阅读说明：本技术 环形天线 (Loop antenna ) 是由 土屋健太 平田修 平冈大介 佐藤光范 竹泽丰 古川裕太郎 于 2018-01-23 设计创作，主要内容包括：环形天线(100)设置有：绝缘基板(101)；天线部分(102),所述天线部分(102)是设置在基板(101)上的导体,并且包括第一供电部分(105)、第二供电部分(106)和天线网格部分(107),所述天线网格部分(107)具有网格结构并通过将两个供电部分(105、106)彼此连接而形成环形形状；和虚拟图案部分(103),所述虚拟图案部分(103)是具有网格结构并设置在被天线部分(102)围绕的区域中,并且所述虚拟图案部分(103)与天线部分(102)分离。所述虚拟图案部分具有切断部分(108),所述切断部分(108)断开包括在网格结构中的路径。(A loop antenna (100) is provided with: an insulating substrate (101); an antenna part (102), the antenna part (102) being a conductor provided on a substrate (101), and including a first feeding portion (105), a second feeding portion (106), and an antenna mesh portion (107), the antenna mesh portion (107) having a mesh structure and forming a ring shape by connecting the two feeding portions (105, 106) to each other; and a dummy pattern portion (103), the dummy pattern portion (103) having a mesh structure and being disposed in a region surrounded by the antenna portion (102), and the dummy pattern portion (103) being separated from the antenna portion (102). The dummy pattern portion has a cut-off portion (108), and the cut-off portion (108) cuts off a path included in the mesh structure.)

1. A loop antenna, comprising:

an insulating substrate including one surface developed in a planar shape;

an antenna portion which is a conductor formed on the one surface of the substrate to receive or transmit radio waves and which includes a first feeding portion, a second feeding portion, and an antenna mesh portion having a mesh structure, the antenna mesh portion being formed in a ring shape to connect the two feeding portions to each other; and

a dummy pattern portion which is a conductor having a mesh structure and is formed in a region of the one surface of the substrate surrounded by the antenna portion, and which is separated from the antenna portion,

wherein the dummy pattern part includes:

a first proximal portion proximal to the first power supply portion;

a second proximal portion proximal to the second power supply portion; and

a cut-off portion formed to cut off a path included in the mesh structure so as to prevent a current affecting an operation of the antenna portion from flowing therethrough, and

wherein the cut-off portion is formed in a minimum loop-shaped path geometrically defined as a path connecting the first proximal end portion and the second proximal end portion with a shortest distance among paths formed by conductors having the mesh structure.

2. The loop antenna of claim 1,

wherein the cut portion is one of a plurality of cut portions formed,

wherein the dummy pattern part includes:

a first dummy loop portion from a loop formed by the conductor of the dummy pattern portion, which is a conductor of a maximum loop formed along the antenna portion.

A second dummy ring portion, which is a conductor of a largest ring formed in a region surrounded by the first dummy ring portion along the first dummy ring portion, from a ring formed by the conductors of the dummy pattern portion; and

a plurality of intersecting lines between the antenna portion and the second virtual loop portion and intersecting the first virtual loop portion, and

wherein the plurality of cut-off portions are formed in each segment of the first virtual ring portion located between two adjacent ones of the plurality of intersecting lines, and in each of the plurality of intersecting lines.

3. The loop antenna of claim 1,

wherein the cut portion includes a plurality of cut portions formed,

wherein the mesh structure of the dummy pattern portion is a structure in which a plurality of unit shapes are connected in a two-dimensional continuous manner, and

wherein at least one cut portion of the plurality of cut portions is formed in each of the plurality of unit shapes.

4. The loop antenna according to any one of claims 1 to 3, wherein the antenna and the dummy pattern have the same mesh structure.

5. The loop antenna of claim 4, wherein the mesh structure has a square or a circle as the plurality of unit shapes.

6. The loop antenna according to any one of claims 1 to 5, wherein the first feeding portion and the second feeding portion are each a conductor having a mesh structure of a higher density than the mesh structure of the antenna mesh portion, or a conductor spread out in a planar shape without a break.

7. The loop antenna according to any one of claims 1 to 6, wherein the substrate includes a resin film.

Technical Field

The present invention relates to a loop antenna.

Background

A loop antenna is one such antenna: including two power supply portions and a loop conductor connecting the two power supply portions to each other. The loop antenna may employ a mesh structure for the loop conductor to form the conductor in a thin film shape so that the conductor becomes inconspicuous.

Sometimes, a loop antenna in the shape of a film is placed on a front windshield glass of an automobile or the like. This is because from the viewpoint of design and ornamental appearance, it is desirable that the loop antenna is inconspicuous and in this case not visually recognized as an antenna.

In patent document 1, there is proposed a film antenna in which a conductive pattern 3A made of a mesh-like conductor and forming an antenna circuit is located on a surface of a resin film, and a pattern 3B having a color and a shape visually similar to those of the mesh-like conductor is formed in a region outside the conductive pattern 3A (see fig. 25). Patent document 1 describes that a pattern 3B formed in a region outside a conductive pattern 3A is electrically isolated from the conductive pattern 3A forming an antenna circuit, as illustrated in fig. 25.

According to patent document 1, by forming the conductive pattern 3A forming the antenna circuit and the pattern in the edge of the antenna circuit into a mesh shape, it is made difficult to recognize the conductive pattern 3A, thereby improving the surface attraction or the decorativeness.

Disclosure of Invention

Problems to be solved by the invention

The invention described in patent document 1 can be applied to make it difficult for the loop antenna (adopting a mesh structure for the loop conductor) described above to be visually recognized as an antenna. In this case, when the loop conductor functioning as an antenna is referred to as an "antenna portion", a pattern having a color and a shape similar to those of the loop conductor (hereinafter referred to as a "dummy pattern portion") is placed in a region surrounded by the antenna portion.

The inventors of the present invention studied the antenna characteristics of a loop antenna including an antenna portion and a dummy pattern portion of this type by electromagnetic field simulation.

To describe in detail, the antenna portion 11 of the loop antenna 10 (loop antenna under study) includes two feeding portions 12 and an antenna mesh portion 13, the antenna mesh portion 13 is formed in a loop shape to connect the two feeding portions 12 to each other and the antenna mesh portion 13 has a mesh structure, as illustrated in fig. 26. The antenna mesh portion 13 is a conductor having a strip-like mesh structure, has a width of 10mm, and is shaped into a rectangular loop. The antenna portion 11 is separated from the dummy pattern portion 14 in the loop antenna 10 under study. The antenna mesh section 13 and the dummy pattern section 14 employ the same mesh structure in which longitudinal and transverse square strings (string) are arranged.

In electromagnetic field simulation, a frequency of 600MHz is used for the transmitted or received electromagnetic wave. The line interval L of the mesh structure of the dummy pattern portion 14 is set to 3.2mm or 6.4 mm. The line width W of the mesh structure of the dummy pattern portion 14 is set to 10 μm or 20 μm.

Fig. 27 is a graph for showing a relationship between antenna radiation efficiency ("vertical axis") as the performance of the loop antenna 10 and a distance D (horizontal axis) between the antenna portion 11 and the dummy pattern portion 14, which is obtained as a result of electromagnetic field simulation. Even when the simulation was performed with the line width W set to different widths (i.e., 10 μm and 20 μm), substantially the same results were obtained. Therefore, in fig. 27, for each of the loop antenna 10 having the line interval L of 3.2mm and the loop antenna 10 having the line interval L of 6.4mm, a graph representing the result obtained when the line width W is 10 μm and a graph representing the result obtained when the line width W is 20 μm overlap in most places. Thus, fig. 27 looks like two graphs. In fig. 27, a graph of the result obtained when the line interval L was 3.2mm is shown by a solid line, and a graph of the knot obtained when the line interval L was 6.4mm is shown by a dotted line.

As a result of the electromagnetic field simulation, it was found that, as shown in fig. 27, too close distance between the antenna portion 11 and the dummy pattern portion 14 causes the performance of the loop antenna 10 to be degraded even to such an extent that the loop antenna 10 no longer functions as an antenna. It is also found that, in order for the loop antenna 10 to fully function as an antenna, the antenna pitch D between the antenna portion 11 and the dummy pattern portion 14 needs to be about 6mm or more regardless of the combination of the spacing and the width for the line spacing L and the line width W.

However, when the antenna part 11 and the dummy pattern part 14 are several millimeters away from each other, the boundary between the antenna part 11 and the dummy pattern part 14 is visually recognizable, which makes it difficult to achieve the object of making it difficult for the loop antenna to be visually recognized as an antenna.

The present invention has been made in view of these circumstances, and an object thereof is therefore to provide a loop antenna which is difficult to visually recognize as an antenna while attenuating deterioration in performance as an antenna.

Means for solving the problems

In order to achieve the above object, a loop antenna according to the present invention includes:

an insulating substrate including one surface developed in a planar shape;

an antenna portion which is a conductor formed on the one surface of the substrate to receive or transmit radio waves and which includes a first feeding portion, a second feeding portion, and an antenna mesh portion having a mesh structure, the antenna mesh portion being formed in a ring shape to connect the two feeding portions to each other; and

a dummy pattern portion which is a conductor having a mesh structure and is formed in a region of the one surface of the substrate surrounded by the antenna portion, and which is separated or separated from the antenna portion,

wherein the dummy pattern part includes:

a first proximal portion proximal to the first power supply portion;

a second proximal portion proximal to the second power supply portion; and

a cut-off portion formed to cut off a path included in the mesh structure, thereby preventing a current affecting an operation of the antenna portion from flowing therethrough, and

wherein the cut-off portion is formed in a minimum loop-shaped path geometrically defined as a path connecting the first proximal end portion and the second proximal end portion at a shortest distance among paths formed by conductors having the mesh structure.

The cut portion may be one of a plurality of cut portions formed,

the dummy pattern part may include

A first dummy loop portion which is a conductor of a maximum loop formed along the antenna portion from a loop formed by the conductor of the dummy pattern portion;

a second dummy ring portion, which is a conductor of a largest ring formed in a region surrounded by the first dummy ring portion along the first dummy ring portion, from a ring formed by the conductors of the dummy pattern portion; and

a plurality of intersecting lines between the antenna portion and the second virtual loop portion and intersecting the first virtual loop portion, and

the plurality of cut-off portions may be formed in each segment of the first virtual ring portion located between two adjacent ones of the plurality of intersecting lines and in each of the plurality of intersecting lines.

The cut-off portion may include a plurality of cut-off portions formed,

the mesh structure of the dummy pattern part may be a structure in which a plurality of unit shapes are connected in a two-dimensional continuous manner, and

at least one cut portion of the plurality of cut portions may be formed in each of the plurality of unit shapes.

The antenna and the dummy pattern may have the same mesh structure.

The lattice structure may have a square or a circle as a plurality of unit shapes.

The first feeding portion and the second feeding portion may each be a conductor having a mesh structure of a higher density than the mesh structure of the antenna mesh portion, or a conductor spread out in a planar shape without a break.

The substrate may include a resin film.

Effects of the invention

According to the present invention, the performance deterioration as an antenna is reduced while the loop antenna is difficult to visually recognize as an antenna.

Drawings

Fig. 1 is a view for explaining the configuration of a loop antenna according to a first embodiment of the present invention.

Fig. 2 is an enlarged view of a portion surrounded by a dashed circle C1 in fig. 1 and its vicinity.

Fig. 3 is a view for explaining the configuration of the loop antenna of modification 1.

Fig. 4 includes views for explaining a modification of the lattice structure.

Fig. 5 is a view for explaining the configuration of a loop antenna according to a second embodiment of the present invention.

Fig. 6 is a view for explaining a first virtual loop portion, a second virtual loop portion, and a first intersection line of the antenna mesh portion.

Fig. 7 is a view for explaining the configuration of the loop antenna of modification 3.

Fig. 8 is a view for explaining a first virtual loop portion, a second virtual loop portion, a third virtual loop portion, and a second intersecting line of the antenna mesh portions.

Fig. 9 is a view for explaining the configuration of a loop antenna according to a third embodiment of the present invention.

Fig. 10 is an enlarged view of a portion surrounded by a dashed circle C2 in fig. 9 and its vicinity.

Fig. 11 includes an enlarged view of a portion corresponding to the portion surrounded by the broken-line circle C2 in fig. 9 and the vicinity thereof, illustrating an example of a minimum loop path and a cut-off portion in a virtual pattern portion which is used in modification 4 and includes a plurality of first proximal end or closed end (close end) portions.

Fig. 12 is a view for explaining the configuration of the loop antenna of modification 5.

Fig. 13 is a view for explaining the configuration of the loop antenna of modification 6.

Fig. 14 includes a view and a graph for explaining the electromagnetic field simulation result of the loop antenna of example 1.

Fig. 15 includes a view and a graph for explaining the electromagnetic field simulation result of the loop antenna of comparative example 1.

Fig. 16 is a graph for illustrating electromagnetic field simulation results of the loop antennas of examples 2 to 5.

Fig. 17 is a graph for illustrating electromagnetic field simulation results of the loop antennas of examples 6 and 7.

Fig. 18 is a graph for illustrating the electromagnetic field simulation results of the loop antennas of comparative example 2 and examples 8 and 9.

Fig. 19 is an enlarged view of a portion corresponding to the portion surrounded by the broken-line circle C2 in fig. 9 and the vicinity thereof, taken from the loop antenna of comparative example 3.

Fig. 20 is a graph for illustrating electromagnetic field simulation results of the loop antenna of example 10 and the loop antenna of comparative example 3.

Fig. 21 is a view for explaining the configuration of the loop antenna of example 11.

Fig. 22 is a view for explaining a configuration of a loop antenna of example 12.

Fig. 23 is a view for explaining a configuration of a loop antenna of example 13.

Fig. 24 is a graph for illustrating electromagnetic field simulation results of the loop antennas of comparative example 3 and examples 11 to 13.

Fig. 25 is a view for explaining the configuration of a film antenna of the related art.

Fig. 26 is a view for explaining a configuration of a virtual loop antenna, which is expected according to application of the invention described in patent document 1 to a loop antenna having a mesh structure for loop conductors.

Fig. 27 is a graph for illustrating the electromagnetic field simulation result of the virtual loop antenna.

Detailed Description

A loop antenna according to an embodiment of the present invention is described below with reference to the drawings. Like parts are designated by like reference numerals throughout the drawings. In the description of the embodiments of the present invention and the accompanying drawings, the terms "upper", "lower", "front", "rear", "right", and "left" are used to describe directions, not to limit the present invention. For ease of understanding, the proportions of the parts of the drawings may be varied as required.

(first embodiment)

The loop antenna 100 according to the first embodiment of the present invention includes a substrate 101, an antenna portion 102, and a dummy pattern portion 103.

The substrate 101 is an insulating transparent member including one surface that is spread out in a planar shape. The substrate 101 of the first embodiment is a resin film. The substrate 101 may be a thin glass plate, and one surface spread out in a planar shape may be bent.

The antenna portion 102 is a conductor formed on the one surface of the substrate 101 for receiving or transmitting radio waves. The antenna portion 102 in fig. 1 is formed in a region between two rectangles (indicated by two-dot chain lines 104_ I and 104_ O). The two-dot chain lines 104_ I and 104_ O are virtual lines for describing the area where the antenna portion 102 is formed.

The antenna portion 102 includes a first feeding portion 105, a second feeding portion 106, and an antenna mesh portion 107, the antenna mesh portion 107 is formed in a ring shape to connect the first feeding portion 105 and the second feeding portion 106 to each other, and the antenna mesh portion 107 has a mesh structure.

The first power supply portion 105 and the second power supply portion 106 are each a contact portion connected to various circuits (for example, an oscillation circuit and an amplification circuit). The first power supply portion 105 and the second power supply portion 106 are each preferably a conductor having a mesh structure with a higher density than that of the antenna mesh portion 107, or a conductor spread out in a planar shape without a break to reduce contact resistance. In the first embodiment, as illustrated in fig. 1, each feeding unit is unfolded without interruption in a rectangular pattern.

The antenna mesh portion 107 of the first embodiment has a strip-like mesh structure having a constant width a (see fig. 2) and extending along the outer edge 104_ O of the rectangle. As a result, the antenna mesh portion 107 is shaped into a rectangular loop. Fig. 2 is an enlarged view of a portion surrounded by a dashed circle C1 in fig. 1 and its vicinity. The width a may be set to a suitable width, for example, 10 mm.

The antenna mesh section 107 has a geometric mesh structure connecting a plurality of unit shapes in a two-dimensional continuous manner. The lattice structure of the first embodiment uses squares as unit shapes, and is a structure in which squares are arranged flush with each other in the longitudinal and lateral directions. The unit shape size (length of one side, and corresponding to the "line interval" described above) L (see fig. 2) may be set to a suitable size, for example, 2mm to 10 mm.

In other words, the antenna mesh portion 107 of the first embodiment is a copper wire, a silver wire, or other conductive wires that are arranged at intervals L in the longitudinal and transverse directions, thereby forming a mesh structure using squares of size L as a unit shape. The thickness W (see fig. 2) of each wire may be set to a suitable thickness, for example, 10 μm to 20 μm.

The dummy pattern portion 103 is a conductor having a mesh structure, and is formed in a region of the one surface of the substrate 101 surrounded by the antenna portion 102. The region surrounded by the antenna portion 102 in the first embodiment corresponds to a region surrounded by a two-dot chain line 104_ I in fig. 1. In the first embodiment, the mesh structure of the dummy pattern portion 103 is the same as that of the antenna mesh portion 107. The fact that the mesh structures are the same means that the unit shape, the size L of the unit shape, and the thickness W of each wire of one mesh structure are the same as those of the other mesh structure, which form one mesh structure.

The dummy pattern part 103 and the antenna mesh part 107 may have different mesh structures from each other.

As illustrated in fig. 1 and 2, the dummy pattern portion 103 is separated from the antenna portion 102. The spacing D (see fig. 2) between the dummy pattern portion 103 and the antenna portion 102 may be set to an appropriate distance as long as the separation portion is made difficult to be visually recognized, for example, 10 μm.

As illustrated in fig. 1 and 2, the dummy pattern portion 103 includes a plurality of cut portions 108, and the cut portions 108 cut paths included in the mesh structure. The cut-off portions 108 each cut off a path to interrupt the current that affects the operation of the antenna portion 102.

In other words, the cut portions 108 in the first embodiment are each a site at which one of the wires forming the lattice structure is cut. The distance S (cut-off distance) by which the wire is cut off (see fig. 2) may be any distance at which the current affecting the operation of the antenna portion 102 is interrupted, for example, 200 μm to 500 μm.

The cut portions 108 of the first embodiment are formed in each square as a unit shape and on four sides of the square, and is an example of forming at least one cut portion 108 in a plurality of unit shapes. In other words, the cut portions 108 of the first embodiment are formed in the wire extending in the longitudinal and transverse directions substantially at the interval L, and therefore, each cut portion 108 is placed substantially at the middle of each side of each square as a unit shape.

In the above, the loop antenna 100 according to the first embodiment of the present invention is described.

As has been described, the dummy pattern portion 103 is separated from the antenna portion 102 and includes the plurality of cut-off portions 108 described above. Therefore, even when the dummy pattern portion 103 is formed in a region inside the antenna portion 102, it is possible to weaken the performance degradation as an antenna while making it difficult for the loop antenna 100 to be visually recognized as an antenna.

The first embodiment may be modified as follows.

For example, the substrate 101, which is transparent in the example described in the first embodiment, may be colored and may be translucent or opaque to suit individual cases. In this case, the same effects as those of the first embodiment can be obtained.

For example, the dummy pattern part 103 may be processed so that letters, designs, and the like are shown in white.

(modification 1)

In the example described in the first embodiment, the antenna mesh portion 107 is a rectangular loop. However, the annular shape into which the antenna mesh portion 107 is formed is not limited to this, and may be a diamond shape, another polygon shape, a circular shape, or other shapes. An example in which the loop shape of the antenna mesh portion 107 is a diamond shape is illustrated in fig. 3. The antenna portion 202 of the loop antenna 200 illustrated in fig. 3 includes an antenna mesh portion 207 shaped as a diamond-shaped loop. The dummy pattern portion 203 is formed so as to have a diamond-shaped outline in the area inside the antenna mesh portion 207. Except for those points, the loop antenna 200 is preferably configured in the same manner as the loop antenna 100 according to the first embodiment.

(modification 2)

In the example described in the first embodiment, the unit shape of the lattice structure is a square. However, the unit shape of the mesh structure may be, for example, a polygon other than a square, a circle, or a part of the polygon or the circle (a broken line, a curved line, or the like). The method of arranging the unit shapes of the lattice structure in a two-dimensional continuous manner is not limited to the method of the first embodiment in which the unit shapes are flush with each other in the longitudinal and lateral directions. The unit shapes may be arranged so as to be staggered from each other in the longitudinal and transverse directions, or a plurality of sets of unit shapes arranged in a two-dimensional continuous manner may be superposed on each other.

Fig. 4(a) to 4(c) are examples in which a circular shape is used as a unit shape, and fig. 4(d) and 4(e) are examples in which a semicircular shape is used as a unit shape.

Fig. 4(a) is a view for explaining an example of a lattice structure in which circles as unit shapes are arranged to be flush with each other in the longitudinal and lateral directions. Fig. 4(b) is a view for explaining an example of a lattice structure in which circles as unit shapes are shifted from each other by half of the unit shape in the longitudinal and transverse directions. Fig. 4(c) is a view for explaining an example of a lattice structure in which two sets of circles arranged flush with each other in the longitudinal and transverse directions are staggered from each other by a half unit shape in the longitudinal and transverse directions.

Fig. 4(d) is a view for explaining an example of a lattice structure in which lines of longitudinally connected semicircles are arranged side by side so that the semicircles in one column are in contact with the semicircles in the other column. Fig. 4(e) is a view for explaining an example of a lattice structure in which semicircles (i.e., longitudinally connected semicircular lines arranged side by side) illustrated in fig. 4(d) are overlapped with transversely connected semicircular lines arranged from top to bottom.

The same effects as those of the first embodiment are also obtained in modifications 1 and 2.

(second embodiment)

The cut-off portions 108 in the example described in the first embodiment are formed in each square (included in the dummy pattern portion 103) and on four sides of the square. In the second embodiment of the present invention, an example is described in which the cut-off portion 108 is formed in a plurality of squares (as unit shapes) forming the largest loop shape among loop shapes substantially similar to the antenna mesh portion 107.

As illustrated in fig. 5, the loop antenna 300 according to the second embodiment includes the same substrate 101 and antenna portion 102 as those of the first embodiment, and includes a dummy pattern portion 303 different from that of the first embodiment.

The dummy pattern portion 303 is a conductor having a mesh structure as in the first embodiment, and is provided with a plurality of cut portions 108 as in the first embodiment. The difference between the dummy pattern portion 303 of the second embodiment and the dummy pattern portion 103 of the first embodiment is the position where the cut-off portion 108 is formed.

In the second embodiment, the plurality of cut-off portions 108 are formed in the first virtual ring portion 309 and the plurality of first intersecting lines 310 within the conductor forming the virtual pattern portion 303 so as to make a round along the ring shape. In detail, the plurality of cut-off portions 108 are formed such that one cut-off portion 108 is formed in each of the first imaginary ring portions of the imaginary pattern portion 303 located between two adjacent first intersecting lines 310 and in each of the plurality of first intersecting lines 310 of the imaginary pattern portion 303.

To describe in more detail about the cut-off portion 108 formed in the first intersecting line 310, in the first intersecting line 310 extending from the first virtual ring portion 309 to the outside by a length greater than half of the size L of the unit shape, the cut-off portion 108 is formed outside the first virtual ring portion 309. In a first intersecting line 310 extending from the first virtual ring portion 309 to the outside by a length equal to or less than half of the size L of the unit shape, the cutout portion 108 is formed inside the first virtual ring portion 309.

As illustrated in fig. 6, the first dummy loop portion 309 is a conductor forming the largest loop along the antenna portion 102 among the loops (rectangles in the second embodiment) formed by the conductors of the dummy pattern portion 303.

As illustrated in fig. 6, the second dummy ring portion 311 is a conductor forming the largest ring along the first dummy ring portion 309 in the region surrounded by the first dummy ring portion 309 in the ring formed by the conductors of the dummy pattern portion 303.

As illustrated in fig. 6, a plurality of first intersection lines 310 are conductors which are located between the antenna portion 102 and the second virtual loop portion 311 and intersect the first virtual loop portion 309.

In the above, the loop antenna 300 according to the second embodiment of the present invention is described.

As has been described, the dummy pattern portion 303 is separated from the antenna portion 102 and includes the plurality of cut-off portions 108 described above. Therefore, even when the dummy pattern portion 303 is formed in a region inside the antenna portion 102, it is possible to weaken the performance degradation as an antenna while making it difficult for the loop antenna 300 to be visually recognized as an antenna.

The second embodiment may be modified as follows.

(modification 3)

The plurality of cut-off portions 108 in the example described in the second embodiment are formed in the first imaginary ring portion 309 and each of the plurality of first intersecting lines 310. In the loop antenna 400 of modification 3, the plurality of cut portions 108 are formed such that they go around the loop shape once as in the second embodiment and go around the loop shape again, that is, two times in total, as illustrated in fig. 7. The plurality of cut portions additionally formed in modification 3 are formed in the second dummy-ring portion 311 in the dummy pattern portion 403 and in each of the plurality of second intersecting lines 412 intersecting the second dummy-ring portion 311 in the pattern portion 403 so as to make a round along the ring shape. In detail, the plurality of cut portions 108 additionally formed in modification 3 are formed such that one cut portion 108 is formed in each piece of the second virtual ring portion 311 located between two adjacent second intersecting lines 412 and in each of the plurality of second intersecting lines 412.

To describe in more detail about the cut-off portion 108 formed in the second intersecting line 412, in the second intersecting line 412 connected to (closest to) the first intersecting line 310 (the first intersecting line 310 extends outward from the first virtual ring portion 309 by a length greater than half of the size L of the unit shape), the cut-off portion 108 is formed outside the second virtual ring portion 311. In a second intersecting line 412 connected to (closest to) the first intersecting line 310 (the first intersecting line 310 extends outward from the first virtual ring portion 309 for a length equal to or less than half of the size L of the unit shape), the cut-off portion 108 is formed inside the second virtual ring portion 311.

As illustrated in fig. 8, the second virtual ring portion 311 is as described in the second embodiment.

As illustrated in fig. 8, the plurality of second intersecting lines 412 are conductors located between the second virtual ring portion 311 and the third virtual ring portion 413 and intersecting the second virtual ring portion 311.

As illustrated in fig. 8, the third dummy ring portion 413 is a conductor forming the largest ring along the second dummy ring portion 311 in the region surrounded by the second dummy ring portion 311 in the ring formed by the conductors of the dummy pattern portion 303.

The modification 3 above also obtains the same effects as the second embodiment.

(third embodiment)

The embodiments described above relate to an example of forming the plurality of cut-off portions 108. In the third embodiment of the present invention, an example of forming one cut-off portion 108 is described.

As illustrated in fig. 9, the loop antenna 500 according to the third embodiment includes the same substrate 101 and antenna portion 102 as those of the first embodiment, and includes a dummy pattern portion 503 different from those of the first embodiment.

The dummy pattern portion 503 is the same conductor having a mesh structure as in the first embodiment. In the third embodiment, unlike the other embodiments, one cut-off portion 108 is formed in the minimum annular path 514.

As illustrated in fig. 10, the minimum loop-shaped path 514 is a path connecting the first proximal end portion 515 and the second proximal end portion 516 at the shortest distance among paths formed by conductors having a mesh structure and forming the dummy pattern portion 503. The minimum circular path 514 is geometrically defined regardless of the presence or absence of the cutout 108.

The first proximal end portion 515 is an end portion closest to the first power supplying portion among end portions of the dummy pattern portion 503. The second proximal end portion 516 is an end portion closest to the second power supplying portion among end portions of the dummy pattern portion 503.

In the above, the loop antenna 500 according to the third embodiment of the present invention is described.

As already described, the dummy pattern portion 503 is separated from the antenna portion 102 and includes the cut-off portion 108 described above. Therefore, even when the dummy pattern portion 503 is formed in the region inside the antenna portion 102, it is possible to weaken the performance degradation as an antenna while making it difficult for the loop antenna 500 to be visually recognized as an antenna.

The third embodiment may be modified as follows.

(modification 4)

The position where the cut-off portion 108 can be placed when one cut-off portion 108 is formed as in the third embodiment is described in modified example 4.

Fig. 11(a) is an enlarged view of a portion corresponding to the portion surrounded by the dashed circle C2 in fig. 9 and its vicinity.

As illustrated in fig. 11(b), the minimum loop-shaped path 614 in the modification 4 is a path connecting the first proximal end portion 615 and the second proximal end portion 516 at the shortest distance among paths formed by conductors having a mesh structure and forming the dummy pattern portion 603. The minimum circular path 614 is geometrically defined regardless of the presence or absence of the cutout 108.

The cut-out portion 108 may be formed so as to cut out the smallest annular path 614 in the manner illustrated in fig. 11 (a). The cut-out portion 108 may be formed so as to cut out the smallest annular path 614 in the manner illustrated in fig. 11 (c). However, even in the case where the path is cut in the portion illustrated in fig. 11(d), the minimum loop path 614 is not cut. Therefore, when the path is cut in the portion illustrated in fig. 11(d), the cutting section 108 cannot obtain the effect of cutting off the path to interrupt the current affecting the operation of the antenna section 102.

When one dummy pattern portion has a plurality of minimum loop paths, it is preferable to form the cut-off portions in all the minimum loop paths. By forming the cut-off portion 108 to interrupt the current affecting the operation of the antenna portion in the minimum loop path (geometrically defined), the loop path through which the current affecting the operation of the antenna portion flows becomes larger, and therefore an effect of making it difficult for the loop antenna to be visually recognized as an antenna while attenuating the performance degradation as an antenna is obtained. When the number of the cut-off portions 108 is further increased as described in the second embodiment and the first embodiment, the loop path through which the current that affects the operation of the antenna portion flows becomes even larger, and therefore the actual performance approaches the full-capacity or load (full-capacity) performance of the loop antenna.

The modification example 4 above also obtains the same effects as the third embodiment.

(modification 5)

As illustrated in fig. 12, the loop antenna 651 of modification 5 includes a substrate 101, an antenna portion 102 (the same as the antenna portion 102 in the first embodiment), an antenna portion 202 and a dummy pattern portion 203 (the same as the antenna portion 202 and the dummy pattern portion 203 in modification 1), and a dummy pattern portion 653.

As illustrated in fig. 12, an antenna portion 202 and a dummy pattern portion 203 are formed in a region surrounded by the antenna portion 102.

The antenna portion 102 includes an antenna mesh portion 107, the antenna portion 202 includes an antenna mesh portion 207, and the antenna portions 102 and 202 share the first power supply portion 105 and the second power supply portion 106. In other words, the antenna mesh portions 107 and 207 are electrically connected to the common first power supply portion 105 and second power supply portion 106. The lengths of the antenna mesh portion 107 and the antenna mesh portion 207 are different from each other, which enables the single loop antenna 651 to receive or transmit radio waves of different frequencies.

The dummy pattern portion 653 is formed in a part of an area surrounded by the antenna portion 102 and excluding the antenna portion 202 and the dummy pattern portion 203. The virtual pattern section 653 has the same mesh structure as the virtual pattern section 103 of the first embodiment.

Also in modification 5, since the dummy pattern portions 203 and 653 are included, the loop antenna 651 provided successfully becomes difficult to visually recognize as an antenna.

In modification 5, the cut-off portion 108 is formed in each of the dummy pattern portions 203 and 653. Accordingly, the performance of the antenna portions 102 and 202 as an antenna can be prevented from being degraded. The minimum loop path in modification 5 is formed in the dummy pattern portion 203, which means that by forming the cut-off portion 108 in the minimum loop path of the dummy pattern portion 203, it is possible to prevent performance as an antenna from being degraded.

In this way, the modification 5 above also obtains the same effects as the first embodiment.

(modification 6)

As illustrated in fig. 13, a loop antenna 661 of modification 6 includes a substrate 101, and upper and lower two sets of an antenna portion 102 and a dummy pattern portion 103.

The antenna portion 102 and the dummy pattern portion 103 in each set are substantially the same as the antenna portion 102 and the dummy pattern portion 103 in the first embodiment. However, in modification 6, the antenna part 102 in the upper group and the antenna part 102 in the lower group share the first power supply part 105 and the second power supply part 106, and the lengths of the antenna mesh parts 107 are different from each other. This enables the single loop antenna 661 to receive or transmit radio waves of different frequencies as in modification 5.

Also in modification 6, since the dummy pattern portion 103 is formed in the area surrounded by the antenna portion 102 in each group, the loop antenna 661 provided successfully becomes difficult to be visually recognized as an antenna.

In addition, in modification 6, a plurality of cut portions 108 are formed in the dummy pattern portions 103 in the corresponding group, similarly to the first embodiment. Therefore, the performance of the antenna portion 102 in each group as an antenna can be prevented from being degraded. The minimum loop path in modification 6 is formed in the dummy pattern portion 103 in each set, which means that by forming the cut-off portion 108 in the minimum loop path of the dummy pattern portion 103, it is possible to prevent a performance degradation as an antenna.

In this way, the modification 6 in the above also obtains the same effects as the first embodiment.

Examples of the invention

(example 1)

The loop antenna 100 of example 1 was obtained by setting the width a of the antenna mesh portion 107 in the loop antenna 100 according to the first embodiment to 10mm, the size L of the unit shape to 3200 μm, the thickness (corresponding to the "line width" described above) W of each of the conductive lines to 10 μm, the pitch D to 10 μm, and the cutting distance S to 320 μm.

The loop antenna 100 of comparative example 1 is different from the loop antenna 100 of example 1 only in that the cutting distance S is set to 10 μm.

Results of electromagnetic field simulation in a case where radio waves of 600MHz were received by the loop antenna 100 of example 1 and the loop antenna 100 of comparative example 1 are shown in fig. 14 and 15, respectively. Fig. 14(a) and 15(a) are views for explaining current distributions obtained as a result of simulation of the loop antenna 100 of example 1 and the loop antenna 100 of comparative example 1, respectively. Fig. 14(b) and 15(b) are graphs for explaining reflection characteristics obtained as a result of simulation of the loop antenna 100 of example 1 and the loop antenna 100 of comparative example 1, respectively.

As is found by comparing fig. 14 and fig. 15, when the cutting distance S is 320 μm, the current affecting the transmission/reception of radio waves does not flow into the conductor of the dummy pattern portion 103, and the reflection characteristic is therefore at a satisfactory level as an antenna. In contrast, when the cutoff distance S is 10 μm, the current distribution is concentrated around the first power supply portion 105 and the second power supply portion 106, and the reflection characteristic is so poor that the loop antenna cannot be used as an antenna. It can be seen from this that, in the case where the cutting distance S is 10 μm, the conductor of the dummy pattern portion 103 is not cut in such a manner as to interrupt the current affecting the operation of the antenna portion 102, that is, there is a loop path of the current that allows the operation of the antenna portion 102 to be adversely affected.

(examples 2 to 5)

Each of the loop antennas 100 of example 2 to 100 of example 5 is obtained by setting the width a of the antenna mesh portion 107 of the loop antenna 100 according to the first embodiment to 10mm and the pitch D to 10 μm, and by changing the combination of the size L of the unit shape and the thickness W of each wire. The size L and the thickness W of the loop antenna 100 of example 2 are 3.2mm and 10 μm, respectively. The size L and the thickness W of the loop antenna 100 of example 3 are 6.4mm and 10 μm, respectively. The size L and the thickness W of the loop antenna 100 of example 4 are 3.2mm and 20 μm, respectively. The size L and the thickness W of the loop antenna 100 of example 5 are 6.4mm and 20 μm, respectively.

Fig. 16 is a graph for illustrating the results of electromagnetic field simulation in the case where radio waves of 600MHz are received by the loop antennas 100 of example 2 to 100 of example 5, in the form of the relationship between the cut-off distance S (μm) and the antenna radiation efficiency (dB). In fig. 16, the results of example 2 to example 5 are indicated by a solid line, a broken line, a one-dot chain line, and a two-dot chain line, respectively, and graphs indicating the simulation results of example 2 and example 4 overlap in most places.

It was found that by setting the cutting distance S to be larger than about 240 μm when the size L of the unit shape is 3.2mm, and by setting the cutting distance S to be larger than about 480 μm when the size L of the unit shape is 6.4mm, the antenna radiation characteristic is at a level at which the loop antenna can function as an antenna.

(examples 6 and 7)

Each of the loop antennas 200 of example 6 and 200 of example 7 was obtained by setting the width a of the antenna mesh portion 107 in the loop antenna 200 of modification 1 to 10mm and the pitch D to 10 μm, and by changing the combination of the size L of the unit shape and the thickness W of each wire. The size L and the thickness W of the loop antenna 200 of example 6 are 3.2mm and 10 μm, respectively. The size L and the thickness W of the loop antenna 100 of example 7 are 6.4mm and 10 μm, respectively.

Fig. 17 is a graph for illustrating the results of electromagnetic field simulation in the case where radio waves of 2GHz are received by the loop antenna 100 of example 6 and the loop antenna 100 of example 7, the graph being in the form of a relationship between the cutoff distance S (μm) and the antenna radiation efficiency (dB). In fig. 17, the results of example 6 and example 7 are indicated by a solid line and a dashed line, respectively.

It was found that by setting the cutting distance S to be larger than about 240 μm when the size L of the unit shape is 3.2mm, and by setting the cutting distance S to be larger than about 480 μm when the size L of the unit shape is 6.4mm, the antenna radiation characteristic is at a level at which the loop antenna can function as an antenna.

(examples 8 and 9)

Example 8 is an example of the loop antenna 300 according to the second embodiment. Example 9 is an example of the loop antenna 400 of modification 3. In the loop antenna 300 of example 8 and the loop antenna 400 of example 9, the width a of the antenna mesh portion 107 was set to 10mm, the pitch D was set to 10 μm, the size L of the unit shape was set to 6,400 μm, the thickness W of each wire was set to 10 μm, and the cutting distance S was set to 480 μm.

Comparative example 2 is an example of a loop antenna in which the cut-off portion 108 is not formed in the dummy pattern portion 303 or 403. In the loop antenna of comparative example 2, the width a, the pitch D, the size L of the unit shape, the thickness W of each wire, and the cutting distance S are the same as those in the loop antenna 300 of example 8 and the loop antenna 400 of example 9.

Fig. 18 is a graph for illustrating the results of electromagnetic field simulation in the case where radio waves of 600MHz are received by the loop antenna of comparative example 2, the loop antenna 300 of example 8, and the loop antenna 400 of example 9, the graph being in the form of antenna radiation efficiency (dB) of the loop antenna.

As can be understood from the results of example 8, by forming the cut-off portion 108 so as to make one turn along the loop shape as in the second embodiment, the antenna radiation characteristic is at a level at which the loop antenna can function as an antenna.

(example 10)

The loop antenna 500 of example 10 was obtained by setting the width a of the antenna mesh portion 107 to 10mm, the pitch D to 10 μm, the size L of the unit shape to 6,400 μm, and the thickness W of each wire to 10 μm in the loop antenna 500 (see fig. 9) according to the third embodiment.

As illustrated in fig. 19, the loop antenna of comparative example 3 is the same as the loop antenna 200 of example 10 except that the cut-off portion 108 is not formed in the minimum loop path 514. Fig. 19 is an enlarged view of a portion corresponding to fig. 10 in the loop antenna of comparative example 3.

Fig. 20 is a graph for illustrating the results of electromagnetic field simulation in the case where radio waves of 600MGHz are received by the loop antenna 500 of example 10 and the loop antenna 500 of comparative example 3, in the form of the relationship between the cut-off distance S (μm) and the antenna radiation efficiency (dB). In fig. 20, the results of example 10 and comparative example 3 are indicated by a solid line and a broken line, respectively.

(example 11 to example 13)

As illustrated in fig. 21, the loop antenna 700 of example 11 is obtained by omitting the cut-off portion 108 in the wire 717 (one column wire extending in the longitudinal direction at the left end among the wires of the dummy pattern portion 703) and connecting the wire 717 to the antenna portion 102 in the loop antenna 100 according to the first embodiment.

As illustrated in fig. 22, the loop antenna 800 of example 12 is obtained by omitting the cut-off portion 108 in the wire 818 (one column line extending in the longitudinal direction at substantially the middle among the wires of the dummy pattern portion 803) and connecting the wire 818 to the antenna portion 102 in the loop antenna 100 according to the first embodiment.

As illustrated in fig. 23, a loop antenna 900 of example 13 is obtained by omitting a cut-off portion 108 in each of the wires 919 extending in the longitudinal direction among the wires of the dummy pattern portion 903 and connecting the wires 919 to the antenna portion 102 in the loop antenna 100 according to the first embodiment.

In each of the loop antenna 700 of example 11, the loop antenna 800 of example 12, and the loop antenna 900 of example 13, the width a of the antenna mesh portion 107 was set to 10mm, the pitch D was set to 10 μm, the size L of the unit shape was set to 6,400 μm, and the thickness W of each wire was set to 10 μm, as in the loop antenna 100 of example 3. In each of the loop antenna 700 of example 11, the loop antenna 800 of example 12, and the loop antenna 900 of example 13, the cutting distance S is set to 480 μm.

Fig. 24 is a graph for illustrating the results of electromagnetic field simulation in the case where radio waves of 600MHz are received by the loop antenna of example 3, the loop antenna 700 of example 11, the loop antenna 800 of example 12, and the loop antenna 900 of example 13, the graph being in the form of antenna radiation efficiency (dB) of the loop antenna. It is found that also when one of the conductive wires extending in the longitudinal direction is connected to the antenna portion 102 as in the dummy pattern portions 703 and 803, the antenna radiation characteristic is at a level at which the loop antenna can function as an antenna.

In the foregoing, the embodiments and the modifications of the present invention have been described. However, the present invention is not limited to these embodiments and modifications. For example, the present invention may include modes in which the above-described embodiments and modifications are partially or entirely combined in an appropriate manner, or modes appropriately changed according to the combined modes.

List of reference numerals

100. 200, 300, 400, 500, 651, 661, 700, 800, 900 loop antennas

101 substrate

102. 202 antenna part

103. 203, 303, 403, 503, 603, 653, 703, 803, 903 virtual pattern part

104_ I, 104_ O two-dot chain line

105 first power supply part

106 second power supply part

107. 207 antenna grid section

108 cut-off part

309 first virtual ring segment

310 first intersection line

311 second virtual ring segment

412 second intersection line

413 third virtual ring segment

514. 614 smallest circular path

515. 615 first proximal end portion

516 second proximal end portion

717. 818 column conductor

919 each conductor extending in a longitudinal direction