Array antenna and antenna element

Abstract

This array antenna comprises a first antenna element and a second antenna element which send and receive radio waves, and a power supply line which supplies power to the first antenna element and the second antenna element in series. The first antenna element and the second antenna element each have a power supply element to which power is supplied from the power supply line and a non-power-supply element part which includes a non-power-supply element and which is provided opposite from the power supply element. The non-power-supply element in the non-power-supply element part of the first antenna element and the non-power-supply element in the non-power-supply element part of the second antenna element differ in number.

Description

Technical Field

[0001] The present invention relates to an array antenna and an antenna element.

Background Art

[0002] With the development of mobile communication, radio waves in frequency bands above the quasi-millimeter wave band with short wavelengths have come to be used. A microstrip antenna (MSA) fed with a microstrip line (MSL) as a feeding line can be manufactured in a small size, lightweight, and inexpensively by processing a printed circuit board, and an array antenna with various directivities can be designed by arraying.

[0003] Non-Patent Document 1 describes a linear array antenna fed in a series feeding method using a patch element having a non-feeding element and applied to the 28.0 GHz sub-millimeter wave band.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as a power supply method for each antenna formed into an array, there are a parallel power supply method using power supply lines branched in parallel by the number of antennas and a series power supply method for power supply with a single power supply line. In a frequency band equal to or higher than the quasi-millimeter wave band, the series power supply method that can reduce the antenna array interval is often used. However, an array antenna using the series power supply method has a narrow usable frequency ratio band of about several percent, and there is a demand for broadbanding for applications to high-speed communication such as 5G and suppression of characteristic deterioration in manufacturing errors. An object of the present invention is to provide an array antenna with a broadband series power supply method and the like.

Means for Solving the Problems

[0006] The array antenna to which the present invention is applied includes a first antenna element and a second antenna element that transmit and receive radio waves, and a power supply line that supplies power in series to the first antenna element and the second antenna element. The first antenna element and the second antenna element each have a power supply element supplied with power from the power supply line, and a non-powered element unit including a non-powered element provided facing the power supply element. The non-powered element in the non-powered element unit of the first antenna element and the non-powered element in the non-powered element unit of the second antenna element are characterized by having different numbers.

[0007] In such an array antenna, it can be characterized by having a substrate made of a dielectric material provided with a non-powered element unit of the first antenna element and a non-powered element unit of the second antenna element, and the power supply element of the first antenna element and the power supply element of the second antenna element are provided on the back side of the substrate or in contact with the back side of the substrate. Further, the substrate can be characterized by having a constant thickness.

[0008] And in such an array antenna, at least one of the non-powered element parts of the first antenna element and the second antenna element is provided separately with the H-plane at the center of the powered element as a boundary, and includes a plurality of non-powered elements including a set of non-powered elements excited in-phase in the fundamental mode. It can be characterized by that. Further, the plurality of non-powered elements can be characterized by including non-powered elements that are not separated with the H-plane as a boundary.

[0009] Furthermore, in such an array antenna, the plurality of non-powered elements can be characterized in that the volume between the non-powered elements and the powered element is larger than the volume when there is one non-powered element.

[0010] In such an array antenna, the non-powered element part of the first antenna element and the non-powered element part of the second antenna element can be characterized in that they overlap the feeding line in a plan view.

[0011] Also, in such an array antenna, it has another substrate made of a dielectric material, the feeding element is provided on the surface side of the other substrate, and the substrate and the other substrate are characterized in that the back surface side of the substrate and the surface side of the other substrate are overlapped.

[0012] In such an array antenna, the feeding line can be characterized by being a corner feeding fed from one end of the array where the antenna elements are arranged, or a central feeding fed in opposite directions from the center of the array. Also, when the feeding line is central feeding and radiates a polarization wave along the array direction or a polarization wave shifted by 45 degrees from the array direction, it can be characterized in that the phases of the powers fed in opposite directions from the center are shifted by 180 degrees.

[0013] And in such an array antenna, the feeding element can be characterized by being a slot or a patch.

[0014] Viewed from another perspective, the antenna element to which the present invention is applied includes a feeding element and a plurality of non-fed elements provided opposite to the feeding element, and the plurality of non-fed elements are separated by the H-plane at the central portion of the feeding element and include at least one set of non-fed elements that are excited in phase in the fundamental mode. Further, the plurality of non-fed elements can include non-fed elements that are not separated by the H-plane at the central portion of the feeding element.

[0015] And in such an antenna element, the plurality of non-fed elements include a substrate provided on the front surface side, and the feeding element is provided on the back surface side of the substrate or in contact with the back surface side.

[0016] Furthermore, in such an antenna element, the feeding element includes another substrate provided on the front surface side, and the substrate and the other substrate are characterized in that the back surface side of the substrate and the front surface side of the other substrate are overlapped.

[0017] And also, in such an antenna element, the feeding element can be a slot or a patch.

Advantages of the Invention

[0018] According to the present invention, a broadband series-fed array antenna or the like can be provided.

Brief Description of the Drawings

[0019]

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Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments (examples) of the present invention will be described in detail with reference to the accompanying drawings. Note that members having the same function may be denoted by the same reference numerals. In addition, some configurations may be given reference numerals, and the same configurations may not be given reference numerals. Hereinafter, the antenna (array antenna and antenna element) will be described as radiating, that is, transmitting radio waves. However, due to the reversibility of the antenna, radio waves can be received.

[0021] (Planar Antenna 100) FIG. 1 is a diagram for explaining a planar antenna 100 as an example of an application example of an array antenna 1 to which the present embodiment is applied. FIG. 1(a) is a plan view, and FIG. 1(b) is a diagram for explaining the radiation direction of radio waves. In FIG. 1(a), the right direction on the paper surface is the x direction, the upward direction on the paper surface is the y direction, and the surface direction of the paper surface is the z direction. In FIG. 1(b), the right direction on the paper surface is the x direction, the downward direction on the paper surface is the z direction, and the surface direction of the paper surface is the y direction. In FIG. 1(a), in addition to the planar antenna 100, a control unit 200 for controlling the planar antenna 100 is illustrated.

[0022] As shown in FIG. 1(a), the planar antenna 100 includes a plurality of array antennas 1 (eight in FIG. 1(a)). The plurality of array antennas 1 are arranged in parallel in the x direction. The array antenna 1 includes a plurality of antenna elements 10 (seven in FIG. 1(a)) and a feeding line 50. In the array antenna 1, the plurality of antenna elements 10 are linearly arranged in the y direction. And the feeding line 50 is connected in series to the plurality of antenna elements 10. Here, as an example, the feeding element 13 (see FIG. 3 described later) of the antenna element 10 is a slot, and the feeding line 50 is provided to overlap the antenna element 10 in a plan view so as to feed the slot. The feeding line 50 is connected to the control unit 200 at the end on the -y direction side. The control unit 200 supplies power for radiating radio waves to the antenna elements 10 included in the array antenna 1 to the feeding line 50 as shown by the white arrow. That is, the plurality of antenna elements 10 of the array antenna 1 are fed in a series feeding method by the feeding line 50. Note that the plan view means looking through the components (the antenna element 10 and the feeding line 50 in FIG. 1(a)) from the z direction. The same shall apply in other cases.

[0023] Since the antenna element 10 can radiate radio waves even when it is alone, it may be referred to as an antenna. In this specification, in order to distinguish it from the array antenna 1, it is referred to as the antenna element 10. The antenna element 10 may be called a radiating element.

[0024] Since the array antenna 1 has a plurality of antenna elements 10 fed by one feeding line 50 linearly arranged, it may be called a linear array antenna or a linear array. In the array antenna 1, the direction in which the antenna elements 10 are arranged (the +y direction in FIG. 1) is referred to as the array direction. In FIG. 1(a), the plurality of antenna elements 10 are linearly arranged in the y direction, but some of the antenna elements 10 may be arranged with a shift in the +x direction or the -x direction. For example, the plurality of antenna elements 10 may be arranged in a zigzag. Further, the plurality of antenna elements 10 may be arranged in an arc shape.

[0025] As shown in FIG. 1(b), when a plurality of array antennas 1 are fed in phase (without providing a phase difference), the planar antenna 100 radiates radio waves 300 in the z direction. On the other hand, when a phase difference is provided between the array antennas 1 for feeding, the direction in which the radio waves 300 are radiated can be tilted (tilted) to the -x direction side or the +x direction side as indicated by the arrow.

[0026] The planar antenna 100 in which a plurality of array antennas 1 are arranged in parallel has been described as an application example using the array antenna 1. The array antenna 1 may be used alone. Hereinafter, the array antenna 1 will be described.

[0027] (Series feeding method) FIG. 2 is a diagram for explaining the feeding method of the array antenna 1. FIG. 2(a) shows the array antenna 1 of the series feeding method, and FIG. 2(b) shows the array antenna 1' of the parallel feeding method. The x, y, and z directions are the same as those in FIG. 1(a). Hereinafter, the array antennas 1, 1', etc. may be denoted without attaching symbols to the array antennas. Similarly, the antenna elements 10, etc. may be denoted without attaching symbols to the antenna elements. The same applies to other terms.

[0028] FIG. 2(a) shows two array antennas 1 of the series feeding method arranged in parallel. The array antenna 1 includes a plurality of antenna elements 10 (antenna elements 10-1 to 10-4 in FIG. 2(a)) and a feeding line 50. As described above, the plurality of antenna elements 10 are arranged on the feeding line 50 along the feeding line 50. As indicated by the white arrow, the feeding line 50 is fed in the y direction from the end on the -y direction side.

[0029] In the series feeding method, a plurality of antenna elements 10 are fed by one feeding line 50. Specifically, as shown in FIG. 4 described later, the supplied power is sequentially distributed to the antenna elements 10 along the feeding line 50. Among the power supplied to the antenna element 10-1, the power radiated as radio waves by the antenna element 10-1subsequent The remaining power is supplied to the antenna element 10-2 side. Next, the power radiated as radio waves by the antenna element 10-2 subsequent The remaining power is supplied to the antenna element 10-3 side. That is, to the antenna element 10 connected in series to the power supply line 50 in is the power radiated as radio waves by the upstream antenna element 10 to which power is supplied subsequent The remaining power is supplied to the downstream antenna element 10. In this way, power is sequentially supplied to all the antenna elements 10 connected to the power supply line 50.

[0030] Let the interval (distance) between the two array antennas 1 arranged in parallel be interval P1. In series power feeding, even if the number of antenna elements 10 constituting the array antenna 1 increases, the interval P1 does not change. For example, the interval P1 is set to 0.5λ to 1.0λ when the center wavelength is λ. When the frequency is 28 GHz, the interval P1 is 5.4 mm to 10.7 mm. Also, when the frequency is 60 GHz, the interval P1 is 2.5 mm to 5 mm.

[0031] Figure 2(b) shows two array antennas 1' of the parallel power feeding method arranged in parallel. The array antenna 1' of the parallel power feeding method includes a plurality of antenna elements 10' (antenna elements 10'-1 to 10'-4 in Figure 2(b)) and a power supply line 50'. The power supply line 50' is branched in a tournament method. And the antenna element 10' is connected to the end branched in the tournament method. As shown by the white arrow, the power supply line 50' is supplied with power from the end on the -y direction side.

[0032] In the parallel power feeding method, the power supply line 50' is set so that the lengths from the end to which power is supplied to the antenna element 10' are the same. Therefore, in parallel power feeding, power is supplied in parallel to a plurality of antenna elements 10'.

[0033] Let the distance (interval) between two array antennas 1' arranged in parallel be interval P2. In the parallel feeding method, since the feeding line 50' is branched in a tournament method, the feeding line 50' is provided in the gap between the array antennas 1'. For this reason, the interval P2 becomes larger than the interval P1 between the two array antennas 1 in the series feeding method shown in Fig. 2(a) (P1 < P2). And, the more the number of antenna elements 10' constituting the array antenna 1' increases, the larger the scale of the feeding line 50' becomes, and the interval P2 becomes larger.

[0034] As described above, for example, when arranging a plurality of array antennas in parallel like the planar antenna 100 shown in Fig. 1, the scale of the feeding line 50 of the series feeding method becomes smaller than that of the feeding line 50' of the parallel feeding method. In other words, the interval P1 between the array antennas 1 of the series feeding method becomes smaller than the interval P2 between the array antennas 1' of the parallel feeding method, and the planar antenna 100 becomes smaller.

[0035] Note that in the series feeding method, as the excitation method of the antenna element 10 in the array antenna 1, there are a traveling wave type and a standing wave type. The standing wave type is a method of designing the antenna element 10 with the entire array antenna 1 as a unit. In contrast, the traveling wave type is a method of designing the antenna element 10 of the array antenna 1 as a unit. In the traveling wave type, since the characteristics can be adjusted for each antenna element 10, the array antenna 1 is easy to design. Hereinafter, the array antenna 1 will be described assuming that it is of the traveling wave type.

[0036] (Array Antenna 1) FIG. 3 is a diagram for explaining an example of the array antenna 1 to which the present embodiment is applied. FIG. 3(a) is a perspective view, and FIG. 3(b) is a cross-sectional view of the portion surrounded by the dashed-dotted line in FIG. 3(a). In FIG. 3(a), the short side direction of the array antenna 1 is the x direction, the long side direction is the y direction, and the direction perpendicular to the x-y plane is the z direction. In FIG. 3(b), the right direction of the paper surface is the y direction, the upward direction of the paper surface is the z direction, and the surface direction of the paper surface is the x direction. The array antenna 1 may be denoted as an example. The y direction is the direction perpendicular to the ground surface (vertical direction), and the x direction is the direction horizontal to the ground surface (horizontal direction).

[0037] As shown in FIG. 3(a), the array antenna 1 includes ten antenna elements 10 (antenna elements 10-1U to 10-5U, 10-1D to 10-5D) and feeding lines 50 (feeding lines 50U, 50D). Each of the antenna elements 10-1U to 10-5U, 10-1D to 10-5D includes a substrate 11 made of a dielectric material, a ground conductor 12 made of a conductive material, feeding elements 13-1U to 13-5U, 13-1D to 13-5D, a substrate 14 made of a dielectric material, and non-feeding element portions 15-1U to 15-5U, 15-1D to 15-5D made of a conductive material. For example, the antenna element 10-1U includes the substrate 11, the ground conductor 12, the feeding element 13-1U, the substrate 14, and the non-feeding element portion 15-1U. When the feeding elements 13-1U to 13-5U, 13-1D to 13-5D are not distinguished from each other, they are denoted as the feeding element 13, and when the non-feeding element portions 15-1U to 15-5U, 15-1D to 15-5D are not distinguished from each other, they are denoted as the non-feeding element portion 15.

[0038] As shown in Fig. 3(a), the array antenna 1 has ten antenna elements 10 arranged in the +y direction (array direction) in the order from antenna element 10-5D to antenna element 10-5U. The array antenna 1 is symmetrically configured in the ±y directions with the central portion in the array direction (+y direction) as the boundary. And the feeding line 50U feeds power from the central portion in the array direction (+y direction) to the +y direction (array direction side), and the feeding line 50D feeds power from the central portion in the array direction (+y direction) to the -y direction (reverse array direction side). That is, the feeding line 50U and the feeding line 50D feed power in opposite directions. And as an example, the feeding line 50U and the feeding line 50D supply power with inverted phases (shifted by 180 degrees). In Fig. 3(a), the feeding line 50U is denoted as +1 in the white arrow, and the feeding line 50D is denoted as -1 in the white arrow. This is denoted as central feeding. As described above, U is attached to the +y direction side and D is attached to the -y direction side for distinction.

[0039] The ground conductor 12 is provided on the surface side (+z direction side surface) of the substrate 11. The ground conductor 12 is set to a reference potential (for example, ground potential). The feeding element 13 is an opening (slot) provided by removing the ground conductor 12. Hereinafter, the feeding element 13 is denoted as the feeding element (slot) 13. The feeding line 50 is provided on the back surface side (-z direction side surface) of the substrate 11. The feeding line 50U is provided so as to overlap the feeding elements 13-1U to 13-5U in plan view. The feeding line 50D is provided so as to overlap the feeding elements 13-1D to 13-5D in plan view. Note that the feeding elements 13-1U to 13-4U and 13-1D to 13-4D are rectangular slots with the x direction as the longitudinal direction and the y direction as the short direction, and the feeding elements 13-5U and 13-5D are H-shaped slots provided with rectangles with the y direction as the longitudinal direction and the x direction as the short direction at both ends of the rectangle. The plurality of feeding elements 13 are manufactured collectively on the substrate 11. Note that the surface side of the substrate 11 may be the surface of the substrate 11, or when another member is provided on the surface of the substrate 11, it may be the surface of the other member. The same applies to the back surface side.

[0040] The non-powered element section 15 is provided on the surface side (the surface on the +z direction side) of the substrate 14. The non-powered element sections 15-1U, 15-2U, 15-1D, and 15-2D each have one non-powered element. The non-powered element sections 15-3U, 15-4U, 15-3D, and 15-4D each have five non-powered elements. The non-powered element sections 15-5U and 15-5D each have four non-powered elements. The plurality of non-powered element sections 15 are manufactured collectively on the substrate 14. Note that the surface side of the substrate 14 may be the surface of the substrate 14 or the surface of another member provided on the surface of the substrate 14. And the non-powered element section 15, when including a plurality of non-powered elements, refers to the region where the plurality of non-powered elements are provided. More specifically, as shown by the dashed line in FIG. 4(a) described later, it refers to the region surrounding the outer edges of the plurality of non-powered elements.

[0041] In the perspective view of FIG. 3(a), a space is provided between the ground conductor 12 (power feeding element 13) provided on the surface side of the substrate 11 and the substrate 14 provided with the non-powered element section 15 for explanation of the structure. However, as shown in FIG. 3(b), no space is provided between the ground conductor 12 provided on the surface side of the substrate 11 and the substrate 14. when Furthermore, the array antenna 1 is configured by overlapping two substrates 11 and 14. Therefore, the array antenna 1 used in a frequency band of the quasi-millimeter wave band or higher has a lower profile, a simple structure, and is easy to manufacture. Note that the surface side of the substrate 11 may be the surface of the substrate 11 or the surface of another member provided on the surface of the substrate 11.

[0042] In the antenna element 10-1U shown as an example in FIG. 3(b), a power feeding line 50 is provided on the back surface side (the surface on the -z direction side) of the substrate 11, and a ground conductor 12 is provided on the surface side (the surface on the +z direction side) of the substrate 11. A slot that functions as the power feeding element 13-1U is provided in the ground conductor 12. As described above, the power feeding line 50 and the power feeding element (slot) 13-1U face each other with the substrate 11 interposed therebetween. The non-powered element section 15 is provided on the surface side (the surface on the +z direction side) of the substrate 14. U is provided, and a ground conductor 12 is provided on the surface side (the surface on the +z direction side) of the substrate 11. A slot that functions as the power feeding element 13-1U is provided in the ground conductor 12. As described above, the power feeding line 50 U and the power feeding element (slot) 13-1U face each other with the substrate 11 interposed therebetween. The non-powered element section 15 is provided on the surface side (the surface on the +z direction side) of the substrate 14. -1Uis provided. The surface side of the substrate 11 where the ground conductor 12 is provided and the back side of the substrate 14 are bonded together by an insulating adhesive sheet (bonding sheet) 16. As a result, the power feeding element 13-1U and the non-power feeding element portion 15-1U face each other with the substrate 14 interposed therebetween. That is, the power feeding element 13-1U is provided in contact with the back side of the substrate 14 on which the non-power feeding element portion 15-1U is provided. Here, the adhesive sheet 16 is used. However, the substrate 11 provided with the power feeding element (slot) 13 on the surface side and the substrate 14 provided with the non-power feeding element portion 15 on the surface side may be overlapped so that there is no space (gap) between the surface side of the substrate 11 and the back side of the substrate 14. That is, the power feeding element (slot) 13 is provided in contact with the back side of the substrate 14 (the adhesive sheet 16 side in FIG. 3(b)) on which the non-power feeding element portion 15-1U is provided -1U only needs to be provided. Note that the ground conductor 12 may be provided on the back side of the substrate 14.

[0043] As described above, in a plan view, the power feeding line 50U, the power feeding elements (slots) 13-1U to 13-5U, and the non-power feeding element portions 15-1U to 15-5U are provided so as to overlap. Also, in a plan view, the power feeding line 50D, the power feeding elements (slots) 13-1D to 13-5D, and the non-power feeding element portions 15-1D to 15-5D are provided so as to overlap. That is, in a plan view, the power feeding line 50, the power feeding elements (slots) 13, and the non-power feeding element portion 15 are provided so as to overlap. The power feeding element (slot) 13 is fed power from the power feeding line 50, and the non-power feeding elements in the non-power feeding element portion 15 are excited by being electromagnetically coupled with the power feeding element 13.

[0044] In the above, the substrate 11, the ground conductor 12, and the substrate 14 are continuous between the antenna elements 10 in the array antenna 1. Here, it is assumed that the antenna elements 10 are provided with the substrate 11, the ground conductor 12, and the substrate 14 for each antenna element 10.

[0045] A power supply line 50 is provided on the back side of the substrate 11, and a ground conductor 12 is provided on the front side of the substrate 11. The power supply line 50 constitutes a microstrip line (MSL). Further, since the feeding element 13 is a slot, the antenna element 10 is a microstrip antenna (MSA). Note that since the antenna element 10 includes a non-feeding element portion 15 having a non-feeding element, the antenna element 10 may be called a microstrip antenna (MSA) with a non-feeding element. The microstrip antenna (MSA) can be made broadband by providing a non-feeding element.

[0046] In the array antenna 1, the shape of the power supply line 50, the shape of the feeding element (slot) 13, and the number of non-feeding elements in the non-feeding element portion 15 are changed for each antenna element 10. This is because broadbanding cannot be achieved in an array antenna in which antenna elements having the same configuration are arranged.

[0047] In the array antenna 1 to which the present embodiment is applied, the number of non-feeding elements included in the non-feeding element portion 15 in the antenna element 10 is different between the antenna elements 10. Any one of the antenna elements 10-1U to 10-2U, 10-1D to 10-2D having one non-feeding element is an example of the first antenna element, and any one of the antenna elements 10-3U to 10-4U, 10-3D to 10-4D having five non-feeding elements and the antenna elements 10-5U, 10-5D having four non-feeding elements is an example of the second antenna element. Also, any one of the antenna elements 10-3U to 10-4U, 10-3D to 10-4D having five non-feeding elements may be an example of the first antenna element, and the antenna elements 10-5U, 10-5D having four non-feeding elements may be an example of the second antenna element. One of the two antenna elements 10 in which the number of non-feeding elements in the non-feeding element portion 15 is different from each other is an example of the first antenna element, and the other is an example of the second antenna element. Also, the substrate 14 is an example of a substrate, and the substrate 11 is an example of another substrate.

[0048] FIG. 4 is a diagram for explaining the shape and dimensions of the wireless power feeding element of the wireless power feeding element unit 15 included in the array antenna 1 to which the present embodiment is applied. FIG. 4(a) shows the planar shape of the wireless power feeding element units 15-1U, 15-2U, 15-1D, and 15-2D each having one wireless power feeding element. FIG. 4(b) shows the planar shape of the wireless power feeding element units 15-3U, 15-4U, 15-3D, and 15-4D each having five wireless power feeding elements. FIG. 4(c) shows the planar shape of the wireless power feeding element units 15-5U and 15-5D each having four wireless power feeding elements. FIG. 4(d) shows the dimensions of the wireless power feeding element. In FIGS. 4(a) to 4(c), the horizontal direction of the paper surface is the x direction, the upward direction of the paper surface is the y direction, and the surface direction of the paper surface is the z direction. In FIG. 4(d), the unit of the dimensions of the wireless power feeding element is mm. Here, the design center frequency of the array antenna 1 is set to 28.5 GHz.

[0049] The substrate 11 is, for example, a printed circuit board with a thickness t1 of 0.127 mm and a relative dielectric constant of 2.19. The substrate 14 is, for example, a high-frequency printed circuit board with a thickness t2 of 0.76 mm and a relative dielectric constant of 3.3. The conductive material is, for example, copper (Cu). The conductive material may be copper (Cu), aluminum (Al), silver (Ag), gold (Au), or an alloy containing these.

[0050] FIG. 4(a) shows one wireless power feeding element. The wireless power feeding element has a rectangular planar shape, with the width in the x direction being width W H and the width in the y direction being width W E . The same applies to the wireless power feeding elements in FIGS. 4(b) and 4(c). Note that H indicates the magnetic field direction and E indicates the electric field direction. FIG. 4(d) shows the dimensions (element dimensions (mm)) of one wireless power feeding element (referred to as one wireless power feeding element) of the wireless power feeding element units 15-1U, 15-2U, 15-1D, and 15-2D.

[0051] Figure 4(b) shows five passive elements. Two sets of two passive elements arranged in the y direction are disposed at the ends in the ±x directions, and one passive element is disposed at the center in the x direction. The four passive elements disposed at the ends in the ±x directions are referred to as corner elements, and the passive element disposed at the center in the x direction is referred to as a center element. The planar shapes of the four corner elements are the same. The distance in the y direction between the two passive elements arranged in the y direction is defined as gap G E and the distance in the x direction between the two sets of two passive elements arranged in the y direction is defined as gap G H . Then, in Fig. 4(d), for the five passive elements (a plurality of passive elements) of 15-3U, 15-4U, 15-3D, and 15-4D having five passive elements, the dimensions of the corner elements (corner element dimensions (mm)), the dimensions of the center element (center element dimensions (mm)), gap G H , G E (gap (mm)) are shown.

[0052] Figure 4(c) shows four passive elements. Two sets of two passive elements arranged in the y direction are arranged in the x direction. These four passive elements are referred to as corner elements. The planar shapes of the four corner elements are the same. The distance in the y direction between the passive elements is defined as gap G E and the distance in the x direction between the passive elements is defined as gap G H . Then, in Fig. 4(d), for the four passive elements (a plurality of passive elements) of 15-5U and 15-5D having four passive elements, the dimensions of the corner elements (corner element dimensions (mm)), gap G H , G E (gap (mm)) are shown.

[0053] Fig. 5 is a diagram showing an array antenna 2 to which the present embodiment is not applied for comparison. Fig. 5(a) is a perspective view, and Fig. 5(b) is a cross-sectional view of the portion surrounded by the dashed-dotted line in Fig. 5(a). The array antenna 2 may be denoted as a comparative example. The xyz directions in Figs. 5(a) and 5(b) are the same as those in Figs. 3(a) and 3(b).

[0054] As shown in FIG. 5(a), the array antenna 2 includes ten antenna elements 20 (antenna elements 20-1U to 20-5U, 20-1D to 20-5D) and power supply lines 60 (power supply lines 60U, 60D). Each of the antenna elements 20-1U to 20-5U, 20-1D to 20-5D includes a substrate 11 made of a dielectric material, a ground conductor 12 made of a conductive material, power supply elements 23-1U to 23-5U, 23-1D to 23-5D, a substrate 14 made of a dielectric material, and non-powered element portions 25-1U to 25-5U, 25-1D to 25-5D made of a conductive material. When not distinguishing the power supply elements 23-1U to 23-5U, 23-1D to 23-5D from each other, they are denoted as the power supply element 23, and when not distinguishing the non-powered element portions 25-1U to 25-5U, 25-1D to 25-5D from each other, they are denoted as the non-powered element portion 25.

[0055] As shown in FIG. 5(a), in the array antenna 2, ten antenna elements 20 are arranged in the +y direction (array direction) in the order from the antenna element 20-5D to the antenna element 20-5U. The array antenna 2 is symmetrically configured in the ±y directions with the central portion in the array direction (+y direction) as a boundary.

[0056] The ground conductor 12 is provided on the surface side (+z direction side) of the substrate 11. The power supply element 23 of the antenna element 20 (antenna elements 20-1U to 20-5U, 20-1D to 20-5D) is an opening (slot) provided by removing the ground conductor 12. The power supply line 60 is provided on the back surface side (-z direction side) of the substrate 11. The power supply element (slot) 23 and the power supply line 60 are the same as the power supply element (slot) 13 and the power supply line 50 of the array antenna 1, but the dimensions are different in part.

[0057] The power feeding element portion 25 of the antenna element 20 (antenna elements 20-1U to 20-5U, 20-1D to 20-5D) is provided on the surface (+z-direction side surface) of the substrate 14. And the power feeding element portion 25 is different from the power feeding element portion 15 of the antenna element 10 in the array antenna 1. The power feeding element portions 25-1U to 25-5U, 25-1D to 25-5D each have one power feeding element.

[0058] FIG. 6 is a diagram for explaining the shape and dimensions of the power feeding element included in the power feeding element portion 25 of the antenna element 20 included in the array antenna 2 to which the present embodiment is not applied. FIG. 6(a) is the planar shape of the power feeding element portion 25 having the power feeding element, and FIG. 6(b) shows the dimensions of the power feeding element. The xyz directions in FIG. 6(a) are the same as those in FIG. 4(a). In FIG. 6(b), the dimensions of the power feeding element are shown in mm. Here too, the array antenna 2 has a design center frequency set to 28.5 GHz.

[0059] As described above, each of the power feeding elements included in the power feeding element portion 25 of the antenna element 20 in the array antenna 2 is one. Note that the power feeding elements included in the power feeding element portions 25-1U, 25-2U, 25-1D, and 25-2D have the same dimensions as the power feeding elements included in the power feeding element portions 15-1U, 15-2U, 15-1D, and 15-2D of the antenna element 10 in the array antenna 1.

[0060] FIG. 7 is a diagram for explaining the relative radiated power and radiation performance set for the antenna element 10 (antenna elements 10-1U to 10-5U, 10-1D to 10-5D) of the array antenna 1 and the antenna element 20 (antenna elements 20-1U to 20-5U, 20-1D to 20-5D) of the array antenna 2. The relative radiated power has a side lobe level S.L.L. (Side Lobe Level) set to about -25 dB. Note that the relative radiated power is the relative amount when the input power is 1.

[0061] In FIG. 7, the relative radiated power is set such that in the array antenna 1, the central portion (antenna elements 10-1U, 10-1D) is large and decreases toward the end side (antenna elements 10-5U, 10-5D). That is, the relative radiated power is set such that the antenna elements 10-1U, 10-1D radiate 37%, the antenna elements 10-2U, 10-2D radiate 30%, and the remaining antenna elements 10-3U to 10-5U, 10-3D to 10-5D radiate 33%. And in the array antenna 1, the antenna elements 10 with U and the antenna elements 10 with D are symmetrically set. The same applies to the array antenna 2.

[0062] On the other hand, the radiation performance is the ratio of the power radiated as radio waves out of the power input to the antenna elements 10, 20. The relative radiated power and the radiation performance will be described for the antenna element 10 with U in the array antenna 1. Out of the input 100% power, the antenna element 10-1U radiates 37% which is the relative radiated power. Therefore, the radiation performance of the antenna element 10-1U is 37%. The subsequent remaining power is 63%. The antenna element 10-2U radiates 47% from the 63% power. Therefore, the relative radiated power radiated by the antenna element 10-2U is 1×0.63×0.47 = 0.3 with the input power taken as 1. In this way, the radiation performance of the antenna elements 10-3U to 10-5U is set. Note that for the antenna element 10-5U, the relative radiated power is 0.06 and since it radiates all of the input power, the radiation performance is 100%.

[0063] FIG. 8 is a diagram showing the radiation characteristics (designed values) and reflection characteristics of the array antennas 1 and 2. FIG. 8(a) shows the radiation characteristics (designed values), and FIG. 8(b) shows the reflection characteristics. The radiation characteristics (designed values) in FIG. 8(a) are the radiation characteristics in the x-z plane at the central part in the y direction of the array antenna 1 in FIG. 3(a). The horizontal axis represents the angle [deg.] with the z direction being 0 degrees, and the vertical axis represents the relative intensity [dB]. FIG. 8(b) shows the reflection characteristics in the z direction, where the horizontal axis is the frequency [GHz] and the vertical axis is S11 [dB] of the S parameter. Note that S11 is sometimes called return loss.

[0064] As shown in FIG. 8(a), as described above, the side lobe level S.L.L. of the array antennas 1 and 2 is designed to be about -25 dB.

[0065] As shown in FIG. 8(b), the reflection characteristics of the array antenna 1 are such that, compared with the array antenna 2, S11 is smaller on the lower frequency side (27 GHz side) and the higher frequency side (30 GHz side) across 28.5 GHz. And in the range from 27 GHz to 30 GHz, S11 is suppressed to -10 dB or less. When calculating the frequency ratio bandwidth from this frequency range, it can be seen that the frequency ratio bandwidth is 10% or more. Note that the frequency ratio bandwidth is the ratio of the difference between the minimum frequency and the maximum frequency at which the return loss is -10 dB or less to the average value of the minimum frequency and the maximum frequency.

[0066] The array antenna 1 has a wider bandwidth compared with the array antenna 2. This is because the number of parasitic elements in the parasitic element part 15 of the array antenna 1 is different between the antenna elements 10. That is, the array antenna 1 is provided with a parasitic element part 15 having a plurality of parasitic elements, such as the parasitic element parts 15-3U, 15-4U, 15-5U, 15-3D, 15-4D, 15-5D shown in FIG. 3.

[0067] Fig. 9 shows the directivity characteristics in the vertical (E) plane of the array antenna 1 to which the present embodiment is applied. Fig. 9(a) shows the case where the frequency is 27.5 GHz, Fig. 9(b) shows the case where the frequency is 28.5 GHz, and Fig. 9(c) shows the case where the frequency is 29.5 GHz. Here, the vertical plane is the y-z plane in Fig. 3 and is the direction perpendicular to the ground surface. The radio wave radiated by the array antenna 1 is vertically polarized. Note that the cross polarization is not shown because it is -60 dB or less. Cross polarization polarization is the horizontal polarization that intersects the vertical polarization. In Figs. 9(a) to (c), the horizontal axis is the angle [deg.] with the z direction being 0 degrees, and the vertical axis is the relative intensity [dB].

[0068] As shown in Figs. 9(a) to (c), the side lobes of the array antenna 1 are suppressed to about -25 dB for any frequency.

[0069] Fig. 10 shows the directivity characteristics in the horizontal (H) plane of the array antenna 1 to which the present embodiment is applied. Fig. 10(a) shows the case where the frequency is 27.5 GHz, Fig. 10(b) shows the case where the frequency is 28.5 GHz, and Fig. 10(c) shows the case where the frequency is 29.5 GHz. Here, the horizontal plane is the x-z plane in Fig. 3 and is the plane parallel to the ground surface. Note that the cross polarization is not shown because it is -60 dB or less. In Figs. 10(a) to (c), the horizontal axis is the angle [deg.] with the z direction being 0 degrees, and the vertical axis is the relative intensity [dB].

[0070] When the beam width is defined at -3 dB, as shown in Figs. 10(a) to (c), a beam width of approximately 75 degrees is obtained for any frequency.

[0071] (Antenna element 10) The antenna element 10 in the array antenna 1 has a different number of parasitic elements in the parasitic element unit 15. The array antenna 1 is broadband compared to the array antenna 2 including the antenna element 20 of the parasitic element unit 25 having one parasitic element. Hereinafter, the antenna element 10 used in the array antenna 1 will be described. First, an array antenna 2 including an antenna element 20 of a wireless power supply element unit 25 having one wireless power supply element will be described.

[0072] FIG. 11 is a diagram for explaining the reflection characteristics in the antenna element 20 in which the wireless power supply element unit 25 has one wireless power supply element. FIG. 11(a) is a perspective view of the antenna element 20, FIG. 11(b) is a cross-sectional view of the portion surrounded by the dashed line in FIG. 11(a), and FIG. 11(c) shows the reflection characteristics due to different radiation performances. In FIG. 11(a), the horizontal direction of the antenna element 20 is the x direction, the vertical direction of the antenna element 20 is the y direction, and the direction perpendicular to the x-y plane is the z direction. In FIG. 11(b), the left direction of the paper surface is the z direction, the upper direction of the paper surface is the y direction, and the surface direction of the paper surface is the x direction. In FIG. 11(c), the horizontal axis is the frequency [GHz], and the vertical axis is S11 [dB] of the S parameter.

[0073] In the perspective view of FIG. 11(a), a space is provided between the ground conductor 12 provided on the surface side of the substrate 11 and the substrate 14 on which the wireless power supply element unit 25 is provided, but this is for explaining the structure, and as shown in the cross-sectional view of FIG. 11(b), no space is provided. Here, the ground conductor 12 side provided on the surface side of the substrate 11 and the back surface side of the substrate 14 are bonded together by an insulating adhesive sheet (bonding sheet) 16. FIG. 11(c) shows that the thickness t2 of the substrate 14 is 0.76 mm, and the cases where the radiation performance is 37%, 47%, 55%, 59%, 100% (see FIG. 7), and the case where the thickness t2 of the substrate 14 is 1 mm and the radiation performance is 100%. The radiation performance (%) when the thickness t2 of the substrate 14 is 0.76 mm corresponds to the antenna element 20 in FIG. 5 as shown in FIG. 7. 37% corresponds to the antenna elements 20-1U and 20-1D, 47% corresponds to the antenna elements 20-2U and 20-2D, 55% corresponds to the antenna elements 20-3U and 20-3D, 59% corresponds to the antenna elements 20-4U and 20-4D, and 100% corresponds to the antenna elements 20-5U and 20-5D.

[0074] As shown in FIG. 11(c), when the thickness t2 of the substrate 14 is 0.76 mm, S11 increases as the radiation performance increases from 37% to 100% on the low-frequency side (27 GHz side) and the high-frequency side (30 GHz side) across 28.5 GHz. When constructing a broadband array antenna, it is preferable that S11 of each antenna element is small. S11 with a radiation performance of 37% is small across the entire frequency range from 27 GHz to 30 GHz. However, S11 with radiation performances of 47%, 55%, 59%, and 100% is smaller than that with a radiation performance of 37% near the design frequency of 28.5 GHz, but is larger than that with a radiation performance of 37% on the low-frequency side (27 GHz side) and the high-frequency side (30 GHz side). Therefore, as shown in FIG. 8(b), for the array antenna 2, S11 is larger than that of the array antenna 1 on the low-frequency side (27 GHz side) and the high-frequency side (30 GHz side).

[0075] As shown in FIG. 11(c), when the thickness t2 of the substrate 14 is 1 mm, even though the radiation performance is 100%, S11 is smaller than when the thickness t2 of the substrate 14 is 0.76 mm. This is because the volume V between the feeding element 13 and the non-feeding element portion 25, which is shown by the dashed-dotted line in FIG. 11(b), is different. That is, when the thickness t2 of the substrate 14 is 1 mm, the volume V is larger than when the thickness t2 of the substrate 14 is 0.76 mm, resulting in a wider bandwidth. Here, it is referred to as the volume V for convenience, but the volume V is not the product obtained by multiplying the area of the non-feeding element portion 25 (non-feeding element) by the thickness of the dielectric material (dielectric) between the feeding element 13 and the non-feeding element part 25. That is, the volume V is a quantity obtained by considering the electric field strength between the feeding element 13 and the non-feeding element portion 25 (non-feeding element). The volume V may be expressed as volume or capacitance.

[0076] Generally, in an array antenna, antenna elements with the same configuration are used. Such an antenna element has one non-feeding element (non-feeding element portion) provided opposite to the feeding element. As described above, the reflection characteristics of the antenna element are determined by the volume V between the feeding element and the non-feeding element. And the radiation performance (FIG7 If the reference (is different), the appropriate volume V is different. When the thickness t2 of the substrate 14 is selected according to the antenna element that requires a small volume V, it is required to increase the volume V for the antenna element that requires a large volume V. At this time, it is necessary to increase the area of the non-fed element or increase the thickness t2 of the substrate 14. However, the area of the non-fed element is limited by the excitation conditions in the non-fed element. Therefore, it is not easy to increase the area of the non-fed element corresponding to the required volume V. On the other hand, if the thickness t2 of the substrate 14 in the part of the antenna element that requires broadband is made different from that of other parts, the manufacturing of the substrate 14 becomes complicated.

[0077] FIG. 12 is a diagram for explaining the reflection characteristics of the antenna element 10 in which the non-fed element portion 15 has four non-fed elements. FIG. 12(a) is a perspective view of the antenna element 10, FIG. 12(b) is a cross-sectional view of the portion surrounded by the dashed-dotted line in FIG. 12(a), and FIG. 12(c) is the reflection characteristic when the radiation performance is 100%. Here, the antenna element 10-5U shown in FIG. 3 will be described. The xyz directions in FIGS. 12(a) and (b) are the same as those in FIGS. 11(a) and (b), and the horizontal axis and vertical axis in FIG. 12(c) are the same as those in FIG. 11(c). In FIG. 12(b), the non-fed element portion 15 not included in the portion surrounded by the dashed-dotted line in FIG. 12(a) is shown by a dashed line. In addition, FIG. 12(c) also shows the case where the radiation performance of the antenna element 20 in which the non-fed element portion 25 has one non-fed element is 100% (corresponding to the antenna element 20-5U in FIG. 5).

[0078] In the perspective view of FIG. 12(a), a space is provided between the ground conductor 12 provided on the front surface side of the substrate 11 and the substrate 14 provided with the non-fed element portion 15, but this is for explaining the structure. As shown in the cross-sectional view of FIG. 12(b), no space is provided. Here, the ground conductor 12 side provided on the front surface side of the substrate 11 and the back surface side of the substrate 14 are bonded together by an insulating adhesive sheet (bonding sheet) 16. The thickness t2 of the substrate 14 is 0.76 mm.

[0079] As shown in Fig. 12(c), the antenna element 10-5U having four parasitic elements (referred to as four parasitic elements) has a smaller S11 in the frequency band from 27 GHz to 30 GHz compared to the antenna element 20 having one parasitic element (referred to as one parasitic element). This is because the antenna element 10-5U with four parasitic elements has a larger volume V between the feeding element 13 and the parasitic element section 15-5U compared to the antenna element 20 (antenna element 20-5U) with one parasitic element. Therefore, in order to increase the volume V and achieve broadband characteristics, it is not necessary to increase the thickness t2 of the substrate 14. That is, the thickness t2 of the substrate 14 may be constant without being changed for the antenna element 10. In other words, the surface of the substrate 14 may be flat. For this reason, the manufacture of the array antenna 1 in which a plurality of antenna elements 10 are arranged becomes easy.

[0080] Fig. 13 is a diagram for explaining the voltage distribution of the parasitic element section 15 having a plurality of parasitic elements. Fig. 13(a) shows the case where there are two parasitic elements, and Fig. 13(b) shows the case where there are five parasitic elements. In both Fig. 13(a) and (b), the right direction on the paper surface is the x direction, the upward direction on the paper surface is the y direction, and the surface direction of the paper is the z direction. The voltage distribution is shown by the shade of color.

[0081] The parasitic element section 15 shown in Fig. 13(a) includes two parasitic elements 15a and 15b. The y direction is the electric field (E) direction, and the x direction is the magnetic field (H) direction. The two parasitic elements 15a and 15b are provided with the central H plane (x-z plane) in the y direction of the feeding element 13 shown by the dashed line as the boundary. In Fig. 13(a), the line where the H plane intersects the x-y plane is shown by a dashed-dotted line. And the two parasitic elements 15a and 15b are set so that only the fundamental mode is excited.

[0082] The centers of the non-powered elements 15a and 15b in the y direction each become nodes of the voltage, the +y direction ends become bellies of the +(or -) voltage, and the -y direction ends become bellies of the -(or +) voltage. And the non-powered elements 15a and 15b are excited in phase. That is, the lengths of the non-powered elements 15a and 15b in the y direction (E direction) are set to approximately 1 / 2 wavelength according to the excitation conditions of the fundamental mode. However, due to the shortening effect, the lengths of the non-powered elements 15a and 15b in the y direction (E direction) are set slightly shorter than 1 / 2 wavelength. On the other hand, the width in the x direction (H direction) is arbitrary, but if it is made too wide, higher-order modes will occur and the directivity characteristics will deteriorate. The upper limit value is the same as the case of using one non-powered element. Therefore, when the non-powered element section 15 has two non-powered elements, the maximum area of the non-powered elements that can be set is twice the maximum value when the non-powered element section 15 has one non-powered element. Note that the above wavelength is the wavelength of the electromagnetic wave in the dielectric (effective wavelength), which is the value obtained by dividing the wavelength in free space by the square root of the relative permittivity of the dielectric (effective wavelength = wavelength in free space / √relative permittivity).

[0083] When non-powered elements 15a and 15b, which are divided by the central H plane in the y direction of the powered element 13 and only the fundamental mode is excited in phase, are provided, the area (total area) of the non-powered elements in the non-powered element section 15 becomes larger without degrading the radiation characteristics compared to the case of providing one non-powered element. Therefore, the volume V (see FIG. 12) between the powered element 13 and the non-powered element section 15 provided with the two non-powered elements 15a and 15b becomes larger compared to the case of providing one non-powered element.

[0084] The non-powered element section 15 shown in Fig. 13(b) includes five non-powered elements 15c, 15d, 15e, 15f, and 15g. Here too, the y direction is the electric field (E) direction and the x direction is the magnetic field (H) direction. The non-powered elements 15c and 15d are separated by the central H plane of the feeding element 13 in the y direction shown by the dashed line. Similarly, the non-powered elements 15f and 15g are provided separated by the central H plane of the feeding element 13 in the y direction. And each of the non-powered elements 15c, 15d, 15f, and 15g is set so that only the fundamental mode is excited in phase. On the other hand, the non-powered element 15e is not separated by the H plane. However, the non-powered element 15e is set so that only the fundamental mode is excited. Thus, in addition to the non-powered elements 15c, 15d, 15f, and 15g that are separated by the H plane and in which only the fundamental mode is excited, a non-powered element 15e that is not separated by the H plane and in which only the fundamental mode is excited may be provided. Note that the upper limit value of the total width in the x direction (H direction) is set to a value close to the upper limit value of the width when using one non-powered element. Even in this case, without degrading the radiation characteristics, the area (total) of the non-powered elements in the non-powered element section 15 becomes larger compared to the case of providing one non-powered element, and the volume V (see Fig. 12) between the feeding element 13 and the non-powered element section 15 becomes larger. By providing the non-powered element 15e that is not separated by the H plane, the adjustment range of the volume is widened. Here, the number of non-powered elements included in the non-powered element section 15 may be other values such as seven.

[0085] In Figs. 13(a) and (b), the plurality of non-powered elements included in the non-powered element section 15 are provided symmetrically in the x direction. Note that when tilting the radiation direction of the radio wave in the x-z plane from the z direction, the plurality of non-powered elements included in the non-powered element section 15 may be provided asymmetrically in the x direction. Similarly, the plurality of non-powered elements included in the non-powered element section 15 are provided symmetrically in the y direction. Note that when tilting the radiation direction of the radio wave in the y-z plane from the z direction, the plurality of non-powered elements included in the non-powered element section 15 may be provided asymmetrically in the y direction.

[0086] FIG. 14 is a diagram for explaining the wireless power element unit 15. FIG. 14(a) shows the case of having one wireless power element, FIG. 14(b) shows the case of having five wireless power elements, FIG. 14(c) shows the case of having four wireless power elements, and FIG. 14(d) shows the case of having two wireless power elements. When the volume V between the wireless power element unit 15 and the power supply element 13 is set with the volume V in the case of having one wireless power element in FIG. 14(a) being 1, the volume V in the case of having two wireless power elements in FIG. 14(d) is approximately doubled. And the volume V increases in the order of the case of having one wireless power element in FIG. 14(a), the case of having five wireless power elements in FIG. 14(b), the case of having four wireless power elements in FIG. 14(c), and the case of having two wireless power elements in FIG. 14(d). Therefore, by having the wireless power element unit 15 with a plurality of wireless power elements separated by the H plane, the volume V between the power supply element 13 and the wireless power element unit 15 can be set in the range from 1 time (when having one wireless power element) to 2 times (when having two wireless power elements).

[0087] The volume V is proportional to the thickness t2 of the substrate 14. From this, if an appropriate thickness t0 of the substrate 14 for the antenna element 10 having the wireless power element unit 15 of one wireless power element is calculated, as the thickness t2 of the substrate 14, a substrate 14 in the range of t0 / 2 < t2 < t0 can be selected. That is, by expanding the selection range of the thickness t2, a substrate 14 with an easily obtainable thickness t2 can be selected.

[0088] FIG. 15 is a diagram for explaining the reflection characteristics of the antenna element 10 included in the array antenna 1 to which the present embodiment is applied. The horizontal axis and the vertical axis are the same as those in FIG. 11(c). The substrate 14 has a thickness t2 of 0.76 mm and a relative dielectric constant of 3.3. FIG. 15 shows the cases where the radiation performance (%) is 37%, 47%, 55%, 59%, and 100%. These radiation performances (%) are , FigureCorresponds to the antenna element 10 in 3. 37% corresponds to the antenna elements 10-1U and 10-1D of one non-powered element (1 non-powered element), 47% corresponds to the antenna elements 10-2U and 10-2D of one non-powered element (1 non-powered element), 55% corresponds to the antenna elements 10-3U and 10-3D of five non-powered elements (5 non-powered elements), 59% corresponds to the antenna elements 10-4U and 10-4D of five non-powered elements (5 non-powered elements), and 100% corresponds to the antenna elements 10-5U and 10-5D of four non-powered elements (4 non-powered elements).

[0089] As shown in FIG. 15, the antenna elements 10 with radiation performances of 55%, 59%, and 100% have a plurality of non-powered elements in the non-powered element section 15. Therefore, as described with reference to FIG. 12(a), the S11 of these antenna elements 10 is smaller than that of the antenna element 20 of the non-powered element section 25 having one non-powered element shown in FIG. 11(b). Therefore, as shown in FIG. 8(b), the array antenna 1 has a smaller S11 than the array antenna 2.

[0090] FIG. 16 is a diagram for explaining the shape of the feeding element (slot) 13. FIG. 16(a) is a rectangular type, FIG. 16(b) is a dumbbell type, FIG. 16(c) is a bowtie (butterfly tie) type, and FIG. 16(d) is an H type. In the array antenna 1 shown in FIG. 3, according to the radiation power and radiation performance of the antenna element 10 shown in FIG. 7(a), the shape and dimensions of the feeding element (slot) 13, the number of non-powered elements in the non-powered element section 15, and the shape of the feeding line 50 are set. Therefore, the shapes shown in FIGS. 16(a) to 16(d) may be used as the shape of the feeding element (slot) 13.

[0091] (Antenna element 10 that radiates other polarization waves) In the above description, the antenna element 10 of vertically polarized waves with the electric field direction oriented in the array direction (y direction in FIG. 3) has been described. Here, in the array antenna 1 provided with the feed line 50 in the array direction, the antenna element 10A of the polarization wave inclined 45 degrees from the array direction (referred to as the 45-degree polarization wave) and the antenna element 10B of the polarization wave inclined 90 degrees from the array direction (referred to as the horizontal polarization wave) will be described.

[0092] FIG. 17 is a diagram for explaining the antenna element 10A of the 45-degree polarization wave to which the present embodiment is applied. FIG. 17(a) is a perspective view of the antenna element 10A, and FIG. 17(b) is a cross-sectional view of the portion surrounded by the dashed-dotted line in FIG. 17(a), which is a cross-sectional view taken along the line XVIIB-XVIIB in FIG. 17(c). FIG. 17(c) is a plan view seen from the side of the non-feed element portion 15A. The xyz directions in FIGS. 17(a) and (b) are the same as those in FIGS. 11(a) and (b). In FIG. 17(c), the right direction on the paper surface is the x direction, the upward direction on the paper surface is the y direction, and the front direction of the paper surface is the z direction.

[0093] The antenna element 10A includes a substrate 11, a ground conductor 12, a feed element 13A, a substrate 14, and a non-feed element portion 15A. Since the substrate 11, the ground conductor 12, and the substrate 14 are the same as those of the antenna element 10, the same reference numerals are given and the description thereof is omitted. Also, the feed line 50 is the same as the feed line 50 shown in FIG. 11. In the perspective view of FIG. 17(a), a space is provided between the substrate 11 provided with the ground conductor 12 and the substrate 14 provided with the non-feed element portion 15A for the purpose of explaining the structure, but as shown in the cross-sectional view of FIG. 17(b), no space is provided. The feed element 13A is provided in contact with the back surface side of the substrate 14 provided with the non-feed element portion 15A. Here, the ground conductor 12 side provided on the front surface side of the substrate 11 and the back surface side of the substrate 14 are bonded together by an insulating adhesive sheet (bonding sheet) 16. As a result, the feed element 13A and the non-feed element portion 15A face each other with the substrate 14 interposed therebetween. That is, the feed element 13-1U is provided in contact with the back surface side of the substrate 14 provided with the non-feed element portion 15-1U. The non-feed element portion 15A is assumed to have the five non-feed elements shown in FIG. 14(b), but may be provided with other numbers of non-feed elements.

[0094] In the antenna element 10A with a 45-degree polarization shown in FIGS. 17(a) and (c), the feeding element 13A is a rectangular slot having a longitudinal direction in a direction 45 degrees clockwise from the array direction (+y direction). And the non-feeding element portion 15A is obtained by rotating the non-feeding element portion 15 in FIG. 14(b) 45 degrees counterclockwise from the array direction (+y direction). When using the antenna element 10A instead of the antenna element 10, the array antenna 1 radiates a 45-degree polarization inclined 45 degrees counterclockwise from the array direction (+y direction).

[0095] As shown in FIG. 17(c), similar to the antenna element 10, also in the antenna element 10A, in a plan view, the feeding line 50 is arranged overlapping the non-feeding element portion 15A. Therefore, when arranging a plurality of array antennas 1 in which the antenna element 10A is arranged instead of the antenna element 10 in parallel, it is not necessary to widen the interval between the array antennas 1 (the interval P1 in FIG. 2(a)) and can be made small. Therefore, an antenna in which a plurality of array antennas 1 are arranged in parallel (an antenna similar to the planar antenna 100 in FIG. 1(a)) can be miniaturized.

[0096] When feeding the array antenna 1 using the antenna element 10A with a 45-degree polarization by central feeding, it is preferable to make the phase differ by 180 degrees between the array direction from the center in the array direction and the reverse array direction.

[0097] FIG. 18 is a diagram for explaining the antenna element 10B with a horizontal polarization to which the present embodiment is applied. FIG. 18(a) is a perspective view of the antenna element 10B, FIG. 18(b) is a cross-sectional view of the portion surrounded by the dashed-dotted line in FIG. 18(a), which is a cross-sectional view taken along the line XVIIIB-XVIIIB in FIG. 18(c), and FIG. 18(c) is a view seen in plan from the non-feeding element portion 15B side. The xyz directions in FIGS. 18(a), (b), and (c) are the same as those in FIGS. 17(a), (b), and (c).

[0098] The antenna element 10B includes a substrate 11, a ground conductor 12, a feeding element 13B, a substrate 14, and a non-powered element section 15B. Since the substrate 11, the ground conductor 12, and the substrate 14 are the same as those of the antenna element 10, they are denoted by the same reference numerals and the description thereof is omitted. In the perspective view of Fig. 18(a), a space is provided between the substrate 11 provided with the ground conductor 12 and the substrate 14 provided with the non-powered element section 15B for the purpose of explaining the structure. However, as shown in the cross-sectional view of Fig. 18(b), no space is provided. Here, the side of the ground conductor 12 provided on the front surface side of the substrate 11 and the back surface side of the substrate 14 are bonded together by an insulating adhesive sheet (bonding sheet) 16. Thereby, the feeding element 13B and the non-powered element section 15B face each other with the substrate 14 interposed therebetween. That is, the feeding element 13B is provided in contact with the back surface side of the substrate 14 provided with the non-powered element section 15B. The non-powered element section 15B is assumed to have five non-powered elements shown in Fig. 14(b), but may be provided with other numbers of non-powered elements.

[0099] As shown in Figs. 18(a) and (c), in the horizontally polarized antenna element 10B, the feeding element 13B is a rectangular slot having a longitudinal direction in the array direction (+y direction). And the non-powered element section 15B is obtained by rotating the non-powered element section 15 shown in Fig. 14(b) 90 degrees clockwise from the array direction (+y direction). The feeding line 50 includes a trunk portion 51 extending in the y direction and cadre 51 a branch portion 52 branching from the trunk portion 51 in the x direction. The trunk portion 51 is provided offset from the feeding element 13B toward the -x direction side. In plan view, the branch portion 52 extends in the +x direction so as to overlap the feeding element 13B. When this antenna element 10B is used, an array antenna 1 that radiates horizontally polarized waves is formed.

[0100] As shown in FIG. 18(c), also in the horizontal polarization antenna element 10B, in a plan view, the power supply line 50 is arranged to overlap with the non-powered element portion 15B. Therefore, when a plurality of array antennas 1 using the antenna element 10B instead of the antenna element 10 are arranged in parallel, it is not necessary to widen the interval between the array antennas 1 (interval P1 in FIG. 2(a)), and it can be made small. Therefore, an antenna in which a plurality of array antennas 1 are arranged in parallel (an antenna similar to the planar antenna 100 in FIG. 1(a)) can be miniaturized.

[0101] In addition, when the array antenna 1 using the horizontal polarization antenna element 10B is fed by central feeding, it is not necessary to make the phases different in the array direction from the center in the array direction and in the reverse array direction.

[0102] (Modification Example 1 of Antenna Element 10) In the antenna element 10, a slot is used as the feeding element 13. When a slot is used as the feeding element 13, the power supply line 50 may be of a coplanar (CPW: coplanar waveguide) type.

[0103] FIG. 19 is a diagram for explaining an example of an antenna element 30 to which a coplanar type power supply line 70, which is Modification Example 1 of the present embodiment, is applied. FIG. 19(a) is a perspective view of the antenna element 30, and FIG. 19(b) is a cross-sectional view of a portion surrounded by a dashed-dotted line in FIG. 19(a). The xyz directions in FIGS. 19(a) and (b) are the same as those in FIGS. 11(a) and (b).

[0104] The antenna element 30 includes a substrate 14, a ground conductor 32, a feeding element 33, and a non-powered element portion 15. Since the substrate 14 and the non-powered element portion 15 are the same as those of the antenna element 10, the same reference numerals are given and the description thereof is omitted. Note that the non-powered element portion 15 is assumed to have five non-powered elements, but may be provided with other numbers of non-powered elements.

[0105] In the antenna element 30, the non-powered element portion 15 is provided on the front surface side of the substrate 14, similar to the antenna element 10, but the ground conductor 32 and the feeding element 33 are provided on the back surface side of the substrate 14. And the feeding line 70 is also provided on the back surface side of the substrate 14. In the perspective view of Fig. 19(a), the ground conductor 32, the feeding element 33, and the feeding line 70 are shown separately from the substrate 14 provided with the non-powered element portion 15, but this is for explaining the structure. As shown in the cross-sectional view of Fig. 19(b), the ground conductor 32, the feeding element 33, and the feeding line 70 are provided on the back surface side of the substrate 14.

[0106] The ground conductor 32, the feeding element 33, and the feeding line 70 are formed of a conductive material provided on the back surface side of the substrate 14. That is, as shown in Fig. 19(a), the feeding line 70 is provided at the central portion in the x direction on the back surface side of the substrate 14, and the ground conductor 32 is provided on both sides in the ±x directions of the substrate 11 with the feeding line 70 in between. The feeding element 33 is an opening (slot) provided by removing the ground conductor 32 so as to expand it in the ±x directions, and is a rectangle with the direction (+x direction) orthogonal to the array direction (+y direction) as the length and the array direction (+y direction) as the width. And the feeding line 70 is provided at the center of the opening (slot). And the feeding element 33 and the non-powered element portion 15 face each other with the substrate 14 in between. That is, the feeding element (slot) 33 is provided on the back surface side of the substrate 14 provided with the non-powered element portion 15.

[0107] In the antenna element 30, the ground conductor 32, the feeding element (slot) 33, and the feeding line 70 are constituted by a layer of a conductive material provided on the back surface side of the substrate 14. Therefore, with the substrate 14 provided with layers of conductive material on both sides (front and back surfaces), the non-powered element portion 15 can be provided on the front surface side, and the ground conductor 32, the feeding element (slot) 33, and the feeding line 70 can be provided on the back surface side. Therefore, while the antenna element 10 uses the substrates 11 and 14, the antenna element 30 does not require the substrate 11. That is, the antenna element 30 has fewer substrates.

[0108] Note that in the antenna element 30 (corresponding to the antenna elements 10-5U and 10-5D in Fig. 3(a)) arranged at the end of the power supply line 70, the power supply line 70 is connected to the ground conductor 32.

[0109] As shown in Figs. 19(a) and (b), also in the antenna element 30, similar to the antenna element 10, in a plan view, the power supply line 70 is arranged to overlap the non-powered element portion 15. Therefore, when a plurality of array antennas 1 with the antenna element 30 arranged instead of the antenna element 10 are arranged in parallel, it is not necessary to widen the interval (interval P1 in Fig. 2(a)) between the array antennas 1 and can be made small. Therefore, an antenna in which a plurality of array antennas 1 are arranged in parallel (an antenna similar to the planar antenna 100 in Fig. 1(a)) can be miniaturized.

[0110] The array antenna 1 using the antenna element 30 and the power supply line 70 instead of the antenna element 10 and the power supply line 50 radiates a polarized wave (vertical polarized wave) in the array direction (+y direction).

[0111] (Modification Example 2 of Antenna Element 10) Slots are used as the power supply element 13 of the antenna element 10 and the power supply element 33 of the antenna element 30. A patch may be used as the power supply element. Hereinafter, it is denoted as the power supply element (patch) 43.

[0112] Fig. 20 is a diagram for explaining an example of an antenna element 40 to which a power supply element (patch) 43, which is a modification example 2 of the present embodiment, is applied. Fig. 20(a) is a perspective view of the antenna element 40, and Fig. 20(b) is a cross-sectional view of the portion surrounded by the dashed-dotted line in Fig. 20(a). The xyz directions in Figs. 20(a) and (b) are the same as those in Figs. 11(a) and (b).

[0113] The antenna element 40 includes a substrate 11, a ground conductor 42, a feeding element (patch) 43, a substrate 14, and a non-powered element portion 15. Since the substrate 11, the substrate 14, and the non-powered element portion 15 are the same as those of the antenna element 10, they are denoted by the same reference numerals and the description thereof is omitted. In the perspective view of Fig. 20(a), a space is provided between the substrate 11 provided with the feeding element (patch) 43 and the substrate 14 provided with the non-powered element portion 15 for the purpose of explaining the structure. However, as shown in the cross-sectional view of Fig. 20(b), no space is provided. Here, the side of the feeding element (patch) 43 provided on the front surface side of the substrate 11 and the back surface side of the substrate 14 are bonded together by an insulating adhesive sheet (bonding sheet) 16. The non-powered element portion 15 is assumed to have five non-powered elements, but may be provided with other numbers of non-powered elements.

[0114] The feeding element (patch) 43 is made of a conductive material on the front surface side of the substrate 11. The feeding element (patch) 43 has a rectangular outer shape and faces the non-powered element portion 15 provided on the substrate 14. The ground conductor 32 is made of a conductive material on the back surface side of the substrate 11. Here, the ground conductor 32 is provided so as to cover the entire back surface side of the substrate 11. However, the ground conductor 32 does not necessarily need to cover the entire back surface side of the substrate 11, and may be provided so as to face the feeding element (patch) 43 provided on the front surface side and the feeding line 80 described later on the back surface side of the substrate 11. Note that the antenna element 40 using the feeding element (patch) 43 is a microstrip antenna (MSA). And the feeding element 43 and the non-powered element portion 15 face each other with the substrate 14 interposed therebetween. That is, the feeding element 13-1U is provided in contact with the back surface side of the substrate 14 provided with the non-powered element portion 15. Note that the feeding element (patch) 43 and the feeding line 80 may be provided on the back surface side of the substrate 14.

[0115] The power supply line 80 is made of a conductive material on the surface side of the substrate 11 and is connected to the power supply element (patch) 43. That is, the power supply line 80 and the power supply element (patch) 43 are constituted by a single layer of conductive material layer provided on the surface side of the substrate 11. In FIG. 20, one antenna element 40 is shown, but in the case of an array antenna in which a plurality of antenna elements 40 are arranged, the power supply line 80 is provided so as to connect between a plurality of power supply elements (patches) 43 in series. Note that the power supply line 80 is terminated by the antenna element 40 disposed at the end (corresponding to the antenna elements 10-5U and 10-5D in FIG. 3(a)).

[0116] Instead of the antenna element 10, the array antenna 1 using the antenna element 40 radiates a vertically polarized wave with an electric field directed in the array direction (+y direction).

[0117] As shown in FIGS. 20(a) and (b), also in the antenna element 40, similar to the antenna element 10, in plan view, the power supply line 80 is disposed so as to overlap the non-power supply element portion 15. Therefore, when a plurality of array antennas 1 in which the antenna element 40 is disposed instead of the antenna element 10 are arranged in parallel, it is not necessary to widen the interval between the array antennas 1 (interval P1 in FIG. 2(a)) and can be made small. Therefore, an antenna in which a plurality of array antennas 1 are arranged in parallel (an antenna similar to the planar antenna 100 in FIG. 1(a)) can be miniaturized.

[0118] Note that when a patch is used as the power supply element 43, it is difficult to configure an array antenna with a polarization wave tilted 45 degrees (45-degree polarization wave) or a polarization wave tilted 90 degrees (horizontal polarization wave) with respect to the direction in which the power supply line 80 is provided (here, the y direction). This is because in order to configure a 45-degree polarization wave array antenna or a horizontal polarization wave array antenna, it is necessary to provide a power supply line branched from the power supply line 80 through an impedance matching circuit or the like for power supply. For this reason, there is a possibility that the interval between adjacent array antennas (interval P1 in FIG. 2(a)) becomes large. Therefore, when a patch is used as the power supply element 43, it is preferable to use the polarization wave in the direction in which the power supply line 80 is provided.

[0119] As described above, the array antenna 1 to which the present embodiment is applied has been described as a series power supply method in which the antenna elements 10 on the array direction (+y direction side) (antenna elements 10-1U to 10-5U in FIG. 3) and the antenna elements 10 on the reverse array direction (-y direction side) (antenna elements 10-1D to 10-5D in FIG. 3) are powered by central power supply. However, one-sided power supply (single-corner power supply) that supplies power from one end (one corner) where the antenna element 10 is arranged may be used.

[0120] In central power supply, power may be supplied to half of the number of antenna elements 10 respectively, and as shown in FIG. 7, power is supplied from the antenna element 10 with a large relative radiated power. On the other hand, in single-corner power supply, power is supplied to all of the antenna elements 10, and power supply starts from the antenna element 10 with a small relative radiated power.

[0121] In the antenna element 10 to which the present embodiment is applied, the planar shape of the non-powered element included in the non-powered element portion 15 is rectangular, but the planar shape of the non-powered element may be a quadrilateral other than a rectangle, a quadrilateral with rounded corners, or other shapes such as a circle, an ellipse, or a polygon.

[0122] As described above, in the array antenna 1 to which the present embodiment is applied, the reflection characteristics of the antenna element 10 are controlled by varying the number of non-powered elements included in the non-powered element portion 15 of the antenna element 10. And the non-powered element portion 15 has a plurality of non-powered elements divided by the H plane at the center of the power supply element 13, so that the volume V between the power supply element 13 and the non-powered element portion 15 can be adjusted. Since the non-powered element portion 15 has a plurality of non-powered elements, the volume V between the power supply element 13 and the non-powered element portion 15 becomes larger than the case where the non-powered element portion 15 has one non-powered element. Therefore, the volume V can be increased without increasing the thickness of the substrate 14. The plurality of non-powered elements are each set to be excited in the fundamental mode. Therefore, while suppressing the deterioration of the radiation characteristics of the antenna element 10, the return loss S11 is suppressed, and the antenna element 10 is broadened in bandwidth.

[0123] When the power feeding element is a slot (power feeding elements 13, 33) or the power feeding element is a patch (power feeding element 43), the power feeding line (power feeding lines 50, 70, 80) is arranged to overlap with the non-power feeding element portion 15 of the antenna element (antenna elements 10, 30, 40) in a plan view. That is, in a plan view, the power feeding line overlaps with the antenna element. Therefore, when the array antennas 1 each including a plurality of antenna elements are arranged in parallel, the interval between the array antennas 1 (interval P1 in FIG. 2(a)) can be reduced. For this reason, an antenna in which a plurality of array antennas 1 are arranged in parallel (an antenna similar to the planar antenna 100 in FIG. 1(a)) can be miniaturized.

[0124] Furthermore, various modifications may be made as long as they do not depart from the gist of the present invention.

Explanation of Reference Numerals

[0125] 1, 1′, 2... array antennas, 10, 10′, 20, 30, 40... antenna elements, 11, 14... substrates, 12, 32, 42... ground conductors, 13, 23, 33, 43... power feeding elements, 15, 25... non-power feeding elements, 16... adhesive sheet (bonding sheet), 50, 50′, 60, 70, 80... power feeding lines, 100... planar antenna, 200... control unit, 300... radio wave, G E 、G H … gap, P1, P2… interval, V… volume, W E 、W H … width

Claims

1. a first antenna element and a second antenna element for transmitting and receiving radio waves; a feed line that feeds power in series to the first antenna element and the second antenna element, The array antenna is characterized in that the first antenna element and the second antenna element each have a feed element fed from the feed line and a parasitic element section including parasitic elements arranged opposite the feed element, and the number of parasitic elements in the parasitic element section of the first antenna element is different from the number of parasitic elements in the parasitic element section of the second antenna element.

2. a substrate made of a dielectric material, on the surface of which a parasitic element section of the first antenna element and a parasitic element section of the second antenna element are provided; 2. The array antenna according to claim 1, wherein the feed element of the first antenna element and the feed element of the second antenna element are provided on the back side of the substrate or in contact with the back side of the substrate.

3. 3. The array antenna according to claim 2, wherein the substrate has a constant thickness.

4. 2. The array antenna according to claim 1, wherein the parasitic element section of at least one of the first antenna element and the second antenna element comprises a plurality of parasitic elements, including a pair of parasitic elements separated by an H-plane at the center of the feed element and excited in phase in a fundamental mode.

5. 5. The array antenna according to claim 4, wherein the plurality of parasitic elements include parasitic elements that are not separated by the H-plane.

6. 6. The array antenna according to claim 4, wherein a volume between the plurality of parasitic elements and the feed element is larger than a volume when there is only one parasitic element.

7. 7. The array antenna according to claim 1, wherein the parasitic element portion of the first antenna element and the parasitic element portion of the second antenna element overlap with the feed line in a planar view.

8. another substrate made of a dielectric material; the power supply element is provided on the front surface side of the other substrate, 4. The array antenna according to claim 2, wherein the substrate and the other substrate are overlapped with each other such that the rear surface of the substrate overlaps the front surface of the other substrate.

9. The power supply line is a single-corner power supply that is powered from one end of an array in which antenna elements are arranged, or a central power supply that is powered in opposite directions from the central part of the array, and is characterized in that it is the array antenna according to any one of claims 1 to 8.

10. When the power supply line is a central power supply and radiates a polarization wave along the array direction or a polarization wave shifted by 45 degrees from the array direction, the phases of the power supplied in opposite directions from the central part are shifted by 180 degrees, and is characterized in that it is the array antenna according to claim 9.

11. The power supply element is a slot or a patch, and is characterized in that it is the array antenna according to any one of claims 1 to 10.

12. A power supply element that is a slot, A plurality of parasitic elements provided to face the power supply element, and The plurality of parasitic elements include at least one set of parasitic elements that are separated by the H-plane at the central part of the power supply element and are excited in phase in the fundamental mode. The plurality of parasitic elements include parasitic elements that are not separated by the H-plane at the central part of the power supply element. An antenna element characterized by this.

13. The plurality of parasitic elements include a substrate provided on the surface side, The power supply element is provided on the back side of the substrate or in contact with the back side, and is characterized in that it is the antenna element according to claim 12.

14. A power supply element that is a slot, A plurality of parasitic elements provided to face the power supply element, The plurality of parasitic elements include a substrate provided on the surface side, and The plurality of parasitic elements include at least one set of parasitic elements that are separated by the H-plane at the central part of the power supply element and are excited in phase in the fundamental mode. The power supply element is provided on the back side of the substrate or in contact with the back side, and is characterized in that it is an antenna element.

15. The power supply element includes another substrate provided on the surface side, The substrate and the other substrate are characterized in that the back side of the substrate and the surface side of the other substrate are overlapped, and is the antenna element according to claim 13 or 14.

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