JP2867202B2 - antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable radio, and more particularly to an antenna suitable for a portable radio telephone.

[0002]

2. Description of the Related Art In recent years, portable radio telephones have become extremely popular.
The housing is miniaturized and the antenna is storable so as to be portable. Then, when waiting for communication, it is necessary to be able to receive a call signal even if the antenna is housed.

Therefore, an antenna technology capable of receiving a call signal even when the antenna is in a stowed state is disclosed in Japanese Patent Laid-Open No. Hei 3-2456.
03 and EP-A-467822 A2.
No. in the official gazette.

The technique proposed in Japanese Patent Application Laid-Open No. 3-245603 is as follows. A loading coil that is electrically connected in series to the end of a rod antenna that can be pulled out and stored in the housing of the wireless device and that is arranged so that the loading coil protrudes from the housing when the antenna is stored. It is. Then, the effective length of the loading coil is set to １ ／ wavelength of the communication signal frequency,
The effective length of the rod antenna is also １ ／ wavelength.
When the antenna is housed, the loading coil acts as an antenna to receive a call signal. Further, when the antenna is pulled out, the antenna functions as an antenna having an effective length of １ ／ wavelength including the loading coil and the rod antenna.

Further, European Patent Application Publication No. 467822A is disclosed.
The technique proposed in Japanese Patent Publication No. 2 is as follows.
An antenna coil was disposed at the end of a rod antenna that can be pulled out and stored in the housing of the wireless device without being electrically connected, and when the antenna was stored, the antenna coil protruded from the housing and was provided in the housing. The antenna is electrically connected to the feeding point, and the rod antenna is electrically connected to the feeding point when the antenna is pulled out. The effective lengths of the antenna coil and the rod antenna are both set to １ ／ wavelength of the communication signal frequency. When the antenna is housed, the antenna coil acts as an antenna to receive a call signal. When the antenna is pulled out, only the rod antenna acts as an antenna.

[0006]

The above techniques are excellent in that a paging signal can be received even when both antennas are housed, but the following points must be improved from a manufacturing technical point of view. Can be

First, in the technique disclosed in Japanese Patent Application Laid-Open No. 3-245603, the effective antenna length is determined by the sum of the rod antenna and the loading antenna when the antenna is pulled out. Have difficulty. Therefore, the effective length of the antenna when the antenna is pulled out tends to vary, and the characteristics of the antenna tend to vary. In order to obtain a high antenna gain, a call is made with the antenna pulled out, but the variation in antenna gain in the pulled-out state is a variation in the characteristics of the radio, and is an important issue to be improved. is there. It is also difficult to firmly connect one end of the coil to the tip of the rod-shaped rod antenna.

Further, European Patent Application Publication No. 467822A is disclosed.
In the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2000-209, an antenna coil is disposed in an insulated state on a rod antenna, and it is difficult to firmly fix the antenna coil to the tip of the rod antenna.

SUMMARY OF THE INVENTION The present invention has been made in view of the prior art as described above, and it is an object of the present invention to provide an antenna having a robust structure without variation in antenna characteristics when the antenna is pulled out.

[0010]

In order to achieve the above object, an antenna of the present invention is provided with a conductive material in a cylindrical body which is disposed in a housing of a wireless device with an open end and is made of a conductive material. A rod is disposed so as to be movable in the axial direction without being electrically connected to the cylindrical body, and a cylindrical member made of a conductive material and having a spiral slit provided at a tip end on the protruding side of the rod is coaxially electrically connected. The tip of the cylinder is electrically connected to the tip of the rod by a short-circuit plate, and the rear end of the cylinder is connected to the tip of the cylinder with the rod housed in the cylinder. The rod is in contact with and electrically connected to the portion, a portion of the rod in the cylinder is used as a power supply point, and the cylinder is grounded.

Further, instead of electrically connecting the cylinder to the rod with the short-circuit plate, the cylinder may be arranged coaxially with the rod without being electrically connected.

[0012] The cylinder may be formed by integrally molding the tip of the rod with an insulating resin.

Further, an inner cylinder made of a conductive material is coaxially disposed in the cylinder via an insulating material, and the inner cylinder and the rod are electrically connected via a conductive spring member. And the outer conductor of the coaxial power supply cable may be electrically connected to the cylindrical body.

[0014]

[Work] When the rod is housed, the other end of the cylinder provided with the spiral slit is electrically connected to the cylinder and grounded, and current is excited at the tip of the rod to act as an antenna. When the rod is pulled out, the rod acts as a rod antenna having a large diameter at the tip.

If the distal end side of the cylinder is not electrically connected to the distal end of the rod by the short-circuit plate, when the rod is stored, voltage is excited at the distal end of the rod to act as an antenna.

If the cylinder is formed integrally with the tip of the rod by using an insulating resin, it can be formed with high dimensional accuracy by insert molding or the like, and there is no variation in antenna characteristics when the rod is stored. .

Further, if the inner cylinder is coaxially arranged in the cylinder via an insulating material and the inner cylinder and the rod are electrically connected via a conductive spring member, the rod moves in the axial direction. However, a reliable electrical connection can be maintained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. FIGS. 1A and 1B are longitudinal sectional views of an embodiment of the antenna according to the present invention, in which FIG. 1A shows a state in which a rod is pulled out, FIG. 2B shows a state in which a rod is housed, and FIG. FIG. 3 is a diagram showing a current distribution of the antenna when the rod is stored.

In FIGS. 1 and 2, a cylindrical tubular body 12 made of a conductive material and having a distal end slightly opened outward and opened is fixed to the side wall of a housing 10 of the portable radio telephone. You. A cylindrical inner cylinder 16 made of a conductive material is coaxially disposed and fixed in the cylindrical body 12 with an insulating material 14 interposed therebetween. A rod 18 made of a conductive material is provided in the inner cylinder 16.
Are provided movably in the axial direction. Here, the rod 18
Are not electrically connected to the cylindrical body 12 by the insulating material 14. A spiral slit 20a made of a conductive material is formed at the tip of the rod 18 on the projecting side.
Is provided coaxially without electrical connection, and the tip of the cylinder 20 and the tip of the rod 18 are
It is electrically connected and fixed by a disk-shaped short-circuit plate 22. A lantern spring 26 formed of a conductive spring member is fixed to the rear end of the rod 18.
The lantern spring 26 is in sliding contact with the inner peripheral surface of the inner cylinder 16 so that the rod 18 and the inner cylinder 16 are electrically connected. In order for this lantern spring 26 not to come out of the inner cylinder 16,
At both ends of the inner cylinder 16, appropriate stoppers such as formation of a narrowed portion are formed. Then, the center conductor 28 a of the coaxial feed cable 28 is electrically connected to the inner cylinder 16, and the outer conductor 28 b is electrically connected to the cylinder 12. Further, a small-diameter portion 20b having a slightly enlarged portion at the front end is formed at a rear end portion of the cylinder 20 opposite to the front end side so as to be exposed.
b is formed so as to fit into a squeezed portion provided at the tip of the cylindrical body 12.

In this configuration, as shown in FIG. 1 (a), when the rod 18 is pulled out, a rod having a large diameter D is connected to the tip of a rod having a small diameter d to form a rod antenna having a total length of L. Works. Therefore, this dimension L
Is set to １ ／ wavelength of the communication signal frequency, so that transmission and reception are possible by resonating with the communication signal frequency. In addition, as shown in FIG. 1B, when the rod 18 is stored, the small diameter portion 20b is fitted to the cylinder 12, and the rear end of the cylinder 20 is electrically connected to the cylinder 12 and grounded. Therefore, as shown in FIG. 3, current excitation is generated on the distal end side of the rod 18 to act as an antenna, so that a paging signal can be received.

By the way, in the structure of the above embodiment,
When the rod 18 is in the pulled-out state, the cylinder 20 does not act as an antenna with respect to the communication signal frequency, but simply functions as a decoration at the tip of the antenna. Therefore, the antenna characteristic is determined by the dimension L of the rod 18 protruding from the cylinder 12, and by accurately setting the dimension L,
It is possible to stabilize the antenna gain at the time of pulling out without causing variation. Further, since the disk-shaped short-circuit plate 22 is fixed to the tip of the rod 18 so as to be electrically connected, the structure can be easily made robust as compared with fixing the tips of the rod-shaped members. And lantern spring 26
Since the rod 18 and the inner cylinder 16 are electrically connected to each other, the electrical connection can be reliably maintained despite the axial movement of the rod 18. Further, since the coaxial structure is formed by the inner cylinder 16 and the cylindrical body 12 and the coaxial power supply cable 28 is connected to them, noise is not superimposed on the signal path from the antenna to the transmission / reception circuit.

FIG. 4 is a longitudinal sectional view of the tip of an antenna according to another embodiment of the present invention. In FIG. 4, FIG.
The same members as those in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted.

4 is different from that shown in FIGS. 1 and 2 in that the tip of the rod 18 is fixed to the short-circuit plate 22 by screwing, and the inside and outside of the cylinder 20 and the slit 20a are made of insulating resin. It is covered with the dielectric material 24. Then, the tip of the antenna is integrally formed with the dielectric material 24 of an insulating resin by insert molding or outsert molding or the like.

In such a configuration, the antenna tip portion is integrated, and the configuration can be made with high dimensional accuracy and robustness.

FIG. 5A is a longitudinal sectional view of a tip portion of an antenna according to still another embodiment of the present invention.
(B) is a figure which shows the voltage distribution of the antenna at the time of rod storage. In FIG. 5A, the same or equivalent members as those in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 5A, the difference from FIG. 4 is that the short-circuit plate 22 is omitted and the tip of the cylinder 20 is
8 is not electrically connected to the tip. The cylinder 20 is coaxially formed integrally with the tip of the rod 18 by a dielectric material 24 made of an insulating resin. The rear end of the cylinder 20 is configured to fit and abut on the front end of the cylinder 12.

In this configuration, when the rod 18 is stored, the rear end of the cylinder 20 is electrically connected to the cylinder 12 and grounded. Therefore, as shown in FIG. 5B, voltage excitation is generated at the distal end side of the rod 18 to act as an antenna, so that a call signal can be received.

In the above embodiment, the tip of the cylindrical body 12 protrudes from the outer wall of the housing 10.
The present invention is not limited to this.
Any structure may be used as long as electrical connection can be obtained by being fitted to the tip of the device. Further, the power supply structure for the rod 18 is not limited to the above-described embodiment.
It can be easily understood that any structure may be used as long as the portion inside the cylindrical body 12 is a feeding point.

[0029]

As described above, since the antenna of the present invention is constituted, the following special effects can be obtained.

In the antenna according to the first aspect, when the rod is pulled out, the cylinder provided at the tip of the rod does not act as an antenna with respect to the communication signal frequency but simply functions as a decoration ball. The portion where the rod is pulled out of the cylinder acts as an antenna. Therefore, by accurately setting the drawing length to a resonance length such as a quarter wavelength of the communication signal frequency, the antenna characteristics when the rod is pulled out become stable. In addition, since the cylinder is fixed to the tip of the rod via the short-circuiting plate, the rod-shaped object is fixed to a flat object, and a more robust structure compared to fixing the rod-shaped ends together. Can be
A member that functions as an antenna when the rod is stored can be firmly fixed to the tip of the rod.

The antenna according to the second aspect also functions as an antenna similar to that of the first aspect.

In the antenna according to the third aspect of the present invention, since the cylinder is integrally formed at the tip of the rod with a dielectric material of an insulating resin, mass production can be performed with high dimensional accuracy by insert molding or the like. The antenna characteristics at the time are stable without any variation.

Further, in the antenna according to the fourth aspect, since the rod and the inner cylinder are electrically connected via the conductive spring member, reliable electric connection is maintained regardless of the axial position of the rod. Is done.

[Brief description of the drawings]

FIGS. 1A and 1B are longitudinal sectional views of an embodiment of the antenna of the present invention, in which FIG.

FIG. 2 is an external view of an antenna tip.

FIG. 3 is a diagram showing a current distribution of the antenna when the rod is housed.

FIG. 4 is a longitudinal sectional view of an antenna tip portion of another embodiment of the antenna of the present invention.

FIG. 5A is a vertical cross-sectional view of a tip of an antenna according to still another embodiment of the present invention, and FIG. 5B is a diagram illustrating a voltage distribution of the antenna when the rod is housed.

[Explanation of symbols]

 Reference Signs List 10 housing 12 cylinder 14 insulating material 16 inner cylinder 18 rod 20 cylinder 20a slit 22 short-circuit plate 24 dielectric material 26 lantern spring 28 coaxial power cable 28a center conductor 28b outer conductor

Claims (4)

(57) [Claims] 1. A rod made of a conductive material, which is disposed in a housing of a wireless device with an open end portion and made of a conductive material, is axially movable without a rod made of a conductive material being electrically connected to the cylinder. Disposed, a cylinder provided with a spiral slit made of conductive material at the protruding end of the rod is disposed coaxially without electrical connection, and the distal end of the cylinder and the tip of the rod are disposed. Electrical connection is made by a short-circuiting plate, and the rear end side of the cylinder is brought into contact with the tip end of the cylinder to electrically connect with the cylinder in a state where the rod is stored in the cylinder, and the cylinder of the rod is An antenna characterized in that a part inside the body is used as a feeding point and the cylindrical body is grounded. 2. The antenna according to claim 1, wherein, instead of electrically connecting said cylinder to said rod with said short-circuit plate, said cylinder is coaxially arranged with said rod without being electrically connected. An antenna characterized by comprising: 3. The antenna according to claim 1, wherein the cylinder is formed by integrally molding an insulating resin at a tip of the rod. 4. The antenna according to claim 1, wherein an inner cylinder made of a conductive material is disposed coaxially in the cylinder via an insulating material, and the inner cylinder and the rod are connected to a conductive spring member. An antenna electrically connected to the inner cylinder, a central conductor of the coaxial feed cable is electrically connected to the inner cylinder, and an outer conductor of the coaxial feed cable is electrically connected to the cylindrical body.