JPH10313209A - Dual band antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the dual band antenna that is applied to a communication equipment. SOLUTION: In the case that a whip antenna 1 is extended, a part of the whip antenna 1 is placed in a helical element 24 and a 1st helical element 24 and a 2nd helical element 25 are connected by a capacitor C so as to attain the resonance with the whip antenna 1 and the helical element 25 at a frequency band of 800 MHz. In this case the 2nd helical element 25 is solely resonated at a frequency band of 1.9 MHz. When the whip antenna 1 is retracted, the 1st helical element 24 and the 2nd helical element 25 are connected by the capacitor C so as to resonate at a frequency band of 800 MHz. In this case, the 2nd helical element 25 is solely resonated at a frequency band of 1.9 MHz. Thus, the dual band antenna in a portable telephone set is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual band antenna provided in portable equipment such as a portable telephone and capable of transmitting and receiving in two frequency bands.

[0002]

2. Description of the Related Art An outline of a conventional antenna provided in a portable telephone is shown in FIGS. 6 (a) to 6 (d). FIG.
FIGS. 6A and 6C show the state of the antenna of the bottom helical type when it is extended and held, and is shown in FIG.
(D) shows a state in which the top helical type antenna is extended and held and stored. When the bottom helical type antenna is extended as shown in FIG. 6A, a linear whip antenna 100 having an electrical length of, for example, a half wavelength of 800 MHz can be operated.
Transmission and reception can be performed by the whip antenna 100. The whip antenna 100 is connected to a signal source 31 via a matching circuit 30.

When a bottom helical type antenna is housed as shown in FIG.
The helical antenna 101 having an electrical length of ＭＨｚ wavelength of 0 MHz is operable, and the helical antenna 101
Can be transmitted and received. Since the upper part of the stored whip antenna 100 is formed of an insulating material as shown by a broken line, even if the upper part of the whip antenna 100 is located inside the helical antenna 101, the operation of the helical antenna 101 is affected. Will not give.
The helical antenna 101 is connected to a signal source 31 via a matching circuit 30.

On the other hand, when the top helical type antenna is extended as shown in FIG.
The whip antenna 110 having an electrical length of ＭＨｚ wavelength of 0 MHz is operable by being connected to the matching circuit 30, and can be transmitted and received by the whip antenna 110. Note that a helical antenna 111 is provided at the upper end of the whip antenna 110 via an insulating portion, and the helical antenna 111 is not connected to any part and is in a non-operating state.

When a top helical type antenna is stored as shown in FIG.
The helical antenna 111 having an electrical length of ＭＨｚ wavelength of 0 MHz is operable by being connected to the matching circuit 30, and can be transmitted and received by the helical antenna 111. The stored whip antenna 11
0 is not connected anywhere and is inactive.

[0006]

At present, the frequency band used by a portable telephone is 800 MHz band and 1.5G.
Hz band and 1.9 GHz band are assigned. In a conventional mobile phone, an antenna as shown in FIG. 6 is provided so as to use only one frequency band among the allocated frequency bands. Therefore, it cannot be used in two of the allocated frequency bands. As a means for solving this, for example, it is conceivable to provide two antennas, an antenna operable in the 800 MHz band and an antenna operable in the 1.9 GHz band, in the mobile phone. However, providing two antennas on a mobile phone requires
It has been complicated to use the device and has problems in design, so that it has been difficult to realize it.

Accordingly, an object of the present invention is to provide a dual band antenna which can transmit and receive in two frequency bands even with one antenna.

[0008]

In order to solve the above problems, a dual band antenna according to the present invention comprises a first helical element, a second helical element, the first helical element and the second helical element. A helical antenna composed of a capacitive coupling means formed between the helical element and a whip antenna slidable in the helical antenna; when the whip antenna is extended, the first
The middle of the whip antenna is connected to the upper end of the helical element, and the lower part of the whip antenna is positioned in the first helical antenna, so that the whip antenna and the second helical An element is connected via the capacitive coupling means so as to be able to transmit and receive in a first frequency band, and the second helical element is capable of being independently transmitted and received in a second frequency band; When the antenna is housed, the insulating portion formed above the whip antenna is located in the helical antenna, so that the first helical element and the second helical element Are connected via the capacitive coupling means so as to be able to transmit and receive in a first frequency band, It is to be transmitted and received in a second frequency band and the second helical element alone.

In the above-mentioned dual-band antenna, a substantially cylindrical helical element forming portion made of an insulating material and provided with a flange having a predetermined thickness is provided in the middle of the insulating material. The first helical element is formed on an outer surface above the flange,
The second helical element is formed on an outer surface of the helical element forming portion below the flange, and the capacitive coupling means is formed by the flange having a conductive thin film formed on an upper surface and a lower surface. And a conductive thin film formed on an upper surface of the flange portion and a lower end of the first helical element are integrally formed so as to be electrically connected to each other. The formed conductive thin film and the upper end of the second helical element may be integrally formed so as to be electrically connected.

Further, an insertion hole which penetrates substantially the center of the helical element forming portion is formed, and the whip antenna is slidably held above the insertion hole,
Holding means for connecting the whip antenna to the upper end of the first helical element when extended may be provided. Furthermore, a helical groove is formed on the outer surface of the helical element forming portion, and the first helical element and the second helical element are respectively formed in the helical groove. Good thing.

According to the present invention, transmission and reception can be performed in two frequency bands simply by installing one antenna on a portable telephone or the like. Therefore, a mobile phone that can be used in two frequency bands only needs to be provided with one antenna, which simplifies the use form and eliminates design problems.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 (a) and 1 (b) show a schematic configuration showing the principle of a dual band antenna according to the present invention. FIG.
1A and 1B, the whip antenna 1 includes a linear element 12 and an insulating section 10 formed on the linear element 12 with an insulating material such as a synthetic resin. This whip antenna 1 is slidable inside a first helical element 24 and a second helical element 25. Therefore, as shown in FIG.
1 can be extended, and as shown in FIG. 1B, the whip antenna 1 can be stored during standby.

The first helical element 24 and the second helical element 25 are arranged one above the other so that their axes are substantially coincident with each other. Is connected to the helical element 25 at a high frequency. Note that the inductance L connected in parallel with the capacitance C is an inductance generated by the wiring.

Here, when the whip antenna 1 is extended as shown in FIG. 1A, the middle of the linear element 12 in the whip antenna 1 is electrically connected to the upper end of the first helical element 24. . For this reason, the lower part of the linear element 12 in the whip antenna 1 is located inside the first helical element 24, and the first helical element 24 does not operate. Therefore, the linear element 1 of the whip antenna 1 is attached to the tip of the second helical element 25.
The dual band antenna operates with the two connected in series. At this time, the linear element 12 of the whip antenna 1 is connected to the lower end of the second helical element 25.
Of the first frequency band, for example, 80
The length is set to resonate in the 0 MHz band. Therefore, the dual band antenna operates in the first frequency band as a whole. Further, the second helical element 25 has an electrical length that resonates in a second frequency band, for example, a 1.9 GHz band. Therefore, the dual band antenna operates in the second frequency band.

When the whip antenna 1 is housed as shown in FIG. 1B, the upper insulating portion 10 of the whip antenna 1 is positioned inside the first helical element 24 and the second helical element 25. Become. Thereby, the second
The dual band antenna operates in a state where the first helical element 24 is connected in series with the tip of the helical element 25 via the capacitor C. In this case, the electrical length from the lower end of the second helical element 25 to the tip of the first helical element 24 is the first frequency band, for example, 800
The length is set to resonate in the MHz band. Therefore, the dual band antenna operates in the first frequency band in the housed state. Further, the second helical element 25 has an electrical length that resonates in a second frequency band, for example, a 1.9 GHz band. Therefore, the dual band antenna operates also in the second frequency band. .

Incidentally, it is preferable that the resonance frequency of the parallel resonance circuit including the capacitance C and the inductance L be a frequency in the second frequency band. In this way, the second
In the frequency band in which the helical element 25 resonates, the impedance of the parallel resonance circuit can be made extremely large, and the first helical element 24 is separated from the second helical element 25 in a high frequency in the second frequency band. Can be. Therefore, the second helical element 25
The first helical element 2
4 is not connected to the second helical element 25, and its influence can be ignored.

When the whip antenna 1 is extended, the electrical length from the lower end of the second helical element 25 to the tip of the linear element 12 of the whip antenna 1 is approximately 1/1/1 of the wavelength in the first frequency band. When the wavelength is two, the dual-band antenna is connected to the signal source 31 via the matching circuit 30 as shown in FIG. When the electric length is approximately 波長 wavelength, the matching circuit 30 is not necessary, and the dual band antenna can be directly connected to the signal source 31. The same applies to the case where the whip antenna 1 is housed, and the electrical length from the lower end of the second helical element 25 to the tip of the first helical element 24 is set to be approximately half the wavelength of the first frequency band. In this case, as shown in FIG.
The dual band antenna is connected to the signal source 31 via the matching circuit 30. Further, the electric length is approximately 1 /
In the case of four wavelengths, the matching circuit 30 is not required,
The dual band antenna can be directly connected to the signal source 31.

The dual-band antenna of the present invention thus configured can be used as an antenna of a mobile phone 40 as shown in FIG. At this time, the first helical element 24 and the second helical element 2
The dual-band antenna is installed on the mobile phone 40 by attaching the lower end of the holder provided at the lower part of the helical antenna 2 composed of the antenna 5 to the housing of the mobile phone 40. An insertion hole is formed substantially along the axis of the helical antenna 2, and the whip antenna 1 is slidable in the insertion hole. The whip antenna 1 shown in FIG. 2 is in an extended state, and a top 11 is provided at the tip.

Next, the detailed structure of the dual band antenna of the present invention is shown in cross sections in FIGS. However, FIG.
Shows a state where the whip antenna 1 is extended, and FIG. 4 shows a state where the whip antenna 1 is stored.
As shown in FIG. 3, the whip antenna 1 includes a top 11 provided at the tip thereof, a small-diameter insulating portion 10 extending from the top 11, and a linear element 12 integrally formed with the insulating portion 10. And a conductive stopper 13 formed of a slightly thick metal or the like to which the lower end of the linear element 12 is connected. At the lower end of the stopper 13, a wide flange portion 13-1 is formed. Therefore, the electrical length of the whip antenna 1 is actually determined by the entire length of the linear element 12 and the conductive stopper 13.

Next, the configuration of the helical antenna 2 will be described. An exploded view of the helical antenna 2 is shown in FIG.
This will be described with reference to FIGS. The outside of the helical antenna 2 is covered with a cylindrical cover 14 having one end face closed. The cover 14 is formed by integrally molding an insulating material such as a synthetic resin, and has an insertion hole 14-1 through which the whip antenna 1 is inserted substantially at the center of the closed one end surface. The helical element forming section 3 including the first helical element forming section 21, the flange section 23, and the second helical element forming section 22 is housed inside the cover 14. The helical element forming section 3 is formed in a cylindrical shape by integrally molding an insulating material such as a synthetic resin having a predetermined dielectric constant. The upper part of the helical element forming part 1 is the first helical element forming part 21.
The lower part of the helical element forming part 3 is a second helical element forming part 22, and a flange 23 whose outer peripheral surface is in contact with the inner surface of the cover 14 is formed at substantially the center of the helical element forming part 3.

Further, at the upper end of the first helical element forming section 21 in the helical element forming section 3, a projection 21-1 having a slightly smaller diameter is formed, and the second helical element in the helical element forming section 3 is formed. At the lower end of the element forming part 22, a projecting part 22-1 having a slightly smaller diameter is formed. Furthermore, a through-hole 2-1 through which the whip antenna 1 is inserted is formed substantially along the axis of the helical element forming section 3. A step is formed in the middle of the through hole 2-1. When the whip antenna 1 is extended,
By engaging the flange 13-1 formed at the lower end of the stopper 13 with the step, further extension is restricted, and the whip antenna 1 is reliably prevented from coming off when extended. it can.

Further, a first helical element 24 is formed on the outer peripheral surface of the first helical element forming portion 21, and the first helical element 24 is formed on the outer surface of the projection 21-1. The conductive layer 24-1 connected to the upper end is formed. A cylindrical top fitting 15 made of metal is fitted into the protruding portion 21-1 so as to be electrically connected thereto, and a sliding spring 16 is housed inside the top fitting 15. Therefore, when the top fitting 15 is fitted to the protrusion 21-1, the spring portion 16-1 of the slide spring 16 is housed in the protrusion 21-1. This allows the whip antenna 1 to be slidably held by the sliding spring 16 and the whip antenna 1
When the linear element 12 is extended, the linear stopper 12 is electrically conductive.
3. The upper end of the first helical element 24 is electrically connected to the slide spring 16 and the conductive layer 24-1 formed on the protrusion 21-1.

A second helical element 25 is formed on the outer surface of the second helical element forming section 22. The second helical element forming portion 22 has a slightly narrower outer surface formed at the lower end of the second helical element forming portion 22.
Conductive layer 25 connected to the lower end of helical element 25
-1 is formed, and a cylindrical holder 17 made of metal is fitted to the protruding portion 22-1. A slightly narrower mounting portion 17-2 formed at the lower portion of the holder 17 is inserted into a mounting hole formed in a casing 50 of a mobile phone or the like, and a nut (not shown) is screwed into the mounting portion 17-2 to form a dual band antenna. It is fixed to the casing 50. Further, since the holder 17 is electrically connected to the conductive layer 25-1 formed on the surface of the protruding portion 22-1, the holder 17 is used as a feeding point of the dual band antenna, and the signal source is connected to the holder 17. 31 are connected.

Further, the lower end of the first helical element 24 is integrally formed so as to be electrically connected to a plating portion 23-1 formed on the upper surface of the flange portion 23, and the second helical element is formed. The upper end of the element 25 is integrally formed so as to be electrically connected to the plating part 23-1 formed on the lower surface of the flange part 23. This flange portion 23 has a thickness t,
Since the plated portions 23-1 are opposed to each other, the capacitance C is generated by this portion. Therefore, the capacitance value of the capacitor C can be adjusted by changing the thickness t of the flange portion 23, the dielectric constant of the helical element forming portion 3, and the area of the facing flange portion 23.

The thus constructed dual-band antenna of the present invention has the linear element 1 of the whip antenna 1 in the extended state as shown in FIG.
2 has an electrical length from the leading end to the holder 17 serving as a power feeding point is 1 in a first frequency band (for example, 800 MHz band).
It has a length of 波長 wavelength or １ ／ wavelength and is operable in the first frequency band. At this time, the upper part of the conductive stopper 13 of the whip antenna 1 comes into contact with the sliding spring 16, and the sliding spring 16 -the projection 21-1 of the first helical element forming part 21 -the first helical element 24-Capacity C of flange 23-Second helical element 25-
Projecting part 22-1 at the lower end of second helical element forming part 22
-Holders 17 are connected in the order of high frequency. In this case, since the conductive stopper 13 is located in the first helical element 24, the first helical element 24 does not operate, and thus the linear element 12 and the second helical element 25 Thus, signals in the first frequency band (for example, 800 MHz band) can be transmitted and received. Further, the second helical element 25 alone resonates in the second frequency band (for example, 1.9 GHz band), and can transmit and receive the signal.

Next, FIG. 4 shows a state in which the whip antenna 1 is housed in a casing 50 of a portable telephone or the like. As shown in this figure, the whip antenna 1 is
When housed inside, the insulating part 10 formed on the upper part of the whip antenna 1 is located in the through hole 2-1 formed in the helical element forming part 3. Therefore, the first helical element 24 and the second helical element 25 become operable. At this time, the first helical element 24
The capacitance C of the flange portion 23, the second helical element 25, the projection 22-1 at the lower end of the second helical element forming portion 22, and the holder 17 are connected in the order of high frequency. As a result, the first helical element 24 and the second helical element 25 use the first frequency band (for example, 800 MHz).
signals in the z-band), and a second frequency band (for example,
(The 1.9 GHz band), and the signal can be transmitted and received. In this case, the linear element 12
Does not work.

Next, the first helical element 24 and the second
An example of a method for forming the helical element 25 on the outer peripheral surface of the helical element forming section 3 will be schematically described. Projection 21 on top
-1, the protrusion 22-1 is formed at the lower end,
A cylindrical helical element forming part 3 having a flange 23 formed substantially at the center is integrally formed of a synthetic resin material. Next, a helical groove is formed in the portion of the outer peripheral surface where the first helical element 24 and the second helical element 25 are to be manufactured. Then, a conductive layer is formed on the entire outer surface of the helical element forming section 3 by plating or the like. Next, only the surface of the outer peripheral surface in the portion where the helical groove is formed is thinly cut. Then, the conductive layer is removed leaving the conductive layer formed in the helical groove. Thereby, the first helical element 24 can be formed on the outer peripheral surface of the first helical element forming section 21, and the second helical element 25 is formed on the outer peripheral surface of the second helical element forming section 22. Will be able to do it. Also, the conductive layers 24-1 and 25-1 are formed on the surface of the protrusion 21-1 and the surface of the protrusion 22-1, respectively, and only the conductive layer on the outer peripheral surface of the flange 23 is cut. Thereby, the plating portion 23-1 can be manufactured at the same time.

As described above, the dual-band antenna according to the present invention has the two frequency bands of the first frequency band and the second frequency band in the state where the whip antenna is extended and the state where the whip antenna which is in the standby state is stored. It operates in the frequency band. Therefore, an antenna suitable for use in a communication device to which two frequency bands are assigned can be obtained. The two frequency bands at this time are 800 MHz in the above description.
Although the z band and the 1.9 GHz band are used, the present invention is not limited to this frequency band, and may be any two of the allocated frequency bands. Further, by applying the principle of the dual band antenna of the present invention, it is possible to provide a multi-band antenna that can be used in three or more frequency bands.

[0029]

Since the present invention is configured as described above, it is possible to transmit and receive in two frequency bands only by installing one antenna in a communication device such as a portable telephone. . Therefore, a mobile phone that can be used in two frequency bands only needs to be provided with one antenna, which simplifies the use form and eliminates design problems. Further, if the usable frequency band of the mobile phone is one of two frequency bands in which the dual band antenna can operate, the dual band antenna of the present invention is provided regardless of the frequency band. Thus, an antenna usable in any frequency band can be used.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the principle of a dual band antenna according to the present invention.

FIG. 2 is a diagram showing a mobile phone equipped with the dual band antenna of the present invention.

FIG. 3 is a sectional view showing a state where a whip antenna is extended in a dual band antenna according to the present invention.

FIG. 4 is a sectional view showing a state in which a whip antenna is housed in the dual band antenna of the present invention.

FIG. 5 is an exploded view showing a detailed configuration of a helical antenna in the dual band antenna of the present invention.

FIG. 6 is a diagram showing a conventional antenna for a mobile phone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Whip antenna 2 Helical antenna 3 Helical element formation part 3-1 Through hole 10 Insulation part 11 Top 12 Linear element 13 Stopper 14 Cover 14-1 Insertion hole 15 Top fitting 16 Slide spring 17 Holder 21 First helical element formation Part 21-1 Projecting part 22 Second helical element forming part 22-1 Projecting part 23 Flange part 24 First helical element 25 Second helical element

Claims (4)

[Claims] 1. A helical antenna comprising a first helical element, a second helical element, a capacitive coupling means formed between the first helical element and the second helical element, A whip antenna slidable within the antenna, wherein when the whip antenna is extended, a midway of the whip antenna is connected to an upper end of the first helical element and a lower portion of the whip antenna Is the first
The whip antenna and the second helical element are connected via the capacitive coupling means so as to be able to transmit and receive in the first frequency band. The second helical element can be independently transmitted and received in the second frequency band, and when the whip antenna is housed, an insulating part formed on an upper part of the whip antenna is located inside the helical antenna. By being located
The first helical element and the second helical element are connected via the capacitive coupling means so that transmission and reception can be performed in a first frequency band.
Wherein the helical element is capable of transmitting and receiving independently in the second frequency band. 2. A substantially cylindrical helical element forming portion comprising an insulating material and having a flange portion having a predetermined thickness in the middle thereof, and an outer surface of the helical element forming portion above the flange portion. The first helical element is formed, and the second helical element is formed on an outer surface of the helical element formation portion below the flange, and a conductive thin film is formed on upper and lower surfaces. The capacitive coupling means is formed by the flange formed with the conductive film, and the conductive thin film formed on the upper surface of the flange and the lower end of the first helical element are electrically connected to each other. And a conductive thin film formed on a lower surface of the flange portion and an upper end of the second helical element are integrally formed so as to be electrically connected to each other. Claim 1 Dual band antenna. 3. An insertion hole penetrating substantially through the center of the helical element forming portion. The whip antenna is slidably held above the insertion hole, and the whip antenna is extended when extended. 3. The dual-band antenna according to claim 2, further comprising: holding means for connecting the first helical element to an upper end of the first helical element. 4. A helical groove is formed on an outer surface of the helical element forming portion, and the first helical element and the second helical element are formed in the helical groove, respectively. The dual band antenna according to any one of claims 1 to 3, wherein: