Antenna structure

Abstract

This invention provides an antenna structure that can improve directivity and extend the communication range. [Solution] The antenna structure of the present invention comprises an electrically insulating substrate, an antenna body formed on the first surface of the substrate, and a reflective material bonded or fixed to the first surface or a second surface opposite to the first surface of the substrate via an adhesive layer.

Description

Technical Field

[0001] The present invention relates to a sheet-like antenna structure provided with a reflector.

Background Art

[0002] Conventionally, a film antenna that is used by being attached to a window glass of a house, a car, etc. to receive television broadcasts, etc. is known. For example, Patent Document 1 discloses a film antenna in which a conductor constituting an antenna element is formed on a base material such as a resin film. In this film antenna, a folded dipole antenna is formed on the base material as an antenna element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In general, a non-directional dipole antenna or a folded dipole antenna, etc. is formed on a base material as an antenna element in a film antenna. Therefore, the film antenna has a problem that the communication distance is short compared to a directional antenna.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an antenna structure capable of improving directivity and increasing the communication distance.

Means for Solving the Problems

[0006] An antenna structure according to an aspect of the present invention includes a base material having electrical insulation, an antenna body formed on a first surface of the base material, and a reflector adhered or fixed via an adhesive layer to the first surface of the base material or a second surface opposite to the first surface.

[0007] In the antenna structure according to the present invention, the antenna body comprises a first conductive path formed on the first surface of the substrate, a second conductive path formed on the first surface of the substrate on the same straight line as the first conductive path, and a third conductive path formed on the first surface of the substrate parallel to the first conductive path and the second conductive path, and having a length approximately equal to the combined length of the first conductive path and the second conductive path.

[0008] In the antenna structure according to the present invention, the first conductive path, the second conductive path, and the third conductive path are formed to be embedded in the substrate.

[0009] In the antenna structure according to the present invention, one end of the first conductive path and the second conductive path are connected to a feed line to which alternating current is supplied, and the other end of each is connected to the end of the third conductive path.

[0010] In the antenna structure according to the present invention, the thickness of the substrate and the adhesive layer, or the thickness of the adhesive layer, is 1 mm or more.

[0011] In the antenna structure according to the present invention, the thickness of the substrate and the adhesive layer, or the thickness of the adhesive layer, is set to 1 mm or more such that the phase of the direct wave radiated from the antenna body and the phase of the reflected wave reflected by the reflecting material are in approximately the same phase.

[0012] In the antenna structure according to the present invention, the antenna comprising the substrate and the antenna body is a film antenna.

[0013] In the antenna structure according to the present invention, the film antenna has an adhesive layer formed by attaching a release sheet to its back surface, and is configured to be attachable to a desired surface. [Effects of the Invention]

[0014] According to the antenna structure of the present invention, it is possible to improve directivity and extend the communication distance.

Brief Description of the Drawings

[0015] [Figure 1] Plan view showing an example of the configuration of a film antenna according to an embodiment [Figure 2] Cross-sectional view taken along line A-A of FIG. 1 [Figure 3] Perspective view showing the film antenna curved in an arc shape [Figure 4] Diagram showing a modification example of the antenna structure of the film antenna [Figure 5] Cross-sectional view showing another example of the configuration of the film antenna [Figure 6] Cross-sectional view showing another example of the configuration of the film antenna [Figure 7] Cross-sectional view showing another example of the configuration of the film antenna

Modes for Carrying Out the Invention

[0016] Hereinafter, the detailed configuration of the present invention will be described with reference to the drawings. Note that the drawings based on the embodiments and modification examples in the following description are schematic, and the relationship between the thickness and width of each part and the ratio of the thickness of each part may be different from the actual situation. It should be noted that there are also parts where the dimensional relationship and ratio are different between the drawings.

[0017] Also, here, in the description of the components shown in the drawings, terms such as "front", "back", "plane", "bottom surface", "side surface", etc. in the orthographic projection method are used, but they are based on the up, down, left, and right directions when looking at the drawing paper, and the direction of the component itself is not defined.

[0018] FIG. 1 is a plan view showing an example of the configuration of a film antenna according to an embodiment. FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1.

[0019] As shown in FIGS. 1 and 2, the film antenna 1 includes a resin film 11, a folded dipole antenna 12, an adhesive layer 13, and a reflector 14.

[0020] The resin film 11 is a base material having electrical insulation properties. The resin film 11 has a first surface S1 on which the folded dipole antenna 12 is formed and a second surface S2 on the opposite side of the first surface S1. This resin film 11 has a rectangular shape and is composed of a flexible sheet-like member. Note that the shape of the resin film 11 is not limited to a rectangular shape and may be other shapes.

[0021] Also, the material of the resin film 11 is not particularly limited. For example, polyester, polyethylene, polypropylene, acrylic, vinyl chloride, polyethylene terephthalate (PET), polyimide, etc. can be adopted, but other materials may be used as long as they have electrical insulation properties.

[0022] The folded dipole antenna 12 is composed of a conductor (first conductive path) 12a, a conductor (second conductive path) 12b, and a conductor (third conductive path) 12c. The folded dipole antenna 12 is an antenna body composed of the conductors 12a to 12c. The conductors 12a to 12c are antenna elements formed of metal, metal foil, or the like. The materials of the conductors 12a to 12c can be, for example, gold, silver, copper, iron, nickel, aluminum, etc., or alloys having these as main components. However, other materials having conductivity, such as indium tin oxide (ITO), indium zinc oxide (IZO), etc., can also be used.

[0023] 4404>Note that the film antenna 1 has the folded dipole antenna 12 formed on the resin film 11, but it is not limited to this. For example, a folded dipole antenna or other antenna may be formed on the resin film 11.

[0024] The conductors 12a to 12c that constitute the folded dipole antenna 12 are formed on the first surface S1 of the resin film 11. The method for forming the conductors 12a to 12c on the resin film 11 is not particularly limited, and for example, vapor deposition, sputtering, etching, electrodeposition, or printing can be used.

[0025] Conductors 12a and 12b each have a length of λ / 4 when the wavelength of the transmitted radio wave is λ, and are arranged on the same straight line, resulting in a total length of λ / 2. Conductor 12c is arranged parallel to conductors 12a and 12b and has a length of λ / 2 (approximately the combined length of conductors 12a and 12b). The parallel spacing between conductors 12a and 12b and conductor 12c is set appropriately according to the transmission frequency.

[0026] Furthermore, the lengths of the conductors 12a and 12b are not limited to λ / 4, but may be less than λ / 4 (for example, λ / 4 × 0.8). Similarly, the length of the conductor 12c is not limited to λ / 2, but may be less than λ / 2 (for example, λ / 2 × 0.8). In this way, by making the lengths of the conductors 12a and 12b less than λ / 4 and the length of the conductor 12c less than λ / 2, the film antenna 1 can be miniaturized.

[0027] The adhesive layer 13 is made of an adhesive or double-sided tape, etc. The adhesive layer 13 is provided on the second surface S2 opposite to the first surface S1 on which the folded dipole antenna 12 of the resin film 11 is formed.

[0028] The reflective material 14 is bonded or fixed to the second surface S2 side of the resin film 11 via the adhesive layer 13. The reflective material 14 is made of, for example, a metal such as aluminum, copper, iron, or stainless steel, or an alloy containing these, and reflects radio waves transmitted from the folded dipole antenna 12. Since the film antenna 1 is arranged in a three-dimensional manner, partially or entirely curved and / or bent, to match the shape of the installation site, it is desirable that the reflective material 14 be made of a flexible sheet-like member.

[0029] The film antenna 1 is configured such that the thickness of the resin film 11 and the adhesive layer 13 is set so that the distance d between the opposing surfaces of the reflector 14 and the folded dipole antenna 12 is 1 mm or more. By setting the distance d between the opposing surfaces of the reflector 14 and the folded dipole antenna 12 to 1 mm or more, the radio waves radiated from the folded dipole antenna 12 can be reflected effectively without being absorbed.

[0030] Furthermore, it is desirable to set the distance d to 1 mm or more appropriately so that the direct wave radiated from the folded dipole antenna 12 and the reflected wave reflected by the reflector 14 do not cancel each other out, that is, so that the phases of the direct wave and the reflected wave are approximately in phase.

[0031] One end of each of the conductors 12a and 12b is connected to a feed line 15 that constitutes an antenna cable. The other ends of the conductors 12a and 12b are connected to the ends of a parallel conductor 12c.

[0032] One end of the power supply line 15 is connected to one end of the conductors 12a and 12b, respectively. The power supply line 15 connected to the conductors 12a and 12b is electrically connected to a wireless communication unit (not shown).

[0033] The folded dipole antenna 12 functions as a folded dipole antenna when it is supplied with alternating current via the feed line 15. That is, when alternating current is supplied to the folded dipole antenna 12 from the wireless communication unit via the feed line 15, transmission data is transmitted from the folded dipole antenna 12.

[0034] The film antenna 1 configured in this way can reflect the radio waves radiated from the folded dipole antenna 12 to the second surface S2 side of the resin film 11 to the first surface S1 side of the resin film 11 using the reflector 14.

[0035] As a result, the film antenna 1 can improve the directivity of the radio waves radiated from the folded dipole antenna 12, thereby extending the communication range.

[0036] The film antenna 1 of this embodiment has an adhesive layer formed by attaching a release sheet to its back surface (the surface opposite to the surface on which the adhesive layer 13 of the reflective material 14 is provided), and is configured to be attachable to a desired surface. By peeling off the release sheet, the adhesive layer on the back surface can be attached to a desired surface, such as a windowpane.

[0037] The film antenna 1 can be used in a straight line by, for example, attaching it to the window glass of a house or vehicle. Furthermore, because the film antenna 1 is flexible, it can be configured to be curved and / or bent in part or all three-dimensionally to match the shape of the housing of various devices, and can be installed inside the housing.

[0038] For example, as shown in Figure 3, the film antenna 1 can be curved in an arc shape (C-shape) and arranged inside the housing. Figure 3 is a perspective view showing the film antenna curved in an arc shape.

[0039] The film antenna 1 is curved in an arc shape such that the resin film 11 (first surface S1) faces outward and the reflector 14 faces inward. The curved film antenna 1 is then placed in a circumferential groove or the like formed inside a housing (not shown). By curving the film antenna 1 in an arc shape and placing it in a circumferential groove or the like, the installation space required can be reduced compared to, for example, placing a folded dipole antenna 12 in a straight line inside the housing.

[0040] Although the film antenna 1 has an arc-shaped, specifically C-shaped, antenna structure as shown in Figure 3, it is not limited to this antenna structure and may have various antenna structures as shown in Figure 4. Figure 4 shows a modified example of the antenna structure of the film antenna.

[0041] The film antenna 1 may have an L-shaped antenna structure, as shown in Figure 4(a). Alternatively, the film antenna 1 may have a roughly circular (roughly O-shaped) antenna structure, as shown in Figure 4(b).

[0042] Furthermore, the film antenna 1 may have a C-shaped antenna structure with a bent portion, as shown in Figures 4(c) to 4(h). Specifically, the film antenna 1 may have an antenna structure in which a part of one side of a rectangle is missing, as shown in Figure 4(c). Also, the film antenna 1 may have an antenna structure in which one side of a rectangle is missing, as shown in Figure 4(d). Furthermore, the film antenna 1 may have an antenna structure in which a part of two adjacent sides of a rectangle (rhombuse) is missing, as shown in Figure 4(e).

[0043] Furthermore, the film antenna 1 may have an antenna structure in which parts of two adjacent sides of a hexagon are missing, as shown in Figure 4(f). Also, the film antenna 1 may have an antenna structure in which two adjacent sides of a hexagon are missing, as shown in Figure 4(g). Furthermore, the film antenna 1 may have an antenna structure in which parts of two adjacent sides of a decagon are missing, as shown in Figure 4(h).

[0044] Furthermore, the film antenna 1 of this embodiment is not limited to the antenna structure shown in Figures 3 and 4(a) to 4(h), but may have any antenna structure in which part or all of it is curved and / or bent in three dimensions.

[0045] Furthermore, the configuration of the film antenna 1 is not limited to the configurations shown in Figures 1 and 2, but may also be the configurations shown in Figures 5 to 7. Figures 5 to 7 are cross-sectional views showing other examples of the film antenna configuration. In Figures 5 to 7, the same reference numerals are used for components similar to those in Figures 1 and 2, and detailed explanations of these components are omitted as appropriate.

[0046] As shown in Figure 5, the film antenna 1A is formed such that the first surface S1 of the resin film 11 and the upper surfaces of the conductors 12a to 12c that form the folded dipole antenna 12 are on the same plane. In other words, the film antenna 1A is formed by providing grooves in the resin film 11 for forming the conductors 12a to 12c, and embedding the conductors 12a to 12c in these grooves.

[0047] An adhesive layer 13 is provided on the second surface S2 of the resin film 11, which is opposite to the first surface S1 on which the folded dipole antenna 12 is formed. The reflective material 14 is adhered or fixed to the second surface S2 side of the resin film 11 via the adhesive layer 13.

[0048] Then, the thickness of the resin film 11 and adhesive layer 13 of the film antenna 1A is set such that the distance d between the opposing surfaces of the reflector 14 and the folded dipole antenna 12 is 1 mm or more.

[0049] In film antenna 1A, conductive elements 12a to 12c constituting a folded dipole antenna 12 are embedded in a resin film 11. As a result, the distance between the reflective material 14 and the opposing surfaces of the folded dipole antenna 12 is shorter than that of film antenna 1 shown in Figure 2. Therefore, in film antenna 1A, the thickness of the adhesive layer 13 is made thicker than that of film antenna 1, so that the distance d is 1 mm or more. Note that this is not limited to changing the thickness of the adhesive layer 13; the distance d may also be set to 1 mm or more by changing the thickness of the resin film 11, or the thickness of both the resin film 11 and the adhesive layer 13.

[0050] The film antenna 1A configured in this way can reflect the radio waves radiated from the folded dipole antenna 12 to the second surface S2 side of the resin film 11 to the first surface S1 side of the resin film 11 using the reflector 14.

[0051] As a result, the film antenna 1A can improve the directivity of the radio waves radiated from the folded dipole antenna 12, thereby extending the communication range.

[0052] As shown in Figure 6, the film antenna 1B has a configuration in which an adhesive layer 13 and a reflective material 14 are placed on the first surface S1 of the resin film 11 on which the folded dipole antenna 12 of the film antenna 1 shown in Figure 2 is formed. That is, in the film antenna 1B, an adhesive layer 13 such as adhesive or double-sided tape is provided on the first surface S1 of the resin film 11. The reflective material 14 is adhered or fixed to the first surface S1 of the resin film 11 via the adhesive layer 13.

[0053] Then, the thickness of the adhesive layer 13 of the film antenna 1B is set such that the distance d between the opposing surfaces of the reflector 14 and the folded dipole antenna 12 is 1 mm or more. In this way, when the adhesive layer 13 is provided on the first surface S1 of the film antenna 1B, only the adhesive layer 13 is interposed between the reflector 14 and the folded dipole antenna 12, so the distance d is set by the thickness of the adhesive layer 13.

[0054] The film antenna 1B configured in this way can reflect the radio waves radiated from the folded dipole antenna 12 towards the adhesive layer 13 towards the resin film 11 using the reflector 14.

[0055] As a result, the film antenna 1B can improve the directivity of the radio waves radiated from the folded dipole antenna 12, thereby extending the communication range.

[0056] As shown in Figure 7, the film antenna 1C has a configuration in which an adhesive layer 13 and a reflective material 14 are placed on the first surface S1 of the resin film 11 on which the folded dipole antenna 12 of the film antenna 1A shown in Figure 5 is formed. That is, in the film antenna 1C, an adhesive layer 13 such as adhesive or double-sided tape is provided on the first surface S1 of the resin film 11. The reflective material 14 is adhered or fixed to the first surface S1 of the resin film 11 via the adhesive layer 13.

[0057] In the film antenna 1C, the thickness of the adhesive layer 13 is set such that the distance d between the opposing surfaces of the reflector 14 and the folded dipole antenna 12 is 1 mm or more. In the film antenna 1C shown in Figure 7, since only the adhesive layer 13 is interposed between the reflector 14 and the folded dipole antenna 12, the distance d is set by the thickness of the adhesive layer 13.

[0058] The film antenna 1C configured in this way can reflect the radio waves radiated from the folded dipole antenna 12 towards the adhesive layer 13 towards the resin film 11 using the reflector 14.

[0059] As a result, the film antenna 1C can improve the directivity of the radio waves radiated from the folded dipole antenna 12, thereby extending the communication range.

[0060] The components of the embodiments described above can be combined with each other insofar as they do not contradict each other, and various modifications can be made without departing from the spirit of the present invention. Furthermore, the above embodiments include inventions of various stages, and various inventions can be extracted by appropriate combinations of the multiple components disclosed.

[0061] For example, if the problem described can be solved and the effects described can be obtained even if some of the constituent elements shown in the embodiment are deleted, then the configuration with the deleted constituent elements can be extracted as an invention. [Explanation of symbols]

[0062] 1.1A~1C Film Antenna 11 Resin film 12. Folded Dipole Antenna 12a~12c Conductor 13 Adhesive layer 14 Reflective material 15 Power line

Claims

1. A substrate having electrical insulating properties, An antenna body formed on the first surface of the above substrate, A reflective material is bonded or fixed to the first surface or the second surface opposite to the first surface of the above-mentioned substrate via an adhesive layer, An antenna structure characterized by having the following features.

2. The antenna body comprises a first conductive path formed on the first surface of the substrate, A second conductive path formed on the first surface of the substrate in the same straight line as the first conductive path, A third conductive path is formed on the first surface of the substrate, parallel to the first conductive path and the second conductive path, and having a length approximately equal to the combined length of the first conductive path and the second conductive path. The antenna structure according to claim 1, characterized by comprising the above.

3. The antenna structure according to claim 2, characterized in that the first conductive path, the second conductive path, and the third conductive path are formed to be embedded in the substrate.

4. The antenna structure according to claim 2, characterized in that one end of the first conductive path and the second conductive path are connected to a power supply line through which alternating current is supplied, and the other end of each is connected to the end of the third conductive path.

5. The antenna structure according to any one of claims 1 to 4, characterized in that the thickness of the substrate and the adhesive layer, or the thickness of the adhesive layer, is 1 mm or more.

6. The antenna structure according to claim 5, characterized in that the thickness of the substrate and the adhesive layer, or the thickness of the adhesive layer, is set to 1 mm or more such that the phase of the direct wave radiated from the antenna body and the phase of the reflected wave reflected by the reflecting material are in approximately the same phase.

7. The antenna structure according to claim 1, characterized in that the antenna comprising the substrate and the antenna body is a film antenna.

8. The antenna structure according to claim 7, characterized in that the film antenna has an adhesive layer formed by attaching a release sheet to its back surface, and is configured to be attachable to a desired surface.

Images