connect the outer ends of the second conductive portions 2022. The first conductive portion 2021, the second conductive portion 2022, and the third conductive portion 2023 may be formed continuously by patterning or inkjet printing the same conductive layer, or they may be formed by combining different components.

[0022] The lower conductor 204 has a first conductive portion 2041, a second conductive portion 2042, and a third conductive portion 2043. The first conductive portion 2041, the second conductive portion 2042, and the third conductive portion 2043 are of the same size and shape as the first conductive portion 2021, the second conductive portion 2022, and the third conductive portion 2023 of the upper conductor 202 described above, and are arranged in the same position. In other words, the first conductive portion 2041, the second conductive portion 2042, and the third conductive portion 2043 of the lower conductor 204 are opposite each other with the dielectric 205 in between. The first conductive portion 2041, the second conductive portion 2042, and the third conductive portion 2043 may be formed continuously by patterning or inkjet printing the same conductive layer, or they may be formed by combining different components.

[0023] In this embodiment, as shown in Figure 6A, the grounding plate 200 has a plurality of voids Sa on the upper surface of the dielectric 205, surrounded by a first conductive portion 2021, a second conductive portion 2022, and a third conductive portion 2023. The plurality of voids Sa are spaces on the upper surface of the dielectric 205 where no conductors are present. The plurality of voids Sa are roughly fan-shaped when viewed in plan, and consist of, for example, eight voids. The plurality of voids Sa are of the same size (area) and are arranged in positions that are rotationally symmetric with respect to the central axis O of the grounding plate 200. Furthermore, the plurality of voids Sa are arranged at equal intervals in the circumferential direction with respect to the central axis O of the grounding plate 200.

[0024] Similarly, as shown in Figure 6B, the grounding plate 200 has a plurality of voids Sb on the lower surface of the dielectric 205, surrounded by the first conductive part 2041, the second conductive part 2042, and the third conductive part 2043. The plurality of voids Sb are spaces where the lower surface of the dielectric 205 is exposed and there are no conductors. The plurality of voids Sb are fan-shaped when viewed in plan, and consist of, for example, eight voids. The plurality of voids Sb are of the same size (area) and are positioned in a rotationally symmetric position with respect to the central axis O of the grounding plate 200. In addition, the plurality of voids Sb are arranged at equal intervals in the circumferential direction with respect to the central axis O of the grounding plate 200.

[0025] Furthermore, while the description above describes the case where multiple air gaps Sa and Sb are formed at rotationally symmetrical positions, equally spaced positions, and of the same size to obtain uniform radiation characteristics in the circumferential direction (around the central axis rotation) of the antenna element 10 as an antenna housed in an offshore buoy, the method is not limited to these. In terms of improving the gain in a specific radiation direction, the desired effect can be obtained by providing at least one air gap in the grounding plate 200. Therefore, the number of air gaps Sa and Sb is not limited to the eight shown in Figure 6A, etc. Also, when forming multiple air gaps Sa and Sb, the gain in a specific radiation direction can be improved even if they are formed to satisfy at least one of the conditions of rotational symmetry, equally spaced positions, and the same size.

[0026] As shown in Figures 2 and 3A, the bandwidth expansion ring 20 includes a ring-shaped conductor 21 having an opening 23 larger than the outer diameter of the cylindrical conductor 201. The conductor 21 is formed on the lower surface of a ring-shaped dielectric 22 having the same opening 23. The bandwidth expansion ring 20 is attached to the upper surface of the ring support plate 30 so as to surround the outer circumference of the cylindrical conductor 201.

[0027] The ring support plate 30 has an insulating material 31 made of, for example, expanded polystyrene. The insulating material 31 is ring-shaped and has an opening 32 that is approximately the same size as the outer diameter of the cylindrical conductor 201. The ring support plate 30 is positioned on the upper surface of the upper surface conductor 202 of the grounding plate 200 and supports the bandwidth expansion ring 20.

[0028] The patterns of the first conductive portion 2021, second conductive portion 2022, third conductive portion 2023, and void Sa of the upper conductor 202 constituting the grounding plate 200 described above can be formed by known printing techniques such as photolithography or inkjet printing. Similarly, the patterns of each layer constituting the antenna element 10 and the bandwidth expansion ring 20 can also be formed by known printing techniques such as photolithography described above. Furthermore, epoxy resin is used for the dielectrics 12, 14, 205, etc. In addition, metal materials such as copper are used for the conductors such as the conductive column 16 constituting the antenna element 10 and the upper conductor 202 and lower conductor 204 constituting the grounding plate 200.

[0029] [Example of operation of antenna device 210] When alternating current is supplied to the intermediate conductor 13, including the feed point, via the feed line 41, current flows through the conductor column 16 and the upper conductor 11, generating an electromagnetic field. As shown in Figure 5, the length obtained by adding the height (ha) between the upper conductor 11 and the intermediate conductor 13 of the conductor column 16, the radius of the upper conductor 11 (1 / 2·da1), and the radius of the intermediate conductor 13 (1 / 2·da2) corresponds to 1 / 4 wavelength of the radio wave used, causing the antenna element 10 to resonate.

[0030] Furthermore, current flows through the cylindrical conductor 201, the upper conductor 202, and the lower conductor 204 of the grounding plate 200. On the upper side, current flows through the side of the cylindrical conductor 201, and through the first conductive part 2021, the second conductive part 2022, and the third conductive part 2023 of the upper conductor 202. On the lower conductor 204, current flows through the third conductive part 2043, the second conductive part 2042, and the first conductive part 2041. In this way, by providing multiple air gaps Sa and Sb in the grounding plate 200, the current flow path is determined, and the current density flowing through the path increases. As shown in Figures 3A and 6A, the sum of the height h2 of the cylindrical conductor 201, the length DS of the second conductive part 2022 that constitutes the air gap Sa, and half the arc length of the third conductive part 2023 that constitutes the air gap Sa (π·D·1 / 8·1 / 2) corresponds to half the wavelength of the radio wave used, resulting in resonance. This resonance is superimposed with the resonance of the antenna element 10 described above, thereby improving the maximum gain.

[0031] [Regarding antenna gain] Next, we will compare the gain obtained by the conventional antenna device 110 with the gain obtained by the antenna device 210 according to this embodiment.

[0032] Here, we will briefly describe the conventional (basic) model antenna device 110, which is used as an example of a comparative example. The conventional antenna device 110 differs from the antenna device 210 according to the present invention in that the grounding plate 100 does not have air gaps Sa and Sb. As other components are substantially the same as those of the antenna device 210 according to this embodiment, the same components are denoted by the same reference numerals, and redundant explanations are omitted.

[0033] Figure 7 is an exploded perspective view of a conventional antenna device 110. Figure 8 is a cross-sectional view of a conventional antenna device 110. As shown in Figures 7 and 8, the conventional antenna device 110 comprises an antenna element 10, a bandwidth expansion ring 20, a ring support plate 30, and a grounding plate 100.

[0034] The grounding plate 100 includes a cylindrical conductor 101, an upper conductor 102, a side conductor 103, a lower conductor 104, and a dielectric 105. The cylindrical conductor 101 is erected in the center of the upper conductor 102, relative to the conductor surface. The upper conductor 102 is formed on the upper surface of the disc-shaped dielectric 105, the side conductor 103 is formed on the side circumferential surface of the disc-shaped dielectric 105, and the lower conductor 104 is formed on the lower surface of the disc-shaped dielectric 105. The upper conductor 102, the lower conductor 104, and the dielectric 105 are provided with power supply line through-holes 106.

[0035] The antenna element 10 is inserted and installed inside the cylindrical conductor 101 of the grounding plate 100. The ring support plate 30 is installed on the upper surface of the upper surface conductor 102 of the grounding plate 100 so as to surround the cylindrical conductor 101. A bandwidth-expanding ring 20 having an opening 23 is installed on the upper surface of the ring support plate 30. The radiation characteristics of the conventional antenna device 110 configured in this way and the antenna device 210 according to this embodiment will be described below.

[0036] Figure 9 shows the radiation characteristics of a conventional antenna device 110, and is a cross-sectional view in the ZX plane passing through the central axis of the antenna element 10 in Figure 5. Figure 10 shows the radiation characteristics of the antenna device 210 according to this embodiment, and is a cross-sectional view in the ZX plane passing through the central axis of the antenna element 10 in Figure 5. In Figures 9 and 10, the Z-upper direction is the zenith direction, and this zenith direction is taken as 0 degrees, with the clockwise angle being θ.

[0037] Here, the frequency used by the conventional antenna device 110 and the antenna device 210 according to this embodiment was set to 924 MHz. The dimensions of the antenna device 110 were as follows, as shown in Figure 8: D=220 mm, d=37 mm, h1=1.6 mm, h2=22 mm, t1=11 mm, t2=1.6 mm. The dimensions of the antenna device 210 according to this embodiment were as follows, as shown in Figures 3A, 6A, and 6B: D=220 mm, d=37 mm, h1=1.6 mm, h2=22 mm, h3=28.4 mm, t1=11 mm, t2=1.6 mm. The length DS of the straight section of the air gap Sa,Sb was set to 86.5 mm.

[0038] In antenna device 110, as shown in Figure 9, radiation was maximized in the direction of θ = 65 degrees, resulting in a maximum gain of 0.734 dB at a frequency of 924 MHz. In contrast, in antenna device 210 according to this embodiment, as shown in Figure 10, radiation was maximized in the direction of θ = 45 degrees, resulting in a maximum gain of 3.155 dB at a frequency of 924 MHz.

[0039] In typical smart buoys (offshore buoys), a gain of approximately 3 dB is required for communication with base stations. With conventional antenna devices 110, the gain is 0.734 dB when the diameter D = 220 mm. Therefore, to achieve a gain of 3 dB using conventional antenna devices 110, the diameter of the antenna device 110 needs to be increased to a diameter D = 650 mm. However, if the priority is to obtain a gain of 3 dB with conventional antenna devices 110, the antenna device 110 cannot be housed inside the offshore buoy because the inner diameter of a typical offshore buoy is approximately 300 mm.

[0040] According to the antenna device 210 of this embodiment, a gain of 3 dB can be achieved with a diameter D = 220 mm. Generally, the maximum gain is determined by the relationship between the wavelength of the radio waves used and the diameter of the grounding plate, and when the frequency is the same, the larger the diameter D of the grounding plate, the higher the gain. In contrast, according to this embodiment, by forming air gaps Sa and Sb in the grounding plate 200, the maximum gain can be improved without increasing the diameter D of the grounding plate 200. Therefore, the antenna device 210 can be housed in a typical smart buoy, making it possible to perform wireless communication such as fixed-point observation without increasing the size of the offshore buoy. In other words, when used in offshore buoys, etc., an antenna device 110 can be provided that has a large maximum gain in the direction of radio wave radiation and a small outer diameter. Furthermore, by forming multiple air gaps Sa and Sb at rotationally symmetrical positions, equally spaced positions, and of the same size, uniform characteristics can be obtained in the circumferential direction (around axial rotation) of the antenna element 10 (conductor column 16).

[0041] [First variation] Next, a first modified example of the grounding plate 200 constituting the antenna device 210 described above will be explained. In the antenna device 310 according to the first modified example, the components other than the grounding plate 300 are the same as those of the antenna device 210, so the same components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0042] Figure 11A is a perspective view of the grounding plate 300 of the antenna device 310 according to the first modified example, and Figure 11B is a top view of the grounding plate 300.

[0043] The antenna device 310 according to the first modified example comprises an antenna element 10, a bandwidth expansion ring 20, a ring support plate 30, and a grounding plate 300, as shown in Figures 1, 11A, and 11B. The grounding plate 300 has an upper conductor 302 including an upper conductive portion 3022 and an air gap Sc, and a lower conductor 304 including a lower conductive portion 3042 and an air gap Sd. A cylindrical conductor 301 is erected in the center of the upper conductive portion 3022.

[0044] The upper conductive portion 3022 of the upper conductor 302 is composed of conductors other than the air gaps Sc described later. The multiple air gaps Sc are regions surrounded by the upper conductive portion 3022 where no conductors exist, and are spaces where the upper surface of the dielectric 305 is exposed. The multiple air gaps Sc are circular in shape when viewed in plan, and consist of, for example, eight gaps. The multiple air gaps Sc are of the same size (area) and are positioned in a rotationally symmetrical manner with respect to the central axis O of the grounding plate 300. Furthermore, the multiple air gaps Sc are arranged at equal intervals in the circumferential direction with the central axis O of the grounding plate 300 as the pivot point.

[0045] Furthermore, the lower conductive portion 3042 and the void Sd of the lower conductor 304 have the same shape and are located in the same position as the upper conductive portion 3022 and the void Sc of the upper conductor 302 described above. Therefore, a detailed explanation of the lower conductive portion 3042 and the void Sd will be omitted.

[0046] In the first modified antenna device 310, the maximum gain of the antenna device 310 was measured when all dimensions except the shape and size of the air gaps Sc and Sd were the same as those of the antenna device 210 described above. With the first modified antenna device 310, the maximum gain was 2.5 dB at a frequency of 924 MHz. Therefore, the first modified antenna device 310 can achieve a higher maximum gain than the conventional antenna device 110, which has the same diameter D = 220 mm.

[0047] [Second variation] Next, a second modified example of the grounding plate 200 constituting the antenna device 210 described above will be explained. In the antenna device 410 according to the second modified example, the components other than the grounding plate 400 are the same as those of the antenna device 210, so the same components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0048] Figure 12A is a perspective view of the grounding plate 400 of the antenna device 410 according to the second modified example, and Figure 12B is a top view of the grounding plate 400.

[0049] The antenna device 410 according to the second modified example comprises an antenna element 10, a bandwidth expansion ring 20, a ring support plate 30, and a grounding plate 400, as shown in Figures 1, 12A, and 12B. The grounding plate 400 has an upper conductor 402 including an upper conductive portion 4022 and an air gap Se, and a lower conductor 404 including a lower conductive portion 4042 and an air gap Sf. A cylindrical conductor 401 is erected in the center of the upper conductive portion 4022.

[0050] The upper conductive portion 4022 of the upper conductor 402 is composed of a conductor, which is a part other than the void Se described later. The multiple voids Se are regions surrounded by the upper conductive portion 4022 where no conductor exists, and are spaces where the upper surface of the dielectric 405 is exposed. The multiple voids Se are circular in shape when viewed in plan, and consist of, for example, four voids Se. The multiple voids Se are of the same size (area) and are arranged in positions that are rotationally symmetric with respect to the central axis O of the grounding plate 400. Furthermore, the multiple voids Se are arranged at equal intervals in the circumferential direction with the central axis O of the grounding plate 400 as the pivot point.

[0051] Furthermore, the lower conductive portion 4042 and the gap Sf of the lower conductor 404 have the same shape and are located in the same position as the upper conductive portion 4022 and the gap Se of the upper conductor 402 described above. Therefore, a detailed explanation of the lower conductive portion 4042 and the gap Sf will be omitted.

[0052] In the second modified antenna device 410, the maximum gain of the antenna device 410 was measured when all dimensions except the shape and size of the air gaps Se and Sf were the same as those of the antenna device 210 described above. With the second modified antenna device 410, the maximum gain was 3.0 dB at a frequency of 924 MHz. Therefore, the second modified antenna device 410 can achieve a higher maximum gain than the conventional antenna device 110, which has the same diameter D = 220 mm.

[0053] While preferred embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the technical scope of the present disclosure is not limited to such examples. It is clear to any person with ordinary skill in the art of the present disclosure that various modifications or alterations may be conceived within the scope of the technical ideas described in the claims, and these will naturally also fall within the technical scope of the present disclosure.

[0054] For example, each dielectric 12, 14, 205, etc., is a support member for forming the conductor using printed circuit board technology and is not a member that affects the antenna characteristics, so it does not need to be provided. Also, the dielectrics 12, 14 of the antenna element 10 and the dielectric 205 of the grounding plate 200 may be voids. Furthermore, in the grounding plate 200, the area where the upper conductor 202 and the lower conductor 204 face each other may not be a void but a solid body filled with conductive material. The same applies to the grounding plates 300 and 400.

[0055] Furthermore, the cylindrical side conductor 2031 extending below the side conductor 203 of the grounding plate 200 is for impedance matching and can be omitted if the sole purpose is to improve gain. Also, the bandwidth expansion ring 20 and ring support plate 30 are for expanding the width of the frequency band where high gain can be obtained and do not contribute to the maximum gain value. If the frequency to be used is specified and the antenna is manufactured with high precision, these may not be necessary.

[0056] Furthermore, the cylindrical conductors 201, 301, and 401 are provided to adjust the total length of the current paths flowing through the grounding plates 200, 300, and 400 to resonate, and their absence can be substituted by slightly increasing the D dimension, etc.

[0057] Furthermore, although the above-described embodiment uses an offshore buoy as an example of a device that houses the antenna device 210, etc., it is not limited to this, and the antenna devices 210, 310, and 410 according to this embodiment can also be applied to devices, equipment, etc. that need to be housed in a container of a certain size to perform wireless communication. [Explanation of symbols]

[0058] 10 Antenna elements 13 Intermediate conductor 15 Lower conductor 16 Conductor Pillars 202 Top conductor (conductor) 204 Bottom conductor (conductor) 100,200,300,400 Ground plate Sa,Sb,Sc,Sd,Se,Sf void

Claims

1. Grounding plate and The antenna element comprises a conductive column having one end in contact with the grounding plate and extending in a direction perpendicular to the grounding surface of the grounding plate, The grounding plate has a conductor in contact with the conductor column and an air gap where there is no conductor. The antenna element is provided between one end and the other end in the longitudinal direction of the conductor column and has an intermediate conductor to which a feed line can be connected. Antenna device.

2. The aforementioned void includes a plurality of voids, The aforementioned plurality of gaps are provided in positions that are rotationally symmetric with respect to the central axis of the grounding plate. The antenna device according to claim 1.

3. The aforementioned void includes a plurality of voids, The aforementioned plurality of gaps are provided at equal intervals around the central axis of the grounding plate. The antenna device according to claim 1.

4. The aforementioned void includes a plurality of voids, The aforementioned multiple voids are of the same size. The antenna device according to claim 1.

5. The aforementioned antenna cable The conductor column is provided at the other end in the longitudinal direction and has an upper conductor that extends in a direction perpendicular to the longitudinal direction of the conductor column, The antenna device according to claim 1.

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