Planar antenna structure

Abstract

To ensure a positional relationship between an antenna substrate and a parasitic element.SOLUTION: A planar antenna structure includes an antenna substrate 6 on which an excitation element 61 is formed and provided, a holding layer 5 made of a dielectric material that is laminated with the antenna substrate 6, holds a parasitic element 51, and fills a space between the antenna substrate 6 and the parasitic element 51, and a support layer 4 made of a dielectric material that is laminated with the holding layer 5 and fills the space between the holding layer 5 and a radome 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a structure suitable for application to a planar antenna having a parasitic element. [Background technology]

[0002] BACKGROUND ART A microstrip antenna is known in which a non-excited element (in other words, a parasitic element) is arranged above an excited element (in other words, a fed element) in parallel with the excited element via a dielectric (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-183388 Summary of the Invention [Problem to be solved by the invention]

[0004] A planar antenna is configured as a structure in which a parasitic element is arranged at a fixed distance and at a fixed position from an antenna substrate on which a patch antenna is mounted, and a radome is placed at a fixed distance from the parasitic element. In order for the planar antenna to function properly, it is necessary to maintain a fixed distance between the antenna substrate (especially the patch antenna) and the parasitic element.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a planar antenna structure that can reliably ensure the positional relationship between the antenna substrate and the parasitic elements. [Means for solving the problem]

[0006] In order to solve the above problems, the structure of the planar antenna according to the present invention comprises: is set up an antenna substrate that can be mounted on the antenna substrate; to a support layer made of a dielectric material that is laminated and supports the parasitic element to fill a space between the antenna substrate and the parasitic element; to The support layer is laminated Plate-shaped a support layer made of a dielectric material that fills the space between the radome and the support layer; a ground plate laminated on a surface of the antenna substrate opposite to the support layer; and a frame to which the radome is attached. With death , the support layer in surface contact with the radome, the holding layer in surface contact with the support layer, and the antenna substrate in surface contact with the holding layer are stacked in the frame, and the frame and the ground plate are fixed to each other. It is characterized by:

[0007] The structure of the planar antenna according to the present invention may be such that the support layer has a recess formed to match the shape and size of the parasitic element, and the parasitic element is placed and supported within the recess.

[0008] The structure of the planar antenna according to the present invention may have a spacing fixing collar as a spacer that penetrates the support layer between the driven element and the parasitic element to keep the spacing between the driven element and the parasitic element constant.

[0009] In the structure of the planar antenna according to the present invention, the radome may be flexible.

[0010] In the structure of the planar antenna according to the present invention, the parasitic element may be formed of a metal plate.

[0011] In the structure of the planar antenna according to the present invention, the parasitic element may be flexible.

[0012] The structure of the planar antenna according to the present invention may be such that a positioning collar serving as a positioning pin is provided on the antenna substrate, and positioning through holes are provided in the retaining layer and the support layer through which the positioning collar can slide and penetrate. [Effects of the Invention]

[0013] According to the structure of the planar antenna of the present invention, the planar antenna has a holding layer that holds the parasitic element and fills the space between the antenna substrate and the parasitic element, and a support layer that fills the space between the holding layer and the radome. Set inAccording to the structure of the planar antenna according to the embodiment, since the space between the radome and the holding layer is filled with the support layer and the space between the parasitic element and the antenna substrate is filled with the holding layer, even if the radome is flexible, it is possible to prevent the radome from being deformed by wind or the like and to keep the distance between the parasitic element and the radome constant, and even if the parasitic element is flexible, it is possible to keep the shape and position of the parasitic element constant and to keep the distance between the parasitic element and the excited element constant.

[0014] According to the structure of the planar antenna of this invention, when the non-excited element is placed and held in the recess, it is possible to more reliably maintain a constant positional relationship between the non-excited element and the excited element formed and provided on the antenna substrate.

[0015] According to the structure of the planar antenna of the present invention, when a spacing fixing collar is provided as a spacer that keeps the spacing between the excited element and the parasitic element constant, it is possible to more reliably keep the spacing between the parasitic element and the excited element formed and provided on the antenna substrate constant.

[0016] According to the structure of the planar antenna of this invention, when a positioning collar is provided as a positioning pin on the antenna substrate and positioning through holes are provided in the holding layer and the support layer, the positioning collar functions as a positioning guide during assembly, making it possible to easily and reliably stack and arrange the support layer and the holding layer. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an exploded perspective view showing the structure of a planar antenna according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view showing a radome and a frame of the planar antenna of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below based on the illustrated embodiments. In the description of the present invention, directions and orientations according to the X-axis, Y-axis, and Z-axis of a three-dimensional Cartesian coordinate system shown in each drawing will be used. Furthermore, in each drawing, illustrations of components that are not relevant to the gist of the present invention and will not be mentioned in the following description (for example, fasteners such as screws, various elements, and circuits) will be omitted.

[0019] Fig. 1 is an exploded perspective view showing the structure of a planar antenna 1 according to an embodiment of the present invention. Fig. 2 is an exploded perspective view showing a radome 2 and a frame 3 of the planar antenna 1 according to the embodiment of the present invention.

[0020] The structure of the planar antenna 1 in the embodiment includes an antenna substrate 6 on which an excitation element (in other words, a feeding element) 61 is formed, a holding layer 5 made of a dielectric that is laminated on the antenna substrate 6 and holds an excitation element (in other words, a parasitic element) 51, filling the space between the antenna substrate 6 and the excitation element 51, and a support layer 4 made of a dielectric that is laminated on the holding layer 5 and fills the space between the holding layer 5 and the radome 2.

[0021] (Overall structure of planar antenna 1) The planar antenna 1 is a planar antenna having a parasitic element 51, and mainly comprises a radome 2, a frame 3, a support layer 4, a holding layer 5, an antenna substrate 6, and a ground plate 7. The planar antenna 1 is equipped with a high-frequency integrated circuit for signal processing, but since the content of the signal processing is not limited to a specific method in this invention and high-frequency integrated circuits for signal processing are well-known technology, illustration and description of the high-frequency integrated circuit will be omitted.

[0022] The radome 2 is a plate-like member made of a dielectric material. In the present invention, the radome 2 may be flexible, and specifically may be made of a polycarbonate plate-like member having a thickness (i.e., the dimension along the Z-axis direction) of about 2 to 4 mm.

[0023] The frame 3 surrounds the predetermined members constituting the planar antenna 1 and maintains the stacked state of the predetermined members between the radome 2 and the ground plate 7. The frame 3 is formed as a frame-shaped member made of a metal such as aluminum.

[0024] The radome 2 is attached to the frame 3 so as to cover the inside of the frame-shaped body of the frame 3, with the four edges of the plate-shaped radome 2 fixed by a plurality of cell stud bolts (in other words, threaded rods) 31 press-fitted into the frame 3 and nuts 32 threaded onto each of these cell stud bolts 31. To ensure dustproofness and waterproofness, the four edges of the radome 2 may be bonded to the frame 3 without any gaps by double-sided tape, adhesive, or the like.

[0025] The support layer 4 is a member that fills the space between the radome 2 and the holding layer 5, supports the radome 2 planarly, and keeps the distance between the radome 2 and the parasitic element 51 constant.

[0026] The support layer 4 is a member made of a dielectric material and formed into a plate shape, and is arranged so that one surface of the plate (specifically, the surface along the XY plane, the surface on the side facing the Z-axis arrow) is in contact with the inner surface of the radome 2 (specifically, the surface along the XY plane, the surface opposite to the Z-axis arrow) and is stacked on the radome 2.

[0027] The dielectric constant of the support layer 4 is adjusted to be lower than that of the antenna substrate 6, and the support layer 4 may be made of, for example, a foam material having a dielectric constant lower than that of the antenna substrate 6. The support layer 4 may also be made of a material (for example, a foam material) that is particularly strong against compressive pressure.

[0028] The support layer 5 is a member that fills the space between the non-excited element 51 and the antenna substrate 6 to maintain a constant distance between the non-excited element 51 and the antenna substrate 6, and also fixes the position and posture of the non-excited element 51 to maintain a constant positional relationship between the non-excited element 51 and the excited element 61 formed and provided on the antenna substrate 6.

[0029] The retention layer 5 is a member made of a dielectric material and is formed in a roughly plate shape, and is arranged so that one surface of the plate (specifically, the surface along the XY plane, the surface facing the Z-axis arrow) is in contact with the surface of the support layer 4 opposite the radome 2 side (i.e., the surface along the XY plane, the surface facing the Z-axis arrow) and is stacked on the support layer 4.

[0030] The permittivity of the retaining layer 5 is adjusted to be lower than that of the antenna substrate 6, and the retaining layer 5 may be made of, for example, a foam material having a permittivity lower than that of the antenna substrate 6. The retaining layer 5 may also be made of a material (for example, a foam material) that is particularly strong against compressive pressure. The support layer 4 and the retaining layer 5 may be made of the same material, or may be made of different materials.

[0031] A parasitic element 51 is arranged and held in a recess 52 formed on the surface of the holding layer 5 facing the support layer 4 (i.e., the surface along the XY plane, the surface on the side in the direction of the arrow of the Z axis).

[0032] The parasitic element 51 is preferably made of a metal plate such as a copper plate. Specifically, the parasitic element 51 may be made of a copper plate with a thickness of about 0.5 mm, for example. In this case, the parasitic element 51 will bend due to its own weight (i.e., the parasitic element 51 may be flexible), but the parasitic element 51 is supported planarly by the recess 52, thereby preventing deformation such as bending of the parasitic element 51 and keeping its position constant.

[0033] By configuring the parasitic element 51 using a metal plate, the following problems that arise when the parasitic element 51 is configured using a film substrate can be avoided. A) Because the film substrate is thin, distortion of the shape may occur, leading to deterioration of characteristics. a) In the fixing method in which a film substrate is laminated on the holding layer 5 (for example, a foam material), the accuracy of the height of the parasitic element 51 is poor, which leads to deterioration of the characteristics. c) Large film substrates, in particular, are usually more expensive than metal plates such as copper plates.

[0034] The antenna substrate 6 is a member made of a dielectric material and formed into a plate shape, and is disposed so that one surface of the plate (specifically, the surface along the XY plane, the surface in the direction of the Z-axis arrow) is in contact with the surface of the retaining layer 5 opposite to the support layer 4 side (i.e., the surface along the XY plane, the surface opposite to the direction of the Z-axis arrow) and is laminated on the retaining layer 5. Specifically, the antenna substrate 6 is a printed circuit board (PCB: abbreviation for Printed Circuit Board).

[0035] An excitation element 61 is formed on the surface of the antenna substrate 6 facing the support layer 5 (i.e., the surface along the XY plane, the surface on the side in the direction of the Z-axis arrow). As the excitation element 61, for example, a planar patch antenna is used.

[0036] The parasitic element 51 and the driven element 61 are arranged facing each other so that their centers are concentric and parallel to each other. The parasitic element 51 is electromagnetically coupled to the driven element 61. The strength of the electromagnetic coupling between the parasitic element 51 and the driven element 61 is determined by the dielectric constant and the distance between them, and the thickness of the retention layer 5 (i.e., the dimension along the Z-axis) is adjusted so that the strength of the electromagnetic coupling between the parasitic element 51 and the driven element 61 is a desired strength.

[0037] The ground plate 7 is formed as a plate-like member made of a metal such as aluminum, and is arranged so that one surface of the plate (specifically, the surface along the XY plane, the surface in the direction of the Z-axis arrow) is in contact with the surface of the antenna substrate 6 opposite to the retaining layer 5 side (i.e., the surface along the XY plane, the surface opposite to the direction of the Z-axis arrow), and is stacked on the antenna substrate 6.

[0038] The excitation element 61 is electrically connected to a signal terminal of a high-frequency integrated circuit (not shown) via a transmission line (not shown), and the ground plate 7 is electrically connected to a ground terminal of the high-frequency integrated circuit (not shown) via a wiring (not shown).

[0039] Within the frame 3 to which the radome 2 is attached, a support layer 4 in surface contact with the radome 2, a holding layer 5 in surface contact with the support layer 4, and an antenna substrate 6 in surface contact with the holding layer 5 are stacked in the Z-axis direction, and the frame 3 and the ground plate 7 are fixed to each other by a plurality of frame mounting screws 33.

[0040] (Fixing structure of parasitic element 51) A recess 52 is formed on the surface of the retaining layer 5 facing the support layer 4 (i.e., the surface along the XY plane, the surface on the side facing the arrow on the Z axis) to function as a countersink for the non-oscillating element 51, positioning the non-oscillating element 51 and supporting it planarly to fix and hold its posture and shape.

[0041] The recess 52 is formed to match the shape and size of the non-oscillating element 51, which is rectangular when viewed in the XY plane, so that the non-oscillating element 51 does not move or rotate along the XY plane, and is formed as a recess with a step that is approximately the same as the thickness of the non-oscillating element 51.

[0042] Note that recess 52 need only have a shape and size that can hold parasitic element 51 so as to prevent parasitic element 51 from moving or rotating along the XY plane, and does not have to have exactly the same shape as parasitic element 51 when viewed in the XY plane. For example, depending on the processing of recess 52, the four corners may not be perfect right angles but may be rounded to some extent.

[0043] A through-hole 53 is provided in the center of the recess 52 of the retention layer 5 in the XY plane, with the through-hole 53 penetrating along the Z-axis direction, and a cylindrical spacing collar 54 with its axis aligned along the Z-axis direction is fitted into the through-hole 53. The dimension of the spacing collar 54 along the Z-axis direction is set to be the same as the spacing in the Z-axis direction between the parasitic element 51 and the excited element 61 (note that this is a predetermined spacing that is set in advance as a design value so as to provide the planar antenna 1 with desired characteristics). The spacing collar 54 is made of resin so as not to affect the antenna characteristics.

[0044] In addition, a through hole 55 is provided at the center of the non-excitation element 51 when viewed in the XY plane, and a through hole 62 is provided at the center of the excitation element 61 when viewed in the XY plane, penetrating the excitation element 61 and the antenna substrate 6 along the Z-axis direction.Furthermore, a screw hole 71 is formed in the ground plate 7 at a position coaxial with the through hole 53 in the recess 52 of the holding layer 5 and the through hole 62 in the excitation element 61 and the antenna substrate 6 in the Z-axis direction.

[0045] The non-excitation element 51 is then screwed and fixed in place by a fixing screw 56 that passes through the through hole 55 of the non-excitation element 51, the spacing fixing collar 54 that is fitted into the through hole 53 of the recess 52 of the holding layer 5, and the through hole 62 of the excitation element 61 and antenna substrate 6 along the Z-axis direction and reaches the screw hole 71 of the ground plate 7.

[0046] Furthermore, fixing through-holes 63 are provided at each of the four corners of the antenna substrate 6 when viewed in the XY plane, and positioning screw holes 72 are formed in the ground plate 7 at positions coaxial with the fixing through-holes 63 of the antenna substrate 6 in the Z-axis direction, and the threaded portion at the tip of a cylindrical positioning collar 64, whose axis is along the Z-axis direction, is screwed into the screw holes 72. The positioning collar 64 is preferably made of metal such as brass so that the antenna substrate 6 and the ground plate 7 can be firmly screwed together (thereby achieving good grounding).

[0047] In addition, at each of the four corners of the support layer 4 when viewed in the XY plane, a positioning through hole 41 is provided, with the penetration direction along the Z axis direction, through which the positioning collar 64 can slide and penetrate freely, and further, at each of the four corners of the retaining layer 5 when viewed in the XY plane, a positioning through hole 57 is provided, with the penetration direction along the Z axis direction, through which the positioning collar 64 can slide and penetrate freely.

[0048] Then, the positioning through holes 57 are fitted into the positioning collars 64 attached to the antenna substrate 6 and the ground plate 7 (in other words, the positioning collars 64 are inserted into the positioning through holes 57), and the retaining layer 5 and the antenna substrate 6 are stacked together.Furthermore, the positioning through holes 41 are fitted into the positioning through holes 41 (in other words, the positioning collars 64 are inserted into the positioning through holes 41), and the support layer 4 and the retaining layer 5 are stacked together.

[0049] In the radiation direction of the excitation element 61 formed and provided on the antenna substrate 6 (specifically, in the direction of the arrow on the Z axis), the non-excitation element 51 is positioned at a fixed distance and at a fixed position from the excitation element 61 by the spacing fixing collar 54 inserted into the recess 52 of the holding layer 5 and the through hole 53 of the recess 52 (i.e., the spacing fixing collar 54 functions as a spacer to maintain a constant distance between the excitation element 61 and the non-excitation element 51), and further, the radome 2 is positioned at a fixed distance from the non-excitation element 51 by the support layer 4.

[0050] In particular, even if the radome 2 is flexible, the radome 2 is supported planarly by the support layer 4, so that the distance between the parasitic element 51 and the radome 2 is kept constant. Furthermore, even if the parasitic element 51 is flexible, the parasitic element 51 is supported planarly by the holding layer 5 (specifically, the recess 52), so that the shape and position of the parasitic element 51 are kept constant and the distance between the parasitic element 51 and the excited element 61 is kept constant.

[0051] Furthermore, while there is a possibility that the non-excitation element 51 may rotate along the XY plane if it is simply screwed in by the fixing screw 56 via the spacing fixing collar 54, by being placed in the recess 52 and having its posture fixed and held, rotation along the XY plane is prevented.

[0052] Furthermore, the positioning through holes 57 provided at the four corners of the retaining layer 5 in the XY plane view and the positioning collars 64 attached to the four corners of the antenna substrate 6 in the XY plane view position the retaining layer 5 relative to the antenna substrate 6, fixing the positional relationship between the retaining layer 5 and the antenna substrate 6 (i.e., the positioning collars 64 function as positioning pins / positioning guides for fixing the positional relationship between the retaining layer 5 and the antenna substrate 6), thereby maintaining a constant positional relationship between the non-excitation element 51 positioned and held by the recess 52 of the retaining layer 5 and the spacing fixing collar 54, and the excitation element 61 formed and provided on the antenna substrate 6.

[0053] Furthermore, the positioning through holes 41 provided at the four corners of the support layer 4 in the XY plane view and the positioning collars 64 provided at the four corners of the antenna substrate 6 in the XY plane view facilitate assembly when stacking the support layer 4 on the support layer 5 (i.e., the positioning collars 64 function as positioning pins / positioning guides for fixing the positional relationship between the support layer 5 and the support layer 4).

[0054] Furthermore, the characteristics of the planar antenna 1 can be adjusted by adjusting the material (particularly, the dielectric constant) and thickness (i.e., the dimension along the Z-axis direction) of the support layer 4 (thereby adjusting the distance between the non-excited element 51 and the radome 2) depending on the functions / performance required of the planar antenna 1.

[0055] Furthermore, depending on the functions / performance required of the planar antenna 1, the material (particularly, the dielectric constant) and thickness (i.e., the dimension along the Z-axis direction) of the retaining layer 5 can be adjusted, and the dimension along the Z-axis direction of the spacing fixing collar 54 can be adjusted (thereby adjusting the spacing between the non-excited element 51 and the excited element 61), thereby adjusting the characteristics of the planar antenna 1.

[0056] The structure of the planar antenna 1 according to the embodiment includes the holding layer 5 that holds the parasitic element 51 and fills the space between the antenna substrate 6 and the parasitic element 51, and the support layer 4 that fills the space between the holding layer 5 and the radome 2, so it is possible to maintain a constant positional relationship between the parasitic element 51 and the driven element 61 formed on the antenna substrate 6, and to maintain a constant interval between the parasitic element 51 and the radome 2. Furthermore, the structure of the planar antenna 1 according to the embodiment fills the space between the radome 2 and the holding layer 5 with the support layer 4, and the space between the parasitic element 51 and the antenna substrate 6 with the holding layer 5. Therefore, even if the radome 2 is flexible, deformation of the radome 2 due to wind or the like can be prevented, and the interval between the parasitic element 51 and the radome 2 can be maintained constant, and even if the parasitic element 51 is flexible, it is possible to maintain a constant shape and position of the parasitic element 51 and to maintain a constant interval between the parasitic element 51 and the driven element 61.

[0057] According to the structure of the planar antenna 1 of the embodiment, the non-excited element 51 is arranged and held within the recess 52, so that it is possible to more reliably maintain a constant positional relationship between the non-excited element 51 and the excited element 61 formed and provided on the antenna substrate 6.

[0058] According to the structure of the planar antenna 1 of the embodiment, it has a spacing fixing collar 54 as a spacer that keeps the distance between the excited element 61 and the parasitic element 51 constant, so it is possible to more reliably keep the distance between the parasitic element 51 and the excited element 61 formed and provided on the antenna substrate 6 constant.

[0059] According to the structure of the planar antenna 1 of the embodiment, the antenna substrate 6 is provided with a positioning collar 64 as a positioning pin, and the retaining layer 5 and the support layer 4 are provided with positioning through holes 41, 57, so that the positioning collar 64 functions as a positioning guide during assembly, making it possible to easily and reliably stack and arrange the support layer 4 and the retaining layer 5.

[0060] The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and even if there are design changes or the like within the scope of the gist of the present invention, they are included in the present invention.

[0061] For example, in the above embodiment, one parasitic element 51 and one excited element 61 are arranged, but the structure of the planar antenna according to the present invention can also be applied to a planar antenna in which a plurality of parasitic elements 51 and excited elements 61 mutually opposite each of the parasitic elements 51 are arranged in a matrix form in the planar view of the support layer 5 or the antenna substrate 6 (i.e., in the XY plane view), and the plurality of parasitic elements 51 and excited elements 61 form an array antenna.

[0062] In the above embodiment, the positioning collar 64, the positioning through hole 41 in the support layer 4, and the positioning through hole 57 in the retaining layer 5 are provided at each of the four corners when viewed in the XY plane, but the positions of the positioning collar 64 and the positioning through holes 41, 57 are not limited to each of the four corners when viewed in the XY plane, and they may be provided at each of two diagonally opposite corners when viewed in the XY plane, or even at a location other than the four corners when viewed in the XY plane (two or more locations are preferred). [Explanation of symbols]

[0063] 1. Planar antenna 2 Radome 3 frames 31 Cell stud bolt 32 Nut 33 Frame mounting screw 4 Support layer 41 Positioning through hole 5 Retention layer 51 Parasitic element 52 recess 53 Through hole 54 Fixed Interval Color 55 Through hole 56 Fixing screw 57 Positioning through hole 6 Antenna board 61 Drive element 62 Through hole 63 Fixing through hole 64 Positioning collar 7 Ground plate 71 screw holes 72 Set screw hole

Claims

1. an antenna substrate on which an excitation element is provided; a support layer made of a dielectric material, laminated on the antenna substrate, supporting the parasitic element, and filling a space between the antenna substrate and the parasitic element; a support layer made of a dielectric material laminated on the retaining layer to fill a space between the retaining layer and the plate-like radome; a ground plate laminated on a surface of the antenna substrate opposite to the support layer; a frame to which the radome is attached, the support layer in surface contact with the radome, the holding layer in surface contact with the support layer, and the antenna substrate in surface contact with the holding layer are stacked in the frame, and the frame and the ground plate are fixed to each other. A planar antenna structure characterized by:

2. the retention layer has a recess formed to match the shape and size of the parasitic element, the parasitic element is disposed and held within the recess; 2. The planar antenna structure according to claim 1.

3. a spacing fixing collar as a spacer that penetrates the retention layer between the driven element and the parasitic element to keep the spacing between the driven element and the parasitic element constant; 3. The structure of a planar antenna according to claim 1 or 2.

4. The radome is flexible.

4. A planar antenna structure according to claim 1, wherein the planar antenna is a flat antenna.

5. The parasitic element is formed of a metal plate.

5. A planar antenna structure according to claim 1.

6. the parasitic element is flexible; 6. A planar antenna structure according to claim 1, wherein the planar antenna is a flat antenna.

7. The antenna substrate is provided with a positioning collar as a positioning pin, The holding layer and the support layer are provided with positioning through holes into which the positioning collars can slide and penetrate.

7. A planar antenna structure according to claim 1.

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