JP2012244267A - Antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna which has visible light transmissivity and excellent characteristics.SOLUTION: An antenna includes a transparent substrate and an antenna element 1 integrally laminated on the transparent substrate. The antenna element 1 has a mesh part 10 having visible light transmissivity and a contour line part 12 with which a contour of the mesh part 10 is fringed.

Description

  The present invention relates to an antenna.

Conventionally, an antenna attached to glass or the like has an antenna element formed of a film body of a conductive material such as a metal foil or a metal mesh.
In particular, an antenna attached to a windshield or the like of an automobile has an antenna element formed in a mesh shape to ensure visibility (see, for example, Patent Document 1).

JP 2010-252175 A

Further, the conventional antenna is formed in a special shape having a curved portion, a slit portion, and the like in order to improve characteristics such as a VSWR characteristic (voltage standing wave ratio).
The shape and dimensions of each part are very important for maintaining the quality and characteristics of the antenna.

Here, as shown in FIG. 9, in the case of the antenna element 90 formed of copper foil, the width dimension and the notch depth dimension of the notch 90c are set to the optimum notch width dimension Ea and the optimum notch depth dimension Da. It's easy to do.
However, as shown in FIG. 8, when the antenna element 80 is formed in a mesh shape, the antenna element 80 is conventionally composed only of a mesh portion (without an outline). For example, the optimal shape of the notch portion 80c is a two-dot chain line. However, since the mesh (mesh) of the mesh portion is interrupted (broken), the notched portion 80c does not have a predetermined band shape, and has an uneven shape whose width changes in size. Was formed. In addition, the outer shape of the bent portion 80d is designed to be an arc shape indicated by a two-dot chain line, but in reality, the outer shape of the bent portion 80d is an uneven shape in which the mesh is interrupted.
That is, the actual shape is an ambiguous shape that is different from the optimum shape (in terms of design), and the dimensions of each part of the antenna element are different from the exact dimensions (in terms of design).

As described above, when the antenna element is in a mesh shape, the desired (optimum) characteristics are not obtained compared to the case where the antenna element is formed of metal foil, and the frame width of the frame portion forming the mesh portion. There is a problem that the characteristic is not stable because it is easily affected by the dimension and the pitch dimension.
Further, since the mesh appears to be broken at the periphery or notch of the antenna element, there is a problem that damage or deformation is likely to occur during manufacture.

  Accordingly, an object of the present invention is to provide an antenna having visible light transparency and having stable and excellent characteristics. Another object of the present invention is to provide an antenna having a low quality defect occurrence rate when manufacturing.

In order to achieve the above object, an antenna of the present invention comprises a transparent substrate and an antenna element integrally laminated on the transparent substrate, wherein the antenna element is a mesh having visible light transmittance. And a contour portion that borders the contour of the mesh portion.
Further, the opening ratio of the mesh portion is set to 80% or more.
The visible light transmittance of the laminate of the transparent substrate and the antenna element is set to 70% or more.

  According to the present invention, it is possible to reliably and accurately obtain a shape and dimensions for obtaining excellent characteristics while having visible light transmittance. In addition, quality (characteristics) is stabilized during manufacturing.

It is a front view of the embodiment of the present invention. It is the A section enlarged view of FIG. FIG. 3 is an enlarged view of a main part of FIG. 2. It is a principal part enlarged view. It is a graph which shows the VSWR characteristic of a 1st Example and a 1st comparative example. It is a graph which shows the VSWR characteristic of a 2nd Example and a 2nd comparative example. It is a principal part enlarged view of a prior art example. It is a principal part enlarged view for demonstrating a prior art. It is a principal part enlarged view for demonstrating a prior art.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
As shown in the embodiment of FIG. 1, the antenna of the present invention includes a pair of left and right antenna elements 1, 1 that are integrally laminated on a transparent substrate 2 and arranged in line symmetry with respect to a straight line L. .
The transparent substrate 2 is formed into a plate shape or a sheet shape using a sheet-like transparent glass or the like, or a transparent resin film such as polyethylene terephthalate, triacetyl cellulose, polycarbonate, or acrylic. The visible light transmittance of the transparent substrate 2 is desirably 80% or more.

  The antenna element 1 is made of a conductive material and has a thin-film surface mesh portion 10. As the material, copper, nickel, aluminum, gold, silver or the like, or a metal paste or carbon paste containing these metal (fine) particles is used. It is formed into a mesh pattern (mesh shape) by a method such as photoetching, etching with a printing resist, or printing a conductive resin paste. Alternatively, a metal oxide such as ITO, zinc oxide, or tin oxide can be used, and it is formed by vacuum deposition, sputtering, plating, electrodeposition, or the like. Alternatively, they are integrally laminated on the transparent substrate 2 by screen printing, roll coating, transfer, vapor deposition, or the like.

Further, in the illustrated example, the mesh portion 10 has an elliptical surface portion 1a, a lower widened leg portion 1b for feeding, a notch portion 1c, a divided loop slit portion 1d, and the like. Further, the mesh portion 10 of one antenna element 1 has a small protruding portion 1e protruding from the elliptical surface portion 1a.
The shape, size, angle, and arrangement of each part are very important elements (parameters) for the antenna characteristics.

In addition, as shown in FIG. 2, the mesh portion 10 includes a plurality of ultrathin ultrathin strip-like (10 or more) frame portions 11 made of a conductive material forming a mesh mesh (mesh). By being arranged in an intersecting manner, it is formed in a square lattice shape.
Further, the aperture ratio of the mesh portion 10 is set so that the visible light transmittance of the antenna element 1 laminated on the transparent substrate 2 (a laminated body in which the antenna element 1 is integrally laminated on the transparent substrate 2) is 70% or more. Is set to 80% or more (more preferably 95% or more). By setting in this way, for example, when pasted on the windshield of the vehicle, the visibility (visibility) is not impaired when the driver looks outside the vehicle. Note that the aperture ratio of the mesh portion 10 is the ratio of the area of the portion excluding the frame portion 11 forming the mesh of the mesh portion 10 to the mesh portion 10.
Further, it is desirable to set the aperture ratio to 99.5% or less. This is because if it exceeds 99.5%, the ratio of the frame portion 11 is small, and desired antenna characteristics may not be obtained.
Further, by setting the visible light transmittance of the laminate of the transparent substrate 2 and the antenna element 1 to 95% or less, an antenna having good visibility can be manufactured easily and stably, and the occurrence rate of quality defects can be reduced. Can be reduced.

Here, FIG. 7 shows an enlarged view of a conventional antenna element 80 corresponding to part A of the antenna element 1 shown in FIG. In the conventional antenna element 80, portions where the mesh of the mesh is broken are formed at the outer peripheral edge and the inner peripheral edge of each part, and the optimum shape and size are not achieved.
For example, as shown in FIG. 8, the optimal (designed) shape of the notch 80c is the shape indicated by the two-dot chain line, but in reality, the mesh (mesh) of the mesh portion is interrupted (broken). Therefore, the optimum notch width dimension Ea was not obtained. Further, the actual notch depth dimension is not the optimum notch depth dimension Da. In addition, the outer shape of the curved portion 80d is an arc shape indicated by a two-dot chain line when it is optimal, but in reality, it is an uneven shape with a broken mesh.
In other words, the shape of the antenna element 1, the dimensions of each part, the distance dimension of each part, the outer peripheral length, and the gap dimension between the antenna elements 1 and 1 are not appropriate dimensions (optimal dimensions), which adversely affects the characteristics. .

  However, according to the present invention, as shown in FIGS. 2 to 4, the outline portion 12 borders the outline of the mesh portion 10 of the antenna element 1 separately from the frame portion 11 that forms the mesh portion 10 in the intermediate plane region. Is provided. The contour portion 12 connects the end portion of the frame portion 11 and the end portion of the frame portion 11 and is disposed on the optimum contour line (matches the designed contour).

  Specifically, as shown in FIG. 2, the contour portion 12 includes a contour portion 12 (12a) that borders the outer shape of the elliptical surface portion 1a, and a contour portion 12 that borders the outer shape of the lower widened leg portion 1b. (12b), a contour portion 12 (12c) bordering the contour of the cutout portion 1c, a contour portion 12 (12d) bordering the contour of the divided loop slit portion 1d, and a contour portion bordering the contour of the small protrusion 1e The mesh portion 10 (conductive portion) such as 12 (12e) is trimmed.

  For example, by providing the contour line part 12, the gap dimension Q between the pair of antenna elements 1 and 1 and the gap dimension (separation dimension) between each part are optimal (proper) dimensions. Further, as shown in FIG. 4, the actual notch width dimension of the notch 1c is the optimum notch width dimension Ea, and the actual notch depth dimension is also the optimum notch depth dimension Da.

3 and 4, when the line width dimension of the contour line portion 12 is Wb and the line width dimension of the frame line portion 11 is Wa, 0.2 Wa ≦ Wb ≦ 5 Wa. More preferably, 0.5 Wa ≦ Wb ≦ 2 Wa is preferable, and further more preferably, Wa = Wb.
The reason for setting as described above is that, if the difference between the line width dimension of the contour line part 12 and the line width dimension of the frame line part 11 is large, it is difficult to manufacture and the characteristics may not be stable. It is.

Next, the shape of the pair of antenna elements 1 and 1 is the shape shown in FIG. 1, and the antenna element 1 is made of a material obtained by processing a copper vapor-deposited film having a thickness of 2 μm into a mesh shape by etching. An antenna in which the line width dimension of the line portion 11 is 10 μm, the pitch dimension P of the frame line portion 11 is 1110 μm, and the contour line portion 12 is provided is the first embodiment. The line width dimension of the contour line portion 12 is 10 μm. The transparent substrate 2 is a glass plate having a thickness of 3 mm. Here, the visible light transmittance of the glass plate is 90.0%, the aperture ratio of the antenna element 1 is 98.2%, and the visible light transmittance of the laminate of the glass plate and the antenna element 1 is 86.9. %Met.
Then, the VSWR characteristics (input characteristics) were compared using the antenna in which the outline portion 12 was omitted from the first embodiment as a first comparative example.
As shown in FIG. 5, in the first embodiment, the average value of the VSWR (voltage standing wave ratio) is better than that of the first comparative example, and in particular, the frequency band (470 to 710 MHz) of terrestrial digital television. ), The first embodiment is clearly superior.

Next, the pair of antenna elements 1 and 1 has the shape shown in FIG. 1, and the antenna element 1 is made of a material obtained by processing a copper vapor deposition film having a thickness of 2 μm into a mesh shape by etching. An antenna in which the line width dimension of 11 is 50 μm, the pitch dimension P of the frame line part 11 is 1110 μm, and the outline part 12 is provided is the second example. The line width dimension of the contour line portion 12 is 50 μm. The transparent substrate 2 is a glass plate having a thickness of 3 mm. Here, the visible light transmittance of the glass plate is 90.0%, the aperture ratio of the antenna element 1 is 91.6%, and the visible light transmittance of the laminate of the glass plate and the antenna element 1 is 80.7. %Met.
Then, the VSWR characteristics were compared using the antenna in which the contour line portion 12 was omitted from the second embodiment as a second comparative example.
As shown in FIG. 6, the second embodiment has a better VSWR value on average than the second comparative example, and particularly in the frequency band (470 to 710 MHz) of terrestrial digital television. Clearly, the second embodiment is superior.

  Thus, the 1st Example and 2nd Example which provided the outline part 12 had a favorable result compared with the 1st comparative example and the 2nd comparative example. The results of the first and second examples were almost the same as the VSWR characteristics when the antenna element 1 was formed of copper foil (non-mesh).

  Although the measurement graph is omitted, the directivity / gain characteristics of the horizontal polarization and the vertical polarization at 650 MHz were excellent in the first and second embodiments, and were excellent.

As for the VSWR characteristics, it is apparent that the characteristics of the antenna of the present invention (Example) are better than the conventional (Comparative Example) over the entire measured frequency. In the example, the overall VSWR characteristic tends to be closer to the high frequency side, but this is because the distance between the two antenna elements 1 and 1 and the outer peripheral length are improved compared to the comparative example. Conceivable.
Also, with regard to directivity, it was revealed that the example gave an optimum (ideal) radiation pattern, and that the gain was also excellent at an average of less than 1 dBi.
That is, it can be said that the shape and dimensions substantially coincide with the optimum values (design specifications), and desired characteristics are obtained. Furthermore, since the transparency which cannot be obtained with copper foil is obtained, it can be said that it is effective for use as a broadband antenna for a terrestrial digital television attached to a windshield or the like of a vehicle.

Further, as shown in FIGS. 7 and 8, the conventional antenna element 80 protrudes from the intersection of the frame line portion 81 and the frame line portion 81 to the outer peripheral edge portion and the inner peripheral edge portion (the contour portion). A protruding frame line end portion 88 was formed.
Therefore, in the conventional antenna element 80, the projecting frame line end portion 88 is weaker than the mesh structure (lattice shape), and therefore, when manufacturing a process of laminating a protective film or the like on the antenna element 80 or other processes, or In use, there is a problem that damage and position (pitch) deviation are likely to occur.
However, according to the present invention, as shown in FIGS. 2 to 4, the protruding frame line end 18 (end of the frame line part 11) and the protruding frame line end 18 (end of the frame line part 11) are By being connected by the contour line portion 12, it is reinforced and damage and misalignment at the time of manufacture and use are prevented.

In the case of a broadband antenna for digital terrestrial television, from the viewpoint of VSWR characteristics, the antenna element 1 is made of a material obtained by processing a 2 μm copper deposition film into a mesh shape by etching, and the line width dimension ( It is desirable that Wa) is 10 μm, the line width dimension (Wb) of the contour portion 12 is 10 μm, and the pitch dimension P between the frame line portions 11 is 300 μm to 3000 μm. More preferably, it is 450 micrometers-650 micrometers.
Alternatively, the line width dimension (Wa) of the frame line part 11 is 50 μm, the line width dimension (Wb) of the outline part 12 is 50 μm, and the pitch dimension P between the frame line parts 11 is 400 μm to 3000 μm. Is desirable. More preferably, it is 550 micrometers-1500 micrometers.
Further, from the viewpoint of visible light transmittance, when the line width dimension (Wa) of the frame line part 11 is 10 μm so that the aperture ratio of the mesh part 10 is 80% or more (more preferably 95% or more). The pitch dimension P between the frame line portions 11 is preferably 100 μm or more (more preferably 450 μm or more).
In addition, when the line width dimension (Wa) of the frame line part 11 is 50 μm, the pitch between the frame line parts 11 is set so that the opening ratio of the mesh part 10 is 80% or more (more preferably 95% or more). It is desirable that the dimension P is 450 μm or more (more preferably 2000 μm or more).

  The design of the present invention can be changed, and the shape of the antenna element 1 may be other than that shown in FIG. 1 and may be any shape, such as a round shape, a rhombus shape, a curved triangle shape, an L shape, or a V shape. It may be in the shape. The shape of the transparent substrate 2 may be a shape other than that shown in FIG. 1 and may be any shape. For example, the shape may be substantially the same as that of the antenna element 1. The mesh of the mesh portion 10 may be a pattern other than the illustrated square lattice shape, and may be a polygonal shape such as a triangular shape, a rectangular shape, or a hexagonal shape. Further, the present invention may be applied to a radio wave shielding shield material.

As described above, the antenna of the present invention includes a transparent substrate 2 and an antenna element 1 laminated integrally on the transparent substrate 2, and the antenna element 1 is a mesh portion having visible light transmittance. 10 and the contour portion 12 that borders the contour of the mesh portion 10, so that the shape and dimensions for obtaining excellent characteristics can be obtained reliably and accurately, and the excellent characteristics and visible light transmittance can be obtained. Can be compatible. Moreover, when manufacturing, quality (characteristic) is stabilized and manufacturing can be performed easily.
In addition, the substantial outer shape (outer shape effective as an antenna) of the antenna element 1 becomes smaller (offset inward), so that it is an effective (effective element of the characteristic) antenna. It is possible to prevent the possibility that the distance between the elements 1 is widened, and that the element length and the outer peripheral length of the antenna element 1 are shortened, thereby preventing adverse effects such as characteristic changes.

  Moreover, since the aperture ratio of the mesh part 10 is set to 80% or more, good visibility can be obtained without degrading the characteristics and quality such as the VSWR characteristics. Accordingly, it is suitable for use by attaching to a place where visibility is desired, such as a windshield of an automobile.

  Moreover, since the visible light transmittance of the laminate of the transparent substrate 2 and the antenna element 1 is set to 70% or more, good visibility can be obtained. Accordingly, it is suitable for use by attaching to a place where visibility is desired, such as a windshield of an automobile.

1 Antenna element 2 Transparent substrate
10 Mesh part
12 Outline part

Claims (3)

In an antenna comprising a transparent substrate (2) and an antenna element (1) integrally laminated on the transparent substrate (2),
The antenna element (1) includes a mesh portion (10) having visible light permeability and a contour portion (12) bordering the contour of the mesh portion (10).   The antenna according to claim 1, wherein the aperture ratio of the mesh portion (10) is set to 80% or more.   The antenna according to claim 1 or 2, wherein the visible light transmittance of the laminate of the transparent substrate (2) and the antenna element (1) is set to 70% or more.

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