JP2001185949A - Dual-mode antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dual-mode antenna which has a horizontal radiation mode of large gain and can send and receive a 1st frequency band f1 and a 2nd frequency band f2 about twice the frequency by one antenna. SOLUTION: A coil antenna 12 of about 1/4 wavelength of the 2nd frequency band 2f is added capacitively coupling with the base end part of a pole antenna 10 of about 1/2 wavelength of the 1st frequency band f1 which is arranged vertically or obliquely. The base end 10a of the pole antenna 10 is connected to an antenna input/output end 18 via a matching circuit 14 and a 1st filter circuit 16 which makes the 1st frequency band f1 pass through sequentially in series. The base end of the coil antenna 12 is connected the to the antenna input/output end 18 via a 2nd filter circuit 20 which makes the 2nd frequency band f2 pass though. This antenna is composed of the pole antenna 10 and the coil antenna 12 which are capacitively coupled to operate as an antenna of about 5/4 wavelength of the 2nd frequency band f2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a radiation mode having a large gain in the horizontal direction, and is capable of transmitting and receiving two frequency bands of a first frequency band and a second frequency band higher than this. It relates to a dual mode antenna.

[0002]

2. Description of the Related Art As a conventional antenna of a portable telephone, an antenna having an electric length of about 1/4 wavelength with respect to a frequency band to be used is generally used. Also, as an on-vehicle antenna, an antenna having a wavelength of about ４ of a used frequency band is widely used. This is to make it easy to match the antenna with the feeder line and to prevent return loss at the joint. Another reason is to make the physical length of the antenna as short as possible to make it convenient for carrying. In addition, in the case of a vehicle, the length protruding outward from the body of the car is made as short as possible so as not to be damaged by contact with other objects and to meet a design demand. .

[0003] Further, as an example of a conventional dual mode antenna capable of transmitting and receiving two frequency bands with one antenna, the pitch at the distal end of a single coil-shaped antenna is closely wound and the pitch at the proximal end is increased. Is coarsely wound so that the whole acts as an antenna for the first frequency band having a low frequency, and only the base end portion acts as an antenna for the second frequency band having a high frequency. There is something. Further, there is a type in which a pole antenna is provided at the axial center of the coil antenna, and the coil antenna and the pole antenna function as antennas in a first frequency band and a second frequency band, respectively.

[0004]

By the way, about one vertically or inclinedly disposed so as to protrude outward from the body of the car.
In the conventional quarter-wavelength vehicle-mounted antenna, in the radiation mode when the antenna is viewed from the horizontal direction, a large gain is generated obliquely upward, and a sufficient gain is not necessarily obtained in the horizontal direction. This is because the body of the car or the like acts as a large ground plane, and the effect of the ground plane causes the directional direction to be obliquely upward in an antenna of about 1/4 wavelength. However, in a mobile phone, the relay antenna is located at a position not so high, and has a substantially horizontal positional relationship with each other. Therefore, if a large gain is obtained in the horizontal direction, the signal can be radiated most efficiently.

[0005] Further, in the above-mentioned conventional dual-mode coil-shaped antenna in which the pitch is changed on the way, only a part of the entire antenna acts as an antenna in the high frequency second frequency band, and the antenna gain is accordingly low. There is a defect. In addition, the combination of the pole antenna at the axis position of the conventional coil antenna,
The mechanical structure is complicated, and the antennas are likely to interfere with each other, so that it is necessary to experimentally obtain desired antenna characteristics, and the design work is complicated.

The present invention has been made in view of the circumstances of the prior art, and has a dual mode antenna having a radiation mode with a large gain in the horizontal direction and capable of transmitting and receiving two frequency bands having different frequencies with one antenna. The purpose is to provide.

[0007]

In order to achieve the above object, a dual mode antenna according to the present invention is a dual mode antenna for transmitting and receiving a first frequency band and a second frequency band twice as high as the first frequency band. A second antenna having approximately one-quarter wavelength of the second frequency band, which is capacitively coupled to a base end of a first antenna element arranged vertically or inclined at approximately one-half wavelength of the first frequency band. An antenna element is attached, and a matching circuit and a first filter circuit that passes the first frequency band are sequentially interposed in series at the base end of the first antenna element and connected to an antenna input / output end; Second
A base end of the antenna element is connected to the antenna input / output end via a second filter circuit that passes the second frequency band, and the second antenna element and the second antenna element capacitively coupled to the first antenna element are connected to the second antenna circuit. It is configured to function as an antenna of about 5/4 wavelength in two frequency bands.

A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or inclined at about one-half wavelength of the first frequency band. At the base end of one antenna element,
A second antenna element is additionally provided for capacitive coupling,
The first antenna element is formed by connecting a coil antenna on the distal end and a pole antenna on the proximal end in series, and sequentially includes a matching circuit at the proximal end of the first antenna element and a first filter circuit for passing the first frequency band. Are connected in series to the antenna input / output end, and the base end of the second antenna element is connected to the antenna input / output end via a second filter circuit that passes the second frequency band;
The pole antenna on the base end side of the first antenna element and the second antenna element capacitively coupled to the pole antenna may be configured to function as an antenna of about 周波 数 wavelength of the second frequency band.

A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or obliquely disposed at about a half wavelength of the first frequency band. At the base end of one antenna element,
A second antenna element is additionally provided for capacitive coupling,
The first antenna element is formed by series connection of a coil antenna whose front end side is densely wound and a coil antenna whose base end side is coarsely wound, and the base end side pole antenna is formed to be about 1 / of the second frequency band. The second antenna is connected to an antenna input / output terminal by sequentially interposing a matching circuit and a first filter circuit for passing the first frequency band in series at a base end of the first antenna element, A second filter circuit for passing the base end of the element through the second frequency band, connected to the antenna input / output end, and the coarsely wound coil antenna on the base end side of the first antenna element; A second antenna element capacitively coupled to the second antenna may be configured to function as an antenna having a wavelength of about ３ of the second frequency band.

A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band having a frequency approximately twice as high as the first frequency band, wherein the dual mode antenna is vertically or inclined at approximately １ ／ wavelength of the first frequency band. A first conductive member is connected in series to the base end of the first antenna element to be formed, and the first conductive member is capacitively coupled to the first conductive member. (2) A capacitor tube made of a tubular conductor is provided so as to surround the first conductive member and the second conductive member so as to be capacitively coupled to the first conductive member and the second conductive member, and is grounded. Match the end with the first circuit
A first filter circuit for passing a frequency band is sequentially interposed in series and connected to an antenna input / output terminal, and a base end of the second conductive member is passed through a second filter circuit for passing the second frequency band. The first antenna element, the first conductive member, and the second conductive member capacitively coupled to the first antenna element and the first conductive member are connected to the antenna input / output terminal by about 5/5 of the second frequency band.
You may comprise so that it may correspond to an antenna of four wavelengths.

A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or tilted at about 波長 wavelength of the first frequency band. At the base end of one antenna element,
A first conductive member is connected in series, a second conductive member is added so as to be capacitively coupled to the first conductive member, and surrounds the first conductive member and the second conductive member so as to be capacitively coupled thereto. A capacitor tube made of a cylindrical conductor is provided and grounded. The first antenna element is formed by connecting a coil antenna on the distal end and a pole antenna on the proximal end in series, and the pole antenna on the proximal end is connected to the second frequency. The base end of the first conductive member is connected to the antenna input / output end by serially interposing a matching circuit and a first filter circuit for passing the first frequency band in series. Connecting a base end of the second conductive member to the antenna input / output end with a second filter circuit interposed through the second frequency band, and connecting the pole antenna on the base end side of the first antenna element to the pole antenna; Said First conductive member and second conductive member which is capacitively coupled may be configured to correspond to the antenna of 3/4 wavelength of the second frequency band.

A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or tilted at about 約 wavelength of the first frequency band. At the base end of one antenna element,
A first conductive member is connected in series, a second conductive member is added so as to be capacitively coupled to the first conductive member, and surrounds the first conductive member and the second conductive member so as to be capacitively coupled thereto. A capacitor tube made of a tubular conductor is provided and grounded, and the first antenna element is formed by series connection of a coil antenna whose top end is densely wound and a coil antenna whose base end is roughly wound. The end-side coil antenna has a wavelength of about の wavelength of the second frequency band, and a base circuit of the first conductive member is sequentially connected in series with a matching circuit and a first filter circuit for passing the first frequency band. The first antenna is connected to the antenna input / output end, and the base end of the second conductive member is connected to the antenna input / output end via a second filter circuit for passing the second frequency band. The proximal end of the element It may be configured to correspond to wound turn coil antenna and the first conductive member and this and about 3/4 wavelength of the antenna of the second frequency band in the second conductive member to capacitive coupling.

[0013]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is an electrical structural diagram of a first embodiment of a dual mode antenna according to the present invention. FIG. 2 shows the current distribution of the antenna of FIG.
Is a current distribution in the first frequency band, and (b) is a current distribution in the second frequency band. FIG. 3 shows the VSW of the antenna of FIG.
It is an R characteristic figure, (a) is VSWR of a 1st frequency band, (b) is VSWR of a 2nd frequency band. FIG.
1A shows a radiation mode of a first frequency band, and FIG. 1B shows a radiation mode of a second frequency band when the dual mode antenna of FIG. 1 is viewed from the front in the horizontal direction.

First, as a first embodiment, Japanese PDC8
00 (810 to 960 MHz) is set in the first frequency band f1, and the PDC 1500 having a frequency twice as high as that of the first frequency band f1 is set.
(1429 to 1501 MHz) will be described as the second frequency band f. The whole of the first antenna element, which is disposed vertically or inclined and acts as an antenna of about １ ／ wavelength λ1 with respect to the first frequency band f1, is formed entirely by the pole antenna 10, and the pole antenna 10 and the Coil antenna 12 as second antenna element to be coupled
Is attached. As shown in FIG. 1, the coil antenna 12 may be arranged beside the base end of the pole antenna 10, but the coil antenna 12 is arranged by loosely fitting the base end of the pole antenna 10. May be. The base end 10a of the pole antenna 10 shares a single capacitance element that forms the matching circuit 14 with a matching circuit 14 in which two capacitance elements and one inductance element are assembled in a π-shape. Are sequentially connected to an antenna input / output terminal 18 via a first filter circuit 16 assembled in an inverted L-shape. The matching circuit 14 converts a high impedance at the base end 10a of the pole antenna 10 set to an electrical length of about 波長 wavelength λ1 with respect to the first frequency band f1 into a low impedance and matches with a feeder line or the like. It is formed as shown. The first filter circuit 16 is formed so as to pass the first frequency band f1 and block the second frequency band f2. Further, the base end of the coil antenna 12 is connected to the antenna input / output end 18 via a second filter circuit 20 in which two capacitance elements and one inductance element are assembled in a T-shape. The second filter circuit 20 allows the second frequency band f2 to pass and the first frequency band f1
Is formed to prevent

In such a configuration, the coil antenna 12
Is about ４ wavelength λ2 with respect to the second frequency band f2.
And the coil antenna 12 and the pole antenna 1
By appropriately setting the stray capacitance Cf generated between the pole antenna 10, the coil antenna 12, and the stray capacitance Cf with respect to the second frequency band f2, about 5/4.
It functions as an antenna of wavelength λ2. Therefore, as shown in FIG. 2A, the pole antenna 10 acts as an antenna having a half wavelength λ1 with respect to the first frequency band f1, and as shown in FIG. 2B, with respect to the second frequency band f2. As a result, the pole antenna 10, the coil antenna 12, and the stray capacitance Cf act as an antenna having a wavelength of about λ wavelength λ2, and the antenna input / output end 18 is relatively low in both the first frequency band f1 and the second frequency band f2. Impedance is generated, and matching with a feeder line or the like can be easily achieved. Then, the pole antenna 10 exhibits a radiation mode of a half wavelength λ1 with respect to the first frequency band f1, and the second frequency band f2 has a frequency approximately twice as high as the first frequency band f1. Generates a current distribution of about one wavelength λ2 in the second frequency band f2, and a radiation mode of one wavelength λ2 appears strongly.

According to experiments by the inventors, the first frequency band f
1, a sufficiently low VSWR as shown in FIG.
was gotten. Also, for the second frequency band f2, FIG.
As shown in (b), a sufficiently low VSWR was obtained. In the radiation mode when the antenna is viewed from the front in the horizontal direction, a large gain is obtained at a low elevation angle with respect to the first frequency band f1, as shown in FIG.
As shown in FIG. 4B, a large gain was obtained at a low elevation angle. Therefore, the first embodiment can transmit and receive any of the frequency bands of Japanese PDC800 and PDC1500 and has a large gain in the horizontal direction, and is most suitable as a dual mode antenna for a mobile phone.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is an electrical diagram of a dual mode antenna according to a second embodiment of the present invention. FIG.
5A shows the current distribution of the antenna of FIG. 5, FIG. 5A shows the current distribution in the first frequency band, and FIG. 5B shows the current distribution in the second frequency band. 5 and 6, FIG. 1 and FIG.
The same reference numerals are given to the same or equivalent members, and duplicate description will be omitted.

The second embodiment differs from the first embodiment in that the entire first antenna element is formed by a single pole antenna 10 having a wavelength of about ２, but the first antenna element is replaced by a first frequency band. The first antenna element 22 of about １ ／ wavelength λ1 with respect to f1, the coil antenna 24 on the tip side and the ア ン テ ナ wavelength λ2 of the second frequency band f2 on the base side.
Are formed by connecting the pole antennas 26 in series. With such a configuration, for the second frequency band f2, an antenna having a total of about ／ wavelength λ2 of the pole antenna 26 and the coil antenna 12 on the base end side of the first antenna element 22 and the stray capacitance Cf generated therebetween. The pole antenna 26, the coil antenna 12, and the stray capacitance Cf are adjusted so as to act as. Note that the coil antenna 24 on the distal end side of the first antenna element 22 is wound with a sufficiently dense pitch with respect to the second frequency band f2 so as not to function as an antenna. Then, for the first frequency band f1, as shown in FIG. 6 (a), the entire first antenna element 22 acts as an antenna of about １ ／ wavelength λ1, and a large gain is obtained in the horizontal direction. As shown in FIG. 6B, a radiation mode of about 波長 wavelength λ2 is strongly generated in the pole antenna 26 on the base end side of the first antenna element 22 with respect to the second frequency band f2,
Again, a large gain is obtained in the horizontal direction.

In the second embodiment, the first antenna element 22 having a wavelength of about に 対 し て with respect to the first frequency band f1 is a coil antenna with the distal end wound at a close pitch and the second antenna element 22 at the proximal end. A similar effect can be obtained even if coil antennas wound at a coarse pitch of about 波長 wavelength λ2 of the frequency band f2 are connected in series. In the second embodiment, the second frequency band f2 is just the first frequency band f1.
In this case, the distal end and the proximal end of the first antenna element 22 may be set to the same electrical length.

Further, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is an electrical structural diagram of a third embodiment of the dual mode antenna of the present invention. In FIG.
Members that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

In the third embodiment, a linear first antenna element is provided at the base end of the pole antenna 10 which is set to about 波長 wavelength λ1 with respect to the first frequency band f1 as a whole of the first antenna element. The conductive members 28 are connected in series, and the base ends thereof are connected to the matching circuit 14. Then, about ４ of the second frequency band f2 is capacitively coupled to the first conductive member 28.
A coil-shaped second conductive member 30 set to the wavelength λ2 is provided, and its base end is connected to the second filter circuit 20. Further, a capacitance tube 32 made of a tubular conductor is provided so as to surround the first conductive member 28 and the second conductive member 30 and to be capacitively coupled thereto, and is grounded. This capacity tube 3
A suitable stray capacitance Cf is generated between the second conductive member 28 and the first conductive member 28 and the second conductive member 30. In addition, it goes without saying that the stray capacitance Cf also occurs between the first conductive member 28 and the second conductive member 30.

In such a configuration, the pole antenna 10 acts as an antenna of about 波長 wavelength λ 1 for the first frequency band f 1, and the impedance of the base end 10 a of the pole antenna 10 is adjusted by the matching circuit 14 via the first conductive member 28. The impedance is converted, and this is supplied to the antenna input / output terminal 18 via the first filter circuit 16. Also, the second frequency band f2
To the pole antenna 10, the first conductive member 28, the stray capacitance Cf, and the entire second conductive member 30 so as to correspond to an antenna of about 約 wavelength λ2. A low impedance is applied to the antenna input / output terminal 18 via the second filter circuit 20. Here, with respect to the second frequency band f2, the second conductive member 30 corresponding to about １ ／ wavelength λ2 is shielded by the capacitance tube 32, and the radiation mode of about one wavelength λ2 is strongly generated in the pole antenna 10. . Thus, in the third embodiment, a large gain in the horizontal direction can be obtained in either the first frequency band f1 or the second frequency band f2. Here, in order for the pole antenna 10 to operate with an electrical length of one wavelength λ2 of the second frequency band f2, it is desirable that the frequency of the second frequency band f2 is exactly twice the frequency of the first frequency band f1. . Therefore, in the third embodiment, the GSM in Europe in which the second frequency band f2 is exactly twice the first frequency band f1
(880-960 MHz) and DCS (1710-188 MHz)
0 MHz) as a dual mode antenna for mobile phones.

FIG. 8 shows a fourth embodiment of the present invention.
This will be described with reference to FIG. FIG. 8 is an electrical structural diagram of a fourth embodiment of the dual mode antenna of the present invention. 8, the same or equivalent members as those in FIG. 7 are denoted by the same reference numerals, and redundant description will be omitted.

The fourth embodiment differs from the third embodiment in that the base end 10a of the pole antenna 10
Of the first frequency band f1 instead of the linear first conductive member 28 of
Is connected to the coil-shaped first conductive member 34 having a wavelength of about 1/4, and the base end of which is passed through the first frequency band f1.
That is, it is directly connected to the filter circuit 16. In addition,
The matching circuit 14 in FIG. 7 is omitted. In such a configuration, a stray capacitance Cf is generated between the capacitance tube 32 and the coil-shaped first conductive member 34. Then, the first frequency band f1
, The pole antenna 10 and the first conductive member 34 function as an antenna of about ／ wavelength, and the inductance component of the coil-shaped first conductive member 34 and the stray capacitance Cf generated between the coil and the capacitance tube 32 are reduced. To form an appropriate matching circuit, and the base end 10a of the pole antenna 10
Is converted to a small impedance and supplied to the antenna input / output terminal 18 via the first filter circuit 16.

A fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is an electrical structural view of a dual mode antenna according to a fifth embodiment of the present invention. 9, the same or equivalent members as those in FIG. 7 are denoted by the same reference numerals, and redundant description will be omitted.

The fifth embodiment is different from the third embodiment in that the entire first antenna element is replaced by a single pole antenna 10 having a wavelength of about 1/2 wavelength λ1, and The first antenna element 22 of about ２ wavelength λ1 is formed by connecting the coil antenna 24 on the distal end side and the pole antenna 26 of about １ ／ wavelength λ2 on the base end side with respect to the second frequency band f2 in series. . In such a configuration, for the second frequency band f2, the total of the pole antenna 26, the stray capacitance Cf, and the second conductive member 30 on the base end side of the first antenna element 22 is about ／ wavelength λ.
The antenna is operated so as to correspond to the second antenna. The first antenna element 22 acts as an antenna of about 約 wavelength λ1 as a whole for the first frequency band f1, and the first antenna element 22 for the second frequency band f2.
In the pole antenna 26 on the base end side, a radiation mode of about 波長 wavelength λ2 is strongly generated, and a large gain is obtained in the horizontal direction in both the first frequency band f1 and the second frequency band f2.

FIG. 1 shows a sixth embodiment of the present invention.
0 will be described. FIG. 10 is an electrical structural diagram of a sixth embodiment of the dual mode antenna of the present invention. FIG.
In FIG. 9, the same or equivalent members as those in FIG. 9 are denoted by the same reference numerals, and redundant description will be omitted.

The sixth embodiment differs from the fifth embodiment in that a base end 22a of the first antenna element 22 is provided.
Instead of the linear first conductive member 28 shown in FIG. 9, a coil-shaped first conductive member having a wavelength λ1 of about １ ／ wavelength with respect to the first frequency band f1.
That is, the conductive member 34 is connected, and its base end is directly connected to the first filter circuit 16 that passes the first frequency band f1. Note that the matching circuit 14 in FIG. 9 is omitted. In such a configuration, for the first frequency band f1,
The first antenna element 22 and the coil-shaped first conductive member 34 function so as to correspond to an antenna of about ／ wavelength λ1. In addition, a matching circuit is formed by the stray capacitance Cf generated between the coil-shaped first conductive member 34 and the capacitance tube 32 with respect to the first frequency band f1, thereby reducing the impedance.

In the above embodiment, the first frequency band f1
And the second frequency band f2 are mainly described as corresponding to PDC800 and PDC1500 which are the frequency bands of Japanese mobile phones, but the present invention is not limited to this. May be set as follows. Further, the second conductive member 30 may have a linear shape instead of a coil shape. As an application of the dual mode antenna of the present invention, it can be used as a dual mode antenna for a wireless communication device requiring a large gain in the horizontal direction, and is not limited to a mobile phone, and may be used as a dual mode antenna for a business radio or the like. The present invention is suitable for use as a dual mode antenna for a fixed station without being limited to a mobile station mounted on a vehicle.

[0030]

As described above, since the dual mode antenna according to the present invention is constituted, the following special effects can be obtained.

In the dual mode antenna according to the first aspect, the first antenna element acts as an antenna having about a half wavelength with respect to the first frequency band, and the first antenna element acts with respect to the second frequency band. The second antenna element and the stray capacitance act as an antenna of about ５ wavelength, and the first antenna element strongly generates a radiation mode of one wavelength. Therefore, while being able to transmit and receive both the first frequency band and the second frequency band, a radiation mode having a large gain in the horizontal direction is obtained, and a dual mode antenna of a wireless communication device such as a mobile phone in a horizontal positional relationship with each other. It is suitable as.

In the dual mode antenna according to the second or third aspect, the first antenna element has a current distribution of about 波長 wavelength for the first frequency band and the first antenna for the second frequency band. A current distribution of about 波長 wavelength can be provided in the pole antenna or the coil antenna roughly wound on the base end side of the element, and radiation having a large gain in the horizontal direction in both the first frequency band and the second frequency band. You can get the mode. Moreover, the second frequency band is the first
If the frequency band is not exactly twice the frequency band but slightly shifted, and the second frequency band does not have a current distribution of about one wavelength in the entire first antenna element, the second
By setting the pole antenna on the base end side of the frequency band or the coil antenna roughly wound to have a desired electrical length of about 波長 wavelength, a モ ー ド wavelength radiation mode can be generated strongly.

In the dual mode antenna according to the fourth aspect, the first antenna element acts as an antenna having about a half wavelength with respect to the first frequency band, and the first antenna element acts with respect to the second frequency band. The first conductive member and the second conductive member capacitively coupled to the first conductive member with stray capacitance correspond to an antenna of about ／ wavelength to achieve resonance. Moreover, the first conductive member and the second conductive member are surrounded by the capacitance tube, and do not function as a radiating element. Therefore, only the first antenna element acts as an antenna for the second frequency band, and a current distribution of about one wavelength occurs in this. Therefore, a radiation mode having a large gain in the horizontal direction can be obtained in any of the first frequency band and the second frequency band.

In the dual mode antenna according to the fifth or sixth aspect, the first antenna element acts on the first frequency band as an antenna of about 波長 wavelength,
The pole antenna or the coarsely wound coil antenna on the base end side of the first antenna element with respect to the second frequency band, the first conductive member, and the second conductive member capacitively coupled to the first conductive member by a stray capacitance are about 3 /. This corresponds to a four-wavelength antenna. Since the first conductive member and the second conductive member are surrounded by the capacitance tube and do not act as radiating elements, only the pole antenna or the coil antenna on the base end side of the first antenna element with respect to the second frequency band is an antenna. , Which produces a current distribution of about に wavelength. Therefore, the gain in the horizontal direction increases in both the first frequency band and the second frequency band.

In the dual mode antenna according to the present invention, the first conductive member connected to the base end of the first antenna element is formed in a coil shape, and a floating generated between the inductance component and the capacitance tube surrounding the coil. A matching circuit can be formed by the capacitance. Moreover, the capacitance component due to the stray capacitance is a distributed constant, and the large impedance generated at the base end of the first antenna element is gently converted in the signal path to a small value by the matching circuit, thereby reducing the return loss.

In the dual mode antenna according to the eighth aspect, the first conductive member connected to the base end of the first antenna element has a wavelength of about １ ／ of the first frequency band.
For the first frequency band, the first antenna element and the first
The conductive member corresponds to an antenna of about ／ wavelength, the impedance generated at the base end of the first conductive member is small, and matching with a feeder line or the like can be easily achieved.

[Brief description of the drawings]

FIG. 1 is an electrical structural diagram of a first embodiment of a dual mode antenna according to the present invention.

2A and 2B show a current distribution of the antenna of FIG. 1, wherein FIG. 2A shows a current distribution in a first frequency band, and FIG. 2B shows a current distribution in a second frequency band.

FIG. 3 is a VSWR characteristic diagram of the antenna of FIG. 1;
(A) is the VSWR of the first frequency band, and (b) is the VSWR of the second frequency band.
This is the VSWR of the frequency band.

4A and 4B show radiation modes of the dual mode antenna of FIG. 1 viewed from the front in a horizontal direction, wherein FIG. 4A shows a radiation mode of a first frequency band and FIG. 4B shows a radiation mode of a second frequency band. .

FIG. 5 is an electrical structural diagram of a dual mode antenna according to a second embodiment of the present invention.

6A and 6B show a current distribution of the antenna of FIG. 5, wherein FIG. 6A shows a current distribution in a first frequency band, and FIG. 6B shows a current distribution in a second frequency band.

FIG. 7 is an electrical diagram of a dual mode antenna according to a third embodiment of the present invention.

FIG. 8 is an electrical structural diagram of a dual mode antenna according to a fourth embodiment of the present invention.

FIG. 9 is an electrical structural diagram of a dual mode antenna according to a fifth embodiment of the present invention.

FIG. 10 is an electrical diagram of a dual mode antenna according to a sixth embodiment of the present invention.

[Explanation of symbols]

 10, 26 Pole antenna 10a, 22a Base end 12, 24 Coil antenna 14 Matching circuit 16 First filter circuit 18 Antenna input / output end 20 Second filter circuit 22 First antenna element 28 First conductive member 30 Second conductive member 32 Capacity Tube 34 coiled first conductive member f1 first frequency band f2 second frequency band Cf stray capacitance λ1 wavelength in first frequency band λ2 wavelength in second frequency band

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5J021 AA02 AA06 AB02 CA01 DB03 EA04 FA23 FA32 HA05 HA10 JA03 5J047 AA02 AB06 AB12 FC06 FD01

Claims (8)

[Claims] 1. A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band having a frequency approximately twice as high as the first frequency band, wherein the dual mode antenna is vertically or inclined at approximately 波長 wavelength of the first frequency band. A second antenna element of about ４ wavelength of the second frequency band is attached to the base end of the first antenna element to be capacitively coupled, and the base end of the first antenna element is connected to a matching circuit. A second filter that passes through the second frequency band at a base end of the second antenna element by connecting a first filter circuit that passes the first frequency band in series with the input / output end of the antenna and sequentially connecting the base end of the second antenna element A circuit is connected to the input / output end of the antenna, and the first antenna element and the second antenna element capacitively coupled to the first antenna element function as an antenna of about ５ wavelength of the second frequency band. A dual mode antenna, characterized in that: 2. A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or inclined at about １ ／ wavelength of the first frequency band. The second antenna having approximately one-quarter wavelength of the second frequency band is capacitively coupled to the base end of one antenna element.
An antenna element is attached, and the first antenna element is formed by connecting a coil antenna on the distal end and a pole antenna on the proximal end in series, and the pole antenna on the proximal end is set to about 波長 wavelength of the second frequency band. A matching circuit and a first filter circuit for passing the first frequency band are sequentially interposed in series at the base end of the first antenna element and connected to an antenna input / output end to connect the base end of the second antenna element; A second filter circuit that passes the second frequency band through the second frequency band, and is connected to the antenna input / output terminal;
The dual antenna, wherein the pole antenna on the base end side of the first antenna element and the second antenna element capacitively coupled to the pole antenna function as an antenna having a wavelength of about 3/4 of the second frequency band. Mode antenna. 3. A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or inclined at about １ ／ wavelength of the first frequency band. The second antenna having approximately one-quarter wavelength of the second frequency band is capacitively coupled to the base end of one antenna element.
An antenna element is attached, and the first antenna element is formed by series connection of a coil antenna whose base end is coarsely wound with a coil antenna whose top end is densely wound, and is coarsely wound on this base end. The coil antenna has a wavelength of about の wavelength of the second frequency band, and a base circuit of the first antenna element is provided with a matching circuit and a first filter circuit for passing the first frequency band in series. Connected to an antenna input / output end, and connected to the antenna input / output end via a second filter circuit interposing a base end of the second antenna element for passing the second frequency band; The coarsely wound coil antenna on the end side and the second antenna element capacitively coupled to the coil antenna are configured to function as an antenna having a wavelength of about ／ of the second frequency band. Dual-mode antenna according to claim. 4. A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band having a frequency approximately twice as high as that of the first frequency band, wherein the dual mode antenna is vertically or tilted at about 約 wavelength of the first frequency band. A first conductive member is connected in series to the base end of the first antenna element to be formed, and the first conductive member is capacitively coupled to the first conductive member. (2) A capacitor tube made of a tubular conductor is provided so as to surround the first conductive member and the second conductive member so as to be capacitively coupled to the first conductive member and the second conductive member, and is grounded. An end of the matching circuit and a first filter circuit for passing the first frequency band are sequentially interposed in series and connected to an antenna input / output end, and a base end of the second conductive member is connected to the second frequency band. Through the second filter circuit that passes The first antenna element, the first conductive member, and the second conductive member capacitively coupled to the first antenna element, the first conductive member, and the second conductive member are configured to correspond to an antenna of about 5/4 wavelength of the second frequency band. A dual mode antenna characterized by: 5. A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or inclined at about １ ／ wavelength of the first frequency band. At the base end of one antenna element, the first
A conductive member is connected in series, a second conductive member is added so as to be capacitively coupled to the first conductive member, and a cylindrical member is formed so as to surround the first conductive member and the second conductive member and to be capacitively coupled thereto. Provide a capacitance tube made of a conductor and ground it,
The first antenna element is formed by connecting a coil antenna on the distal end and a pole antenna on the proximal end in series, and the pole antenna on the proximal end is set to about 波長 wavelength of the second frequency band, and A matching circuit and a first filter circuit for passing the first frequency band are sequentially interposed in series at a base end thereof, connected to an antenna input / output end, and a base end of the second conductive member is connected to the second frequency band. Through the second
A filter circuit is interposed and connected to the antenna input / output end, and the pole antenna on the base end side of the first antenna element, the first conductive member, and a second capacitively coupled therewith
A dual mode antenna, wherein the conductive member corresponds to an antenna having a wavelength of about ／ of the second frequency band. 6. A dual-mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the second mode antenna is vertically or inclined at about 波長 wavelength of the first frequency band. At the base end of one antenna element, the first
A conductive member is connected in series, a second conductive member is added so as to be capacitively coupled to the first conductive member, and a cylindrical member is formed so as to surround the first conductive member and the second conductive member and to be capacitively coupled thereto. Provide a capacitance tube made of a conductor and ground it,
The first antenna element is formed by series connection of a coil antenna whose front end side is densely wound and a coil antenna whose base end side is coarsely wound. The base end of the first conductive member is connected to the antenna input / output end by serially interposing a matching circuit and a first filter circuit for passing the first frequency band in series. Connecting a base end of the second conductive member to the antenna input / output end with a second filter circuit passing the second frequency band interposed therebetween, and winding the base end side of the first antenna element roughly. A dual mode antenna, comprising a turned coil antenna, the first conductive member, and a second conductive member capacitively coupled to the turned coil antenna so as to correspond to an antenna having a wavelength of about 3/4 of the second frequency band. 7. The dual mode antenna according to claim 4, wherein said first conductive member is formed in a coil shape. 8. The dual mode antenna according to claim 4, wherein said first conductive member is formed so as to correspond to an antenna having a wavelength of about １ ／ of said first frequency band. A dual mode antenna, wherein the antenna element and the first conductive member correspond to an antenna having a wavelength of about ／ of the first frequency band.