JP3364417B2 - Antenna for portable radio - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna for a mobile wireless device such as a mobile phone. More specifically, the present invention relates to a small-sized portable wireless device antenna capable of transmitting and receiving even in two or more frequency bands having an even multiple relationship.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a linear (rod-shaped) antenna has been used as an antenna for a portable wireless device such as a mobile phone. This linear antenna has about 1/4 wavelength, about 3/8 wavelength of the received signal,
Alternatively, it is formed to have a length of about ½ wavelength. Therefore, when the frequency band to be received is determined, the length of the linear antenna is uniquely determined. Therefore, the antenna that transmits and receives a signal in a low frequency band inevitably has a long length. In order to shorten the external dimension of the antenna, the lengthened linear antenna has been adopted by winding an antenna wire such as a piano wire in a coil shape and coating the outer circumference of the antenna wire with resin to shorten the length.

On the other hand, the antenna of such a portable device is
It is housed in a portable device so that it does not get in the way when moving, and only part of the antenna is attached so that it is exposed from the portable device to receive the call signal, or an antenna for receiving the incoming call signal is attached separately. The antenna is provided so as to extend out of the portable device during communication. As a result, the incoming call signal can be received,
At the time of communication, the sensitivity is increased so that communication can be performed.

Therefore, the antenna for receiving the incoming call signal alone has about 1/4 wavelength or about 1/2 of the received signal.
It is necessary to have a wavelength length, and on the other hand, it is preferably small so that it does not get in the way when carrying it, and it is usually wound in a coil shape to shorten the external length as an antenna. Further, even when the antenna for communication is used, if the frequency band of the received signal is low, it becomes too long and inconvenient to handle, and the antenna for communication is also shortened in the form of a coil.

[0005]

As described above, when the antenna is formed in a coil shape so as to reduce its length as the outer shape, when the coil interval is large, it does not become a problem electrically, but if it is sufficiently short. However, when the coil spacing becomes narrower (the coil is tightly wound), it becomes shorter, but the radiation resistance of the antenna decreases, and even if a matching circuit is added and used, the antenna performance deteriorates.

Further, for example, in a mobile phone, a frequency of 900 MHz band is used in GSM (Group Special Mobile) (corresponding to PDC (Personal Digital Cellular) in Japanese system) in the European system, and DCS (Digital Cellular System). ) (PHS (Personal Handy Phone On System) supported in Japanese system) 1800M
A frequency in the Hz band is used, and it is preferable that both of them can be transmitted and received. However, conventionally, in order to transmit and receive both of them, two antennas are provided separately, or an antenna wire is further connected to the tip of the antenna for the high frequency band through a trap to match the length of the low frequency band. It has to be used as an antenna and has a problem that it becomes large.

Further, the sensitivity is improved by a small antenna so that communication can be performed only by the antenna for incoming calls without improving the sensitivity of the antenna and extending the antenna for communication. It is desired to transmit and receive signals in a plurality of frequency bands.

The present invention has been made in order to solve such a problem, and it is an antenna that needs to be miniaturized, such as an antenna for transmitting and receiving in a portable device, and has a small outer dimension so that a plurality of antennas can be provided. it is possible to receive the incoming call signal in the frequency band of, as it can also be communicate, concrete of the mobile phone antenna using <br/> antenna elementary bets can improve the characteristics of the antenna It is intended to provide a structure.

[0009]

[0010]

Yet another object of the present invention is to provide a small antenna as the first antenna section, which can be combined with a second antenna section for communication to further improve the sensitivity during communication. It is to provide a specific structure of an antenna for a portable wireless device in which an antenna unit and a second antenna unit are combined.

[0012]

SUMMARY OF THE INVENTION An antenna for a portable wireless device according to the present invention is an insulator composed of an insulating column or an insulating cylinder, an antenna element provided on the outer periphery of the insulator, and a lower end portion of the insulator. And a cap made of metal that is attached to the antenna element and is in contact with one end of the antenna element, and a cap that covers the antenna element and is fixed to the holder. is formed by being folded a plurality of times so as to be substantially parallel along the longitudinal direction at intervals, at least one set of elements adjacent to each other by being folded said were short-circuited by a conductor at least a part shape It consists of an antenna element formed on the. Substantially parallel here means perfect flatness.
Does not mean a row, but adjacent antenna elements
Location that can couple capacitively and / or inductively between
Means get involved.

The antenna element that contacts the holder
Wider than the width of the antenna element at one end of the
By forming the tongue piece formed,
It is preferable because electrical contact can be easily obtained. In addition, by insulating film is pressed against the antenna element to the insulator on the surface of the antenna element provided on the outer periphery of the insulator is covered, it is possible to fix the antenna element to firmly <br/> lithograph insulator can Ru. As the insulating coating, a material such as a heat-shrinkable tube that shrinks after being covered, taping of an insulating tape, or a resin coating that is solidified after being applied to the surface can be used.

Further, the antenna element is formed on a surface of the flexible film, by the flexible film is found wound around the insulator, without the antenna element is deformed also facilitates assembly work . further,
The collar portion of the holder with which the lower end portion of the cap abuts
The cross-section is trapezoidal, that is, tapered.
The outer diameter of the antenna, that is, the thickness of the cap
Contact the holder at the bottom edge of the cap without thickening
The mechanical strength of the parts that
It will be strong against the impact of.

The insulator comprises an insulating cylinder, and
A through hole is provided in the center of the top of the
A ring spring is provided on the upper part of the inner circumference of the cylinder,
Through the ring spring at the lower end and the upper end.
A second antenna part that can be fixed more is further provided, and
The lower end side of the second antenna part is formed by the ring spring.
A first having said antenna element when fixed
The antenna part and the second antenna part are connected via a dielectric.
By making the structure electrically coupled, at the time of communication
Can lengthen the antenna and improve the sensitivity
It

[0016]

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an antenna for a portable wireless device of the present invention will be described with reference to the drawings.

In order to obtain an antenna of a portable device or the like, which does not deteriorate the performance, even if the antenna portion that can receive a calling signal (incoming signal) when the antenna is housed due to movement is small, Furthermore, the small antenna was earnestly studied in order to obtain an antenna that can transmit and receive signals in two or more frequency bands other than odd multiples. As a result, as shown in a plan view of the example in FIG. 5, the folded-back portion 1a is formed by bending the antenna element so as to be substantially (substantially) parallel along the longitudinal (axial) direction. If the number is about 10 or so, for example, the electrical length of the antenna element does not change much for the first frequency band of about 900 MHz, and the electrical length of the antenna element is set to about 1
It acts as an antenna with a length of / 4 wavelength, and the electrical length changes significantly for the second frequency band, which is about twice as high, and the
It has been found that a signal of two or more desired frequency bands, which is not an odd multiple frequency, can be transmitted / received by acting as a / 4 wavelength antenna and adjusting the number of times of folding and the interval thereof, and Japanese Patent Application No. 8-160016. No.

[0021] That is, the antenna element 1, for example formed in a length of about 1/4 wavelength of a frequency band f ₁
In addition, due to the formation of the folded portion 1a, due to capacitive coupling between the adjacent antenna elements 1 and the relationship between the even mode (even) and the odd mode (odd) of the modes propagating through the antenna element 1, Frequency band f ₁
And the electrical length does not change much for frequency bands that are an odd multiple thereof, but for even multiples such as double and frequency bands in the vicinity thereof, the number of times of folding and the spacing between antenna elements due to folding. The electric length can be drastically changed by adjusting. As a result of further intensive studies by the present inventors, by rounding this folded antenna into a cylindrical shape (ring shape), it is easy to match two or more frequency bands, the sensitivity is improved, and the reliability of communication is improved. It has been found that the coupling with the second antenna is also very good.

The antenna for a portable wireless device of the present invention has an insulating cylindrical body (core), as shown in a side view of a partial cross section in FIG.
An antenna element 12 is provided on the outer circumference of 11. The antenna element 12 forms the above-mentioned folded antenna in which a folded portion is formed at least once in the axial direction, as shown in the plan view developed in FIG. 2B.
In the example shown in FIG. 1, an insulating coating 16 such as a heat-shrinkable tube is covered from the upper side of the antenna element 12 and firmly fixed to the insulating cylindrical body 11. However, the antenna element 12 formed in a ring shape may be press-fitted or fixed to the insulating cylinder 11 by an adhesive or the like. The lower end portion of the insulating cylinder 11 is fixed by press fitting or the like to a metal holder 13 having a screw portion 13a formed on the outer periphery of the lower portion so as to be attached to a housing of a wireless device or the like. At this time, the tongue piece 12a at one end of the antenna element 12 contacts the inner wall of the holder 13 and is electrically connected thereto. Therefore, the lower end portion of the holder 13 is brought into contact with the inside of the housing to connect to the transmission / reception circuit in the housing. Further, a cap 14 that covers and protects the antenna element 12 is screwed and fixed to the holder 13 around the periphery.

The insulating cylinder 11 is an insulating cylinder made of polyethylene (PE), polyoxymethylene (POM), etc., as shown in a perspective view of the antenna element 12 wound in FIG. 2 (a). It consists of The outer circumference thereof is a smooth arc-shaped surface, and the antenna element 12 described later can be press-fitted into a ring shape. When used only with this antenna, the inner circumference is not limited and may be a cylindrical body or a cylindrical body.
Further, it may be a polygonal prism or a prism, and any insulator including them may be used.

In the case of penetrating a second antenna section 20 described later, an insulating cylinder 11 having a structure as shown in FIG. 2A is used, and its inner peripheral surface is shown in a sectional view in FIG. As shown in FIG.
Is used as a fixing means when the second antenna portion 20 described later is extended from the housing or housed in the housing. Further, the inner diameter has a two-step configuration, the upper step portion is an inner diameter at which the joint portions 24a and 26 of the second antenna portion 20 are slid when the second antenna portion 20 is extended from the housing, and the lower step portion is With an inner diameter that passes through a large-diameter stopper portion 27 provided at the lower end of the second antenna portion,
The stopper portion 27 has a structure that passes through this large diameter portion and is stopped at the small diameter portion of the upper step portion so as not to come off when the second antenna portion 20 is extended from the housing.

As shown in FIG. 2B, a plan view of the antenna element 12 is folded back so that it is substantially parallel to the longitudinal direction of the conductor (axial direction of the insulating cylinder). Parts are formed. In the example shown in FIG. 2 (b), the folded portion is provided more than once, the two sets of elements of adjacent elements by being folded back is short throughout the element between folding, wide element 12b Are provided in two places. That is,
As shown in FIG. 5, the folded portions are regularly formed and the gaps between the adjacent elements are filled with the conductor at two places. With such a shape, as shown in FIG. 4 which shows the change of the voltage standing wave ratio with respect to the frequency, it is small over the entire desired frequency band (f _L is the lower limit frequency and f _H is the upper limit frequency). Becomes
The frequency characteristics are greatly improved. In addition, in FIG. 4, the broken line is the result when the antenna element having the shape shown in FIG. 5 is used and the other conditions are the same.

When short-circuiting such adjacent elements, in the example shown in FIG. 2B, the wide element 1 is short-circuited over the entire length of the adjacent elements.
Although it was formed in 2b, as shown in FIG. 2 (c), similar characteristics were obtained even in the structure in which the short-circuited portion 12c was formed at the root portion or other portion of the adjacent element. Further, a tongue piece 12a is formed at one end of the tongue piece 12a to increase its area so that electrical contact can be easily obtained when the tongue piece 12a is fitted to a holder 13 described later.

Such an antenna element 12 is rounded by punching a leaf spring such as phosphor bronze or beryllium copper into a shape as shown in FIG. 2 (b) by pressing.
After mounting , it can be press-fitted into a cylindrical insulating cylinder 11 as shown in FIG. 2 (a), for example. However, it is not limited to punching a plate-shaped body, and a sheet formed by folding back a conductive wire or the like can also be used.
Further, each element formed by folding back is not necessarily linear, but a zigzag portion is formed in part,
The spacing between the elements may be different depending on the location.

Further, the antenna element 12, which is made of a conductor alone, may not be provided on the outer circumference of the insulating cylinder 11. That is, the antenna element may be formed by patterning on the surface of a flexible film made of, for example, polyimide, and the flexible film may be wound around and fixed to the insulating cylinder 11. With such a structure, antenna elements can be mass-produced by vapor deposition and patterning of a metal film such as a copper foil. Moreover, since a flexible film may be wound and fixed, it is very easy to handle. Therefore, deformation of the element does not occur.

The holder 13 is, as shown in FIG.
A screw portion 13a is provided below the collar portion 13b that is in contact with the surface of the housing so that the insulating tubular body 11 that holds the above-mentioned antenna element 12 is fixed and can be attached to the housing of a portable wireless device or the like. It can be screwed into the housing as it is. Further, a screw portion is also formed on the upper portion of the collar portion 13b, and the cap 14 is screwed in so that the antenna element 12 and the like can be protected. The cap 14 holds the ring spring 15 (see FIG. 3) and also has a role of protecting the antenna element 12 provided on the surface of the insulating cylinder 11, and is made of ABS (acrylic butadiene styrene), elastomer, or the like. ing.

In the example shown in FIG. 1, as is apparent from FIG. 1, the side surface of the collar portion 13b has a trapezoidal portion 13c having a cross-sectional shape.
Is formed in. If such a trapezoidal portion 13c is not formed, the wall thickness of the lower end portion of the cap 14 around the collar portion 13b becomes thin, and it is easily damaged when an impact is applied. On the other hand, these antennas are required to be extremely small in size with the miniaturization of mobile phones and the like.
It is not allowed to increase the dimension by mm. Under this circumstance, the trapezoidal portion 13c is formed, so that the cap 14
It is possible to increase the thickness of the bottom portion 14a of the cap 14 by matching it with a trapezoid, which increases mechanical strength, and the reliability of the cap 14 against a drop or impact without increasing the outer diameter such as increasing the diameter of the cap 14. Is greatly improved.

This structure is not limited to the antenna using the folded antenna described above, but is also applied to the antenna portion formed by the conventional coil. That is, it has an antenna element, a holder to which one end of the antenna element is connected and which has a mounting portion to a housing, and a cap which covers the antenna element and whose lower end is fixed to the holder. If the antenna has a structure, a robust antenna is obtained without being limited to the shape and structure of the antenna element and other structures.

The above-mentioned antenna element 12 is press-fitted or fixed to the outer periphery of the insulating cylinder 11 by an adhesive or the like, so that the antenna element 12 folded back along the axial direction of the insulating cylinder 11 is wound in a cylindrical shape. It becomes an antenna with a different structure. While the antenna element 12 is attached to the outer circumference of the insulating cylinder 11, by covering the insulating cylinder 16 with an insulating coating 16 such as a heat-shrinkable tube to shrink the antenna element 12, the antenna element 12 is firmly fixed.
It is fixed at 1. The insulating coating 16 is not limited to a heat-shrinkable tube, but may be any one that can fix the antenna element 12, such as one formed by winding an insulating tape (taping) or applying and curing an insulating resin. Good. Then, the lower part of the insulating cylindrical body 11 is press-fitted and fixed to the lower part of the holder 13. At this time, the tongue piece 12 provided at one end of the antenna element 12
a comes into contact with the holder 13 and an electrical contact is obtained. As a result, power is supplied to the antenna element 12 from the holder 1
It is obtained by contacting the lower part of 3. Then, the lower end portion of the holder 13 is inserted and attached into the housing by screwing the screw portion 13a of the holder 13 into the housing such as a mobile phone.

According to the antenna of the present invention, since the antenna element is bent along its longitudinal direction, the longitudinal direction of the antenna element with respect to the plane of polarization of electromagnetic waves is always constant, and the electrical length is about 1/4. If the wavelength is adjusted to be an odd multiple of the wavelength, it is possible to reduce the overall length of the antenna without deteriorating the performance of the antenna without adding a matching circuit. Moreover, since the antenna element 12 is wound in a cylindrical shape (ring shape), not only the odd multiple but also the even multiple and any frequency band can be adjusted, and the multi-frequency resonant antenna is obtained. Further, when this antenna is used as a first antenna section so that the second antenna section can pass through the central portion of the first antenna section and the second antenna section is extended from the casing and coupled, the first antenna section 10 Since the antenna element 12 has a ring shape, it is easy and convenient to match in two or more frequency bands.

Next, with regard to the antenna for portable radio equipment, which uses the above-mentioned antenna as the first antenna part, extends the second antenna part from the central part at the time of communication etc. and can be coupled with the first antenna part. Description will be given with reference to FIG.
In addition, in FIG. 3, (a) is a state in which the second antenna unit 20 is extended from the housing for communication, and (b) is a diagram in which the second antenna unit 20 is housed in the housing. The first antenna unit 10 is the same as the antenna described with reference to FIGS.

The second antenna section 20 is used by extending it from the housing to the outside at the time of communication. For example, a piano wire or copper wire having an electric length of about ½ wavelength of the frequency band for transmission / reception is used as a coil. Shaped antenna element 21 is integrally molded by resin portion 28, and the periphery thereof is protected by tube 22 made of POM, elastomer, etc.
It is formed so as to be movable inside the insulating cylindrical body (core) 11 of the antenna section 10. In the example shown in FIG. 3, the second
In the antenna element 21 of the antenna unit 20 of
A straight line portion 21a is formed at least on the lower end side thereof (the side where the first antenna portion 10 is coupled), and the first antenna portion 10 and the second antenna portion 20 are coupled via the straight portion 21a. is doing. The second antenna unit 20 may be provided with a trap or the like (not shown) in the middle thereof so as to be compatible with two frequency bands. Second antenna section 2
At the lower end of 0, the second antenna part 2
A joint portion 26 made of POM and a stopper portion 27 are provided by molding or the like so that 0 can be held. Further, the top 24 made of ABS, elastomer, etc. and the joint portion 24 are provided on the upper end.
Similarly, a is integrally formed, and the top 24 serves as a knob for pulling the second antenna unit 20 out of the housing.

A recess 26a is formed on the outer periphery of the joint portion 26 so that the second antenna portion 20 can be fitted with the ring spring 15 of the first antenna portion 10 when the second antenna portion 20 is pulled out from the housing and extended. ing. As a result, when the second antenna unit 20 extends, the recess 26a of the joint unit 26 and the ring spring 15 are fitted and fixed, and the antenna of the second antenna unit 20 is provided in the vicinity of the first antenna unit 10. The straight line portion 21a of the element 21 is close to. And
The second antenna unit 20 and the first antenna unit 10 are electrically coupled mainly via capacitive coupling via the linear portion 21a and the dielectric (resin portion 28), and transmission / reception is performed by both antenna units. It becomes an antenna of about (1/4 + 1/2) wavelength of the signal, and can resonate to transmit and receive.

Furthermore, the top 2 of the second antenna section 20
4 is also provided with a recess 24b on the outer periphery of the joint portion 24a at the lower end, and the joint portion 24a at the lower end of the top 24 makes the core 1 when the second antenna portion 20 is housed in the housing.
1 is inserted up to the upper part of the recess 24 of the joint portion 24a.
The ring spring 15 is fitted and fixed to b. Top 24
Is made of resin, and the other end portion (tip portion) of the antenna element 21 is separated from the top 24. Therefore, the second antenna portion 20 housed in the housing is completely electrically separated to serve as an antenna. Does not work. Therefore, only the first antenna unit 10 functions as an antenna that receives an incoming call signal.

According to the coupled antenna of the present invention, FIG.
(B) The first antenna unit 10 in which the folded antenna is wound in a cylindrical shape, and the second antenna unit 2 in which the linear portion 21a is formed on the antenna element 21 on the lower end side.
By combining with 0, as shown in FIG.
The voltage standing wave ratio VSWR of this antenna is reduced over the entire desired frequency band (f _L is the lower limit frequency and f _H is the upper limit frequency), and the frequency characteristics are greatly improved. Figure 4
In FIG. 5, the broken line shows the frequency characteristic when the conventional antenna element of the first antenna section is formed by the pattern of the constant width shown in FIG.

[0039]

According to the present invention, since the folded antenna is wound in a cylindrical shape (ring shape) to form an antenna, it is easy to handle a plurality of frequency bands, and is compact and high-performance portable. A radio antenna is obtained. As a result, the short antenna for incoming calls can be used for communication, and the communication can be performed without extending the second antenna portion during communication. In addition, even when the second antenna section is extended during communication to further increase the sensitivity,
Since it is coupled with the first antenna part wound in a cylindrical shape, it is particularly easy to couple with two or more frequency bands, and a high-performance antenna can be obtained in a wide frequency band mainly composed of capacitive coupling.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view of an embodiment of an antenna for a portable wireless device of the present invention.

FIG. 2 is an explanatory diagram of a state in which an antenna element is wound around an insulating cylinder of the antenna of FIG. 1 and an example of the shape of the antenna element.

FIG. 3 is an explanatory diagram of a state of extension and storage of the second antenna unit when the second antenna unit is coupled to the antenna of FIG.

FIG. 4 is a diagram showing VSWR characteristics with respect to the frequency of the antenna of FIG.

FIG. 5 is an explanatory diagram of an antenna in which a conductor is bent along the lengthwise direction.

FIG. 6 is an explanatory diagram of an antenna attached to a conventional portable wireless device.

[Explanation of symbols]

10 First antenna section 11 Insulation cylinder 12 antenna elements 12a tongue 12b wide element 13 holder 13b collar part 13c Trapezoid 14 cap 16 Insulating film 20 Second antenna section

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-10-13135 (JP, A) JP-A-9-102707 (JP, A) JP-A-5-347507 (JP, A) JP-A-5- 243834 (JP, A) Actual Kaihei 6-34309 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 1/24 H01Q 1/10 H01Q 1/38 H01Q 1/40 H01Q 5/00

Claims (3)

(57) [Claims] 1. An insulator composed of an insulating column or an insulating cylinder, an antenna element provided on the outer periphery of the insulator, and an antenna element attached to the lower end of the insulator and in contact with one end of the antenna element. The antenna element is composed of a metal holder and a cap that covers the antenna element and is fixed to the holder. The antenna element has long conductors that are substantially parallel to each other at predetermined intervals along the length direction. several times is formed by being folded back, at least one set of elements adjacent to each other by being turned back the consists of an antenna element formed in a shape which is short-circuited by a conductor at least a part mobile phone antenna so. 2. The antenna for a portable wireless device according to claim 1, wherein a tongue piece formed wider than the width of the antenna element is formed at one end of the antenna element that is in contact with the holder. 3. The insulating body is an insulating cylindrical body, a through hole is provided in the center of the cap top, and a ring spring is provided on the upper part of the inner circumference of the insulating cylindrical body so as to pass through the insulating cylindrical body and a lower end. A second antenna portion that can be fixed by the ring spring on the side of the section and on the side of the upper end is further provided;
A first antenna having the antenna element when the lower end side of the second antenna portion is fixed by the ring spring.
The antenna for portable wireless device according to claim 1 or 2, wherein the antenna part and the second antenna part are electrically coupled via a dielectric.