JP2000068736A - Multi-frequency antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized multi-frequency antenna which can be applied to even a system of not less than three frequencies. SOLUTION: A ground conductor board 101 and a radiation conductor board 102 facing each other with a prescribed interval interposed are connected through a short circuit board 103. A coaxial cable 104 feeding power for the board 102 is provided and the board 102 is provided with three unit radiation conductor boards 1021, 1022 and 1023 of different lengths. Thus, the miniaturized multi-frequency antenna capable of coping with three frequencies is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-frequency antenna such as an inverted F antenna used as a built-in antenna of a small and thin radio terminal such as a portable telephone.

[0002]

2. Description of the Related Art One example of a conventionally used built-in antenna is an inverted-F antenna as shown in FIG. FIG. 15 is a diagram illustrating a general configuration of a plate-shaped inverted-F antenna in the case of a one-side short circuit.
In the figure, a radiation conductor plate 802 is placed on a ground conductor plate 801.
The radiation conductor plate 802 is connected to the ground conductor plate 801 by a short-circuit plate 803, and the coaxial feed line 804 is connected to a transmission / reception circuit (not shown). Radiating conductor plate 80
It is known that No. 2 resonates at a frequency at which the length of L1 in the drawing is about λ / 4 (λ is a wavelength).

As examples of applying this inverted F antenna to two systems, there are JP-A-7-131234 in which inverted F antennas having different resonance points are arranged side by side, and JP-A-6-232625 in which the inverted F antennas are vertically stacked. Is known. These conventional multi-frequency antenna technologies have a problem that the mounting area and the mounting volume are increased as compared with the case of a single frequency inverted F antenna. Also, many wireless systems coexist,
In the future, the emergence of terminals capable of simultaneously transmitting and receiving three or more systems is expected, and there is a demand for an antenna operating at three or more frequencies to apply to such a system. There is no technology,
When the above-described conventional technique is applied to three or more frequencies, a remarkable increase in mounting area and mounting volume is expected.

Further, as shown in FIG. 16, a U-shaped slot is provided in a radiation conductor plate, and the outside of the slot and the inside of the slot are used as independent radiation conductors having different resonance frequencies, so that two resonances can be obtained. Has also been proposed (Japanese Patent Application No. 9-329824).
This prior art is also effective for downsizing in two-frequency operation, but when applied to a system with three or more frequencies, a problem is expected that the mounting area and mounting volume increase.

Further, there is also known a two-frequency antenna as shown in FIG. 18 in which a radiation conductor plate is constituted by two unit radiation conductors having different lengths. That is, as shown in FIG.
On the ground conductor plate 901, two unit radiation conductor plates 9021,
A radiating conductor plate 902 having a 9022 is installed, the radiating conductor plate 902 is connected to a ground conductor plate 901 by short-circuit pins 903, and a coaxial feeder 904 is connected to a transmitting / receiving circuit (not shown). However, even in this two-frequency antenna technology, there is no suggestion of application to a system with three or more frequencies.

[0006]

As described above, in the conventional configuration, it is impossible to apply the present invention to a system having three or more frequencies. There was a problem that the area and the mounting volume became large.

The present invention solves the above-mentioned drawbacks of the prior art, and can be realized without increasing the mounting area and mounting volume as compared with a single-frequency ground conductor plate. It is an object of the present invention to provide a multi-frequency antenna that can be applied even to such a multi-frequency antenna.

[0008]

In order to achieve the above object, a multi-frequency antenna according to the present invention comprises a ground conductor plate and a radiation conductor plate facing each other at a predetermined interval, a ground conductor plate and a radiation conductor plate. And a power supply means for supplying power to the radiation conductor plate, wherein the radiation conductor plates are arranged at predetermined intervals and have at least three unit radiation conductors having different lengths. It is characterized by having.

With this configuration, it is possible to easily realize a miniaturized multi-frequency antenna applicable to a system with three or more frequencies. Further, the present invention provides a ground conductor plate and a radiation conductor plate facing each other with a predetermined space therebetween,
A short-circuit plate that connects the ground conductor plate and the radiation conductor plate, and a power supply unit that supplies power to the radiation conductor plate, wherein the radiation conductor plates are arranged at predetermined intervals and have a length. In a multi-frequency antenna having a plurality of different unit radiation conductors,
A feeding point is arranged at a position farthest from a unit radiation conductor resonating at a lowest resonance frequency among a plurality of resonance frequencies, and the short-circuit plate is provided only in the vicinity thereof. With such a configuration, a further miniaturized multi-frequency antenna can be realized.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following drawings, the same symbols indicate the same or corresponding parts.

(First Embodiment) First, a first embodiment of a multi-frequency antenna according to the present invention will be described. In the first embodiment, as shown in FIG. 1, the radiation conductor plate has a configuration having a plurality of unit radiation conductors having different lengths.

A radiation conductor plate 1 having three unit radiation conductor plates 1021, 1022 and 1023 on a ground conductor plate 101
02 is installed. The radiation conductor plate 102 is a short-circuit plate 1
03 is connected to the ground conductor plate 101, and is connected to a transmitting / receiving circuit (not shown) by a coaxial feeder 104.

Next, the operation of the multi-resonant operation of the three-band antenna shown in FIG. 1 will be described. As already described, for example, it is known that the radiation conductor of the inverted-F antenna shown in FIG. 15 resonates at a frequency where the length of L1 in the figure is about λ / 4 (λ is a wavelength).

Therefore, as shown in FIG.
02 has a plurality of unit radiating conductor plates having different lengths, for example, three unit radiating conductor plates 1021, 1022, and 1023, so that one radiating conductor plate can operate at three or more frequencies. Becomes

FIG. 2 is a diagram showing the frequency characteristics of the reflection coefficient of the multi-frequency antenna shown in FIG. By configuring the multi-frequency antenna as shown in FIG.
2 is the frequency at which the length (LA in the figure) of the first unit radiation conductor plate 1021 in FIG. 1 is λ / 4 (λ is the wavelength), that is, FIG.
A, the frequency where the length (LB in the figure) of the second unit radiation conductor plate 1022 in FIG. 1 is λ / 4, that is, B in FIG. 2 and the third in FIG. Resonating at a frequency where the length (LC in the figure) of the unit radiating conductor plate 1023 is λ / 4, that is, three frequencies of C in FIG.
2 can realize a multi-frequency antenna.

Further, this antenna can be regarded as the antenna of the above-mentioned conventional example of Japanese Patent Application No. Hei 9-329824, except that the hatched portion in FIG. 17 is removed.
6, a three-frequency antenna is realized with a smaller area than the two-frequency antenna disclosed in Japanese Patent Application No. 9-329824.

Incidentally, when configuring this multi-frequency antenna,
Plural unit radiation conductor plates 1021, 1022, 1023
May be arranged in any order, but if the lengths of adjacent unit radiation conductor plates are substantially the same, the characteristics of the antenna may be deteriorated due to interference between the unit radiation conductor plates. As shown in FIG. 3, the unit radiation conductor plate 1 having the same length
By arranging such that the pixels Nos. 021 and 1023 are not adjacent to each other, it is possible to avoid such characteristic deterioration.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In the second embodiment, the short-circuiting plate and the coaxial feeder are arranged at positions farthest from the unit radiation conductor that resonates at the lowest frequency.

In FIG. 4 showing the configuration of the second embodiment, three unit radiation conductor plates 202 are placed on a ground conductor plate 201.
A radiation conductor plate 202 having 1, 2022, and 2023 is provided. The radiation conductor plate 202 is connected to the ground conductor plate 201 by a short-circuit plate 203,
Is connected to a transmitting / receiving circuit (not shown). In this embodiment, the short-circuit plate 203 and the coaxial feed line 204 are connected to the unit radiation conductor plate 2 that resonates at the lowest frequency.
021. By adopting such a configuration, unlike the case of FIG. 1, the first unit radiation conductor plate 2021 has a length LA ′ + LD1 in FIG. 2 has a length of about λ ′ + LD2 in FIG.
And the third unit radiation conductor plate 20
Reference numeral 23 resonates at a frequency at which the length of LC in FIG. 4 is about λ / 4 (λ is a wavelength), and the radiation conductor plate 202 resonates at these three frequencies.

By arranging the short-circuit plate 203 and the coaxial feed line 204 in this manner, the antenna can be further reduced in size as compared with the case of the first embodiment shown in FIG. Becomes

FIG. 5 shows GSM, PDC and PHS.
Assuming a built-in antenna of a multi-mode terminal capable of transmitting and receiving three systems, GSM radio frequency 800 MHz
1 shows a multi-frequency antenna according to an embodiment of the present invention which realizes a multi-frequency antenna capable of transmitting and receiving both the z-band, the PDC radio frequency band of 1.5 GHz, and the PHS radio frequency band of 1.9 GHz. In the figure, 201 is a ground conductor plate, 202 is a radiation conductor plate, 203 is a short-circuit plate, and 204 is a coaxial feeder.

FIG. 6 shows the reflection characteristics of each antenna when the characteristics of the multi-frequency antenna having the shape shown in FIG. 5 are analyzed using electromagnetic field analysis (moment method). As shown in FIG. 6, this antenna has an 800 MHz band (D: 0.963 GH in the figure).
z, -21.4 dB), 1.5 GHz band (E in the figure:
1.495 GHz, -25.5 dB), and 1.9 GH
z band (F in the figure: 1.923 GHz, -15.6 dB)
It can be seen that resonance occurs in the three frequency bands.

Next, the radiation pattern of the antenna of FIG.
An example is shown for a frequency of 800 MHz. FIG. 7 shows 800M
FIG. 6 shows an analysis result of a horizontal radiation pattern (xy plane of the coordinate system shown in FIG. 5) in the Hz band. 8 and 9 show vertical plane radiation patterns (yz) in the 800 MHz band.
And (xz plane) are shown. As shown in these figures, this multi-frequency antenna has the same directivity as a one-side short-circuited plate antenna. Therefore, by configuring a multi-frequency antenna as in this embodiment, small and thin antennas of various multi-mode terminals can be easily realized.

(Third Embodiment) Next, a third embodiment of the multi-frequency antenna according to the present invention will be described. In the third embodiment, a unit radiation conductor is bent.

As shown in FIG. 10, three unit radiation conductor plates 3021, 3022, 302 are placed on the ground conductor plate 301.
3 is provided. The radiation conductor plate 302 is connected to the ground conductor plate 301 by a short-circuit plate 303 and is connected to a transmission / reception circuit (not shown) by a coaxial feed line 304. In this embodiment, one of the unit radiation conductor plates, that is, the first unit radiation conductor plate 3
No. 021 is bent in an L-shape. By doing so, it is possible to reduce the antenna area as a whole.

(Fourth Embodiment) Next, a fourth embodiment of the multi-frequency antenna according to the present invention will be described. In the fourth embodiment, the height of the unit radiation conductor is adjusted.

In FIG. 11 showing the configuration of the fourth embodiment, three unit radiation conductor plates 40 are placed on a ground conductor plate 401.
A radiation conductor plate 402 having 21, 4022 and 4023 is provided. The radiation conductor plate 402 is connected to the ground conductor plate 401 by a short-circuit plate 403, and
4 connects to a transmitting / receiving circuit (not shown).
In the radiation conductor plate 402, as shown in FIGS. 7A and 7B, the heights of the first, second, and third unit radiation conductor plates 4021, 4022, and 4023 are adjusted, whereby The radio frequency bandwidth can be adjusted separately. That is, it is possible to achieve a wide band by increasing the height of the unit radiation conductor plate, and to achieve a narrow band by decreasing the height.

(Fifth Embodiment) Next, a fifth embodiment of the multi-frequency antenna according to the present invention will be described. In the fifth embodiment, the way of providing the short-circuit plate is changed in various ways, and the configuration is shown in FIGS. 12 (a) to 12 (d).

In each of the figures, a radiation conductor plate 502 having a plurality of unit radiation conductor plates is provided on a ground conductor plate 501. The radiation conductor plate 502 is connected to the ground conductor plate 501 by the short-circuit plate 503, and
4 connects to a transmitting / receiving circuit (not shown).

The arrangement of the short-circuit plate 503 of the antenna is arbitrary. The short-circuit plate structure of the first embodiment shown in FIG. 1A and the short-circuit plate of the second embodiment shown in FIG. Not only the plate structure, but also the width, number, and position of the structure shown in FIGS. 3C and 3D can be freely determined, and the resonance frequency and the bandwidth can be freely set by setting these. , Input impedance and the like can be adjusted. In FIGS. 9C and 9D, a portion 503A on the right side of the short-circuit plate 503 is provided for impedance matching in order to facilitate resonance.

(Sixth Embodiment) Next, a sixth embodiment of the multi-frequency antenna according to the present invention will be described. In the sixth embodiment, a dielectric is interposed between a unit radiation conductor and a ground conductor plate, and the configuration is shown in FIG.

As shown in the figure, a plurality of unit radiation conductor plates 6021, 6022, 602 are placed on a ground conductor plate 601.
3 is provided. The radiation conductor plate 602 is connected to the ground conductor plate 601 by a short-circuit plate 603, and is connected to a transmission / reception circuit (not shown) by a coaxial feed line 604.

A first dielectric 6051 is provided between the first unit radiation conductor plate 6021 and the ground conductor plate 601, and a second dielectric 6052 is provided between the second unit radiation conductor plate 6022 and the ground conductor plate 601. The third dielectric 6053 is filled between the third unit radiation conductor plate 6023 and the ground conductor plate 601, and the dielectric constant of each of the dielectrics 6051, 6052, and 6053 can be arbitrarily determined. And

As described above, each unit radiation conductor plate 6021,
By independently determining the dielectric constants of the dielectrics 6051, 6052, and 6053 that fill the space between 6022 and 6023 and the ground conductor plate 601, the resonance frequency, the bandwidth, and the like can be adjusted independently. That is, by increasing the dielectric constant, it is possible to lower the resonance frequency and narrow the bandwidth.

(Modification) In each of the above embodiments, each unit radiating conductor plate has a rectangular shape.
As shown in (d), the shape of the conductor plate may be any shape. Further, as described above, by reducing the width of one side 71 of the radiation conductor plate shown in FIG. 14, the antenna in the case where the portion of one side 71 is not reduced, that is, the antenna 72 whose outline is indicated by a dotted line. Thus, it is possible to further reduce the size. In addition, the power supply method is not limited to the method using the coaxial line as described above, and may be arbitrarily selected and implemented, such as a strip line or power supply by electromagnetic coupling.

[0036]

According to the present invention, the present invention can be applied to a small, thin, three-frequency or more system without increasing both the mounting area and the mounting volume as compared with a generally used single-frequency inverted F antenna. A possible multi-frequency antenna can be easily realized. Further, as in the present invention, it is easy to form the radiation conductor plate, so that the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the configuration of a first embodiment of a multifrequency antenna according to the present invention.

FIG. 2 is a diagram showing reflection characteristics of the multi-frequency antenna according to the first embodiment.

FIG. 3 is an exemplary perspective view showing a configuration of a modification of the multi-frequency antenna according to the first embodiment;

FIG. 4 is a perspective view showing a configuration of a multi-frequency antenna according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a specific example of a multi-frequency antenna according to the present invention.

FIG. 6 is a view showing a simulation result of reflection characteristics of the multi-frequency antenna shown in FIG.

FIG. 7 shows the 800 MHz of the multi-frequency antenna shown in FIG.
The figure which shows the analysis result of the horizontal plane radiation pattern in a zone | band.

FIG. 8 shows the 800 MHz of the multi-frequency antenna shown in FIG.
The figure which shows the analysis result of the vertical plane radiation pattern (yz plane) in a band.

FIG. 9 shows the 800 MHz of the multi-frequency antenna shown in FIG.
The figure which shows the analysis result of the vertical plane radiation pattern (xz plane) in a band.

FIG. 10 is a perspective view showing a configuration of a third embodiment of the multi-frequency antenna according to the present invention.

FIG. 11 is a perspective view showing a configuration of a multi-frequency antenna according to a fourth embodiment of the present invention.

FIG. 12 is a perspective view showing a configuration of a multi-frequency antenna according to a fifth embodiment of the present invention.

FIG. 13 is a perspective view showing a configuration of a multi-frequency antenna according to a sixth embodiment of the present invention.

FIG. 14 is a plan view showing an example of an arbitrary-shaped radiating conductor plate as a modification of each embodiment of the present invention.

FIG. 15 is a perspective view showing a configuration of a conventional inverted F antenna.

FIG. 16 is a perspective view showing a configuration of a conventional example of a two-frequency antenna.

FIG. 17 is a perspective view for comparing and explaining a conventional example of a two-frequency antenna and the multi-frequency antenna of the first embodiment of the present invention.

FIG. 18 is a perspective view showing the configuration of another conventional example of a two-frequency antenna.

[Explanation of symbols]

101, 201, 301, 401, 501, 601 ... ground conductor plate 102, 202, 302, 402, 502, 602 ... radiation conductor plate 103, 203, 303, 403, 503, 603 ... short-circuit plate 104, 204, 304, 404, 504, 604 ... coaxial feeder lines 1021, 2021, 3021, 4021, 6021 ...
First unit radiation conductor plates 1022, 2022, 3022, 4022, 6022 ...
2nd unit radiation conductor plate 1023, 2023, 3023, 4023, 6023 ...
Third unit radiation conductor plate 6051 First dielectric 6052 Second dielectric 6053 Third dielectric 71 One side of radiation conductor plate 72 Antenna when not narrowed 801 901 earth conductor Plates 802, 902: radiation conductor plate 803: short-circuit plate 804, 904: coaxial feeder line 903: short-circuit pin 9021, 9022: unit radiation conductor plate

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Amano 3-1-1 Asahigaoka, Hino-shi, Tokyo F-term in Toshiba Hino Plant (reference) 5J021 AB05 JA03 5J045 AB05 DA08 DA10 NA03 5J047 AA07 AA19 AB08 FD01

Claims (2)

[Claims] 1. A ground conductor plate and a radiation conductor plate facing each other at a predetermined interval, a short-circuit plate connecting the ground conductor plate and the radiation conductor plate, and a power supply for supplying power to the radiation conductor plate. Means, wherein the radiation conductor plate has three or more unit radiation conductors having different lengths and arranged at a predetermined interval. 2. A ground conductor plate and a radiation conductor plate facing each other at a predetermined interval, a short-circuit plate connecting the ground conductor plate and the radiation conductor plate, and a power supply for supplying power to the radiation conductor plate. Means, wherein the radiation conductor plate is arranged at a predetermined interval, in a multi-frequency antenna having a plurality of unit radiation conductors having different lengths, at a lowest resonance frequency among a plurality of resonance frequencies. A multi-frequency antenna, wherein a feed point is arranged at a position farthest from a resonating unit radiation conductor and the short-circuit plate is provided only in the vicinity thereof.