JP2007295051A - Antenna and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna in which orthogonal conversion of the plane of polarization can be carried out and the position of arrangement can be selected freely without taking account of polarization of reception or transmission, and to provide an electronic apparatus employing it. <P>SOLUTION: The antenna comprises a first radiator 141 having a plane 141a of predetermined length and width, a second radiator 142 having an upper end face 142b arranged in parallel with the plane 141a of the first radiator 141 while spaced apart by a predetermined distance, and a return conductor 143 for coupling the intermediate portion of the first radiator 141 in the lengthwise direction and a part of the second radiator 142 opposing the intermediate portion electrically and mechanically. A part of the first radiator 141 separated by a predetermined distance from the return conductor 143 in the lengthwise direction of the first radiator 141, and a part of the second radiator 142 opposing that part, serve as feeding points 144 and 145. Orthogonal conversion of the plane of polarization is carried out by setting the length of the first radiator 141 and the distance between the return conductor 143 and the feeding point 144 at predetermined values. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna used for a flat-screen television receiver for receiving UHF band television broadcasting, a fixed-format or mobile-type wireless communication device, and an electronic device using the antenna, and more particularly, to a main polarization plane of a radio wave. The present invention relates to an antenna that can be converted into a polarized wave that is orthogonal to each other and an electronic device using the antenna.

As an indoor antenna for a television receiver that receives a UHF band television broadcast, for example, the one shown in Patent Document 1 is known.
As shown in FIG. 15, this type of antenna has first and second radiation plates 151 and 152, and a ground plate or a shield plate provided in the receiver casing is used for the first radiation plate 151. The The second radiation plate 152 is disposed to extend in parallel with the length direction of the first radiation plate 151 at a predetermined distance from the upper end surface 151a of the first radiation plate 151. One end of the second radiation plate 152 is a short-circuit plate. 153 is coupled to the upper end surface 151 a of the first radiating plate 151, and a feeding point 154 is provided in the middle portion of the second radiating plate 152 in the length direction, and between the feeding point 154 and the first radiating plate 151. Power is supplied.
JP 2000-68737 A

Such an antenna is a so-called vertically polarized antenna whose main polarization plane is formed on a line connecting the upper end surface 151 a of the first radiation plate 151 and the second radiation plate 152. The directivity characteristics of the horizontally polarized wave and the vertically polarized wave of this antenna are as shown in FIG.
In FIG. 16, a curve 161 represents the directivity gain of vertical polarization, and a curve 162 represents the directivity gain of horizontal polarization. As apparent from FIG. 16, the antenna gain of the vertically polarized wave is higher than that of the horizontally polarized wave.

By the way, radio waves used for UHF band television broadcasting have many horizontally polarized waves, and it is preferable that the antenna for receiving these radio waves be horizontally polarized waves. However, since the antenna described above is for vertically polarized waves, when it is installed horizontally on the upper end surface of the television receiver housing, its polarization plane does not coincide with the polarization plane of the received radio wave. Could not receive efficiently.
Therefore, if a vertically polarized antenna is installed vertically on the top surface of the receiver housing, etc., it will be horizontally polarized, but there are restrictions on the arrangement of the antenna in the receiver housing, and the antenna gain is reduced. The current situation is to sacrifice. In particular, when it is mounted on a recent flat-screen television receiver, there is a problem that the design balance is deteriorated and it is not suitable for an indoor antenna for a flat-screen television receiver.

  The present invention has been made in view of such circumstances, and an object of the present invention is to make it possible to orthogonally transform the plane of polarization and to arrange the location and position on a television receiver or the like without considering the polarization of reception or transmission. An object of the present invention is to provide an antenna that can be freely selected and an electronic device using the antenna.

  In order to achieve the above object, an antenna of the present invention includes a first radiator having a surface having a width and a length, and a second radiator having a surface disposed in parallel to the surface so as to face the surface. A return conductor that electrically and mechanically couples between a location on the surface of the first radiator and a location on the surface of the second radiator facing the location, from the return conductor to the first The length of the surface of the first radiator is defined as a feeding point with the location of the surface of the first radiator spaced apart in the length direction of the surface of the radiator and the location of the surface of the second radiator facing the location. The polarization plane is orthogonally transformed by setting a distance between the surface portion of the first radiator constituting the feeding point and the return conductor to a predetermined value.

  The present invention is also an electronic apparatus equipped with an antenna, the antenna being arranged in parallel to the first radiator having a surface having a width and a length, facing the surface, and parallel to the surface. A second radiator having a curved surface, and a return conductor that electrically and mechanically couples between the location of the surface of the first radiator and the location of the surface of the second radiator facing the location. Provided with the location of the surface of the first radiator spaced from the return conductor in the length direction of the surface of the first radiator and the location of the surface of the second radiator facing the location as a feeding point, The polarization plane is orthogonally transformed by setting the length of the surface of the first radiator and the distance between the location of the surface of the first radiator constituting the feeding point and the return conductor to a predetermined value. It is characterized by comprising.

  In the antenna and the electronic apparatus of the present invention, the length of the first radiator and the distance between the return conductor and the feed point with respect to the length of the first radiator are set to predetermined values to orthogonally transform the plane of polarization. As a result, the main polarization plane of the antenna can be matched to the polarization of the received or transmitted radio wave without increasing the number of antenna elements, and efficient reception or transmission is possible. It is possible to freely select the location and position of the antenna on the television receiver without considering the above.

(First embodiment)
Embodiments of an antenna according to the present invention and an electronic apparatus using the antenna will be described below with reference to the drawings. The antenna and the electronic device according to the present invention are not limited to the television receiver and the antenna as in the embodiments described below, and may be an electronic device such as a fixed-type or mobile-type wireless communication device. Is also applicable.

  FIG. 1 is a front view showing an example of a television receiver provided with the antenna of the present invention, FIG. 2 is a rear view showing the state of the television receiver of FIG. 1 viewed from the back, and FIG. 3 is an antenna portion in the present embodiment. It is a perspective view for description.

As shown in FIG. 1, the television receiver 10 according to the present embodiment faces the front from the receiver casing 11 and the window hole 111 </ b> A of the front frame 111 of the receiver casing 11 in the receiver casing 11. The stand 13 is attached to the lower end of the receiver housing 11.
Further, behind the liquid crystal display panel 12, a circuit device including a printed circuit board and circuit elements mounted on the printed circuit board is disposed (none of which is shown), and the receiver housing 11 has the following structure. An antenna 14 having the configuration is mounted on the upper end surface of the receiver housing 11.

As shown in FIGS. 1 to 3, the antenna 14 shown in this embodiment includes two plate-shaped first radiators 141 and second radiators 142 having different sizes.
The larger second radiator 142 is a ground plate that also serves as a shield plate disposed between the liquid crystal display panel 12 and a printed circuit board (not shown) so as to cover the liquid crystal display panel 12 from the back. The ground plate, that is, the second radiator 142 has a rectangular shape, and an end surface 142 a having a width equal to or greater than that of the first radiator 141 is formed around the second radiator 142.

  The smaller first radiator 141 is made of a conductive metal plate and has a flat surface 141a facing the upper end surface 142b forming the upper side of the second radiator 142, and the flat surface 141a of the first radiator 141. And the upper end surface 142b of the second radiator 142 extend in parallel. That is, the plane 141a of the first radiator 141 has a predetermined length L1 (for example, about λ / 2, where λ is the wavelength of a radio wave received (transmitted) by the antenna 14) and a predetermined width W1 (for example, about 20 mm = 0). .04λ) and the upper end surface 142b of the second radiator 142 has a dimension (for example, λ / 2 or more) equal to or longer than the extended length L1 of the plane 141a of the first radiator 141. And a width larger than the width W1 of the first radiator 141.

As shown in FIGS. 2 and 3, the first radiator 141 has a predetermined distance H1 (for example, about 30 mm = 0.06λ) from the upper end surface 142b of the second radiator 142 in the length direction of the upper end surface 142b. Arranged parallel to And between the intermediate part of the length direction of the 1st radiator 141 and the location of the upper end surface 142b which opposes this intermediate part, it is electrically and mechanically by the return conductor 143 for a high frequency current return from a conductive metal plate material. Combined.
Further, the location of the first radiator 141 that is separated from the return conductor 143 in the length direction of the first radiator 141 by a predetermined distance R1 (for example, about 0.04λ) and the location of the second radiator 142 that faces this location. The feeding points are 144 and 145, respectively. Further, the feeding point 144 of the first radiator 141 is offset rearward from the intermediate point in the width direction in the width direction of the first radiator 141 as shown in FIG.
An inner conductor (core wire) 146a of a coaxial cable 146 used as an antenna feeding line is connected to the feeding point 144 of the first radiator 141 by soldering or the like. Further, the outer conductor (outer skin: mesh wire) 146 b of the coaxial cable 146 is electrically and physically connected to the feeding point 145 of the second radiator 142 by a clamp member 147. The other end of the coaxial cable 146 is connected to a tuner unit (not shown) mounted on a printed board (not shown).

In the antenna including the arrangement structure of the first and second radiators 141 and 142 and the feeding structure, the high-frequency current flowing out from the feeding point 144 flows toward both ends of the first radiator 141 in the length direction. In this case, when the coupling position of the return conductor 143 with respect to the first radiator 141 is substantially in the middle of the length direction of the first radiator 141, the high-frequency current that flows toward both ends of the length direction of the first radiator 141 A phase difference occurs, and the current distribution of the first radiator 141 becomes asymmetrical about the return conductor 143. That is, a large current flows through the first radiator 141 toward the feeding point 144 with the return conductor 143 as the center, and the current density decreases in the opposite direction from the feeding point 144 to the return conductor 143.
Similarly, also on the upper end surface 142b of the second radiator 142, the current distribution is asymmetrical with respect to the return conductor 143, and the current density follows the direction opposite to the return conductor 143 from the feeding point 144. Decrease. Such an operation is estimated from an analysis result by a computer.
As a result, the main polarization plane of the antenna is orthogonally transformed. That is, in the past, what functioned as a vertically polarized antenna came to function as a horizontally polarized antenna, and the directivity gain of the horizontally polarized wave could be increased by about 6 dB.
Therefore, even if such an antenna 14 is horizontally disposed on the upper end surface of the receiver housing 11 as shown in FIGS. 1 and 2, it can efficiently receive horizontally polarized radio waves.
The antenna 14 mounted on the upper end surface of the receiver housing 11 is covered with a cover 148 made of a dielectric insulating material such as a synthetic resin material provided on the upper end surface of the receiver housing 11.

  As shown in FIG. 3, the horizontal direction of the television receiver 10 is the X-axis direction, the vertical direction of the television receiver 10 is the Y-axis direction, and the front-rear direction of the television receiver 10 (on the surfaces of the first radiator 141 and the plane 141a). (Parallel direction) is the Z-axis direction, the directivity characteristics of the antenna composed of the first radiator 141 and the second radiator 142 when the distance R1 from the return conductor 143 to the feeding point 144 is changed are shown in FIGS. Further, the directivity characteristics of the antenna including the first radiator 141 and the second radiator 142 when the distance H1 between the first radiator 141 and the upper end surface 142b is changed are shown in FIGS. 11 as shown.

FIG. 4 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance R1 from the return conductor 143 to the feeding point 144 is set to R1 = 60 mm, and the curve 41 shows the directivity characteristics of the horizontal polarization. A curve 42 indicates the directivity of vertical polarization.
FIG. 5 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance R1 from the return conductor 143 to the feeding point 144 is set to R1 = 40 mm. A curve 51 indicates the directivity of the horizontal polarization. The curve 52 shows the directivity of vertical polarization.
FIG. 6 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance R1 from the return conductor 143 to the feeding point 144 is set to R1 = 20 mm. A curve 61 indicates the directivity of the horizontal polarization. The curve 62 shows the directivity of vertical polarization.
FIG. 7 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance R1 from the return conductor 143 to the feeding point 144 is set to R1 = 10 mm. A curve 71 indicates the directivity of the horizontal polarization. The curve 72 shows the directivity of vertical polarization.

As is clear from the above description, when the distance R1 is 60 mm or 40 mm, the peak gain of the antenna 14 is larger in the vertical polarization than in the horizontal polarization. Further, when the distance R1 is 20 mm or 10 mm, the peak gain of the antenna 14 is larger in the horizontally polarized wave than in the vertically polarized wave.
That is, in the antenna having the arrangement structure shown in FIG. 2 and FIG. 3, when the distance R1 is 60 mm or 40 mm, vertical polarization is likely to occur, but when the distance R1 is 20 mm or less, the main polarization is vertical polarization. More than the directivity gain of horizontal polarization. The antenna gain at this time is R20 = 5.2 dBi when R1 = 20 mm, R10 = 4.2 dBi when R1 = 10 mm, and the optimum value is around R1 = 20 mm.

FIG. 8 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance H1 between the first radiator 141 and the upper end surface 142b is set to H1 = 50 mm. A curve 81 indicates the horizontal polarization. The curve 82 shows the directivity of vertical polarization.
FIG. 9 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance H1 between the second radiator 142 and the upper end surface 141b is set to H1 = 30 mm. The polarization directivity is shown, and the curve 92 shows the vertical polarization directivity.
FIG. 10 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance H1 between the second radiator 142 and the plane 141a is set to H1 = 20 mm. The directivity characteristic of the wave is shown, and the curve 102 shows the directivity characteristic of the vertically polarized wave.
FIG. 11 shows the directivity characteristics of horizontal polarization and vertical polarization when the distance H1 between the second radiator 142 and the upper end surface 141b is set to H1 = 5 mm, and the curve 111 is horizontal. The polarization directivity is shown, and the curve 112 shows the vertical polarization directivity.

  As apparent from FIGS. 8 to 11, the numerical value of the distance H1 does not affect the directivity characteristics of the horizontal and vertical polarizations, but when H1 ≧ 20 mm, there is no distortion and the directivity characteristics of the 8-shaped horizontal polarization. Can be obtained.

FIG. 12 is a characteristic diagram showing the relationship between the VSWR (voltage standing wave ratio) of the antenna 14 and the frequency in the present embodiment.
As shown in FIG. 12, the VSWR at a frequency of 470 MHz is 1.9249, the VSWR at a frequency of 557 MHz is 2.9816, and the VSWR at a frequency of 710 MHz is 1.8433. The antenna can operate satisfactorily at a wide frequency range including these frequencies of 470 MHz (1), 557 MHz (2), and 710 MHz (3). Thereby, it can be used as an indoor antenna of a receiver that receives a UHF band television broadcast such as a terrestrial digital broadcast.

FIG. 13 shows Smith showing the reflection characteristics when the distance H1 between the first radiator 141 and the upper end surface 142b is set to H1 = 60 mm, H1 = 50 mm, H1 = 30 mm, H1 = 20 mm, and H1 = 5 mm. It is a chart. The impedance trajectories corresponding to these distances H1 = 60 mm (1), H1 = 50 mm (2), H1 = 30 mm (3), H1 = 20 mm (4), and H1 = 5 mm (5) are shown in parentheses in FIG. Is shown.
As apparent from FIG. 13, H1 = about 30 mm is most desirable for matching over a wide band of 470 MHz, 557 MHz, and 710 MHz. Therefore, in this embodiment, H1 = 30 mm is set as the optimum value.

Next, the width W1 of the first radiator 141 will be examined.
As shown in FIG. 14, it is a Smith chart showing the reflection characteristics when the width W1 of the first radiator 141 is set to W1 = 30 mm, W1 = 20 mm, W1 = 10 mm, and W1 = 2 mm. The respective impedance trajectories corresponding to these widths W1 = 30 mm (1), W1 = 20 mm (2), W1 = 10 mm (3), and W1 = 2 mm (4) are indicated by parenthesized numbers in FIG.
As is apparent from FIG. 14, W1 ≧ 20 mm is most desirable for matching over a wide band of 470 MHz, 557 MHz, and 710 MHz.

  According to the antenna 14 of this embodiment, the length L1 of the first radiator 141 is set to about ½ of the reception or transmission wavelength λ, and the coupling point of the return conductor 143 is set to the first radiator 141. The distance R1 between the return conductor 143 and the feed point 144 is set to about 0.04λ (= 20 mm) so that the plane of polarization is orthogonally transformed. The main polarization plane of the antenna can be matched to the polarization of the received radio wave or transmission radio wave without increasing the number, and efficient reception or transmission is possible. The location and position of the TV receiver can be freely selected.

Further, according to the antenna shown in the present embodiment, since the shield plate or the ground plate of the receiver housing 11 is used, the newly added parts are only the first radiator 141 and the return conductor 143. Manufacturing cost can be reduced. In addition, since only the first radiator 141 bulges upward from the upper end surface of the receiver housing 11, the amount of bulge of the antenna itself can be greatly suppressed, and the antenna can be reduced in size and thickness. It can be easily realized.
In addition, since the antenna can be reduced in size and thickness, the design match with the liquid crystal flat-screen television receiver is further improved, and the television receiver can be moved and carried between rooms. In addition, it can be easily carried and viewed on kitchens and verandas that do not have antenna terminals, and there is no need to purchase outdoor antennas or construction, and it is possible to view immediately by purchasing a TV receiver. is there.

In the above embodiment, the case where the antenna 14 is mounted on the upper end surface of the receiver housing 11 has been described. However, the present invention is not limited to this. For example, the shield plate or the ground plate of the receiver housing 11 can be used to provide the back surface portion near the upper end of the receiver housing 11 or the left and right side surfaces of the receiver housing 11.
Further, in the present invention, if the positions of the return conductor 143 and the feeding point 144 are physically or electrically variable, switching between horizontal / vertical polarized waves becomes possible.
Moreover, although the case where the upper end surface 142b of the 1st radiator 141 and the 2nd radiator 142 was a plane was demonstrated in the said embodiment, this invention is not limited to this, Even if these surfaces are curved surfaces. Good.
In the above embodiment, a shield plate or a ground plate of an electric device is used for the second radiator 142. However, when the shield plate or the ground plate is less than 1 / 2λ of the wavelength, A second radiator having a length of 1 / 2λ may be provided separately from the shield plate or the ground plate.

It is a front view which shows an example of a television receiver provided with the antenna of this invention. It is a perspective view for description of the antenna part in the present embodiment. It is a rear view which shows the state which looked at the television receiver of FIG. 1 from the back. It is a figure which shows the directional characteristic of a horizontal polarization and vertical polarization when the distance R1 of the antenna in this Embodiment is set to R1 = 60 mm. It is a figure which shows the directional characteristic of a horizontal polarization and vertical polarization when the distance R1 of the antenna in this Embodiment is set to R1 = 40mm. It is a figure which shows the directional characteristic of a horizontal polarization and vertical polarization when the distance R1 of the antenna in this Embodiment is set to R1 = 20mm. It is a figure which shows the directional characteristic of a horizontal polarization and a vertical polarization when the distance R1 of the antenna in this Embodiment is set to R1 = 10mm. It is a figure which shows the directional characteristic of a horizontal polarization and a vertical polarization when the distance H1 of the antenna in this Embodiment is set to H1 = 50mm. It is a figure which shows the directional characteristic of a horizontal polarization and a vertical polarization when the distance H1 of the antenna in this Embodiment is set to H1 = 30mm. It is a figure which shows the directivity characteristics of a horizontal polarization and a vertical polarization when the distance H1 of the antenna in this Embodiment is set to H1 = 20 mm. It is a figure which shows the directional characteristic of a horizontal polarization and a vertical polarization when the distance H1 of the antenna in this Embodiment is set to H1 = 5mm. It is a characteristic view which shows the relationship between the VSWR and frequency of the antenna in this Embodiment. It is a Smith chart which shows the reflective characteristic of the antenna in this Embodiment. It is a Smith chart which shows the reflective characteristic of the antenna in this Embodiment. It is explanatory drawing of the antenna in the past. It is a figure which shows the directional characteristic of the horizontal polarization and vertical polarization of the antenna in the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Television receiver, 11 ... Receiver housing, 12 ... Liquid crystal display panel, 13 ... Stand, 14 ... Antenna, 141 ... First radiator, 141a ... Plane, 142 ... Second Radiator, 142a... End face, 142b... Upper end face, 143... Return conductor, 144, 145 .. feeding point, 146... Coaxial cable, 147.

Claims (10)

A first radiator with a surface having a width and a length;
A second radiator having a surface opposite the surface and disposed parallel to the surface;
A return conductor that electrically and mechanically couples between the location of the surface of the first radiator and the location of the surface of the second radiator facing the location;
The location of the surface of the first radiator spaced from the return conductor in the length direction of the surface of the first radiator and the location of the surface of the second radiator facing the location are feed points,
The polarization plane is orthogonally transformed by setting the length of the surface of the first radiator and the distance between the surface of the first radiator constituting the feeding point and the return conductor to a predetermined value. Configured
An antenna characterized by that.   2. The antenna according to claim 1, wherein when the plane of polarization is orthogonally converted, the coupling portion of the return conductor is set to a portion excluding both ends in the length direction of the surface of the first radiator. .   The antenna according to claim 1, wherein the second radiator is a grant plate or a shield plate of an electronic device provided with the antenna.   The grant plate or shield plate has an end surface extending along the periphery of the casing of the electronic device, and the surface of the second radiator is formed of a part of the end surface of the grant plate or shield plate. The antenna according to claim 3, wherein the end face of the part extends with a dimension equal to or longer than an extension length of the face of the first radiator.   The length of the surface of the first radiator is set to about ½ of the reception or transmission wavelength λ, the coupling portion of the return conductor is an intermediate portion in the length direction of the first radiator, and the return conductor and the power supply 2. The antenna according to claim 1, wherein a distance between the points is about 0.04λ. An electronic device equipped with an antenna,
The antenna is
A first radiator with a surface having a width and a length;
A second radiator having a surface opposite the surface and disposed parallel to the surface;
A return conductor that electrically and mechanically couples between the location of the surface of the first radiator and the location of the surface of the second radiator facing the location;
The location of the surface of the first radiator spaced from the return conductor in the length direction of the surface of the first radiator and the location of the surface of the second radiator facing the location are feed points,
The polarization plane is orthogonally transformed by setting the length of the surface of the first radiator and the distance between the surface of the first radiator constituting the feeding point and the return conductor to a predetermined value. Configured
An electronic device characterized by that.   7. The electron according to claim 6, wherein when the polarization plane is orthogonally converted, the coupling portion of the return conductor is set to a portion excluding both ends in the length direction of the surface of the first radiator. machine.   The electronic device according to claim 6, wherein the second radiator includes a grant plate or a shield plate of the electronic device provided with the antenna.   The grant plate or shield plate has an end surface extending along the periphery of the casing of the electronic device, and the surface of the second radiator is formed of a part of the end surface of the grant plate or shield plate. 9. The electronic apparatus according to claim 8, wherein the part of the end surface extends with a dimension equal to or longer than an extension length of the surface of the first radiator. The length of the first radiator is about ½ of the reception or transmission wavelength λ, the coupling point of the return conductor is an intermediate portion in the length direction of the first radiator, the return conductor, the feeding point, 7. The electronic apparatus according to claim 6, wherein a distance between the two is about 0.04λ.

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