Compact wideband antenna

Abstract

To provide a compact wideband antenna which can be made small and can be used in a wide frequency band.SOLUTION: A compact wideband antenna includes a ground plate having a ground surface parallel to X and Y directions, a feed plate provided on the ground surface, a power feed unit that is provided between the ground plate and the feed plate and feeds a high-frequency signal to the feed plate, a housing that covers the ground surface, the power feed unit, and the feed plate, and a slot provided on a top plate that is provided on the ground surface of the housing and faces the ground surface. The feed plate has a first portion that is connected to the power feed unit and extends in a Z direction, a second portion extending in an opposite direction to the X direction from an end of the first portion extending in the Z direction, and a third portion that extends in the opposite direction to the Z direction from an end of the second portion extending in the opposite direction to the X direction and is connected to the ground plate. The slot is a single-line slot extending in the Y direction, and a part of the single-line slot overlaps with a part of the feed plate.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure relates to a small broadband antenna, and more particularly to a small broadband antenna that can be miniaturized and used in a wide frequency band.

Background Art

[0002] Small and broadband antennas are very important technologies because they can be embedded in the ceiling of a building as a base station antenna for mobile communication, or installed on the fuselage of an aircraft as an aircraft-mounted antenna to minimize air resistance. In base station antennas for mobile communication and aircraft-mounted antennas, patch antennas, monopole antennas, or dipole antennas are used. In the case of these antennas, a cover called a radome made of a dielectric is provided to protect the antenna from wind, rain, snow, hail, etc. The material of the radome is made of FRP (Fiber Reinforced Plastics), etc., and both the material and molding are more expensive than metal materials, and the environmental resistance performance is inferior to that of metal materials. Therefore, it is desired to miniaturize the antenna and also miniaturize the radome covering the antenna. In addition, with the explosive increase in demand for mobile communication, various frequencies have been used for mobile communication, and it is desired to realize an antenna corresponding to broadband.

[0003] Patent Document 1 describes "an antenna device including a floor, a linear feeding element, and two mushroom cells, wherein the linear feeding element is a linear conductor element arranged parallel to the floor, the end of which is connected to a feeding circuit, and each mushroom cell has a mushroom structure combined with a pair of opposing conductor plates parallel to the floor and a short-circuit portion that electrically connects the center of the pair of opposing conductor plates to the floor, and each mushroom cell is arranged side by side along the linear feeding element." Patent Document 1 does not disclose a small broadband antenna that can be miniaturized and used in a wide frequency band.

[0004] Patent Document 2 describes "a first conductive member having a first conductive surface, a second conductive member having a second conductive surface facing the first conductive surface, and a third conductive member located between the first conductive member and the second conductive member. A waveguide member having a stripe-shaped conductive waveguide surface facing the first conductive surface and extending in a first direction along the first conductive surface, and artificial magnetic conductors located on both sides of the waveguide member between the first conductive member and the second conductive member. The first conductive member has a slot, and the slot is a composite slot having a pair of vertical portions and a horizontal portion connecting the pair of vertical portions. The horizontal portion faces the waveguide surface and intersects the first direction, a slot antenna". Patent Document 2 does not disclose an antenna using a loop-shaped power supply board. Further, Patent Document 2 does not disclose a small broadband antenna that can be miniaturized and used in a wide frequency band.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, it is difficult to realize a small broadband antenna that can be miniaturized and used in a wide frequency band by the techniques described in Patent Document 1 and Patent Document 2, and such an antenna has been desired.

[0007] An object of the present disclosure is to provide a small broadband antenna that solves the above-described problems.

Means for Solving the Problems

[0008] The small broadband antenna according to the present disclosure is A ground plate having a ground surface parallel to the X direction and the Y direction, A power supply plate provided on the ground surface, A power supply unit provided between the ground plate and the power supply plate for supplying a high-frequency signal to the power supply plate, A housing covering the ground surface, the power supply unit, and the power supply plate, A slot provided on the upper surface plate on the ground surface of the housing and facing the ground surface, comprising: The power supply plate is connected to the power supply unit and has a first portion extending in the Z direction, a second portion extending in the direction opposite to the X direction from the tip of the first portion extending in the Z direction, and a third portion extending in the direction opposite to the Z direction from the tip of the second portion extending in the direction opposite to the X direction and connected to the ground plate. The slot is a single-line slot extending in the Y direction, or a dog-leg slot extending in the X direction, bifurcating midway, one branch extending in the X direction, the other extending in the Y direction, bifurcating again at the tip of the branch extending in the Y direction, one branch extending in the X direction, and the other extending in the direction opposite to the X direction, when viewed from the Z direction, a part of the dog-leg slot overlaps with a part of the power supply plate, The ground plate, the power supply plate, and the housing are made of a conductor.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a small-sized broadband antenna that can be miniaturized and used in a wide frequency band.

Brief Description of the Drawings

[0010]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions will be omitted as necessary for clarity of explanation.

[0012] [Embodiment 1] [Configuration] FIG. 1A is a perspective view illustrating the small broadband antenna according to the present disclosure. FIG. 1B is a perspective view illustrating the power supply method of the small broadband antenna according to the present disclosure. In FIGS. 1A and 1B, the upward direction is the Z direction, and the directions perpendicular to the Z direction are the X direction and the Y direction. Also, the Y direction is perpendicular to the X direction. The X direction may be referred to as the first direction, the Y direction may be referred to as the second direction, and the Z direction may be referred to as the third direction. Note that XYZ coordinates are also used in the following drawings as necessary. In FIG. 1B, for ease of understanding, only the ground plate, the feeding plate, and the coaxial cable (corresponding to the feeding portion) are shown.

[0013] As shown in FIG. 1A, the small broadband antenna 11 according to the present disclosure includes a ground plate 111, a feeding plate 112, a feeding portion 113, a housing 114, and a slot 115. The ground plate 111, the feeding plate 112, and the housing 114 are made of conductors.

[0014] The ground plate 111 has a ground plane 111s1 parallel to the X direction and the Y direction.

[0015] The feeding plate 112 is provided on the ground plane 111s1. The feeding plate 112 has a first portion 1121, a second portion 1122, and a third portion 1123. The first portion 1121 is connected to the feeding portion 113 and extends in the Z direction. The second portion 1122 extends in the direction opposite to the X direction from the tip of the first portion 1121 extending in the Z direction. The third portion 1123 extends in the direction opposite to the Z direction from the tip of the second portion 1122 extending in the direction opposite to the X direction and is connected (grounded) to the ground plate 111. Note that when the feeding plate is viewed from the Y direction, it has a loop shape (U-shaped), so the feeding plate may also be referred to as a loop element or a loop antenna.

[0016] The feeding portion 113 is provided between the ground plate 111 and the feeding plate 112 and feeds a high-frequency signal to the feeding plate 112. As shown in FIG. 1B, the feeding portion 113 feeds a high-frequency signal to the feeding plate 112 by, for example, a coaxial cable 113. Specifically, the feeding portion 113 is composed of a coaxial cable. The feeding portion 113 has a core wire 1131 and an outer conductor 1132 of the coaxial cable. The core wire 1131 is connected to the feeding plate 112, and the outer conductor 1132 is connected (grounded) to the ground plate 111.

[0017] The housing 114 covers the ground surface 111s1, the power feeding unit 113, and the power feeding plate 112. The plate in the Z direction of the housing 114 is referred to as the upper surface plate 1141.

[0018] The slot 115 is provided in the upper surface plate 1141 on the ground surface 111s1 of the housing 114. The upper surface plate 1141 faces the ground surface 111s1. The first surface (not shown) of the upper surface plate 1141 includes a flat surface or a curved surface. The slot 115 is an elongated cutout provided in the upper surface plate 1141. The upper surface plate 1141 is a part of the housing 114. The slot 115 is a single-line slot extending in the Y direction, or a dog-leg slot. The dog-leg slot extends in the X direction, branches into two in the middle of the extension, one extends in the X direction, the other extends in the Y direction, branches into two at the end of the extension in the Y direction, one extends in the X direction, and the other extends in the opposite direction of the X direction. The shape of the dog-leg slot, when viewed from the Z direction, is in the shape of a capital letter H of the alphabet. The height (length) of the housing 114 in the Z direction is higher than the height in the Z direction of the first part 1121 and the third part 1123, and the second part 1122 does not contact the upper surface plate 1141.

[0019] When the small broadband antenna 11 is viewed from the Z direction, a part of the dog-leg slot and a part or all of the power feeding plate 112 overlap, or are in a positional relationship where they do not overlap but are at a close distance. That is, the dog-leg slot and the power feeding plate 112 are arranged in the vicinity. The relative position of the power feeding plate 112 and the slot 115, that is, the relative distances in the X direction, Y direction, and Z direction, are determined based on the impedance characteristics at the feeding point. Specifically, the relative position of the power feeding plate 112 and the slot 115 is determined so that the return loss at the feeding point becomes sufficiently low. In Embodiment 1, it is determined to be -14.0 dB or less. It is known that when a dog-bone slot is used as the slot, the frequency band becomes wider than that of a single-line slot.

[0020] <Operation> The operation of the small broadband antenna 11 will be described. As shown in FIG. 1A, a power feeding unit 113 provided between a power feeding plate 112 and a ground plate 111 feeds a high-frequency signal to the power feeding plate 112. Here, the power feeding plate 112 has its third portion 1123 (tip) grounded to the ground plate 111 (electrically connected to the ground). The high-frequency signal fed (excited) from the power feeding unit 113 to the power feeding point at the center of the first portion 1121 of the power feeding plate 112 causes current to flow from the power feeding point (one side of the power feeding unit 113) to the power feeding plate 112, that is, current flows from the first portion 1121 to the second portion 1122 and then to the third portion 1123, and returns from the lower side of the third portion 1123 to the other side of the power feeding unit 113 via the ground plane 111s1. Since the high-frequency signal from the power feeding unit 113 flows through the power feeding plate 112 in a loop shape, the power feeding plate 112 and the ground plane 111s1 operate as a loop antenna. The electric field generated by this loop antenna undergoes electromagnetic coupling at the portion where the slot 115 is in proximity, and is radiated to the outside as radio waves from the slot 115.

[0021] During operation, broadband characteristics are obtained because the power feeding plate 112 has a plate-like loop shape. Also, by providing a dog bone slot on the upper surface plate 1141 of the housing 114 instead of a single-line slot, it operates as a broadband antenna compared to a single-line slot.

[0022] FIG. 2A is a perspective view illustrating a small broadband antenna according to the present disclosure. FIG. 2B is a perspective view illustrating a small broadband antenna according to the present disclosure, with a perspective view of the power feeding plate portion. FIG. 2C is a plan view illustrating a small broadband antenna according to the present disclosure. FIG. 2D is a cross-sectional view taken along the line segment A1 - A2 shown in FIG. 2C.

[0023] In FIGS. 2A to 2D, representative dimensions of the small broadband antenna are shown. For example, in FIGS. 2A and 2B, the length of the housing 114 in the X direction is preferably 0.4 to 0.5 times the wavelength of the high-frequency signal, and thus a representative value is 0.45λ O is described. However, λ Ois the wavelength of the high-frequency signal radiated from the antenna. Similarly, since the recommended value for the length of the housing 114 in the Y direction is 0.4 to 0.5 times the wavelength of the high-frequency signal, the representative value is 0.45λ O is described. Also, since the recommended value for the length of the housing 114 in the Z direction is 0.12 to 0.14 times the wavelength of the high-frequency signal, the representative value is 0.13λ O is described.

[0024] In FIG. 2C, the length of the power supply plate 112 in the Y direction is 0.07λ as a representative value O is described. The width of the dogbone slot is 0.019λ O or 0.026λ O is described. The length of the dogbone slot in the Y direction is 0.29λ O is described. The length of the dogbone slot in the X direction is 0.18λ O is described. In FIG. 2D, since the recommended value for the length of the second portion 1122 of the power supply plate 112 in the X direction is 0.12 to 0.14 times the wavelength of the high-frequency signal, the representative value is 0.13λ O is described. Since the recommended value for the length of the third portion 1123 of the power supply plate 112 in the Z direction is 0.09 to 0.11 times the wavelength of the high-frequency signal, the representative value is 0.10λ O is described. A predetermined distance or more is provided between the power supply plate 112 and the housing 114 (upper panel 1141) so that they do not contact each other.

[0025] The small broadband antenna 11 according to the present disclosure operates the power supply plate 112 as a loop antenna and radiates a high-frequency signal to the outside from the slot 115 electromagnetically coupled to the power supply plate 112. And, the small broadband antenna 11 can realize a wide bandwidth by using a dogbone slot as the slot. Also, the size of the small broadband antenna 11 is 0.45λ O ×0.45λ O ×0.13λ O and can be realized in a small size.

[0026] As a result, according to the present disclosure, it is possible to provide a small broadband antenna that can be realized in a small size and can be used in a wide frequency band.

[0027] Also, in the small broadband antenna 11, by adopting a structure in which the slot 115 is fed by the feeding plate (loop antenna) 112 and the ground plane 111s1, the feeding portion 113, and the feeding plate 112 are covered with a housing 114 made of a conductor, the interference from the surroundings is reduced, and the antenna can operate stably.

[0028] Also, since the small broadband antenna 11 is small and has a structure in which the ground plane 111s1, the feeding portion 113, and the feeding plate 112 are covered with a housing 114 made of a conductor, it can be embedded and installed in the ceiling of a building. Thereby, for design reasons, when it is not desired to recognize the presence of the antenna, the small broadband antenna 11 can be installed on the indoor ceiling or wall surface and used as an antenna for a mobile base station. Also, since the small broadband antenna 11 is small and has a structure covered with a housing, it can be embedded and installed in the body of a vehicle or an aircraft. Thereby, the air resistance of a moving body moving at high speed such as a vehicle or an aircraft can be reduced.

[0029] FIG. 3 is a schematic diagram illustrating the shape of the slot of the small broadband antenna according to the present disclosure. FIG. 3 shows the shapes of various slots when viewed from the Z direction. FIGS. 3(a) to 3(c) show a dock horn slot, and FIGS. 3(d) to 3(f) show a single-line slot.

[0030] In FIG. 1A and the like, a dock horn slot as shown in FIG. 3(a) is described as the shape of the slot, but it is not limited thereto.

[0031] In the present disclosure, in addition to the dock horn slot shown in FIG. 3(a), dock horn slots as shown in FIGS. 3(b) and 3(c) may also be used. The dock horn slot shown in FIG. 3(b) differs from the dock horn slot shown in FIG. 3(a) in that the ends of the slot are formed by curves (circles). Further, the dock horn slot shown in FIG. 3(c) differs from the dock horn slot shown in FIG. 3(a) in that the ends of the slot form a circle, and the diameter of the circle is larger than the width of the dock horn slot.

[0032] In the present disclosure, in addition to the dock horn slot shown in FIG. 3(a), single-line slots as shown in FIGS. 3(d) to 3(f) may also be used. The dock horn slot shown in FIG. 3(e) differs from the dock horn slot shown in FIG. 3(d) in that the ends of the slot are formed by curves (circles). Further, the dock horn slot shown in FIG. 3(f) differs from the dock horn slot shown in FIG. 3(d) in that the ends of the slot form a circle, and the diameter of the circle is larger than the width of the dock horn slot. Note that a small broadband antenna using a dock horn slot is known to be broadband as compared with a small broadband antenna using a single-line slot.

[0033] FIG. 4 is a perspective view illustrating a power supply board of the small broadband antenna according to the present disclosure. FIG. 4 shows various shapes of the power supply board.

[0034] In FIG. 1A etc., the shape of the power supply board is described as being as shown in FIG. 4(a), but it is not limited thereto.

[0035] In the present disclosure, in addition to the power supply board shown in FIG. 4(a), power supply boards as shown in FIGS. 4(b) to 4(g) may also be used. The power supply boards shown in FIGS. 4(b) and 4(c) differ from the power supply board shown in FIG. 4(a) in that the length of the first part 1121 of the power supply board in the Y direction becomes smaller as it goes in the opposite direction of the Z direction.

[0036] In addition, the power supply plates shown in FIGS. 4(d) and 4(e) are different from the power supply plate shown in FIG. 4(a) in that the maximum length of the second portion 1122 of the power supply plate in the Y direction is greater than the maximum length of the first portion 1121 in the Y direction, and the maximum length of the second portion 1122 of the power supply plate in the Y direction is greater than the maximum length of the third portion 1123 in the Y direction.

[0037] The power supply plate shown in FIG. 4(f) has a shape in which a part of the second portion 1122 of the power supply plate is recessed. In addition, the shape of the power supply plate shown in FIG. 4(g) as viewed from the Y direction is curved or arc-shaped.

[0038] [Embodiment 2] FIG. 5 is a perspective view illustrating the small broadband antenna according to the present disclosure.

[0039] As shown in FIG. 5, the small broadband antenna 21 according to the present disclosure is different from the small broadband antenna 11 according to the present disclosure in that it further includes a radome 116. The radome 116 is a cover made of a dielectric provided so as to cover the slot 115. The dielectric used for the radome 116 is formed of fiber reinforced plastics (FRP). In addition, materials such as polycarbonate, ABS resin, AES material, and Teflon may be used for the radome 116. Simply, a tape-like material of the above-mentioned materials may be used.

[0040] By covering the slot 115 with the radome 116, the inside of the antenna can be protected from wind, rain, snow, and hail. Thereby, malfunction of the small broadband antenna 11 can be prevented. In FIG. 5, the radome 116 is provided outside the housing 114, but the present invention is not limited to this. The radome 116 may be provided inside the housing 114.

[0041] In addition, when covering a patch antenna, a monopole antenna, or a dipole antenna used as a base station antenna for mobile communication or an antenna mounted on an aircraft with a radome, the cost increases because the entire antenna is covered with the radome. On the other hand, in the case of the small broadband antenna 21 according to the present disclosure, since only the slot 115 portion is covered with the radome 116, the cost can be significantly reduced compared to the former case.

[0042] Furthermore, in the case of the present disclosure, since the portion covered by the radome 116 is the radiating element portion (i.e., the slot 115), the portion covered with FRP or the like is very small, and since the portion to be covered is flat, the radome 116 can be realized at a low cost. In addition, since the portion (range) covered by the radome 116 is small, the amount of FRP required is small, so that strong environmental resistance (robustness) can be obtained.

[0043] [Modification of Embodiment 2] FIG. 6 is a perspective view illustrating the small broadband antenna according to the present disclosure.

[0044] As shown in FIG. 6, the small broadband antenna 21a according to the modification is different in that it includes a radome 116a with an enlarged radome size compared to the small broadband antenna 21 according to the present disclosure. The small broadband antenna 21a can reduce the cost compared to the case where the entire antenna is covered with a radome.

[0045] [Simulation Results] FIG. 7 is a graph illustrating the matching characteristics of the small broadband antenna according to the present disclosure. The horizontal axis of FIG. 7 indicates the frequency, and the vertical axis indicates the return loss (|S11|).

[0046] FIG. 7 shows the matching characteristics of the antenna calculated with the antenna dimensions shown in FIGS. 2A to 2D. At this time, the outer dimensions of the antenna are 0.45λ O ×0.45λ O ×0.13λ O That is.

[0047] As shown in FIG. 7, in the range of 1.8 GHz to 2.0 GHz, the return loss is -14.0 dB or less (when converted to VSWR, VSWR < 1.5), indicating good matching characteristics. The frequency band of 1.8 GHz to 2.0 GHz corresponds to a fractional bandwidth of 10.5%. Note that return loss and |S11| are synonymous.

[0048] Here, many antennas in the world are resonant type, and the widely used patch antenna has a fractional bandwidth of 1 - 2%. For these antennas, those with a fractional bandwidth exceeding 10% are expressed as "broadbanding ~". Therefore, since the small broadband antenna 11 according to the present disclosure achieves a fractional bandwidth of 10.5%, it can be said to be broadband.

[0049] FIG. 8 is a graph illustrating the radiation pattern of the small broadband antenna according to the present disclosure. The solid line shows the radiation pattern in the φ = 0 degree plane, i.e., the XZ plane, and the dashed line shows the radiation pattern in the φ = 90 degree plane, i.e., the YZ plane. In both radiation patterns, a broad radiation pattern with a peak in the Z - axis direction is obtained.

[0050] FIG. 8 shows the radiation pattern characteristics of the antenna calculated with the antenna dimensions shown in FIGS. 2A - 2D. As shown in FIG. 8, according to the small broadband antenna 11 according to the present disclosure, when the frequency is 1.9 GHz, uniform and broad good directivity characteristics can be obtained.

[0051] <Features> The features of the small broadband antenna according to the present disclosure are shown below. The small broadband antenna according to the present disclosure is fed by a plate - shaped loop element arranged under the slot with respect to the slot. That is, in the small broadband antenna, the feeding plate below the slot (in the Z - direction) becomes a kind of loop antenna and has a structure for feeding the slot.

[0052] <Effects> The effects of the small broadband antenna according to the present disclosure are shown below. i) It is an antenna with a small external shape. ii) It is an antenna having broadband characteristics. iii) It is an antenna having directivity. iv) It is an antenna that can be used without performance degradation even when embedded in a wall surface such as metal. v) It is an antenna having low cost and high environmental resistance. vi) Since the antenna itself is covered with a conductor housing, there is no leakage of radio waves to the surroundings. Thus, when the antennas are arranged in an array, the amount of interference with adjacent antennas is small, and the design when arranging the antennas in an array is easy.

[0053] Note that the present disclosure is not limited to the above-described embodiments, and can be appropriately modified without departing from the gist.

[0054] Some or all of the above-described embodiments can be described as follows in the appended claims, but are not limited thereto. (Appended Claim 1) A ground plate having a ground plane parallel to the X direction and the Y direction, A power supply plate provided on the ground plane, A power supply unit provided between the ground plate and the power supply plate for supplying a high-frequency signal to the power supply plate, A housing covering the ground plane, the power supply unit, and the power supply plate, A slot provided on the upper surface plate on the ground plane of the housing and facing the ground plane, comprising The power supply plate is connected to the power supply unit and has a first portion extending in the Z direction, a second portion extending in the direction opposite to the X direction from the tip of the first portion extending in the Z direction, and a third portion extending in the direction opposite to the Z direction from the tip of the second portion extending in the direction opposite to the X direction and connected to the ground plate. The slot is a single-line slot extending in the Y direction, or A dog-leg slot that extends in the X direction, bifurcates during the extension process such that one branch extends in the X direction and the other extends in the Y direction, and at the end of the extension in the Y direction, bifurcates again such that one branch extends in the X direction and the other extends in the opposite direction of the X direction. When viewed from the Z direction, a part of the dog-leg slot overlaps with a part of the power supply plate. The ground plate, the power supply plate, and the housing are composed of conductors. Small broadband antenna. (Appendix 2) The length of the first part of the power supply plate in the Y direction decreases as going in the opposite direction of the Z direction. The small broadband antenna according to Appendix 1. (Appendix 3) The maximum length of the second part of the power supply plate in the Y direction is greater than the maximum length of the first part of the power supply plate in the Y direction. The maximum length of the second part of the power supply plate in the Y direction is greater than the maximum length of the third part of the power supply plate in the Y direction. The small broadband antenna according to Appendix 1. (Appendix 4) The power supply plate has a shape in which a part of the second part of the power supply plate is recessed. The small broadband antenna according to Appendix 1. (Appendix 5) The shape of the power supply plate when viewed from the Y direction is an arc shape. The small broadband antenna according to Appendix 1. (Appendix 6) Further includes a radome made of a dielectric provided to cover the slot. The small broadband antenna according to Appendix 1. (Appendix 7) The dielectric of the radome is formed by fiber-reinforced plastics (FRP). The small broadband antenna according to Appendix 6. (Appendix 8) The power supply part A core wire connected to the power supply plate, An external conductor connected to the ground plate The small broadband antenna according to Supplementary Note 1. (Supplementary Note 9) The shape of the dog-leg slot is H-shaped when viewed from the Z direction. The small broadband antenna according to Supplementary Note 1. (Supplementary Note 10) The length of the housing in the X direction is 0.4 to 0.5 times the wavelength of the high-frequency signal. The length of the housing in the Y direction is 0.4 to 0.5 times the wavelength of the high-frequency signal. The length of the housing in the Z direction is 0.12 to 0.14 times the wavelength of the high-frequency signal. The length of the second part of the feeding plate in the X direction is 0.12 to 0.14 times the wavelength of the high-frequency signal. The length of the third part of the feeding plate in the Z direction is 0.09 to 0.11 times the wavelength of the high-frequency signal. The small broadband antenna according to Supplementary Note 1. (Supplementary Note 11) The first surface of the top plate includes a flat surface or a curved surface. The small broadband antenna according to Supplementary Note 1.

Explanation of Signs

[0055] 11, 21... Small broadband antenna 111... Ground plate 111s1... Ground surface 112... Feeding plate 1121... First part 1122... Second part 1123... Third part 113... Feeding part, coaxial cable 1131... Core wire 1132... External conductor 114... Housing 1141... Top plate 115... Slot 116, 116a... Radome

Claims

1. A ground plate having a ground surface parallel to the X and Y directions, A power supply plate provided on the ground surface, A power supply unit provided between the ground plate and the power supply plate for supplying a high-frequency signal to the power supply plate, A housing covering the ground surface, the power supply unit, and the power supply plate, A slot provided on the upper surface plate on the ground surface of the housing and facing the ground surface, Comprising, The power supply plate is, Connected to the power supply unit and having a first portion extending in the Z direction, A second portion extending in the direction opposite to the X direction from the tip of the first portion extending in the Z direction, A third portion extending in the direction opposite to the Z direction from the tip of the second portion extending in the direction opposite to the X direction and connected to the ground plate, The slot is, A single-line slot extending in the Y direction, or A dog-leg slot extending in the X direction, bifurcating midway and one branch extending in the X direction, the other extending in the Y direction, bifurcating again at the tip of the branch extending in the Y direction with one branch extending in the X direction and the other extending in the direction opposite to the X direction, When viewed from the Z direction, a part of the dog-leg slot overlaps with a part of the power supply plate, The ground plate, the power supply plate, and the housing are made of a conductor, A small broadband antenna.

2. The length of the first portion of the power supply plate in the Y direction decreases as it goes in the direction opposite to the Z direction, The small broadband antenna according to Claim 1.

3. The maximum length of the second portion of the power supply plate in the Y direction is greater than the maximum length of the first portion of the power supply plate in the Y direction, The maximum length of the second portion of the power supply plate in the Y direction is greater than the maximum length of the third portion of the power supply plate in the Y direction, The small broadband antenna according to Claim 1.

4. The power supply plate has a shape in which a part of the second portion of the power supply plate is recessed, The small broadband antenna according to Claim 1.

5. The shape of the power supply plate when viewed from the Y direction is an arc shape, The small broadband antenna according to Claim 1.

6. Further comprising a radome made of a dielectric provided to cover the slot, The small broadband antenna according to Claim 1.

7. The dielectric of the radome is formed by fiber-reinforced plastics (FRP), The small broadband antenna according to Claim 6.

8. The power supply unit is, A core wire connected to the power supply plate, an external conductor connected to the ground plate The small broadband antenna according to claim 1.

9. The shape of the dog-leg slot is H-shaped when viewed from the Z direction. The small broadband antenna according to claim 1.

10. The length of the housing in the X direction is 0.4 to 0.5 times the wavelength of the high-frequency signal. The length of the housing in the Y direction is 0.4 to 0.5 times the wavelength of the high-frequency signal. The length of the housing in the Z direction is 0.12 to 0.14 times the wavelength of the high-frequency signal. The length of the second portion of the feeding plate in the X direction is 0.12 to 0.14 times the wavelength of the high-frequency signal. The length of the third portion of the feeding plate in the Z direction is 0.09 to 0.11 times the wavelength of the high-frequency signal. The small broadband antenna according to claim 1.

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