JP2006025084A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an antenna which is made small-sized and whose VSWR characteristics can be improved more. <P>SOLUTION: The antenna is equipped with an antenna element having a main part 1a in a shape obtained by approximating a nearly semicircular shape or a nearly semicircular arc by a polygon and an attached part 1b which is smaller than the main part 1a, and has a monopole structure feeding electricity to one end part of the diameter of the main part 1a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antenna provided in a mobile communication device or the like.

A disk monopole antenna using a circular antenna element is known as an antenna that realizes wideband characteristics. In addition, in order to reduce the size of the disk monopole antenna, a circular antenna element is conventionally deformed. For example, a circular antenna element is bent at a right angle with a crease in diameter (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-164731

  However, the conventional miniaturization method described above has a problem that the space occupied by the antenna element is still large and the miniaturization is insufficient. For example, when the mounting space is limited like a mobile communication device such as a mobile phone, further downsizing is required.

  In addition, when a circular antenna element is folded in half, an anti-resonance point is generated in a desired frequency band, VSWR (Voltage Standing Wave Ratio) characteristics are disturbed, and it is difficult to obtain uniform broadband characteristics. is there.

  In order to solve the above problems, it is conceivable to configure the antenna element in a semicircular or semielliptical shape. As a result, it is possible to achieve a good wideband characteristic and to reduce the size, but further improvement of the VSWR characteristic and downsizing are desired.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an antenna having a better VSWR characteristic than the conventional one and a smaller antenna than the conventional one.

  In order to solve the above-described problems, an antenna according to the present invention includes a main portion having a substantially semicircular shape or a shape that approximates a substantially semicircular arc with a polygon, and an accessory portion that is smaller than the main portion. And a monopole or dipole structure that feeds power to one end of the diameter of the main portion of the antenna element.

  In the antenna according to the present invention, the incidental portion of the antenna element has a shape that fits in a rectangle having a side that is twice the length in a direction orthogonal to the diameter of the main portion and half of the length. It is characterized by.

  In the antenna according to the present invention, the antenna element is bent with a rectangular parallelepiped as a mold.

  The antenna according to the present invention is characterized in that the antenna element is formed on a dielectric.

  The antenna according to the present invention is characterized in that a slit is provided in an incidental portion of the antenna element.

  According to the present invention, improvement or downsizing of the VSWR characteristics can be further promoted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a schematic configuration of an antenna according to a first embodiment of the present invention. In this embodiment, the antenna element is assembled into a monopole structure.

The antenna element 1 is a member made of a conductor plate having a semicircular portion 1a and a rectangular portion 1b. The rectangular portion 1b is provided on the diameter side of the semicircular portion 1a. The antenna element 1 has such a length that the diameter of the semicircular portion 1a is approximately ¼ of the resonance wavelength λ of the antenna.
The power feeding unit 2 is a member that feeds power to the antenna element 1. The power feeding unit 2 is connected to one end of the diameter of the semicircular portion 1 a of the antenna element 1 and the ground plane 3.

  2 and 3 are side views showing a schematic configuration of a modified example of the antenna according to the first embodiment. In FIG. 2, the antenna element 10 is a member made of a conductor plate having a horizontally long semi-elliptical portion 10a and a rectangular portion 10b. In FIG. 3, the antenna element 20 is a member made of a conductor plate having a vertically long semi-elliptical portion 20a and a rectangular portion 20b.

  The antenna element may be provided perpendicular to the ground plane 3 as shown in FIG. 4A, or may be provided parallel to the ground plane 3 as shown in FIG. 4B. FIG. 4 illustrates the antenna element 1 of FIG.

  FIG. 5 is a dimension diagram of the antenna element 1 shown in FIG. As shown in FIG. 5, with respect to the radius r of the semicircular portion 1a, the rectangular portion 1b has a vertical length of 2r and a horizontal length of maximum r / 2.

  FIG. 6 is a dimension diagram of the antenna element 10 shown in FIG. As shown in FIG. 6, the rectangular portion 10b has a vertical length of 2b and a horizontal length that is the maximum with respect to the semi-long axis length a and the semi-short axis length b of the horizontally long semi-elliptical portion 10a. a / 2.

  FIG. 7 is a dimension diagram of the antenna element 20 shown in FIG. As shown in FIG. 7, the rectangular portion 20b has a vertical length of 2b and a horizontal length that is the maximum with respect to the half-long axis length b and the semi-short axis length a of the vertically long semi-elliptical portion 20a. a / 2.

FIG. 8 is a graph showing a simulation result for showing the effect of improving the VSWR characteristic according to the present invention.
In FIG. 8, a waveform A is a simulation result of the VSWR characteristics when the antenna element 1 of the antenna according to the present invention shown in FIG. 1 is provided in parallel with the ground plane 3 as shown in FIG. 4B. . Waveform B is a simulation result of the VSWR characteristics when the semicircular antenna element 1000 (no rectangular portion) shown in FIG. 9 is provided in parallel with the ground plane 3 as in FIG. 4B.
In this simulation condition, the radius r of the semicircular portion 1a of the antenna element 1 is about 0.08λ with respect to the wavelength λ of the lowest resonance frequency (f), and the horizontal length of the rectangular portion 1b. Is r / 2. Similarly, the radius of the antenna element 1000 is about 0.08λ. The ground plane 3 is a square having a side of about 0.67λ.

  As apparent from FIG. 8, the VSWR characteristic waveform A of the antenna according to the present invention is generally improved as compared with the VSWR characteristic waveform B of the antenna composed of the semicircular antenna element 1000. .

  As described above, according to the first embodiment, the antenna element has a substantially semicircular (semicircular or semielliptical) main part (semicircular part 1a, semielliptical part 10a, 20a) and a rectangular shape. It is comprised from the incidental part (rectangular part 1b, 10b, 20b) of a shape. Thereby, the further improvement of the VSWR characteristic can be aimed at.

Next, a second embodiment will be described.
FIG. 10 is a perspective view for explaining a configuration of an antenna element used for the antenna according to the second embodiment of the present invention. In the present embodiment, the antenna element is bent so as to lie over a rectangular parallelepiped surface. In FIG. 10, for convenience of explanation, a rectangular parallelepiped that is a folding mold is illustrated so that the folding method can be easily understood.
An antenna element 100 shown in FIG. 10 is a member made of a semicircular conductor plate. In FIG. 10, the antenna element 100 is bent so as to face a rectangular parallelepiped surface. When configured as an antenna, the bent antenna element 100 is used instead of the antenna element 1 of FIG. 1, for example.

  FIG. 11 is a dimensional view of a rectangular parallelepiped serving as a bending mold. With respect to the radius r of the semicircular antenna element 100, the rectangular parallelepiped serving as a bending mold satisfies the conditions of the following expressions (1) to (3) in terms of dimensions (width W, height H, thickness T). Use what you want.

  FIG. 12 is a development view showing the bending dimensions of the antenna element 100 shown in FIG. In FIG. 12, the dimension of the rectangular parallelepiped serving as a bending mold is expressed by the following equation (4). In this bending example, the antenna element 100 is arranged so that the center of the original circle of the semicircle, which is the shape of the antenna element 100, is located at the center of one longitudinal side of the front edge of the rectangular parallelepiped. And it bends so that it may crawl on the surface of a rectangular parallelepiped.

  FIG. 13 is another developed view for explaining a bending example of the antenna element according to the second embodiment. The example of FIG. 13 is a case where the width W of the rectangular parallelepiped is “3r / 4”.

  FIG. 14 is a perspective view for explaining a configuration of a modified example of the antenna element according to the second embodiment. FIG. 15 is a development view showing the bending dimensions of the antenna element 100a shown in FIG. In this bending example, the antenna element 100a is arranged so that the center of the original circle of the semicircle, which is the shape of the antenna element 100a, is located at a position shifted by β from the center of one longitudinal side of the front edge of the rectangular parallelepiped. . And it bends so that it may crawl on the surface of a rectangular parallelepiped. The height H ′ of the rectangular parallelepiped satisfies the condition of the following expression (5) with respect to H of the above expression (2).

  FIG. 16 is a perspective view for configuring the shape of another modification of the antenna element according to the second embodiment. FIG. 17 is a development view showing the bending dimensions of the antenna element 100b shown in FIG. In this example of bending, it is bent only on the left side of the rectangular parallelepiped. The dimensions of the rectangular parallelepiped are “r / 2 ≦ width W <r”, “height H = 2r”, and “thickness T = r−W” with respect to the radius r of the semicircular antenna element 100b.

FIG. 18 and FIG. 19 are development views showing bending dimensions for explaining the configuration of another modification of the antenna element according to the second embodiment. In these examples, the semi-elliptical antenna elements 200 and 200a are bent so as to lie over a rectangular parallelepiped surface.
FIG. 18 shows a bending method similar to FIG. The rectangular parallelepiped that is the bending mold has the following dimensions (width W, height H, thickness T) with respect to the semi-major axis length a and the semi-minor axis length b of the semi-elliptical antenna element 200 (6 ) To (8) satisfying the conditions.

  In the example of FIG. 18, the dimensions of a rectangular parallelepiped serving as a bending mold are expressed by the following equation (9).

  FIG. 19 shows a bending method similar to FIG. The height H ′ of the rectangular parallelepiped serving as the bending mold is a condition of the following expression (10) with respect to H of the expression (7).

  As described above, according to the second embodiment, the antenna can be further miniaturized by bending the antenna element.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

  FIG. 20 is a side view showing an embodiment of an antenna element used for the antenna of the present invention. In Example 1, a slit 101s is provided in a rectangular portion of the antenna element according to the first embodiment. In the example of FIG. 20, the antenna element 101 is a member made of a conductor plate having a semicircular portion 1a and a rectangular portion 101b, like the antenna element 1 of FIG. The rectangular portion 101b is provided with a slit 101s. The number and arrangement of the slits 101s may be appropriately changed based on desired VSWR characteristics. Thereby, the VSWR characteristic can be adjusted. A semi-elliptical part may be used instead of the semi-circular part 1a.

FIG. 21 is a side view showing another embodiment of the antenna element used for the antenna of the present invention. In Example 2, a semi-elliptical portion 102b is provided instead of the rectangular portion in the antenna element according to the first embodiment. In the example of FIG. 21, the antenna element 102 is a member made of a conductor plate having a semicircular portion 1a (main portion) and a semi-elliptical portion 102b (attached portion). As shown in FIG. 21, the semi-elliptical part 102 b (attachment part) may have a length less than the diameter of the semi-circular part 1 a (main part).
A semi-elliptical part may be used as the main part instead of the semi-circular part 1a. 22 to 24 show dimensional diagrams when a semi-elliptical portion is provided instead of the rectangular portion in the antenna element according to the first embodiment.

  FIG. 22 is a dimensional diagram of the antenna element 103 having a semicircular portion 1a (main portion) and a semi-elliptical portion 103b (accompanying portion). As shown in FIG. 22, with respect to the radius r of the semicircular portion 1a, the semielliptical portion 103b has a maximum length of 2r and a maximum length of r / 2 of the semishort axis. That is, the maximum shape of the semi-elliptical portion 103b which is an incidental portion is set to be within a rectangle having a vertical length of 2r and a horizontal length of r / 2.

  FIG. 23 is a dimensional diagram of the antenna element 104 having a horizontally long semi-elliptical portion 10a (main portion) and a semi-elliptical portion 104b (accompanying portion). As shown in FIG. 23, the semi-elliptical portion 104b has a maximum length of 2b and a length of the semi-short axis with respect to the semi-elliptical portion 10a. The maximum is a / 2. In other words, the maximum shape of the semi-elliptical portion 104b that is an incidental portion is set to be within a rectangle having a vertical length of 2b and a horizontal length of a / 2.

  FIG. 24 is a dimension diagram of the antenna element 105 having a vertically long semi-elliptical portion 20a (main portion) and a semi-elliptical portion 105b (attached portion). As shown in FIG. 24, the semi-elliptical portion 105b has a maximum length of 2b and a length of the semi-short axis with respect to the semi-elliptical portion 20a. The maximum is a / 2. That is, the maximum shape of the semi-elliptical portion 105b which is an incidental portion is set to be within a rectangle having a vertical length of 2b and a horizontal length of a / 2.

  In the second embodiment described above, the VSWR characteristics can be adjusted by adjusting the shape of the incidental portion.

  As described above, the incidental part of the antenna element according to the present invention fits in a rectangle having a side that is twice the length in the direction orthogonal to the diameter of the main part of the antenna element and half the length. Any shape can be used.

25 to 32 are views for explaining another embodiment of the antenna element used for the antenna of the present invention.
FIG. 25 is a perspective view for explaining a configuration in which the antenna element 1 of FIG. 1 is bent so as to lie over a rectangular parallelepiped surface. FIG. 26 is a development view of the antenna element 1 shown in FIG. In this example, the rectangular portion 1b is bent to the side of the rectangular parallelepiped.

  FIG. 27 is a perspective view for explaining a configuration in which the antenna element 101 of FIG. 20 is bent so as to lie over a rectangular parallelepiped surface. FIG. 28 is a development view of the antenna element 101 shown in FIG. In this example, the rectangular portion 101b including the slit 101s is bent toward the side surface of the rectangular parallelepiped.

  FIG. 29 is a perspective view for explaining a configuration in which the antenna element 102 of FIG. 21 is bent so as to lie over a rectangular parallelepiped surface. FIG. 30 is a development view of the antenna element 102 shown in FIG. In this example, the semi-elliptical portion 102b is bent to the side surface side of the rectangular parallelepiped.

  FIG. 31 is a perspective view for explaining a configuration in which the antenna element 110 having the semicircular part 1a and the rectangular part 110b is bent so as to lie on a rectangular parallelepiped surface. FIG. 32 is a development view of the antenna element 110 shown in FIG. The length of the rectangular portion 110b is shorter than the diameter of the semicircular portion 1a. In this example, the rectangular portion 110b is bent to the left side of the rectangular parallelepiped. Further, the semicircular portion 1a is bent from the right side surface and the upper surface side to the back surface side.

  In the above-described third embodiment, the antenna element can be adjusted while balancing the improvement in the VSWR characteristics and the miniaturization of the antenna by providing the antenna element with the incidental portion and bending the antenna element.

33 and 34 are diagrams for explaining another embodiment of the antenna element used for the antenna of the present invention. In Example 4, the antenna element is formed on a rectangular parallelepiped dielectric.
FIG. 33 is a perspective view for explaining a configuration in which the antenna element 1 of FIG. 25 is formed on the dielectric 200. FIG. 34 is a development view of the antenna element 1 and the dielectric 200 shown in FIG. In this example, the dielectric 200 is a rectangular parallelepiped member. The antenna element 1 shown in FIG. 25 is formed on the dielectric 200 by being bent over the surface of the rectangular parallelepiped dielectric 200. The semicircular portion 1a of the antenna element 1 is formed on the front surface of the dielectric 200, and the rectangular portion 1b is bent on the side surface side of the dielectric 200 and formed on the left side surface. The dielectric 200 is made of a ceramic material, for example.

FIG. 35 is a graph showing a simulation result for showing the effect of improving the VSWR characteristic according to the fourth embodiment.
In FIG. 35, a waveform C is a simulation result of the VSWR characteristics in the case where there is a dielectric shown in FIG. A waveform D is a simulation result of the VSWR characteristic in the case of no dielectric shown in FIG. As is clear from FIG. 35, the waveform C of the VSWR characteristic when the dielectric is present according to the fourth embodiment has an improved VSWR characteristic compared to the waveform D of the VSWR characteristic when the dielectric is not present.

  Note that a pad for fixing the antenna element to the antenna substrate can be appropriately provided on the dielectric. In addition, it is possible to provide the feeding electrode on the antenna element as appropriate. 36 and 37 are diagrams showing a configuration example of the fixing pad and the power feeding electrode, FIG. 36 is a perspective view, and FIG. 37 is a development view. As shown in FIGS. 36 and 37, a fixing pad 301 is provided on the dielectric 200. The number and arrangement of the fixing pads 301 may be changed as appropriate. The antenna element 100a is provided with a power feeding electrode 302. The feeding electrode 302 is provided at one end of the diameter line of the antenna element 100a.

  FIG. 38 is a side view for explaining another embodiment of the antenna element used for the antenna of the present invention. In the fifth embodiment, the main portion of the antenna element has a shape that approximates a semicircular arc with a polygon. In the example of FIG. 38, the antenna element 400 includes a main portion 400a having a shape obtained by approximating a semicircular arc with a half of an octagon, and a rectangular auxiliary portion 400b. The condition relating to the shape of the main part is expressed by the following equation (11).

However, S is the area of the approximate semicircle or semi-ellipse, and P is the area of the main part.
In addition, the main part should just be a shape approximated to the polygon within the range which satisfy | fills the conditions of said (11) Formula.

  FIG. 39 is a diagram showing a schematic configuration of a dipole antenna according to the present invention. In Example 6, the antenna element is used to assemble a dipole structure. The dipole antenna includes what is called a cross dipole. In the example of FIG. 39, two antenna elements 1 of FIG. 1 are used to assemble a dipole structure. In the example of FIG. 39 (a), both antenna elements 1 are arranged in the same direction, and in the example of FIG. 39 (b), both antenna elements 1 are arranged in the opposite direction.

It is a side view showing a schematic structure of an antenna concerning a 1st embodiment of the present invention. It is a side view which shows schematic structure of the modification of the antenna which concerns on 1st Embodiment. It is a side view which shows schematic structure of the modification of the antenna which concerns on 1st Embodiment. It is a figure for demonstrating the arrangement | positioning relationship between the antenna element which concerns on this invention, and a ground plane. It is a dimension figure of the antenna element 1 shown in FIG. FIG. 3 is a dimension diagram of the antenna element 10 shown in FIG. 2. FIG. 4 is a dimension diagram of the antenna element 20 shown in FIG. 3. 6 is a graph showing simulation results for showing the effect of improving the VSWR characteristics according to the present invention. FIG. 6 is a side view of an antenna using a semicircular antenna element 1000. It is a perspective view for demonstrating the structure of the antenna element used for the antenna which concerns on the 2nd Embodiment of this invention. It is a dimensional drawing of the rectangular parallelepiped used as a bending type | mold. It is an expanded view which shows the bending dimension of the antenna element 100 shown in FIG. It is another expanded view for demonstrating the example of bending of the antenna element which concerns on 2nd Embodiment. It is a perspective view for demonstrating the structure of the modification of the antenna element which concerns on 2nd Embodiment. It is an expanded view which shows the bending dimension of the antenna element 100a shown in FIG. It is a perspective view for comprising the shape of other modifications of the antenna element concerning a 2nd embodiment. It is an expanded view which shows the bending dimension of the antenna element 100b shown in FIG. It is an expanded view which shows the bending dimension for demonstrating the structure of the other modification of the antenna element which concerns on 2nd Embodiment. It is an expanded view which shows the bending dimension for demonstrating the structure of the other modification of the antenna element which concerns on 2nd Embodiment. It is a side view which shows one Example of the antenna element used for the antenna of this invention. It is a side view which shows the other Example of the antenna element used for the antenna of this invention. It is a dimension figure of the antenna element 103 which has the semicircle-shaped part 1a (main part) and the semi-elliptical part 103b (attachment part). It is a dimension figure of the antenna element 104 which has the horizontally long semi-elliptical part 10a (main part) and the semi-elliptical part 103b (attachment part). It is a dimension figure of the antenna element 104 which has the vertically long semi-elliptical part 20a (main part) and the semi-elliptical part 103b (attachment part). It is a perspective view for demonstrating the structure bent so that the antenna element 1 of FIG. 1 might crawl on the surface of a rectangular parallelepiped. FIG. 26 is a development view of the antenna element 1 shown in FIG. 25. It is a perspective view for demonstrating the structure by which the antenna element 101 of FIG. 20 was bent so that it might crawl on the surface of a rectangular parallelepiped. It is an expanded view of the antenna element 101 shown in FIG. It is a perspective view for demonstrating the structure bent so that the antenna element 102 of FIG. 21 might crawl on the surface of a rectangular parallelepiped. FIG. 30 is a development view of the antenna element 102 shown in FIG. 29. It is a perspective view for demonstrating the structure by which the antenna element 110 which has the semicircle-shaped part 1a and the rectangular-shaped part 110b was bent so that it might face over the surface of a rectangular parallelepiped. FIG. 32 is a development view of the antenna element 110 shown in FIG. 31. FIG. 26 is a perspective view for explaining a configuration in which the antenna element 1 of FIG. 25 is formed on a dielectric 200. FIG. 34 is a development view of the antenna element 1 and the dielectric 200 shown in FIG. 33. It is the graph by which the simulation result for showing the improvement effect of the VSWR characteristic by Example 4 which concerns on this invention is shown. It is a perspective view which shows the structural example of the pad for fixation, and the electrode for electric power feeding. It is an expanded view which shows the structural example of the pad for fixation and the electrode for electric power feeding. It is a side view for demonstrating the other Example of the antenna element used for the antenna of this invention. It is a figure which shows schematic structure of the antenna of the dipole structure which concerns on this invention.

Explanation of symbols

1,10,20,100,100a, 100b, 101,102,103,104,105,110,200,200a, 400 ... antenna element, 1a ... semicircular part (main part of antenna element), 1b, 10b , 20b, 101b, 110b, 400b ... rectangular part (attachment part of the antenna element), 10a, 20a ... semi-elliptical part (main part of the antenna element), 101s ... slit, 102b, 103b, 104b, 105b ... semi-ellipse Shape part (attachment part of antenna element), 400a ... half-octagon part (main part of antenna element), 2 ... feeding part, 3 ... ground plate, 200 ... dielectric, 301 ... fixing pad, 302 ... feeding electrode.

Claims (5)

An antenna element having a substantially semicircular shape or a main portion of a shape approximating a semicircular arc with a polygon, and an incidental portion smaller than the main portion;
An antenna having a monopole or dipole structure for supplying power to one end of a diameter of a main portion of the antenna element.   2. The antenna element according to claim 1, wherein the incidental portion of the antenna element has a shape that fits in a rectangle having a side that is twice the length in a direction orthogonal to the diameter of the main portion and half of the length. The described antenna.   The antenna according to claim 1, wherein the antenna element is bent with a rectangular parallelepiped as a mold.   The antenna according to any one of claims 1 to 3, wherein the antenna element is formed on a dielectric. The antenna according to any one of claims 1 to 4, wherein a slit is provided in an incidental portion of the antenna element.

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