JPH1155022A - Multiband antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts, to configure a trap circuit which is easy to be manufactured and also is small-sized, to have a high transmission characteristic with being inexpensive and to improve the reliability against a shock, etc., by configuring an LC parallel resonant circuit with the self- resonance of an inductor itself. SOLUTION: This antenna is provided with a linear element 1 on an open end side as a 1st radiation element, a linear element as a 2nd radiation element and a trap circuit that is connected between the elements 1 and 2. The part of the trap circuit is constituted of self-resonance of an inductor, and a chip laminated inductance element 3 is used as a self-resonance inductor of a surface mounted type. Thus, because the trap circuit is basically one inductance element L and a capacitance C is formed by a distribution capacity of the element L, it is possible to reduce the number of parts, manufacturing processes and man-hour and to improve a manufacturing property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device used for a mobile radio device and the like, and more particularly, to a multi-band antenna which realizes transmission and reception of a plurality of different frequency bands with one antenna device.

[0002]

2. Description of the Related Art When using radio equipment in different frequency bands, there are generally a plurality of antenna devices, and a typical example is an FM / AM radio. On the other hand, there is a trap antenna that can share a distant frequency band with one antenna device.
This trap antenna is widely used for amateur radio as a multiband antenna.

Conventionally, as a trap antenna of this type,
For example, one disclosed in Japanese Patent Application Laid-Open No. 5-121924 (hereinafter referred to as Conventional Technique 1) can be exemplified. The trap antenna according to the prior art 1 is composed of a linear antenna element and a resonance circuit including an inductance element and a capacitance element. The principle of the trap antenna will be described with reference to FIG. I do. Referring to FIG. 9, the trap antenna 50 according to the prior art 1 is
When the higher frequency to be resonated is fHigh, the trapping circuit 53 that causes anti-resonance at the frequency at l1 at λ / 2 of the higher frequency fHigh to be resonated of the linear antenna elements 51, 52, that is, , LC parallel resonance circuit, the antenna 50 near the frequency.
Resonates. On the other hand, the lower frequency fLow to be resonated
With respect to the above, since the trap circuit 53 loaded to resonate at the above-mentioned frequency fHigh acts as a reactance, the total length l2 of the antenna rod is adjusted to resonate. According to this, an antenna that resonates at two different frequencies can be configured.

FIG. 10 shows a trap circuit 53 of the antenna used in the antenna of FIG.
FIG. 4 is a diagram illustrating an example in which the capacitance element 55 (0.2 pF) is replaced by 4 nH).

FIG. 11 shows an example of a conventional mobile phone antenna. Referring to FIG. 11, an antenna 60 includes a helical-type antenna element 61 (hereinafter, referred to as a helical element) in which a helical coil 62 is wound around a helical coil guide 63, and an elongated wire connected to one end of the helical coil 62. Antenna element (hereinafter, referred to as a linear element) 52, a mold portion 8 made of an insulating resin covering the periphery of the antenna element 61, and a tube 4 made of an insulating resin provided around the linear element 52
And The resin of the mold section 8 and the tube 4 are formed integrally. The other end of the antenna 60 opposite to the mold portion 8 is provided with a holder 5 and a stopper 7 for attaching to an unillustrated mobile phone housing. The antenna shown in FIG.
2 and a helical element 61 are connected. The length of the linear element 52 is shortened by having the helical element 61.

FIG. 12 shows another example of a conventional mobile phone antenna. Referring to FIG. 12, the antenna 70 insulates the helical element 61 from the linear element 52,
In a standby state in which the helical element 61 and the linear element 52 are stored in a telephone body (not shown), only the helical element 61 is independent, and in a talking state in which the antenna is pulled out of the telephone body, the linear element 52 is independent. An antenna for a set of assigned frequencies set to function as an antenna. Here, the set of assigned frequencies includes two frequencies, a reception frequency and a transmission frequency, and even with the single assigned frequency conventional antenna shown in FIG. 11 or 12, the helical element 61 is tuned to the reception frequency. And the linear element 51 or 5
Two-frequency antennas have been used that tune the two to an intermediate frequency between the receiving and transmitting frequencies.

However, with the recent spread of mobile phones, for example, due to the congestion of the initially allocated 800 MHz band,
The use of the 1.5 GHz band is increasing, and the two assigned frequencies (4 frequencies in the sense of transmission and reception) are used. In an area where a 1.5 GHz band is used and a 1.5 GHz band service is not provided, a multi-band antenna capable of using an 800 MHz band has been required. For example, 800 in Japan
MHz band and 1.5GHz band PDC system, or 800
MHz band PDC, 1.9 GHz band PHS, 8 in the US
00MHz band and 1.9GHz band, 900MHz in Europe
There are similar requirements, such as the band and the 1.8 GHz band.

[0008]

The prior art 1
And the trap circuit 5 of such a trap antenna.
3 was composed of an inductance element and a capacitance element, that is, a coil and a capacitor.

However, according to such a conventional technique, there is a problem that the number of parts and the number of manufacturing steps are large.
In addition, if a trap circuit including a coil and a capacitor is configured in an external antenna, there is a problem in strength, and there is a disadvantage that the external antenna is easily damaged when subjected to an impact or the like. This is a significant drawback in portable devices.

Therefore, the technical problem of the present invention is to solve the above-mentioned problems by reducing the number of parts, configuring a trap circuit that is easy to manufacture and small in size, thereby reducing the cost and the transmission characteristics. It is an object of the present invention to provide a small-sized multi-band antenna capable of transmitting and receiving signals at different frequencies with a single antenna device, which can improve the reliability against impact and the like.

[0011]

SUMMARY OF THE INVENTION As described above, the present inventors, for example, use 800 different frequencies at two different allocated frequencies to cover the respective transmit and receive frequencies.
In order to tune to the intermediate frequencies of transmission and reception at both the assigned frequencies of the MHz band and the 1.9 GHz band, and to obtain a bandwidth capable of covering both the transmission and reception frequencies at each frequency (for example, the VSWR value) 2.3 or less), and the conditions of the LC resonance circuit were examined by simulation and experiment.
Above nH (in this example, a capacitance value of 1 pF or less), the above condition is easily obtained, and this condition is realized by self-resonance of the inductance element itself, instead of combining the inductance element and the actual capacitance element in parallel. This has been found to be easy, and the present invention has been accomplished. In summary, in the present invention, a trap antenna is configured by using self-resonance of an inductor itself as a trap circuit. That is, a multi-band antenna as described below is used as means for solving the problem.

According to the present invention, there is provided (1) a multi-band antenna including an antenna element having first and second radiating elements connected to both ends of an LC parallel resonance circuit.
A multi-band antenna is obtained in which the LC parallel resonance circuit is formed by self-resonance of the inductor itself.

According to the present invention, (2) the above (1)
In the multi-band antenna described above, the inductor is mounted on a printed circuit board, thereby obtaining a multi-band antenna.

According to the present invention, (3) the above (1)
In the multi-band antenna according to (1), the inductance value L of the inductor is L ≧ 7 nH.

According to the present invention, (4) the above (1)
In the multiband antenna according to any one of the first to third aspects, the first radiating element has a spiral shape (or a helical coil shape).

According to the present invention, (5) the above (4)
In the multi-band antenna of the first aspect, a part of the first radiating element has a self-resonance, and the self-resonance constitutes the LC parallel resonance circuit. Can be

Further, according to the present invention, (6) in a multiband antenna in which one of the first and second radiating elements has a helical shape, between the first radiating element and the second radiating element. And a multi-band antenna characterized by having an LC parallel resonance circuit.

According to the present invention, (7) the above (4)
Or in the multiband antenna according to (6), wherein
The multi-band antenna is characterized in that the radiating element is made of an elongated superelastic alloy.

According to the present invention, (8) the above (7)
In the multiband antenna according to the above item (1), the second radiating element is molded with an insulating material made of a flexible polymer or elastomer.

According to the present invention, (9) the above (4)
In the multiband antenna according to any one of (6) to (6), the LC parallel resonance circuit is molded with an insulating material together with the first radiating element.

According to the present invention, (10) in the multi-band antenna according to the above (9), the multi-band antenna is characterized in that the insulating material is made of a flexible polymer or an elastomer. .

According to the present invention, (11) in the multi-band antenna according to (5), wherein the first radiating element is formed of a printed board having a Myander pattern. An antenna is obtained.

According to the present invention, (12) the above (1)
1) The multi-band antenna according to 1), wherein the Myander pattern of the printed circuit board has a self-resonance in a part thereof, and the self-resonance constitutes the LC parallel resonance circuit. A band antenna is obtained.

According to the present invention, (13) in the multiband antenna according to the above (9) or (11),
A multi-band antenna is obtained, wherein the LC parallel resonance circuit is mounted on the printed circuit board.

According to the present invention, (14) the above (1)
In the multiband antenna according to 1) or 12), the printed board is molded with a flexible insulating resin made of a polymer or an elastomer.

According to the present invention, (15) in the multiband antenna according to any one of the above (9) to (13), the second radiating element is formed of an elongated superelastic alloy. Thus, a multi-band antenna characterized by the above is obtained.

Further, according to the present invention, (16) in the multiband antenna according to (14), the second element is molded with an insulating resin made of a flexible polymer or an elastomer. The characteristic multi-band antenna is obtained.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment of the present invention, as an example of a multiband antenna, a frequency of 8
A multi-band antenna corresponding to two assigned frequencies of the 00 MHz band and the 1.9 GHz band will be described.

FIG. 1 is a diagram showing a schematic configuration of a multi-band antenna according to a first embodiment of the present invention. Referring to FIG. 1, a multi-band antenna 10 includes a linear element 1 on the open end side as a first radiating element, a linear element 2 as a second radiating element, and a trap circuit connected therebetween. It has. A superelastic alloy made of a TiNi alloy is used for the two linear elements 1 and 2.

The multi-band antenna 10 according to the first embodiment of the present invention differs from the conventional trap antenna in that the trap circuit is formed by the self-resonance of the inductor. Regarding the self-resonance of the inductor, in the first embodiment of the present invention, a chip laminated inductance element (hereinafter, referred to as a chip inductor) 3 is used as a surface-mounted (SMD) type self-resonant inductor. Chip inductor 3 is 1
005 size (1.0 mm × 0.5 mm) is used.

FIG. 2 is a diagram showing a chip inductor 3 used in the antenna of FIG. As shown in FIG. 2, a trap circuit is formed by providing only the chip inductor 3 on the substrate.

From the comparison between the chip inductor 3 shown in FIG. 2 and the above-described FIG. 10, the capacitance element 55 shown in FIG. 10 can be omitted, and the trap circuit is small, inexpensive, and requires a small number of assembling steps. It can be seen that it can be obtained.

In the first embodiment of the present invention, the length of the linear elements 1 and 2 is generally λ / 2 wavelength, λ / 4 or 3λ / 8 wavelength. However, here, the wavelength of λ / 4 will be described as an example.

In the case of FIG. 1, the length of the linear element 1 on the telephone side is 3.9 cm, the length of the linear element 2 on the open end side is 2.9 cm, and the wire diameter of each is 0.8 cm.
mm NiTi alloy, the value of the chip inductor 3 is 39 nH, and the stray capacitance of the inductor is 0.18 pF.
As a result, multiband characteristics (shown by return loss characteristics using a 50Ω network analyzer) as shown in FIG. 3 were obtained.

FIG. 4 is a sectional view showing a multiband antenna 20 according to a second embodiment of the present invention. Referring to FIG. 4, a multi-band antenna 20 is an example in which the linear element 1 on the open end side, which is the first radiating element in the first embodiment, is changed to a helical element 11, and the telephone element is a line element. The element 2 is left as it is, and the trap circuit uses the chip inductor 3 having the same value as that of the first embodiment.

Specifically, the helical element 11 is
A helical coil guide 17 around which a helical coil 16 is wound; and a chip inductor 3 housed in the helical coil guide 17 and having one end of the helical coil 16 connected thereto.
The other end of the chip inductor 3 on the side opposite to the helical coil 16 is connected to one end of a linear element 2 as a second radiating element. A sleeve 6 made of a conductive material is provided so as to reach the helical coil guide 17 around one end of the linear element 2.
The insulating element covers one end of the helical element 11 and one end of the sleeve 6 to form a molded part 8. A tube 4 made of insulating resin is provided from the other end of the sleeve 6 to the linear element 2 so as to cover the linear element 2. At the other end of the linear element 2, a holder 5 for attaching to a mobile phone (not shown) is inserted slidably in the axial direction of the linear element 2. Terminates at the stopper 7.

The configuration of the helical element 11 is a wire diameter φ.
It is configured such that the coil has an outer diameter of 2.8 mm and a length of 18 mm with 4 turns (Turns) at 0.4 mm.

With this configuration, the same multi-band characteristics as in the first embodiment were obtained.

FIG. 5 is a sectional view showing a multi-band antenna according to a third embodiment of the present invention. As shown in FIG. 5, the multiband antenna 3 according to the third embodiment
Reference numeral 0 denotes a part in which the helical element 11 as the first radiating element has an inductor portion 23 made of an air-core coil having self-resonance, and forms an LC parallel trap circuit by the self-resonance. The configuration of the part
This is the same as the multiband antenna 20 of the embodiment. FIG. 6 is a diagram showing an integrated coil of the inductor section 23 and the helical coil 16 of the trap circuit of FIG. In FIG. 5, the linear element 2 on the telephone side has the same shape as that of the first embodiment, and is formed of an integral coil of the inductor 23 and the helical coil 16 of the trap circuit shown in FIG. By using the riical element 11, the multi-band antenna 1 according to the first embodiment
The same multi-band characteristics as those of 0 were obtained. Here, a composite coil composed of the inductor 23 and the helical coil 16 will be described with reference to FIG.
m is 2 mm in inner diameter and the trap circuit section is turned for 6 turns (Tur
ns), length 5mm, 10T of helical element 11
By using a coil continuously wound so as to have a urns length of 13 mm, the same multi-band characteristics as in the first embodiment were obtained.

FIG. 7 is a partial sectional view showing a multi-band antenna according to a fourth embodiment of the present invention. As shown in FIG. 7, a multi-band antenna 40 according to the fourth embodiment includes a Myander element 21 having a self-resonant inductor part 33 on a part of a printed circuit board 24 on which a Myander pattern 22 is formed. Thus, an LC parallel trap circuit is formed by the self-resonance. FIG. 8 is a partially cutaway plan view showing the printed circuit board 24 on which the Myander pattern 22 of FIG. 7 is formed. FIG.
, The linear element 2 on the telephone side has a wire diameter φ0.
The same multi-band characteristics as in the first embodiment can be obtained by using a TiNi superelastic wire having a shape of 8 mm and a length of 31 mm and using a Myander element 21 including a trap circuit shown in FIG.

The Myanda pattern element 21 will be described in more detail with reference to FIG. 8 using a helical element formed with a pattern width of 0.5 mm, 24 turns, a coil width of 4 mm, and a total coil length of 24 mm. I have. With this configuration, the multiband antenna according to the fourth embodiment has the same multiband characteristics as those according to the first embodiment.

[0042]

As described above, according to the present invention,
In a multiband antenna including an antenna element having two radiating elements connected to both ends of an LC parallel resonance circuit, the LC parallel resonance circuit can provide a multiband antenna formed by self-resonance of the inductor itself.

Generally, when using an LC parallel resonance circuit composed of a combination of an inductance element and a capacitance element, two or more components such as a capacitor and a coil are required. However, the resonance circuit using the self-resonance of the inductor according to the present invention is basically one inductance element, and the capacitance is formed by the distributed capacitance of the coil. Since the capacitance is small as a constant, LC resonance mainly composed of inductance (for example, 7 nH or more at 1.9 GHz,
(8 nH or more and 1 pF or less at 1 GHz or less at 1.8 GHz)
, The bandwidth at each frequency can be made large (for example, VSWR 2.2 or less). Therefore, compared to a conventional trap antenna realized by mounting L and C components on a substrate, the number of components is small, the number of manufacturing steps and man-hours are small, and a multiband antenna with good manufacturability is supplied at a low cost. can do.

Further, the present invention relates to a radio communication system for transmitting / receiving one communication service which is implemented in different frequencies such as 800 MHz band and 1.9 GHz band in the field of mobile communication and the like. When used as an antenna part and applied as a small antenna device for transmitting and receiving radio signals when transmitting and receiving with one antenna device, it can greatly contribute to miniaturization of a multi-band portable wireless device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a multiband antenna according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an example of a chip inductor used for the multi-band antenna of FIG.

FIG. 3 is a diagram illustrating a characteristic example of the multiband antenna of FIG. 1;

FIG. 4 is a sectional view showing a multi-band antenna according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a multi-band antenna according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a helical element of the multi-band antenna of FIG. 6;

FIG. 7 is a sectional view showing a multi-band antenna according to a fourth embodiment of the present invention.

FIG. 8 is a partially cutaway view showing a Myander pattern element of the multiband antenna of FIG. 8;

FIG. 9 is a diagram showing the principle of a conventional trap antenna.

FIG. 10 is a perspective view showing an example of an LC resonator used in the resonance circuit of the trap antenna of FIG.

FIG. 11 is a cross-sectional view showing an example of a conventional non-insulated single band antenna.

FIG. 12 is a cross-sectional view illustrating an example of a conventional insulating single band antenna.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Linear element 2 Linear element 3 Chip laminated inductance element (chip inductor) 4 Tube 5 Holder 6 Sleeve 7 Stopper 8 Mold part 10, 20, 30, 40 Multiband antenna 11 Helical element 16 Helical coil 17, 18 Helical coil guide 21 Myanda pattern element 22 Myanda pattern 23, 33 Inductor section 24 Printed circuit board 50 Trap antenna 51, 52 Linear element 53 Trap circuit

Claims (16)

[Claims] A first and a second terminal at both ends of an LC parallel resonance circuit.
A multi-band antenna comprising an antenna element to which the above-mentioned radiating element is connected, wherein the LC parallel resonance circuit is formed by self-resonance of the inductor itself. 2. The multi-band antenna according to claim 1, wherein said inductor is mounted on a printed circuit board. 3. The multi-band antenna according to claim 1, wherein the inductance value L of the inductor is L ≧ 7.
A multi-band antenna having nH. 4. The multi-band antenna according to claim 1, wherein said first radiating element has a helical shape. 5. The multi-band antenna according to claim 4, wherein a part of the first radiation element has a self-resonance, and the self-resonance constitutes the LC parallel resonance circuit. A multi-band antenna characterized by the following. 6. A multi-band antenna in which one of the first and second radiating elements has a helical shape, wherein an LC parallel resonance circuit is provided between the first radiating element and the second radiating element. Features a multi-band antenna. 7. The multi-band antenna according to claim 4, wherein said second radiating element is made of an elongated superelastic alloy. 8. The multi-band antenna according to claim 7, wherein said second radiating element is molded with an insulating material made of a flexible polymer or an elastomer. 9. The multiband antenna according to claim 4, wherein the LC parallel resonance circuit is molded with an insulating material together with the first radiating element. And a multi-band antenna. 10. The multi-band antenna according to claim 9, wherein the insulating material is made of a flexible polymer or estramer. 11. The multi-band antenna according to claim 5, wherein said first radiating element is formed by a printed circuit board having a Myander pattern. 12. The multi-band antenna according to claim 11, wherein the Myander pattern of the printed circuit board has a part of self-resonance, and the self-resonance constitutes the LC parallel resonance circuit. A multi-band antenna. 13. The multi-band antenna according to claim 9, wherein the LC parallel resonance circuit is mounted on the printed circuit board. 14. The multi-band antenna according to claim 11, wherein the printed circuit board is molded with a flexible insulating resin made of a polymer or an estramer. 15. The multi-band antenna according to claim 9, wherein said second radiating element is formed of an elongated superelastic alloy. 16. The multi-band antenna according to claim 14, wherein said second element is molded with an insulating resin made of a flexible polymer or an estramer.