JPH11317612A - Folded antenna, antenna device and radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a folded antenna, wherein the physical length of an antenna in an axial direction and which is reduced easily adjusts plural resonance frequencies. SOLUTION: A linear or strip-like conductor is arranged from a base end 20a to the first folding point 20b on a top end side, a 1st element 20d is formed by successively folding back the conductor on the top end side and on the base end side respectively more than one time and parallelly arranging them, and a 2nd element 20f is formed by branching the conductor at the point 20b, successively folding back the branched conductor on the top end side and on the base end side respectively by more than one time in the same manner and arranging them in parallel. Then, the effective length from the end 20a to a front top end 20c of the element 20d is set to 1/4 wavelength of a 1st frequency f1 and the effective length from the end 20a to a front top end 20e of the element 20f is set to 1/4 wavelength of a 2nd frequency f2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible to shorten the physical length of an antenna in the axial direction, to easily adjust a plurality of resonance frequencies, and to transmit and receive a plurality of desired frequencies with a high gain. It relates to a folded antenna. The present invention also relates to an antenna device which can perform standby reception at a plurality of desired frequencies using the folded antenna and obtain a high antenna gain in a pulled-out state. Further, the present invention relates to a wireless device suitable for a dual-band mobile phone using the antenna device.

[0002]

2. Description of the Related Art The present inventors have disclosed in Japanese Patent Application No. 8-160016.
The antenna device as shown in FIG. The antenna device shown in FIG. 14 includes a folded antenna 10, a whip antenna element 12, and a helical antenna element 14. In the folded antenna 10, a linear or band-shaped conductor is disposed in a direction from the base end to the tip side, and is folded at the tip side so as to be parallel to the direction from the base end to the tip side, and further folded back at the base end side. It is arranged so as to be parallel and to end with its front end facing the front end. This conductor is formed in a cylindrical shape with the direction from the base end to the tip side as the axis. Further, a helical antenna element 14 is coaxially arranged at the tip of the whip antenna element 12 and integrated therewith, and the integrated one can be pulled out and stored in the axial direction with respect to the cylindrical folded antenna 10. You. In addition, in the drawer state,
The base end of the whip antenna element 12 is capacitively coupled to the front end of the cylindrical folded antenna 10.

[0003] In the folded antenna 10, the effective length from the base end to the front end is set to １ ／ wavelength of the first frequency f1. Here, in the folded antenna 10,
Folding causes stray capacitance between lines arranged in parallel, and acts as an antenna longer than its actual physical length. Further, the effective length from the base end to the first turn is set to １ ／ wavelength of the second frequency f2, and the effective length from the base end to the tip is set to ／ wavelength of the second frequency f2. Is done. The second frequency f2 is higher than the first frequency f1, and the stray capacitance generated between the parallel lines acts more so that its effective length is longer than the physical length. Therefore, in the folded antenna 10 in which the first frequency f1 resonates, the second frequency f3 having a frequency lower than three times the first frequency f1 is used.
2 can resonate. By appropriately setting the stray capacitance generated between the parallel conductor lines, FIG.
As shown in FIG. 5, the second frequency f
2 can be set to almost twice the frequency.

Further, the whip antenna element 12
The effective length from the base end of the whip antenna element 12 to the tip of the helical antenna element 14 is set to １ ／ wavelength of the first frequency f1, and the effective length from the base end of the whip antenna element 12 to the tip of the second frequency f2 is set to 1/2 of the second frequency f2. It is set to two wavelengths.

In such a configuration, as shown in FIG. 14, when the whip antenna element 12 and the helical antenna element 14 are pulled out from the folded antenna 10, the folded antenna 10
A maximum voltage is generated at the distal end of the antenna, and the base end of the whip antenna element 12 and the distal end of the folded antenna 10 are electrically connected at high frequency by a coupling capacitor C1, and transmission and reception of the first frequency f1 is possible. Also, for the second frequency f2, a maximum voltage is generated at the first turning point of the folded antenna 10, and the base end of the whip antenna element 12 and the first turning point of the folded antenna 10 are electrically connected at high frequency by the coupling capacitance C2. And the transmission and reception of the second frequency f2 is possible. For this second frequency f2, the helical antenna element 14 acts as a choke coil and does not act as an antenna. In the stowed state, the first frequency f1 and the second frequency f
2 transmission and reception are possible.

Therefore, if the first frequency f1 is set in the 900 MHz band and the second frequency f2 is set in the 1800 MHz band, it is possible to transmit and receive a dual band such as GSM / DCS or PDC / PHS with one antenna device. it can. In this manner, even with the technology proposed above, it is possible to cope with dual bands, perform standby reception in the housed state, and obtain high-gain antenna characteristics in the pulled-out state.

[0007]

By the way, in the technique proposed above, both the first frequency f1 and the second frequency f2 are resonated by the folded antenna 10 in which one conductor is appropriately folded. In order to adjust one resonance frequency, the folded antenna 1
If the physical length to the zero point, the distance between the parallel lines, the length of the parallel part, and the length to the first turning point are changed, the other resonance frequency is affected and the first frequency f1 is changed. It is difficult to adjust both the second frequency f2 and the second frequency f2 to desired frequencies. Further, in order to adjust the input / output impedance at the base end of the folded antenna 10, it is sufficient to adjust the coupling capacitance C1 and the coupling capacitance C2, but it is difficult to adjust them independently of each other. Difficult to adjust. Further, the length from the base end to the first turning point is defined as a high frequency, that is, １ ／ wavelength of the second frequency f2, and cannot be shorter in the axial direction.

The present invention has been made to further improve the above-mentioned technology, and provides a folded antenna capable of independently adjusting a plurality of resonance frequencies and shortening the axial length. The purpose is to do. It is another object of the present invention to provide an antenna device which can obtain a high antenna gain in a pulled-out state by using the folded antenna and can perform standby reception in a housed state. further,
An object of the present invention is to provide a wireless device suitable for a dual-band mobile phone or the like using the antenna device.

[0009]

In order to achieve the above object, a folded antenna according to the present invention has a linear or band-shaped conductor arranged in a direction from the base end to the tip end of the antenna. A first element is formed by arranging the conductor at least one time in parallel with the direction to form a first element, and branching the conductor in the middle from the base end to the first turning point on the distal end side or at the first turning point. A second element is formed by arranging at least one turn in parallel with the direction to form a second element, and setting an effective length from the base end to the tip of the first element so that a first frequency resonates;
An effective length from the base end to the tip of the second element is set so that the second frequency resonates.

A linear or band-shaped conductor is provided in the direction from the base end of the antenna to the distal end side, and is folded back at least once at each of the distal end side and the base end side so as to be disposed in parallel with the aforementioned direction. Forming a first element, branching the conductor at an intermediate point from the base end to the first turning point on the distal end side or at the first turning point, and separating the branched conductors at the distal end side and the proximal end side, respectively. It is sequentially turned over once or more and arranged in parallel with the above-mentioned direction to form a second element,
An effective length from the base end to the tip of the first element is set so that a first frequency resonates, and an effective length from the base end to the tip of the second element is set so that a second frequency resonates. It may be configured as follows.

Further, the conductor provided from the base end to the first turning point on the front end side may be arranged in a zigzag shape.

The effective length of the base element from the base end to the tip of the first element with respect to the first frequency and the effective length of the base end to the tip of the second element with respect to the second frequency are defined by the base. The input and output impedances may be set to be substantially the same at the ends.

Further, the conductor is branched at the distal end side and further extended in the direction to form a third element, and a third element is formed from the base end to the distal end of the third element so that another frequency resonates. It is also possible to configure by setting the effective length.

The effective length from the base end to the tip of the first element is set to 1/4 wavelength for the first frequency, and the effective length from the base end to the first turning point is set for another frequency. And the effective length from the base end to the tip of the first element is set to 3/4.
It is also possible to configure by setting the wavelength.

Further, the folded antenna may be arranged in a cylindrical shape with the axis from the base end toward the tip end as an axis.

Further, in the antenna device according to the present invention, the distal ends of the first and second elements of the folded antenna are disposed toward the distal end side of the antenna, and the first and second elements are disposed from the base end.
The effective length up to the tip of the element is 1/1 of the first frequency.
The wavelength is set to 4 wavelengths, the effective length from the base end to the tip of the second element is set to 波長 wavelength of the second frequency, and the helical antenna element is disposed coaxially at the tip of the whip antenna element. The whip antenna element and the helical antenna element can be pulled out and stored in the direction with respect to the folded antenna, and the effective length from the base end of the whip antenna element to the tip end of the helical antenna element is 1/1 of the first frequency. 2 wavelengths, and the effective length from the base end of the whip antenna element to the tip end thereof is set to the second
The frequency is set to a half wavelength, and the base end of the whip antenna element is capacitively coupled to the front end of the folded antenna in the pulled-out state.

Further, in the pulled-out state, coupling between the tip of one of the first and second elements at which the lower frequency of the first or second frequency resonates and the base end of the whip antenna element. The capacity may be configured to be smaller than the coupling capacity between the other end and the base end of the whip antenna element.

Further, the first and second antennas of the folded antenna are provided.
The tip of the element is arranged facing the tip of the antenna,
The effective length from the base end to the tip of the first element is set to １ ／ wavelength of the first frequency, and the effective length from the base end to the tip of the second element is set to 1 / １ ／ of the second frequency. Set to 4 wavelengths, the whip antenna element can be pulled out and stored in the direction with respect to the folded antenna, and the effective length from the base end to the tip of the whip antenna element is １ ／ wavelength with respect to the first frequency. Set to be one wavelength with respect to the second frequency,
The whip antenna element may be configured so that a base end of the whip antenna element is capacitively coupled to a front end of the folded antenna in the pulled-out state.

The effective length of the folded antenna from the base end to the tip of the first element is set to １ ／ wavelength of the first frequency, and the effective length from the base end to the tip of the second element is set. Is set to １ ／ wavelength of the second frequency so that the whip antenna element can be pulled out and stored in the direction with respect to the folded antenna. In this pulled-out state, the effective length from the base end of the folded antenna to the front end of the whip antenna element is １ ／ wavelength with respect to the first frequency and ／ wavelength with respect to the second frequency. It is also possible to set and configure such that

Further, the wireless device of the present invention uses the antenna device and includes a power supply fitting electrically connected to a base end side of the folded antenna so as to project the folded antenna outward. Arranged by penetrating the side wall of the body,
A wireless circuit housed in the wireless device housing is electrically connected to the power supply fitting.

[0021] Further, the wireless device is a device used close to the temporal region, and a conductor disposed from the base end of the folded antenna to the first folded portion is connected to the temporal portion of the wireless device housing. It can also be configured by arranging it on the side opposite to the side approaching the part.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the folded antenna according to the present invention will be described below with reference to FIGS. FIG. 1 is a developed view of a folded antenna according to a first embodiment of the present invention. FIG. 2 is an external perspective view in which the folded antenna of the first embodiment shown in FIG. 1 is arranged in a cylindrical shape.

In the folded antenna 20 shown in FIG. 1, a linear or band-shaped conductor is disposed in a direction centered on the distal end side of the antenna from the base end 20a, and is branched into two at the distal end side. Is turned back at the first turning point 20b and disposed in parallel with the direction of the axis, is turned back and forth in parallel at the distal end side and the base end side, and becomes a zigzag shape extending in the direction orthogonal to the axis. The distal end 20c ends toward the distal end. First turning point 2 where this conductor is branched
0b to the distal end 20c is the first element 20d, and the proximal end 20a to the distal end 20c of the first element 20d.
The effective length is set to １ ／ wavelength of the first frequency f1. Also, the other of the branched conductors is similarly folded back and arranged in parallel with the axis direction, further folded back at the base end side and arranged in parallel with the axis direction, and sequentially at the distal end side and the base end side. Each of the zigzags has a zigzag shape which is folded back to be parallel to each other and extends in a direction orthogonal to the axis, and the end 20e is terminated toward the end. The second element 20f extends from the first turning point 20b where the conductor branches to the tip 20e, and the tip 20e extends from the base end 20a to the second element 20f.
The effective length is set to １ ／ wavelength of the second frequency f2.

The folded antenna 20 shown in FIG. 1 is arranged so that the direction from the base end 20a to the front end is an axis.
As shown in FIG. In order to form the cylindrical folded antenna 20, a conductor having a shape as shown in FIG. 1 is provided on a flexible substrate by an appropriate technique such as etching or vapor deposition, and is wound around an outer peripheral surface of a cylindrical core member or the like. It is sufficient to arrange them. Alternatively, a conductor having a shape as shown in FIG. 1 may be punched out of a copper plate or the like and bent into a cylindrical shape. Further, a conductor may be appropriately arranged on the outer peripheral surface of the cylindrical core member by plating or the like in a shape as shown in FIG.

In the folded antenna 20 having such a configuration, the resonating first frequency f1 can be changed to a desired frequency by appropriately setting the deployed length of the first element 20d, the distance between parallel lines, and the parallel length. Can be adjusted.
Also, by appropriately setting the deployed length of the second element 20f, the distance between parallel lines, the parallel length, and the like, it is possible to adjust the resonating second frequency f2 to a desired frequency. Then, even if the first element 20d is adjusted, the second frequency f2 is not affected and the second element 20d is adjusted.
Adjusting f does not affect the first frequency f1. Therefore, they can be adjusted independently of each other. Therefore, the folded antenna 20 of the present invention can more easily adjust the first frequency f1 and the second frequency f2 than the folded antenna 10 previously proposed shown in FIG. It should be noted that the folded antenna 20 can be made compact and have the same shape as the helical antenna by making it cylindrical as shown in FIG. 2. However, even if the folded antenna 20 is unfolded as shown in FIG. The antenna functions as an antenna that can transmit and receive both the frequency f1 and the second frequency f2. The effective length from the base end 20a to the front end 20c or 20e is not limited to １ ／ wavelength of the resonance frequency, but may be an odd multiple of １ ／ wavelength such as 波長 wavelength. In addition, it may be an odd multiple of １ ／ wavelength or an odd multiple of 波長 wavelength of the resonance frequency. The effective length from the base end 20a to the front ends 20c and 20e is 3/3 for the first and second frequencies f1 and f2, respectively.
If it is an odd multiple of 4 wavelengths, or an odd multiple of 1/8 wavelength, or an odd multiple of 1/2 wavelength, the input / output impedance at the base end 20a for the first and second frequencies f1 and f2. Are almost the same. First and second frequencies f1,
There is no need for a matching circuit for making the input / output impedance of the base end 20a the same for f2. In addition, the base 2
If the input / output impedance at 0a is not taken into consideration, it may be an integer multiple of 1/8 wavelength, 1/4 wavelength or 1/2 wavelength with respect to the resonance frequency. And the first and second
If the input / output impedance at the base end 20a is different from the frequencies f1 and f2, a matching circuit such as an inductance is provided at the base end 20a, and the input / output impedance of the matching circuit is utilized by utilizing the impedance difference due to the frequency difference. Should be approximately the same.

FIG. 3 shows a second embodiment of the folded antenna according to the present invention.
It is a development view of an example. The folded antenna 30 of the second embodiment shown in FIG.
The conductor between 0b is formed in a zigzag shape extending in the axial direction. In addition, the first turning point 30 from the base end 30a.
The conductor is branched in the middle of b, and the branched conductor is folded at the branch point 30g and disposed in parallel with the axial direction.
A first element 30d is formed from the first turning point 30b to the tip 30c, and from the branch point 30g to the tip 30e.
By this, the second element 30f is formed. Then, from the base end 30a through the first turning point 30b, the tip 30c
The effective length from the base end 30a to the distal end 30e through the branch point 30g is set to １ ／ wavelength of the second frequency f2.

The folded antenna 30 having such a configuration has the first frequency f as in the folded antenna 20 shown in FIG.
It functions as an antenna that can transmit and receive the first and second frequencies f2. And, from the base end 30a, the first turning point 30b
The zigzag-shaped conductor is provided between the folded antenna 2 and the folded antenna 2 shown in FIG.
It can be shorter than zero. If the folded antenna 30 is used alone, as shown in FIG. 3, the folded element 30 may be disposed with its distal end facing the base end side, like the distal end 30c of the first element 30d.

FIG. 4 shows a third embodiment of the folded antenna according to the present invention.
It is a development view of an example. In the folded antenna 40 of the third embodiment shown in FIG. 4, the branch point 40g is provided at a position closer to the base end 40a side. In FIG. 4, lowercase letters attached to the numerals of the reference numerals shown in FIG. 4 indicate the same parts or portions as those shown in FIGS. 1 to 3, and duplicate description will be omitted. The same applies to the description of FIGS. 5 to 7 below.

FIG. 5 shows a fourth embodiment of the folded antenna according to the present invention.
It is a development view of an example. The folded antenna 50 of the fourth embodiment shown in FIG.
The zigzag shape that extends in the axial direction of the conductor disposed between Ob is bent at 90 degrees. In addition,
The zigzag shape may be a shape that is bent in a U-shape and meanders.

FIG. 6 shows a fifth embodiment of the folded antenna according to the present invention.
It is a development view of an example. The folded antenna 60 of the fifth embodiment shown in FIG. 6 has three conductors at the first folded point 60b.
Branches into two. Two branched conductors, a first element 60d and a second element 60f as in the first embodiment.
Is formed. The branched remaining conductor is extended in the axial direction, and the third element 60i is formed from the first turning point 60b to the tip 60h. And the base end 6
The effective length from 0a to the distal end 60c of the first element 60d is set to １ ／ wavelength of the first frequency f1.
The effective length from a to the distal end 60e of the second element 60f is set to １ ／ wavelength of the second frequency f2, and the base end 60a
Of the third element 60i to the tip 60h of the third element 60i is set to a quarter wavelength of the third frequency f3 which is another frequency. Therefore, in the folded antenna 60 of the fifth embodiment, the first frequency f1, the second frequency f2, and the third frequency f3
Can be transmitted and received.

FIG. 7 shows a sixth embodiment of the folded antenna according to the present invention.
It is a development view of an example. The folded antenna 70 of the sixth embodiment shown in FIG.
The effective length up to 0b is set to １ ／ wavelength of the fourth frequency f4, which is another frequency, and the effective length from the base end 70a to the tip end 70c of the first element 70d is の of this fourth frequency f4. Set to wavelength. Sixth such configuration
In the folded antenna 70 of the embodiment, three frequencies of the first frequency f1, the second frequency f2, and the fourth frequency f4 can be transmitted and received.

Next, a radio using the folded antenna of the present invention will be described with reference to FIGS. FIG. 8 is a longitudinal sectional view of a main part of one embodiment of the wireless device of the present invention. FIG. 9 is an equivalent circuit diagram of the antenna device of the wireless device shown in FIG.
(B) shows a stored state. FIG. 10 is an example of a Smith chart showing input and output impedances for the first frequency and the second frequency in the antenna device shown in FIG.
FIG. 11 is a diagram illustrating an example in which a folded antenna is provided in a wireless device housing so as to improve SAR. As the folded antenna, the first to sixth embodiments described above are used.
Although any of the embodiments can be used, a description will be given using the first embodiment as an example.

In FIG. 8, a cylindrical core member 8 made of an insulating material is provided on the distal end side of a substantially cylindrical power supply fitting 80 made of a conductive material.
2 are disposed coaxially, and on the outer peripheral surface of the core member 82,
The folded antenna 20 of the first embodiment is wound and arranged, and its base end 20a is electrically connected to the power supply fitting 80 in a DC manner as appropriate. A C-shaped resin spring 84 is disposed on the tip end side of the core member 82, and a cover member 86 is provided so as to restrict the axial movement of the resin spring 84 and cover the outer periphery of the folded antenna 20. The base end is screwed and fixed to the power supply fitting 80. Furthermore, NiTi
A helical antenna element 90 is coaxially electrically connected to the tip of a whip antenna element 88 made of a wire having flexibility and conductivity, and is disposed, fixed and integrated. This integrated thing,
It is configured to be movable in the axial direction with respect to the power supply fitting 80 and the core member 82 and to be able to be retracted and housed. A large-diameter stopper 92 made of an insulating material is provided at the base end of the whip antenna element 88 to prevent the whip antenna element 88 from coming off in the pull-out direction. Are engaged and the pulled-out state is elastically maintained. The helical cover member 9 made of an insulating material covering the outer periphery of the helical antenna element 90
A large-diameter portion having the same diameter as the stopper 92 is provided on the distal end side of 4.
A resin spring 8 is provided in a groove provided around the axis on the outer periphery of the large diameter portion.
4 are engaged and the stored state is elastically maintained. And
A large-diameter decorative ball 96 is provided at the tip of the helical cover member 94.
Is provided, which is used as a knob for restricting the movement in the storage direction at a predetermined position and for pulling out. Thus, an antenna device using the folded antenna 20 is configured.

Further, a power supply receiving member 100 made of a conductive material is fixed to the wireless device housing 98 by penetrating the side wall by insert molding or the like. Then, this power receiving member 100
Then, the power supply fitting 80 of the antenna device is screwed into the antenna device, and the antenna device is fixed to the wireless device housing 98. A board 102 on which a radio circuit is mounted is appropriately disposed in the wireless device housing 98, and a leaf spring 104 made of a conductive material provided on the substrate 102 is provided inside the wireless device housing 98 of the power receiving member 100. Elastic contact with the protruding part. The leaf spring 104 is, of course, electrically connected to the high frequency stage of the wireless circuit, and the power supply fitting 80 of the antenna device is connected to the power receiving member 100 and the leaf spring 1.
A wireless device is configured by being electrically connected to a wireless circuit via the wireless communication circuit 04.

The base end 20 of the folded antenna 20
The effective length from a to one end 20c is the first frequency f1.
Is set to １ ／ wavelength, and from the base end 20a to the other end 2
The effective length up to 0e is set to １ ／ wavelength of the second frequency f2. Further, the effective length from the base end of the whip antenna element 88 to the tip of the helical antenna element 90 is set to の wavelength of the first frequency f1, and the effective length from the base end of the whip antenna element 88 to its tip is the second. It is set to １ ／ wavelength of two frequencies f2.

In this configuration, when the antenna is pulled out as shown in FIG. 9A, a maximum voltage is generated at one end 20c of the folded antenna 20 with respect to the first frequency f1, and this end 20c and the whip antenna element 88
Are capacitively coupled by a coupling capacitance C1, and the first frequency f
1 is resonated with a high antenna gain. Also, for the second frequency f2, the other end 20 of the folded antenna 20
A maximum voltage is generated at the point e, the tip 20e and the base end of the whip antenna element 88 are capacitively coupled by the coupling capacitance C2, and the second frequency f2 resonates with a high antenna gain.
Here, the folded antenna 20 is adjusted so that both the first frequency f1 and the second frequency f2 resonate in an optimum state, respectively, so that the antenna device is higher than the first frequency f1 and the second frequency f2 as an antenna device. Antenna gain is obtained.

By the way, in the antenna device as shown in FIG. 9, the input and output impedances for the first frequency f1 and the second frequency f2 are almost the same and are set to a desired value, for example, about 50 ohms. desirable. However, as shown in FIG. 10, the input / output impedance tends to be larger than a desired value with respect to the first frequency f1 at a low frequency, and the second frequency f1 at a high frequency.
2 tends to be smaller than the desired value. The values of these input / output impedances increase as the values of the coupling capacitances C1 and C2 are increased to increase the degree of capacitive coupling. Therefore, the tip 20c of the folded antenna 20 on the side where the first frequency f1 resonates is provided lower than the tip of the antenna by L, and the coupling capacitance C1 between the tip 20c and the base end of the whip antenna element 88 is set small. You. Then, the input / output impedance with respect to the first frequency f1 can be reduced, and can be adjusted to a desired value. If necessary, the tip 20e on the side where the second frequency f2 resonates may be brought closer to the base end of the whip antenna element 88 to increase the coupling capacitance C2 and increase the input / output impedance for the second frequency f2. good. Thus, the folded antenna 20
By appropriately setting the two tips 20c and 20e respectively to adjust the coupling capacitance C1 and the coupling capacitance C2 separately, the input / output impedance for the first frequency f1 and the second frequency f2 can be set to 50 ohms or the like. It can be easily set to the same desired value. In order to adjust the coupling capacitance C1 and the coupling capacitance C2, the ends 20c and 20c are adjusted.
e is not limited to the adjustment of the positional relationship with respect to the base end portion of the whip antenna element 88, but may be such that the opposing area of the tip end may be adjusted, and the core member 82 and the corresponding portion of the stopper 92 have an appropriate dielectric constant. May be used.

As shown in FIG. 9B, even when the antenna device of the present invention is in the housed state, the folded antenna 20
As a result, the first frequency f1 and the second frequency f2 resonate, which is suitable for standby reception and the like. Moreover, the first frequency f1
And the second frequency f2 can be easily and independently adjusted as described above, so that a higher antenna gain can be obtained for both of the two frequencies than the conventional one even in the housed state. It is.

Therefore, if the first frequency f1 is set in the 900 MHz band and the second frequency f2 is set in the 1800 MHz band, the GSM / DCS or PSM
Dual antennas such as DC / PHS can be transmitted and received by one antenna device. Moreover, it is easier to adjust the antenna characteristics to the frequency to be transmitted and received than the previously proposed technology, and is suitable for mass production.

Further, the power supply fitting 80 of the antenna device is
The structure for fixing the wireless device housing 98 to the power receiving member 100 is changed from that shown in FIG. 8 so that the attitude of the antenna device around the axis with respect to the wireless device housing 98 becomes a predetermined relative position, As shown in FIG. 11, the conductor between the base end 20a of the folded antenna 20 and the first folded point 20b may be arranged on the side opposite to the side approaching the temporal region of the user during use.

As shown in FIG. 11, in a portable telephone or the like used close to the temporal region of the user, as shown in FIG.
8 by disposing the folded antenna 20, S
The AR (Specific Absorption Rate) can be greatly improved as compared with a conventional antenna formed by using a helical coil to protrude outward for standby reception. The reason is as follows. First,
Regardless of whether it is in the drawer state or the storage state, the first
Due to the resonance at the frequency f1 and the second frequency f2, a maximum current is generated at the base end of the antenna device. Therefore, in the conventional helical coil, the distance between the temporal region and the outer periphery of the helical coil is short, and there is a possibility that the electromagnetic field due to the current flowing through the coil portion on the near side greatly affects the temporal region. On the other hand, in the folded antenna 20 of the present invention, the conductor between the base end 20a through which the largest current flows and the first folded point 20b is arranged on the farthest side from the temporal region. The effect of the electromagnetic field on the temporal region due to the current flowing through is greatly reduced. According to experiments,
The effect of the electromagnetic field has a large attenuation change depending on the distance, and a great effect can be obtained even if the distance is slightly increased by a slight difference in position.

FIG. 12 is an equivalent circuit diagram of the antenna device according to another embodiment of the present invention in a pulled-out state.
The operation for the frequency is shown, and (b) shows the operation for the second frequency.

In the antenna device of another embodiment shown in FIG. 12, a whip antenna element 88 is configured to be movable in the axial direction with respect to the folded antenna 20 and to be retractable. The helical antenna element 90 as shown in FIG. 9 is not provided. Here, if the first frequency f1 is in the 900 MHz band and the second frequency f2 is in the 1800 MHz band, the effective length of the whip antenna element 88 is 波長 wavelength with respect to the first frequency f1 and the second frequency is Can be set to one wavelength. The folded antenna 20
Is that the effective length from the proximal end 20a to the distal end 20c or 20e is 1 for each of the first and second frequencies f1 and f2.
/ 4 wavelength.

Therefore, in the pulled-out state, the 1/4 wavelength of the folded antenna 20 and the whip antenna element 8 with respect to the first frequency f1 as shown in FIG.
8 are capacitively coupled by the coupling capacitance C1,
The frequency f1 resonates. Also, as shown in FIG. 12B, one of the folded antennas 20 with respect to the second frequency f2.
The wavelength and one wavelength of the whip antenna element 88 are capacitively coupled by the coupling capacitance C2, and the second frequency f2 resonates.

Incidentally, in the technology of another embodiment of the antenna device shown in FIG.
As in the case of the MHz band, the present invention can be applied if the second frequency f2 is twice as high as the first frequency f1. Further, if the second frequency f2 is an integer multiple such as three times the first frequency f1, the technology of the antenna device shown in FIG. 12 can be applied.

FIG. 13 is an equivalent circuit diagram of the antenna device according to still another embodiment of the present invention in a pulled-out state.
Shows the operation for the first frequency, and (b) shows the operation for the second frequency.

In the antenna device of another embodiment shown in FIG. 13, the whip antenna element 88 is movable in the axial direction with respect to the folded antenna 20 so that it can be pulled out and housed, and the helical antenna as shown in FIG. Element 90 is omitted and is similar to that shown in FIG. However, its operation state is different. Then, in the pulled-out state, the whip antenna element 88
Is made to overlap with the distal end of the folded antenna element 20 to increase the degree of capacitive coupling. Further, for the first frequency f1, (a)
As shown in the figure, the effective length from the base end 20a of the folded antenna 20 to the tip of the whip antenna element 88 is set to be 1/4 wavelength. Further, as shown in (b), the whip antenna element 88 from the base end 20a of the folded antenna 20 with respect to the second frequency f2.
Is set so that the effective length up to the tip of is 3/4 wavelength. Note that, in the folded antenna 20, the effective length from the base end 20a to the front end 20c or 20e is equal to the first and second frequencies f.
1 and f2 are respectively set to 1/4 wavelength.

In such a configuration, according to an experiment, a current flows through the coupling capacitance at the base end of the whip antenna element 88, and the operation differs from that of the antenna device shown in FIGS. 9 and 12. Then, the inductance component of the folded antenna 20 and the capacitance component of the coupling capacitance and the whip antenna element 88
It is considered that the first and second frequencies f1 and f2 resonate with each other as shown in FIGS.

In the description of the above embodiment, the feeding device 80 and the leaf spring 104 are used for the antenna device and the radio.
Performs the antenna function, the folded antenna 20
It will be readily understood that the base end 20a as the antenna of the present invention is not a physical base end of itself but a connection point of the leaf spring 104 to the substrate 102.

[0050]

As described above, since the folded antenna, the antenna device, and the wireless device of the present invention are constituted, the following special effects can be obtained.

In any of the folded antennas according to the first and second aspects, the first element and the second element are provided by branching the conductor, and the first frequency and the second frequency are resonated respectively. , The resonance frequency can be adjusted independently of each other. Moreover, since the length from the base end to the first turning point is not defined by the resonance frequency, the folded antenna according to the present invention has a shorter axial length, as in the previously proposed folded antenna. Can be.

In the folded antenna according to the third aspect, by providing a zigzag conductor from the base end to the first folded point, the length in the antenna axial direction can be made shorter.

In the folded antenna according to the fourth aspect, the effective length from the base end to the front ends of the first and second elements is the input / output impedance at the base end for the first frequency and the second frequency. Are almost the same value,
There is no need for a matching circuit or the like for providing the same input / output impedance for the first frequency f1 and the second frequency f2.

In the folded antenna according to the fifth and sixth aspects, three frequencies can be resonated by one antenna.

In the folded antenna according to the seventh aspect, the size is reduced by making the antenna a cylindrical shape, and the outer shape similar to the helical coil can be obtained.

In the antenna device according to the eighth aspect,
Since the folded antenna can be easily adjusted to the desired first and second frequencies, the capacitive coupling between the whip antenna element and the helical antenna element, which can be adjusted relatively accurately, makes it possible to control either the first frequency or the second frequency. However, a high antenna gain can be obtained.

In the antenna device according to the ninth aspect,
By separately adjusting the coupling capacitance in the pulled-out state for the first frequency and the second frequency, the input / output impedance at the base end is adjusted to substantially the same desired value for the first frequency and the second frequency. Can be.

In the antenna device according to the tenth or eleventh aspect, the only antenna to be pulled out in the pulled-out state is the whip antenna element, and the helical antenna element is omitted, so that the structure is simple and the cost is low. Can be manufactured. In the antenna device according to the tenth aspect, the structure is simplified by utilizing the fact that the second frequency is twice as high as the first frequency. As for the antenna gain, almost the same high gain can be obtained as when the antenna to be extracted has a whip antenna element and a helical antenna element at the tip thereof.

In the wireless device according to the twelfth aspect, a high antenna gain can be obtained for the first frequency and the second frequency in the pulled-out state and the housed state, respectively.
It is suitable for dual-band mobile phones such as GSM / DCS or PDC / PHS.

In the wireless device according to the thirteenth aspect, the conductor disposed from the base end of the folded antenna to the first folded point with respect to the wireless device housing is arranged farthest from the temporal region. Therefore, the SAR can be improved. Therefore, the present invention is suitable for a wireless device such as a mobile phone used close to the temporal region when used, or a wireless microphone fixed to the temporal region.

[Brief description of the drawings]

FIG. 1 is a development view of a folded antenna according to a first embodiment of the present invention.

FIG. 2 is an external perspective view in which the folded antenna of the first embodiment shown in FIG. 1 is arranged in a cylindrical shape.

FIG. 3 is a developed view of a folded antenna according to a second embodiment of the present invention.

FIG. 4 is a development view of a third embodiment of the folded antenna of the present invention.

FIG. 5 is a development view of a fourth embodiment of the folded antenna of the present invention.

FIG. 6 is a development view of a fifth embodiment of the folded antenna of the present invention.

FIG. 7 is a development view of a sixth embodiment of the folded antenna of the present invention.

FIG. 8 is a longitudinal sectional view of a main part of one embodiment of the wireless device of the present invention.

9A and 9B are equivalent circuit diagrams of the antenna device of the wireless device shown in FIG. 8, wherein FIG. 9A shows a pulled-out state and FIG. 9B shows a housed state.

10 is an example of a Smith chart showing input and output impedances with respect to a first frequency and a second frequency in the antenna device shown in FIG. 9;

FIG. 11 is a diagram illustrating an example in which a folded antenna is provided in a wireless device housing so as to improve SAR.

FIGS. 12A and 12B are equivalent circuit diagrams of an antenna device according to another embodiment of the present invention in an extended state, in which FIG. 12A shows an operation for a first frequency, and FIG. 12B shows an operation for a second frequency.

FIGS. 13A and 13B are equivalent circuit diagrams of the antenna device according to still another embodiment of the present invention in an extended state, in which FIG. 13A shows an operation for a first frequency, and FIG. 13B shows an operation for a second frequency.

FIG. 14 is an equivalent circuit diagram of the antenna device proposed by the present inventors in an extended state.

15 is an antenna characteristic diagram of the folded antenna used in the previously proposed antenna device shown in FIG.

[Explanation of symbols]

10, 20, 30, 40, 50, 60, 70 Folded antenna 12, 88 Whip antenna element 14, 90 Helical antenna element 20a, 30a, 40a, 50a, 60a, 70a Base end 20b, 30b, 40b, 50b, 60b, 70b First turning point 20c, 20e, 30c, 30e, 40c, 40e, 5
0c, 50e, 60c, 60e, 60h, 70c, 7
0e Tip 20d, 30d, 40d, 50d, 60d, 70d First element 20f, 30f, 40f, 50f, 60f, 70f Second element 30g, 40g Branch point 60i Third element 80 Power supply fitting 98 Radio housing 100 Power supply receiving Member 102 Substrate 104 Leaf spring C1, C2 Coupling capacity f1 First frequency f2 Second frequency f3 Third frequency f4 Fourth frequency

Claims (13)

[Claims] 1. A linear or band-shaped conductor is disposed in a direction from a base end to a distal end of an antenna, and the conductor is turned at least once at the distal end and disposed parallel to the direction.
Forming an element, branching the conductor at an intermediate point from the base end to the first turning point on the distal end side or at the first turning point, and arranging the conductor at least one turn to be parallel to the direction; Forming the first
An effective length from the base end to the tip of the first element is set so that a frequency resonates, and an effective length from the base end to the tip of the second element is set so that a second frequency resonates. A folded antenna, comprising: 2. A linear or band-shaped conductor is disposed in the direction from the base end of the antenna to the distal end side, and is folded back at least once at the distal end side and the base end side, respectively, and is disposed in parallel with said direction. Forming a first element, branching the conductor at an intermediate point from the base end to the first turning point on the distal end side or at the first turning point, and separating the branched conductors at the distal end side and the proximal end side, respectively. It is folded back one or more times sequentially and arranged in parallel with the above-mentioned direction to form a second element.
An effective length from the base end to the tip of the first element is set so that a frequency resonates, and an effective length from the base end to the tip of the second element is set so that a second frequency resonates. A folded antenna, comprising: 3. The folded antenna according to claim 1, wherein the conductor arranged from the base end to the first turning point on the distal end side is arranged in a zigzag shape. Folded antenna. 4. The folded antenna according to claim 1, wherein the effective length from the base end to the tip of the first element with respect to the first frequency, and the effective length from the base end to the tip of the second element. A folded antenna, wherein the effective length for the second frequency is set so as to have substantially the same input / output impedance at the base end. 5. The folded antenna according to claim 1, wherein the conductor is branched at the distal end and further extended in the direction to form a third element, so that another frequency resonates. A folded antenna, wherein an effective length from a base end to a front end of the third element is set. 6. The folded antenna according to claim 1, wherein the first frequency is a first frequency from the base end with respect to the first frequency.
Set the effective length to the tip of the element to 1/4 wavelength,
For another frequency, the effective length from the base end to the first turning point is set to ４ wavelength, and the effective length from the base end to the front end of the first element is set to ／ wavelength. A folded antenna, comprising: 7. A folded antenna according to claim 1, wherein the folded antenna according to any one of claims 1 to 6 is arranged in a cylindrical shape whose axis is the direction from the base end to the tip end. 8. The folded antenna according to claim 1, wherein the distal ends of the first and second elements are arranged toward the distal end of the antenna, and an effective length from the base end to the distal end of the first element. Is set to １ ／ wavelength of the first frequency, the effective length from the base end to the tip of the second element is set to １ ／ wavelength of the second frequency, and coaxial with the tip of the whip antenna element. A helical antenna element, and the whip antenna element and the helical antenna element can be pulled out and stored in the direction with respect to the folded antenna, and the effective length from the base end of the whip antenna element to the tip of the helical antenna element Is １ ／ of the first frequency
Wavelength, the effective length from the base end of the whip antenna element to the tip thereof is set to 波長 wavelength of the second frequency, and in the pulled-out state, the base end of the whip antenna element is An antenna device configured to be capacitively coupled to a tip portion. 9. The antenna device according to claim 8, wherein
In the pulled-out state, the coupling capacitance between the distal end of one of the first or second element at which the lower frequency of the first or second frequency resonates and the proximal end of the whip antenna element is the other. An antenna device characterized in that it is configured to be smaller than a coupling capacity between a tip and a base end of the whip antenna element. 10. The folded antenna according to claim 1, wherein the distal ends of the first and second elements are disposed toward the distal end of the antenna, and an effective length from the base end to the distal end of the first element. Is set to １ ／ wavelength of the first frequency, the effective length from the base end to the tip of the second element is set to １ ／ wavelength of the second frequency, and the whip antenna element is connected to the folded antenna. The whip antenna element is set so that the effective length from the proximal end to the distal end is 波長 wavelength for the first frequency and 1 wavelength for the second frequency. An antenna device, wherein a base end of the whip antenna element is capacitively coupled to a front end of the folded antenna in the pulled-out state. 11. The folded antenna according to claim 1, wherein an effective length from the base end to the front end of the first element is set to に wavelength of the first frequency, and the second antenna is connected to the second antenna from the base end. The effective length up to the tip of the element is
The frequency is set to 波長 wavelength, and the whip antenna element can be pulled out and stored in the direction with respect to the folded antenna so that the base end of the whip antenna element is capacitively coupled to the folded antenna in the pulled-out state. In this state, the effective length from the base end of the folded antenna to the front end of the whip antenna element is set to １ ／ wavelength with respect to the first frequency and ／ wavelength with respect to the second frequency. An antenna device characterized by being set and configured. 12. A power supply fitting provided by using the antenna device according to claim 8 and electrically connected to a base end side of the folded antenna so as to protrude outward. A wireless device, wherein the wireless device is configured so as to penetrate a side wall of a device housing and electrically connect a wireless circuit housed in the wireless device housing to the power supply fitting. 13. The wireless device according to claim 12, wherein the wireless device is used near the temporal region, and a conductor disposed from a base end of the folded antenna to a first folded point is provided. A wireless device that is arranged on a side of the wireless device housing opposite to a side approaching the temporal region.