Array antenna

Abstract

An array antenna is provided that can suppress increases in power consumption and heat generation that accompany an increase in the number of antenna elements, and can also suppress gain degradation and disturbance in radiation characteristics during beamforming. [Solution] The array antenna includes a reflector and multiple antenna elements. Each of the multiple antenna elements has an antenna element body having a first element and a second element, a first support portion connected to an end of the first element, and a second support portion connected to an end of the second element. The multiple antenna elements include multiple antenna elements to be fed and multiple antenna elements to be unfed, and are configured so that the antenna elements to be fed and the unfed antenna elements are adjacent to each other. The first support portion and second support portion of the unfed antenna elements are short-circuited at the position of the inter-element gap between the first element and the second element of the antenna element body or at a position away from the position of the inter-element gap.

Description

[Technical Field]

[0001] The present disclosure relates to an array antenna having a plurality of antenna elements arranged in an array. [Background technology]

[0002] BACKGROUND ART Conventionally, an array antenna (called a phased array antenna (PAA)) capable of beamforming by supplying signals of predetermined phases and amplitudes to each of a plurality of antenna elements arranged in an array has been known.

[0003] Non-Patent Document 1 discloses a configuration in which some of the antenna elements constituting an array antenna are replaced with parasitic elements that are not driven (not fed). According to this document, even though 60% of all antenna elements in the array antenna are not driven (not fed), it is possible to obtain an antenna gain in the front direction equivalent to that when all antenna elements are driven (fed). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] T. Takano, T. Imura, M. Okumura and Y. Kazama, "A Partially Driven Array Antenna with Parasitic Elements of 60% in Number", Proc. 2nd European Conference on Antennas and Propagation (EuCAP 2007), Edinburgh, UK, November 2007. Summary of the Invention

[0005] An array antenna according to one aspect of the present disclosure includes a conductive reflector and a plurality of antenna elements arranged in an array along the surface of the reflector. Each of the plurality of antenna elements includes an antenna element body having a first element and a second element, a conductive first support portion connected to an end of the first element and supporting the first element at a predetermined distance from the reflector, and a conductive second support portion connected to an end of the second element and supporting the second element at a predetermined distance from the reflector. The plurality of antenna elements include a plurality of powered antenna elements functioning as powered elements and a plurality of parasitic antenna elements functioning as parasitic elements, with the powered antenna elements and the parasitic antenna elements being adjacent to each other. The first support portion and the second support portion of the parasitic antenna elements are short-circuited at an inter-element gap between the first element and the second element or at a position away from the inter-element gap.

[0006] In the array antenna, the plurality of antenna elements to be fed may be staggered at a pitch of 1.0λ (λ: free space wavelength of the target radio wave) in two mutually perpendicular directions, the plurality of antenna elements to be unfed may be staggered at a pitch of 1.0λ in the two directions, and the antenna elements to be fed and the antenna elements to be unfed may be arranged alternately adjacent to each other in each of the two directions.

[0007] In the array antenna, the plurality of antenna elements to be fed may be arranged in a staggered pattern at a pitch of 1.0λ (λ: free space wavelength of the target radio wave) in two mutually perpendicular directions, the plurality of antenna elements to be unfed may be arranged consecutively at a pitch of 0.5λ in the two directions, and each of the plurality of antenna elements to be fed may be arranged in the center of an arrangement area of ​​four antenna elements to be unfed.

[0008] In the array antenna, the distance between the position where the first support portion and the second support portion are short-circuited and the position of the element gap portion may be 0.169λ or more and 0.221λ or less (λ: free space wavelength of the target radio wave).

[0009] In the array antenna, the reflecting member may be a square plate-like member having a plurality of individual reflector portions facing the plurality of antenna elements, the first element and the second element of the antenna element body may each be a columnar or cylindrical member having a diameter D of 0.02λ to 0.03λ, the overall length L of the antenna element body may be 0.4λ to 0.6λ, the height h of the first support portion and the second support portion may be 0.2λ to 0.3λ, and the width of the gap G between the first support portion and the second support portion may be 0.01λ to 0.02λ. [Brief explanation of the drawings]

[0010] [Figure 1] Fig. 1(a) is a perspective view showing an example of the basic configuration of antenna elements constituting an array antenna according to an embodiment, and Fig. 1(b) is an enlarged perspective view of an inter-element gap portion of the antenna element in Fig. 1(a) and its surrounding area. [Figure 2] 2(a) and 2(b) are a plan view and a perspective view, respectively, showing an example of an array antenna according to a reference example, and FIG. 2(c) is an explanatory diagram showing an example of the arrangement of feed elements in the array antenna according to the reference example. [Figure 3] 3(a) and 3(b) are explanatory diagrams each showing another example of the arrangement of feed elements in an array antenna according to a reference example. [Figure 4] Fig. 4(a) is a plan view showing an example of an array antenna according to an embodiment, and Fig. 4(b) is an explanatory diagram showing an example of the arrangement of feed elements and parasitic elements in the array antenna of Fig. 4(a). [Figure 5] 5(a) and 5(b) are explanatory diagrams each showing another example of the arrangement of the feed elements and the parasitic elements in the array antenna according to the embodiment. [Figure 6]6(a) and 6(b) are partial perspective views showing examples of short-circuited portions of parasitic elements in the array antenna according to the embodiment. [Figure 7] Fig. 7(a) is a plan view showing yet another example of the array antenna according to the embodiment, and Fig. 7(b) is an explanatory diagram showing an example of the arrangement of the feed elements and the parasitic elements in the array antenna of Fig. 7(a). [Figure 8] FIG. 8 is an explanatory diagram showing yet another example of the arrangement of feed elements and parasitic elements in the array antenna according to the embodiment. [Figure 9] 9(a) and 9(b) are explanatory diagrams each showing still another example of the arrangement of the feed elements and the parasitic elements in the array antenna according to the embodiment. [Figure 10] 10(a) and 10(b) are explanatory diagrams each showing another example of the arrangement of the feed elements and the parasitic elements in the array antenna according to the embodiment. [Figure 11] 11(a), 11(b), 11(c), and 11(d) are explanatory diagrams showing examples of the arrangement of elements of four types of array antennas in the first simulation. [Figure 12] 12(a), 12(b), 12(c), and 12(d) are explanatory diagrams showing examples of radiation characteristics (directional beam characteristics) of four types of array antennas in the first simulation. [Figure 13] FIG. 13 is an explanatory diagram showing the definition of the azimuth angle (Phi) in the horizontal plane (xy plane) in the simulation of the array antenna. [Figure 14] 14(a), 14(b), and 14(c) are graphs showing examples of main beam gain characteristics during beamforming when the azimuth angle (Phi) in the first simulation is 0 degrees, 45 degrees, and 90 degrees, respectively. [Figure 15] 15(a), 15(b), and 15(c) are graphs showing examples of main beam gain characteristics during beamforming when the azimuth angle (Phi) in the first simulation is 135 degrees, 225 degrees, and 315 degrees, respectively. [Figure 16] FIG. 16 is a graph showing an example of the relationship between the short-circuit positions of a plurality of parasitic elements of the array antenna and the gain of the main beam in the second simulation. [Figure 17] Figure 17(a) is a partial perspective view showing an example of the short-circuit position (h2) of the parasitic elements of the array antenna in the third simulation. Figure 17(b) is an explanatory diagram showing an example of the radiation characteristics (directional beam characteristics) of the array antenna having the parasitic elements of Figure 17(a). Figure 17(c) is an explanatory diagram showing an example of the current distribution in the array antenna having the parasitic elements of Figure 17(a). [Figure 18] Figure 18(a) is a partial perspective view showing another example of the short-circuit position (h2) of the parasitic elements of the array antenna in the third simulation. Figure 18(b) is an explanatory diagram showing an example of the radiation characteristics (directional beam characteristics) of the array antenna having the parasitic elements of Figure 18(a). Figure 18(c) is an explanatory diagram showing an example of the current distribution in the array antenna having the parasitic elements of Figure 18(a). [Figure 19] Fig. 19(a) is a partial perspective view showing the short-circuit position (h2) of a parasitic element in an array antenna according to a first example in the fourth simulation. Fig. 19(b) is an explanatory diagram showing an example of the arrangement of parasitic elements and fed elements in the array antenna according to the first example. Fig. 19(c) is an explanatory diagram showing an example of the electric field distribution in the array antenna according to the first example. [Figure 20] Fig. 20(a) is a partial perspective view showing the short-circuit position (h2) of a parasitic element in an array antenna according to a second example in the fourth simulation. Fig. 20(b) is an explanatory diagram showing an example of the arrangement of parasitic elements and fed elements in the array antenna according to the second example. Fig. 20(c) is an explanatory diagram showing an example of the electric field distribution in the array antenna according to the second example. [Figure 21]Fig. 21(a) is a partial perspective view showing the short-circuit position (h2) of a parasitic element in an array antenna according to a third example in the fourth simulation. Fig. 21(b) is an explanatory diagram showing an example of the arrangement of parasitic elements and fed elements in the array antenna according to the third example. Fig. 21(c) is an explanatory diagram showing an example of the electric field distribution in the array antenna according to the third example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each drawing merely schematically illustrates shapes, sizes, positional relationships, corresponding relationships, configurations, processing, steps, procedures, etc., to the extent that the contents of the present disclosure can be understood, and therefore the present disclosure is not limited to only the shapes, sizes, positional relationships, corresponding relationships, configurations, processing, steps, and procedures exemplified in each drawing. Furthermore, the numerical values ​​exemplified in the present disclosure are merely preferred examples, and therefore the present disclosure is not limited to the exemplified numerical values.

[0012] An antenna according to an embodiment of the present disclosure is a beamforming-capable array antenna (also referred to as a phased array antenna (PAA)) in which a plurality of antenna elements are arranged in an array and a signal of a predetermined phase and amplitude is supplied to each of the plurality of antenna elements to change the direction of a main beam of the antenna's directional characteristics. According to the array antenna of this embodiment, by configuring the plurality of antenna elements so that the fed elements (antenna elements to be fed) and the unfed parasitic elements (antenna elements to be unfed) are alternately adjacent to each other, it is possible to maintain beamforming characteristics and suppress increases in power consumption and heat generation that accompany an increase in the number of antenna elements. In particular, according to the array antenna of this embodiment, by optimizing the number and shape of the parasitic elements arranged in the array antenna, it is possible to suppress gain degradation and radiation characteristic disturbance during beamforming.

[0013] [Basic configuration of antenna elements] FIG. 1(a) is a perspective view showing an example of the basic configuration of an antenna element 100 constituting an array antenna according to an embodiment. In FIG. 1, the antenna element 100 is provided to correspond to an individual reflector portion 110A that forms part of the reflecting member of the array antenna. The antenna element 100 has a conductive antenna element body 120, a conductive first support portion 131, and a conductive second support portion 132. The antenna element body 120 has a first element 121 and a second element 122 that form a single dipole antenna. The first support portion 131 is connected to the longitudinal end of the first element 121 of the antenna element body 120 (the end portion toward the center of the antenna element body 120) and positions and supports the first element 121 at a position spaced a predetermined distance h above the individual reflector portion 110A of the reflecting member. The second support part 132 is connected to an end part (a center-side end part of the antenna element body 120) of the second element 122 of the antenna element body 120 in the longitudinal direction, and supports the second element 122 at a position spaced a predetermined distance h above the individual reflector portion 110A of the reflecting member 110. The antenna element body 120 has an inter-element gap S where the inner ends in the longitudinal direction of the first element 121 and the second element 122, which are connected to and supported by the first support part 131 and the second support part 132, face each other with a predetermined gap G between them. The inter-element gap S functions as a feeding point when the antenna element 100 is used as a feeding element.

[0014] The first element 121 and the second element 122 of the antenna element body 120 are each, for example, a columnar or cylindrical member having a predetermined diameter D, and may be a metal rod or metal pipe. The first support portion 131 and the second support portion 132 are each, for example, a columnar or cylindrical member having a predetermined diameter, and may be a metal rod or metal pipe. The first support portion 131 and the second support portion 132 may be members forming a signal transmission path. The diameter D of the first element 121 and the second element 122 is, for example, 0.02λ to 0.03λ, and may be 0.026λ. Here, λ is the free-space wavelength of the target radio wave to be transmitted, received, or transmitted and received by the array antenna (the same applies to the following examples). The target radio wave is, for example, a microwave (wavelength: 10 to 100 mm) or a millimeter wave (wavelength: 1 mm to 10 mm).

[0015] The lower ends of the first support portion 131 and the second support portion 132 may be fixed to the individual reflector portion 110A of the reflective member via an insulating member. For example, the lower end of the first support portion 131 may be connected to a transmitter, a receiver, or a transceiver, and the lower end of the second support portion 132 may be connected to the individual reflector portion 110A of the reflective member.

[0016] The total length L of the antenna element body 120 in the longitudinal direction is, for example, 0.4λ to 0.6λ, and may be 0.5λ or 0.41λ. The height h of the antenna element body 120, which is the distance between the antenna element body 120 and the individual reflector portion 110A of the reflecting member, is, for example, 0.2λ to 0.3λ, and may be 0.25λ or 0.26λ. The individual reflector portion 110A of the reflecting member is, for example, a square (Lr×Lr) plate-shaped member with each side having a predetermined length Lr (for example, 1.0λ) as shown in the figure.

[0017] The antenna element body 120 may be configured as a single dipole antenna, or may be configured as a cross dipole antenna made up of multiple dipole antennas that cross each other.

[0018] Fig. 1(b) is an enlarged perspective view of the inter-element gap S of the antenna element 100 of Fig. 1(a) and its surrounding area. In the inter-element gap S of the antenna element 100, a predetermined gap G is formed between the longitudinal end (the end toward the center of the antenna element body 120) of the first element 121 of the antenna element body 120 and the longitudinal end (the end toward the center of the antenna element body 120) of the second element 122. The width (gap length) of the gap G between the first element 121 and the second element 122 is, for example, 0.01λ to 0.02λ, and may be 0.0175λ.

[0019] The antenna element 100 can be configured as a fed antenna element that functions as a fed element to which a transmission signal can be fed, or as a parasitic antenna element that functions as a parasitic element to which a transmission signal is not fed. The array antenna of this embodiment is configured so that fed elements and parasitic elements, which have the antenna element 100 in the basic configuration shown in Figure 1(a), are adjacent to each other.

[0020] 2(a) and 2(b) are a plan view and a perspective view, respectively, showing an example of an array antenna 10 according to a reference example. FIG. 2(c) is an explanatory diagram showing an example of the arrangement of the feed elements 100A in the array antenna according to the reference example. The array antenna 10 of the reference example includes a total of 16 (=4 × 4) feed elements 100A arranged in an array above a reflecting member 110 as multiple antenna elements to be fed. The reflecting member 110 is a square, conductive, plate-like member with a predetermined side length (e.g., 2.5λ). The multiple feed elements 100A are arranged at a predetermined height h from the reflecting member 110 in the z direction in the figure, and at a predetermined pitch (e.g., 0.5λ) in the mutually orthogonal x and y directions. In the array antenna 10 of the reference example, power consumption and heat generation increase due to power being supplied to all of the multiple feed elements 100A. In particular, when the number of power supply elements 100A becomes large, such as 64 (= 8 × 8) and 144 (= 12 × 12), as in the reference examples of Figures 3(a) and 3(b), the power consumption and heat generation of the array antenna 10 further increase.

[0021] In the array antenna 10 of this embodiment, in order to suppress an increase in power consumption and heat generation, power-supply elements (antenna elements to be powered) and non-power-supply elements (antenna elements to be non-powered) are arranged alternately adjacent to each other, thereby performing thinning-out power supply.

[0022] [First example of array antenna configuration] FIG. 4(a) is a plan view showing an example of an array antenna 10 according to an embodiment. FIG. 4(b) is an explanatory diagram showing an example of the arrangement of feed elements 100A and parasitic elements 100B in the array antenna 10 of FIG. 4(a). The array antenna 10 of this example includes a total of 16 (=4 × 4) antenna elements (feed elements 100A and parasitic elements 100B) arranged in an array above a reflecting member 110. The reflecting member 110 is a square, conductive, plate-like member with a predetermined side length (e.g., 2.5λ). The multiple antenna elements (feed elements 100A and parasitic elements 100B) have a predetermined height h from the reflecting member 110 and are arranged at a predetermined pitch (e.g., 0.5λ) in the x and y directions that are orthogonal to each other.

[0023] A plurality of feed elements (antenna elements to be fed) 100A are arranged in a staggered pattern at a pitch of 1.0λ in two mutually orthogonal directions (x and y directions in the figure). A plurality of parasitic elements (antenna elements to be fed) 100B are arranged in a staggered pattern at a pitch of 1.0λ in the two directions (x and y directions). The feed elements 100A and the parasitic elements 100B are arranged so as to be alternately adjacent to each other in each of the two directions (x and y directions). In the array antenna 10 of this example, by arranging the feed elements 100A and the parasitic elements 100B so as to be alternately adjacent to each other and performing thinned feeding, it is possible to maintain the beamforming characteristics and suppress increases in power consumption and heat generation of the array antenna 10. In particular, in configurations in which the total number of antenna elements 100 is large, such as 64 (= 8 × 8) and 144 (= 12 × 12), as in the examples of Figures 5(a) and 5(b), the number of power supply elements 100A can be limited to 32 and 72, thereby suppressing increases in power consumption and heat generation of the array antenna 10.

[0024] Furthermore, the first support part 131 and the second support part 132 of the parasitic element 100B are short-circuited at the position of the element gap S between the first element 121 and the second element 122 of the antenna element body 120 or at a position spaced downward from the position of the element gap S. The first support part 131 and the second support part 132 can be short-circuited, for example, by connecting a conductive member such as a metal wire between the support members or by filling the gap between the support members with a conductive material.

[0025] By adjusting the short-circuit position of the parasitic element 100B, it is possible to weaken the current (current flowing in the opposite direction to that of the fed element 100A) that flows through the parasitic element 100B when the fed element 100A is fed, and to align the direction of the electric field generated in the parasitic element 100B with the direction of the electric field generated in the fed element 100A. This makes it possible to suppress gain degradation and disturbance of radiation characteristics during beamforming of the array antenna 10. In particular, even when the number of fed elements 100A is limited to 32 and 72 as in the examples of FIGS. 5(a) and 5(b), it is possible to suppress gain degradation and disturbance of radiation characteristics during beamforming of the array antenna 10 by adjusting the short-circuit positions of the first element 121 and the second element 122 in the parasitic element 100B.

[0026] 6(a) and 6(b) are partial perspective views showing an example of a short-circuit portion 123 of a parasitic element 100B in the array antenna 10 according to the embodiment. In Fig. 6(a), the first support portion 131 and the second support portion 132 of the parasitic element 100B are short-circuited at the position of the inter-element gap S between the first support portion 131 and the second support portion 132 and the first element 121 and the second element 122 of the antenna element body 120. In other words, the position of the short-circuit portion 123 of the parasitic element 100B is the position of the upper end of the first support portion 131 and the second support portion 132 in the height direction (+z direction).

[0027] 6(b), the first support portion 131 and the second support portion 132 of the parasitic element 100B are short-circuited at a position that is a predetermined distance h2 downward (in the −z direction) from the position of the inter-element gap S between the first support portion 131 and the second support portion 132 and the first element 121 and the second element 122 of the antenna element body 120. That is, the position of the short-circuit portion 123 of the parasitic element 100B is a position that is a predetermined distance h2 downward from the upper ends of the first support portion 131 and the second support portion 132 in the height direction (in the z direction). Here, the distance h2 between the position of the short-circuit portion 123 of the parasitic element 100B and the position of the inter-element gap S is, for example, not less than 0.169λ and not more than 0.221λ.

[0028] [Second example of array antenna configuration] FIG. 7(a) is a plan view showing yet another example of the array antenna 10 according to the embodiment. FIG. 7(b) is an explanatory diagram showing an example of the arrangement of the feed elements 100A and the parasitic elements 100B in the array antenna of FIG. 7(a). The array antenna 10 of this example includes a total of 33 antenna elements (8 feed elements 100A and 25 parasitic elements 100B) arranged in an array above a reflecting member 110. The reflecting member 110 is a square, conductive, plate-like member with a predetermined side length (e.g., 2.5λ). The multiple antenna elements (the feed elements 100A and the parasitic elements 100B) have a predetermined height h from the reflecting member 110 and are arranged at predetermined pitches (e.g., 1.0λ and 0.5λ) in the x and y directions, which are orthogonal to each other.

[0029] A plurality (8 = 2 × 2 × 2) of feed elements (antenna elements to be fed) 100A are arranged in a staggered pattern at a pitch of 1.0λ in two mutually orthogonal directions (x and y directions in the figure). A plurality (25 = 5 × 5) of parasitic elements (antenna elements to be fed) 100B are arranged consecutively at a pitch of 0.5λ in the two directions (x and y directions). Each of the plurality of feed elements 100A is arranged in the center of the arrangement area of ​​four adjacent parasitic elements 100B. In the array antenna 10 of this example, by arranging the feed elements 100A and the parasitic elements 100B adjacent to each other and performing thinned feeding, it is possible to maintain beamforming characteristics and suppress increases in power consumption and heat generation of the array antenna 10. In particular, in the array antenna 10 of this example, the number of parasitic elements 100B facing the reflecting member 110 (25 = 5 × 5 elements) can be made larger than that of the first configuration example (8 elements) described above, and in each of the multiple fed elements 100A, the distance between the fed element 100A and the four parasitic elements 100B that can generate an electric field in the same direction as the fed element 100A can be shortened. This improves the effect of suppressing gain degradation and disturbance in radiation characteristics during beamforming of the array antenna 10.

[0030] 7(a) and 7(b), the position of the short-circuit portion 123 of the parasitic element 100B can be set in the same manner as in the first configuration example. For example, in the array antenna 10 according to the second configuration example, the first support portion 131 and the second support portion 132 of the parasitic element 100B may be short-circuited at the position of the inter-element gap S between the first support portion 131 and the second support portion 132 and the first element 121 and the second element 122 of the antenna element body 120, as shown in FIG. 6(a). In other words, the position of the short-circuit portion 123 of the parasitic element 100B may be the position of the upper end of the first support portion 131 and the second support portion 132 in the height direction (+z direction).

[0031] Furthermore, in the array antenna 10 according to the second configuration example, the first support portion 131 and the second support portion 132 of the parasitic element 100B may be short-circuited at a position a predetermined distance h2 downward (in the −z direction) from the position of the inter-element gap S between the first support portion 131 and the second support portion 132 and the first element 121 and the second element 122 of the antenna element body 120, as shown in FIG. 6(b) above. That is, the position of the short-circuit portion 123 of the parasitic element 100B may be a predetermined distance h2 downward from the upper end of the first support portion 131 and the second support portion 132 in the height direction (in the z direction). Here, the distance h2 between the position of the short-circuit portion 123 of the parasitic element 100B and the position of the inter-element gap S is, for example, 0.169λ or more and 0.221λ or less.

[0032] 8 is an explanatory diagram showing yet another example of the arrangement of the feed elements 100A and the parasitic elements 100B in the array antenna 10 according to the embodiment. In the array antenna 10 of this example, no antenna elements (parasitic elements) are formed in the upper right and lower left areas 100C that are not adjacent to the feed elements 100A in the figure. This makes it possible to reduce the number of parasitic elements 100B compared to the configuration examples shown in FIGS. 7(a) and 7(b) while enhancing the effect of suppressing gain degradation and disturbance in radiation characteristics during beamforming of the array antenna 10.

[0033] 9(a) and 9(b) are explanatory diagrams showing still other examples of the arrangement of the feed elements 100A and the parasitic elements 100B in the array antenna 10 according to the embodiment. Fig. 9(a) is an example of a multi-element arrangement based on the element arrangement of Figs. 7(a) and 7(b), in which the number of feed elements 100A is increased to 32 (=4×4×2) and the number of parasitic elements 100B is increased to 81 (=9×9). Fig. 9(b) is an example of a multi-element arrangement based on the element arrangement of Figs. 7(a) and 7(b), in which the number of feed elements 100A is increased to 72 (=6×6×2) and the number of parasitic elements 100B is increased to 169 (=13×13). Even when the number of antenna elements (powered elements and parasitic elements) is increased to enhance the beamforming control function as shown in Figures 9(a) and 9(b), it is possible to suppress increases in power consumption and heat generation of the array antenna 10 while maintaining the beamforming characteristics, and it is also possible to improve the effect of suppressing gain degradation and disturbance of radiation characteristics during beamforming.

[0034] 10(a) and 10(b), an array antenna 10 with an increased number of antenna elements (feed elements and parasitic elements) may be configured so that no antenna elements (parasitic elements) are formed in areas 100C at the upper right and lower left that are not adjacent to the fed elements 100A in the figures. This makes it possible to reduce the number of parasitic elements 100B compared to the configuration examples shown in FIGS. 9(a) and 9(b), while improving the effect of suppressing gain degradation and radiation characteristic disturbance during beamforming of the array antenna 10.

[0035] Next, a computer simulation was performed on the beamforming characteristics of the array antenna 10 according to the embodiment. The basic configuration of the antenna elements 100 constituting the array antenna 10 for which this simulation was performed is the same as that shown in FIGS. 1(a) and 1(b), and the dimensions and shapes of each component were set as follows: The reflecting component 110 is a square plate-like component (reflecting component) with a side length of 2.5λ. The pitch of the antenna elements 100 in two mutually orthogonal directions (x direction and y direction) is 0.5λ. The first element 121 and the second element 122 of the antenna element body 120 are cylindrical components each having a diameter D of 0.026λ. The overall length L of the antenna element body 120 is 0.41λ, the height h of the first support portion 131 and the second support portion 132 is 0.26λ, and the width of the gap between the first support portion 131 and the second support portion 132 is 0.0175λ. The wavelength λ of the target radio wave was set to 7.69 mm.

[0036] [First simulation] Figures 11(a), 11(b), 11(c), and 11(d) are explanatory diagrams showing examples of element arrangements of four types of array antennas 10 in the first simulation. Figure 11(a) is an example of an all-element feed type array antenna 10 in which all 16 (=4 × 4) antenna elements are feed elements 100A, similar to Figures 2(a) to 2(c) described above. Figure 11(b) is an example of a thinned-feed type array antenna 10 in which 8 (=2 × 2 × 2) feed elements 100A are arranged in a staggered pattern and no parasitic elements are used. Figure 11(c) is an example of a thinned-feed type array antenna 10 in which 8 (=2 × 2 × 2) feed elements 100A are arranged in a staggered pattern and there are parasitic elements, similar to Figures 4(a) and 4(b) described above. In the array antenna 10 of Fig. 11(c), the short-circuit position (h2) of the parasitic elements 100B was not adjusted and h2 was set to 0 [mm]. Fig. 11(d) shows an example of a thinned-feed type array antenna 10, similar to Figs. 7(a) and 7(b) above, in which 8 (=2 × 2 × 2) fed elements 100A are arranged in a staggered pattern with a pitch of 1.0λ and 25 (=5 × 5) parasitic elements 100B are arranged continuously with a pitch of 0.5λ, improving the arrangement of the 25 (=5 × 5) parasitic elements 100B. In the array antenna 10 of Fig. 11(d), the short-circuit position (h2) of the parasitic elements 100B was adjusted and h2 was set to 1.4 [mm] (=0.182λ).

[0037] 12(a), 12(b), 12(c), and 12(d) are explanatory diagrams showing examples of radiation characteristics (also referred to as "radiation patterns" or "directional beam characteristics") of four types of array antennas 10 in the first simulation. FIG. 13 is an explanatory diagram showing the definition of the azimuth angle (Phi) in a horizontal plane (xy plane) in the simulation of the array antenna 10. The x direction of the azimuth angle (Phi) in the diagram is set to 0 degrees, and the counterclockwise direction is set to a positive angle. Furthermore, the elevation / depression angle (Theta) in a vertical plane (e.g., zx plane, zy plane) in the simulation of the array antenna 10 is set to 0 degrees in the z direction (forward in the diagram) and +90 degrees in the direction along the horizontal plane (xy plane).

[0038] Figure 12(a) shows the radiation characteristics (directional beam characteristics) of the array antenna 10 of Figure 11(a) with full element feed. In this array antenna 10, the side lobes SL generated around the main beam MB are small, and the radiation characteristics are only slightly disturbed. Figure 12(b) shows the radiation characteristics (directional beam characteristics) of the array antenna 10 of Figure 11(b) with thinned feed and no parasitic elements. In this array antenna 10, like the array antenna 10 of the full element feed type, the side lobes SL generated around the main beam MB are small, and the radiation characteristics are only slightly disturbed. Figure 12(c) shows the radiation characteristics (directional beam characteristics) of the array antenna 10 of Figure 11(c) with thinned feed and parasitic elements. In this array antenna 10, relatively large side lobes SL are generated around the main beam MB, and the radiation characteristics are only slightly disturbed. Fig. 12(d) shows the radiation characteristics (directional beam characteristics) of the thinned-feed type array antenna 10, in which the arrangement of the parasitic elements 100B in Fig. 11(d) has been improved and the short-circuit position (h2) of the parasitic elements 100B has been adjusted. In this array antenna 10, the occurrence of side lobes SL around the main beam MB is suppressed, and disturbances in the radiation characteristics are suppressed.

[0039] 14(a), 14(b), and 14(c) are graphs showing an example of main beam gain characteristics during beamforming when the azimuth angle (Phi) is 0 degrees, 45 degrees, and 90 degrees in the first simulation, respectively. 15(a), 15(b), and 15(c) are graphs showing an example of main beam gain characteristics during beamforming when the azimuth angle (Phi) is 135 degrees, 225 degrees, and 315 degrees in the first simulation, respectively. As shown in the simulation results of FIGS. 14(a) to 14(c) and 15(a) to 15(c), the main beam gains (C103 to C153) during beamforming of the thinned-out feed type array antenna 10 with parasitic elements in FIG. 11(c) are smaller than the main beam gains (C101 to C151) of the fully fed array antenna 10 over the entire elevation / depression angle (Theta) range from 0 degrees to 60 degrees. However, the fluctuation in main beam gain during beamforming of the thinned-out feed type array antenna 10 with parasitic elements shown in FIG. 11(c) is about the same as that of the full-element feed type array antenna 10.

[0040] Furthermore, as shown in the simulation results in Figures 14(a) to 14(c) and Figures 15(a) to 15(c), in the array antenna 10 of the thinned-out feed type with parasitic elements in which the element arrangement of the parasitic elements in Figure 11(d) has been improved and the short-circuit position has been adjusted, it is possible to significantly improve (suppress) the degradation of the main beam gain (C104 to C154) during beamforming over the entire elevation / depression angle (Theta) from 0 degrees to 40 degrees at any azimuth angle (Phi).

[0041] [Second simulation] 16 is a graph showing an example of the relationship between the short-circuit position of multiple parasitic elements 100B of the array antenna 10 and the gain of the main beam in the second simulation. The array antenna 10 in the second simulation is a thinned-feed type array antenna 10, similar to that shown in FIGS. 7(a) and 7(b) above, in which 8 (=2×2×2) fed elements 100A are arranged in a staggered pattern with a pitch of 1.0λ and 25 (=5×5) parasitic elements 100B are arranged continuously with a pitch of 0.5λ, with the arrangement of the 25 (=5×5) parasitic elements 100B improved. The position (h2) of the short-circuited portion 123 made of a metal wire of the parasitic elements 100B in the array antenna 10 was varied within a range of 0.5 mm (=0.065λ) to 1.7 mm (=0.221λ). The vertical axis in Fig. 16 represents the gain [dBi] when the elevation / depression angle (Theta) of the main beam of array antenna 10 is 0 degrees (when the direction of the main beam is perpendicular to the antenna surface). According to the results of the second simulation in Fig. 16, a gain of 16 [dBi] or more can be ensured when the position (h2) of short-circuit portion 123 of parasitic element 100B is within the range of 1.3 [mm] (=0.169λ) to 1.7 [mm] (=0.221λ).

[0042] [Third Simulation] Figure 17(a) is a partially enlarged perspective view showing an example of the short-circuit position (h2) of the parasitic element 100B of the array antenna 10 in the third simulation. Figure 17(b) is an explanatory diagram showing an example of the radiation characteristics (directional beam characteristics) of the array antenna 10 having the parasitic element 100B of Figure 17(a). Figure 17(c) is an explanatory diagram showing an example of the current distribution in the array antenna 10 having the parasitic element 100B of Figure 17(a). The array antenna 10 is a thinned-out feed type array antenna with parasitic elements, in which eight (= 2 × 2 × 2) feed elements 100A are arranged in a staggered pattern, similar to Figures 4(a) and 4(b) above. The arrows in Figure 17(c) indicate the direction and magnitude of the current flowing through the feed element 100A and the parasitic element 100B. The short-circuit position (h2) of the parasitic element 100B was set to 0.8 mm (0.104λ) (see the arrow in Figure 16). In this case, as shown in Figure 17(b), the side lobes SL generated around the main beam MB are large, causing disturbances in the radiation characteristics. This disturbance in the radiation characteristics occurs when the current I of the fed element 100A flows into the parasitic element 100B adjacent to the fed element 100A where the element gap (feed point) S is located, as shown in the area surrounded by the ellipse I in the current distribution in Figure 17(c). A The current I B This is due to the flow of

[0043] Figure 18(a) is a partially enlarged perspective view showing another example of the short-circuit position (h2) of the parasitic element 100B of the array antenna 10 in the third simulation. Figure 18(b) is an explanatory diagram showing an example of the radiation characteristics (directional beam characteristics) of the array antenna 10 having the parasitic element 100B of Figure 18(a). Figure 18(c) is an explanatory diagram showing an example of the current distribution in the array antenna 10 having the parasitic element 100B of Figure 18(a). The array antenna 10 is a thinned-out feed type array antenna with parasitic elements, in which eight (=2 × 2 × 2) feed elements 100A are arranged in a staggered pattern, similar to Figures 4(a) and 4(b) above. The arrows in Figure 18(c) indicate the direction and magnitude of the current flowing through the feed element 100A and the parasitic element 100B. The short-circuit position (h2) of the parasitic element 100B was set to 1.4 mm (0.182 λ) (see the arrow in FIG. 16). In this case, as shown in FIG. 18(b), the side lobes SL generated around the main beam MB are reduced, and the disturbance of the radiation characteristics is reduced. This reduction in disturbance of the radiation characteristics is due to the reverse current I generated in the parasitic element 100B, as shown in the area surrounded by the ellipse I in the current distribution in FIG. 18(c). B This is because it has become smaller.

[0044] [Fourth Simulation] FIG. 19(a) is a partial perspective view showing the short-circuit position (h2) of the parasitic element 100B of the array antenna 10 according to the first example in the fourth simulation. FIG. 19(b) is an explanatory diagram showing an example of the arrangement of the parasitic element 100B and the fed element 100A in the array antenna 10 according to the first example. FIG. 19(c) is an explanatory diagram showing an example of the electric field distribution in the array antenna 10 according to the first example. The arrows in FIG. 19(c) indicate the direction and magnitude of the electric field formed around the fed element 100A and the parasitic element 100B. As shown in FIG. 19(b), the array antenna 10 according to the first example is a thinned-out feed type array antenna with parasitic elements, in which eight (=2 × 2 × 2) fed elements 100A are arranged in a staggered pattern (see FIGS. 4(a) and 4(b) above). The position of the short-circuit portion 123 of the parasitic element 100B is the position of the upper end portion in the height direction (+z direction) of the first support portion 131 and the second support portion 132. In this case, the electric field E formed in the feed element as shown in the area surrounded by the ellipse E in the electric field distribution of FIG. A The electric field E B is formed in the parasitic element. This reverse electric field E B This makes it easier for the aforementioned disturbance in the radiation characteristics to occur.

[0045] FIG. 20(a) is a partial perspective view showing the short-circuit position (h2) of a parasitic element in an array antenna 10 according to a second example in the fourth simulation. FIG. 20(b) is an explanatory diagram showing an example of the arrangement of parasitic elements and fed elements in the array antenna 10 according to the second example. FIG. 20(c) is an explanatory diagram showing an example of the electric field distribution in the array antenna 10 according to the second example. The arrows in FIG. 20(c) indicate the direction and magnitude of the electric field formed around the fed element 100A and the parasitic element 100B. As shown in FIG. 20(b), the array antenna 10 according to the second example is a thinned-out feed type array antenna with parasitic elements, in which eight (=2 × 2 × 2) fed elements 100A are arranged in a staggered pattern (see FIGS. 4(a) and 4(b) above). However, the position (h2) of the short-circuit part 123 of the parasitic element 100B is 1.4 mm (0.182λ) from the upper end of the first support part 131 and the second support part 132 in the height direction (+z direction). In this case, the electric field E formed in the feed element is shown in the area surrounded by the ellipse E in the electric field distribution of FIG. A and the electric field E formed on the parasitic element B are oriented in the same direction, reducing the disturbance in the radiation characteristics described above.

[0046] Fig. 21(a) is a partial perspective view showing the short-circuit position (h2) of a parasitic element in an array antenna 10 according to a third example in the fourth simulation. Fig. 21(b) is an explanatory diagram showing an example of the arrangement of parasitic elements and fed elements in an array antenna 10 according to the third example. Fig. 21(c) is an explanatory diagram showing an example of the electric field distribution in an array antenna 10 according to the third example. The arrows in Fig. 21(c) indicate the direction and magnitude of the electric field formed around the fed element 100A and the parasitic element 100B. As shown in FIG. 21(b), the array antenna 10 of the third example is a thinned-feed type array antenna in which 8 (=2×2×2) feed elements 100A are arranged in a staggered pattern at a pitch of 1.0λ and 25 (=5×5) parasitic elements 100B are arranged continuously at a pitch of 0.5λ, improving the arrangement of the 25 (=5×5) parasitic elements 100B (see FIGS. 7(a) and 7(b) above). The position (h2) of the short-circuited portion 123 of the parasitic element 100B is 1.4 mm (0.182λ) from the upper end of the first support portion 131 and the second support portion 132 in the height direction (+z direction). In this case, too, the electric field E formed at the feed element is as shown in the area surrounded by the ellipse E in the electric field distribution of FIG. 21(c). A and the electric field E formed on the parasitic element B are oriented in the same direction, reducing the disturbance in the radiation characteristics described above.

[0047] As described above, according to the embodiment of the present disclosure, it is possible to maintain the beamforming characteristics of the array antenna 10 while suppressing the increase in power consumption and heat generation that accompanies an increase in the number of antenna elements of the array antenna 10, and furthermore, it is possible to suppress gain degradation and disturbance of radiation characteristics during beamforming.

[0048] In particular, according to an embodiment of the present disclosure, by adjusting at least one of the number, arrangement, and position (h2) of the parasitic elements 100B adjacent to the powered element 100A of the array antenna 10, the effect of suppressing gain degradation and disturbance of radiation characteristics during beamforming of the array antenna 10 can be improved.

[0049] The array antenna 10 disclosed herein can suppress increases in power consumption and heat generation, as well as suppress gain degradation and disturbances in radiation characteristics during beamforming, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote inclusive and sustainable industrialization, and promote industrial and technological innovation."

[0050] The array antenna 10 of the present disclosure can be used in a variety of fields, including terrestrial communications, satellite communications, weather and ship radar, mobile communications satellites, and remote power feeding using radio waves such as microwaves or millimeter waves. The array antenna 10 described in this specification can also be used in repeater-type or base station-type relay communication stations mounted on high altitude platform stations (HAPS) (also called "high altitude pseudo satellites") located in the sky, low earth orbit (LEO) satellites, geostationary orbit (GEO) satellites, etc.

[0051] It should be noted that the processing steps for signals transmitted and received by the array antenna 10 described herein and the components of the device and system including the array antenna can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

[0052] For hardware implementation, the processing units and other means used to implement the above steps and components in an entity (e.g., various wireless communication devices, Node Bs, terminals, hard disk drive devices, or optical disk drive devices) may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, computers, or combinations thereof.

[0053] Furthermore, with regard to firmware and / or software implementations, the means, such as a processing unit, used to realize the above components may be implemented with a program (e.g., code, such as procedures, functions, modules, instructions, etc.) that performs the functions described herein. In general, any computer / processor-readable medium tangibly embodying firmware and / or software code may be used to implement the means, such as a processing unit, used to realize the above steps and components described herein. For example, the firmware and / or software code may be stored in a memory and executed by a computer or processor, such as in a controller. The memory may be implemented within the computer or processor or external to the processor. Furthermore, the firmware and / or software code may be stored in a computer- or processor-readable medium, such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage device, etc. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

[0054] The medium may be a non-transitory recording medium. The program code may be in any format as long as it can be read and executed by a computer, processor, or other device or machine. For example, the program code may be in any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

[0055] Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. [Explanation of symbols]

[0056] 10: Array antenna 100: Antenna element 100A: Power supply element 100B: Parasitic element 100C: Area where no antenna elements are formed 110: Reflective member 110A: Individual reflector part 120: Antenna element body 121: First element 122: Second element 123: Short circuit 131: 1st support part 132:Second support part

Claims

1. A conductive reflective member; a plurality of antenna elements arranged in an array in a direction along the surface of the reflecting member, Each of the plurality of antenna elements includes an antenna element body having a first element and a second element, a conductive first support part connected to an end of the first element and positioning and supporting the first element at a position a predetermined distance away from the reflecting member, and a conductive second support part connected to an end of the second element and positioning and supporting the second element at a position a predetermined distance away from the reflecting member, the plurality of antenna elements include a plurality of antenna elements to be fed that function as fed elements and a plurality of antenna elements to be unfed that function as unfed elements, and the antenna elements to be fed and the antenna elements to be unfed are configured to be adjacent to each other; the first support portion and the second support portion of the parasitic antenna element are short-circuited at a position of an inter-element gap between the first element and the second element or at a position away from the inter-element gap, The plurality of antenna elements to be fed are arranged in a staggered pattern at a pitch of 1.0λ (λ: wavelength of the target radio wave) in two directions perpendicular to each other, The plurality of parasitic antenna elements are staggered at a pitch of 1.0λ in the two directions, The antenna elements to be fed and the antenna elements to be unfed are arranged alternately adjacent to each other in each of the two directions. An array antenna characterized by:

2. In the array antenna of claim 1, the first support portion and the second support portion of the antenna element to be parasitic are short-circuited at a position away from an inter-element gap between the first element and the second element, The distance between the position where the first support portion and the second support portion are short-circuited and the position of the element gap portion is 0.169λ or more and 0.221λ or less (λ: wavelength of the target radio wave). An array antenna characterized by:

3. A conductive reflective member; a plurality of antenna elements arranged in an array in a direction along the surface of the reflecting member, Each of the plurality of antenna elements includes an antenna element body having a first element and a second element, a conductive first support part connected to an end of the first element and positioning and supporting the first element at a position a predetermined distance away from the reflecting member, and a conductive second support part connected to an end of the second element and positioning and supporting the second element at a position a predetermined distance away from the reflecting member, the plurality of antenna elements include a plurality of antenna elements to be fed that function as fed elements and a plurality of antenna elements to be unfed that function as unfed elements, and the antenna elements to be fed and the antenna elements to be unfed are configured to be adjacent to each other; the first support portion and the second support portion of the parasitic antenna element are short-circuited at a position of an inter-element gap between the first element and the second element or at a position away from the inter-element gap, The plurality of antenna elements to be fed are arranged in a staggered pattern at a pitch of 1.0λ (λ: wavelength of the target radio wave) in two directions perpendicular to each other, The plurality of parasitic antenna elements are arranged continuously at a pitch of 0.5λ in the two directions, Each of the plurality of antenna elements to be fed is arranged at the center of an arrangement area of ​​four antenna elements to be unfed. An array antenna characterized by:

4. In the array antenna of claim 3, the first support portion and the second support portion of the antenna element to be parasitic are short-circuited at a position away from an inter-element gap between the first element and the second element, The distance between the position where the first support portion and the second support portion are short-circuited and the position of the element gap portion is 0.169λ or more and 0.221λ or less (λ: wavelength of the target radio wave). An array antenna characterized by:

5. A conductive reflective member; a plurality of antenna elements arranged in an array in a direction along the surface of the reflecting member, Each of the plurality of antenna elements includes an antenna element body having a first element and a second element, a conductive first support part connected to an end of the first element and positioning and supporting the first element at a position a predetermined distance away from the reflecting member, and a conductive second support part connected to an end of the second element and positioning and supporting the second element at a position a predetermined distance away from the reflecting member, the plurality of antenna elements include a plurality of antenna elements to be fed that function as fed elements and a plurality of antenna elements to be unfed that function as unfed elements, and the antenna elements to be fed and the antenna elements to be unfed are configured to be adjacent to each other; the first support portion and the second support portion of the antenna element to be parasitic are short-circuited at a position away from an inter-element gap between the first element and the second element, The distance between the position where the first support portion and the second support portion are short-circuited and the position of the element gap portion is 0.169λ or more and 0.221λ or less (λ: wavelength of the target radio wave). An array antenna characterized by:

6. The array antenna of claim 2, 4 or 5, the reflecting member is a square plate-like member having a plurality of individual reflector portions that the plurality of antenna elements face, The first element and the second element of the antenna element body are each a columnar or cylindrical member having a diameter D of 0.02λ to 0.03λ, The overall length L of the antenna element body is 0.4λ to 0.6λ, a height h of the first support portion and the second support portion is 0.2λ to 0.3λ; The width of the gap G between the first support portion and the second support portion is 0.01λ to 0.02λ. An array antenna characterized by:

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