JPH06260828A - Antenna - Google Patents

Abstract

PURPOSE:To firmly fix a member whose antenna characteristic is stable in a state a rod is pulled out and functioning as an antenna when the rod is housed at the tip part of the rod. CONSTITUTION:The rod 18 consisting of a conductive material is arranged movably freely in an axial direction without connecting electrically to a cylinder 12 consisting of the conductive material. A cylinder 20 provided with a slit 20a consisting of the conductive material and formed spirally is arranged at the tip of the rod 18 in coaxial and without connecting electrically, and the tip part of the cylinder 20 and the tip of the rod 18 are fixed by connecting electrically by a disk shape short-circuited plate 22. The cylinder 20 is grounded by bringing the rear terminal side of the cylinder 20 into contact with the tip of the cylinder 12 and connecting them electrically when the rod 18 is housed. The cylinder 12 is grounded setting the inner part of the cylinder 12 of the rod 18 as a feed point.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, portable wireless telephones have become extremely popular,
The housing is downsized so that it can be carried easily, and the antenna can be stored. Further, at the time of standby for communication, it must be possible to receive a call signal even if the antenna is housed.

Therefore, an antenna technology capable of receiving a calling signal even when the antenna is housed is disclosed in Japanese Patent Laid-Open No. 3-2456.
03 and European Patent Application Publication No. 467822A2.
It is shown in the publication.

The technique proposed in Japanese Patent Laid-Open No. 3-245603 is as follows. A configuration in which a loading coil is electrically connected in series at the tip of a rod antenna that can be pulled out and stored in the housing of the radio, and the loading coil projects from the housing when the antenna is housed. Is. Then, the effective length of the loading coil is set to ¼ wavelength of the communication signal frequency,
The effective length of the rod antenna is also set to 1/4 wavelength.
When the antenna is housed, the loading coil acts as an antenna to receive the calling signal. When the antenna is pulled out, it functions as an antenna having an effective length of ½ wavelength, which is the combination of the loading coil and the rod antenna.

European Patent Application Publication No. 467822A
The technique proposed in Japanese Patent Publication No. 2 is as follows.
An antenna coil was installed at the tip of a rod antenna that can be pulled out and stored in the housing of the wireless device without being electrically connected, and this antenna coil was provided on the housing while protruding from the housing when the antenna was housed. The rod 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 ¼ wavelength of the communication signal frequency. When the antenna is housed, the antenna coil acts as an antenna to receive the calling signal. Further, when the antenna is pulled out, only the rod antenna acts as an antenna.

[0006]

Both of the above techniques are excellent in that they can receive a call signal even when the antenna is housed, but the following points should be improved from the viewpoint of manufacturing technology. To be

First, in the technique disclosed in Japanese Patent Laid-Open No. 3-245603, the antenna effective length is determined by the sum of the rod antenna and the loading antenna when the antenna is pulled out. However, the coil of this loading antenna cannot be mass-produced with an appropriate effective length. Have difficulty. Therefore, the antenna effective length when the antenna is pulled out is likely to vary, and the antenna characteristics are likely to vary. Calls are made with the antenna pulled out in order to obtain a high antenna gain, but the variation in antenna gain in this pulled out state is the variation in the characteristics as a radio device, 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.

European Patent Application Publication No. 467822A
In the technique of Japanese Patent No. 2 publication, the antenna coil is disposed in the rod antenna in an insulated state, and it is difficult to firmly fix the antenna coil to the tip of the rod antenna.

The present invention has been made in view of the above-mentioned conventional techniques, and an object of the present invention is to provide an antenna having a robust structure that does not cause variations in antenna characteristics when the antenna is pulled out.

[0010]

In order to achieve the above object, the antenna of the present invention is made of a conductive material in a cylindrical body made of a conductive material, which is disposed in a housing of a radio with its tip open. The rod is arranged so as to be movable in the axial direction without being electrically connected, and a cylinder with a spiral slit made of a conductive material at the tip of the protruding side of this rod is coaxially arranged without being electrically connected. The tip end of the cylinder and the tip of the rod are electrically connected by a short-circuit plate, and the rear end of the cylinder is in contact with the tip of the cylinder in a state where the rod is housed in the cylinder. The rod is electrically connected to the inside of the cylindrical body of the rod as a feeding point, and the cylindrical body 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.

The cylinder may be integrally formed with the insulating resin at the tip of the rod.

Further, an inner cylinder made of a conductive material is coaxially arranged in the cylinder through an insulating material, and the inner cylinder and the rod are electrically connected to each other through a conductive spring member. Alternatively, the central conductor of the coaxial power feeding cable may be electrically connected, and the outer conductor of the coaxial power feeding cable may be electrically connected to the cylindrical body.

[0014]

[Operation] 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 the tip of the rod excites a current to function as an antenna. When the rod is pulled out, the distal end portion functions as a rod antenna having a large diameter.

If the tip of the cylinder is not electrically connected to the tip of the rod by the short-circuiting plate, the tip of the rod is excited by voltage and acts as an antenna when the rod is housed.

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

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

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be described with reference to. FIG. 1 is a vertical cross-sectional view of an embodiment of the antenna of the present invention, where (a) is a rod withdrawn, (b) is a rod housed, and FIG. 2 is an external view of the tip of the antenna. FIG. 3 is a diagram showing a current distribution of the antenna when the rod is housed.

In FIGS. 1 and 2, a cylindrical tubular body 12 made of a conductive material is disposed and fixed on the side wall of a casing 10 of a portable radio telephone, the tip of which is slightly outwardly projected and opened. It An inner cylinder 16 made of a conductive material is coaxially arranged 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.
Is movably provided in the axial direction. A cylinder 20 provided with a spiral slit 20a made of a conductive material is coaxially and electrically connected to the tip of the rod 18 on the projecting side. The tip of the cylinder 20 and the rod 18 are not connected to each other. The tip is electrically connected and fixed by the disc-shaped short-circuit plate 22. Further, a lantern spring 26 formed of a conductive spring member is fixed to the rear end of the rod 18, and the lantern spring 26 slidably contacts the inner peripheral surface of the inner cylinder 16 to electrically connect the rod 18 and the inner cylinder 16. The connection is made. In order to prevent the lantern spring 26 from coming out of the inner cylinder 16, appropriate stoppers such as formation of a narrowed portion are formed at both ends of the inner cylinder 16. And the coaxial power supply cable 28
The central conductor 28a is electrically connected to the inner cylinder 16, and the outer conductor 28b is electrically connected to the cylinder 12. Further, a small diameter portion 20b having a slightly enlarged portion at the tip is formed so as to be exposed at the rear end portion of the cylinder 20 opposite to the tip end side. Formed to fit into the section.

In such a structure, as shown in FIG. 1 (a), when the rod 18 is pulled out, a rod-shaped body having a large diameter D is connected to the tip of a rod-shaped body having a small diameter d to form a rod antenna having a total length L. To work. Therefore, this dimension L
Is set to 1/4 wavelength of the communication signal frequency, it becomes possible to transmit and receive at resonance with the communication signal frequency. Further, as shown in FIG. 1B, when the rod 18 is housed, the small diameter portion 20b is fitted to the tubular body 12 and the rear end of the cylinder 20 is electrically connected to the tubular body 12 and grounded. Therefore, as shown in FIG. 3, current excitation is generated on the tip end side of the rod 18 to act as an antenna, and the ringing signal can be received.

By the way, in the structure of the above embodiment,
When the rod 18 is pulled out, the cylinder 20 does not act as an antenna with respect to the communication signal frequency, but merely functions as a decorative ball at the tip of the antenna. Therefore, the antenna characteristic is determined by the dimension L of the rod 18 protruding from the cylindrical body 12, and the dimension L is set with high accuracy.
It is possible to stabilize the antenna gain when it is pulled out without causing variations. 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 the case where the tips of the rod-shaped members are fixed to each other. 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 inner cylinder 16 and the cylindrical body 12 form a coaxial structure and the coaxial feed cable 28 is connected to these, noise is not superimposed on the signal path from the antenna to the transmission / reception circuit.

FIG. 4 is a vertical sectional view of the tip of the antenna of another embodiment of the antenna of the present invention. In FIG. 4, FIG.
Further, the same members as those in FIG.

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 an insulating resin. It is covered with the dielectric material 24. Then, the tip end portion of the antenna is integrally molded with the dielectric material 24 of the insulating resin by insert molding or outsert molding.

In this structure, the tip of the antenna is integrated, and the structure can be formed with high dimensional accuracy and robustness.

FIG. 5A is a vertical cross-sectional view of the tip of the antenna of yet another embodiment of the antenna of the present invention.
(B) is a diagram showing a voltage distribution of the antenna when the rod is housed. In FIG. 5A, the same or equivalent members as those in FIG. 4 are designated by the same reference numerals, and duplicate 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 the rod 1.
It is in a place where it is not electrically connected to the tip of 8. The cylinder 20 is coaxially integrally formed with the tip of the rod 18 by a dielectric material 24 made of an insulating resin. Then, the rear end of the cylinder 20 is configured to fit and abut the front end of the cylindrical body 12.

In this structure, the rear end of the cylinder 20 is electrically connected to the cylinder 12 and grounded when the rod 18 is accommodated. Therefore, as shown in FIG. 5B, voltage excitation is generated at the tip end side of the rod 18 to act as an antenna, and the ringing signal can be received.

In the above embodiment, the tip of the cylindrical body 12 is shown protruding from the outer wall of the housing 10.
The present invention is not limited to this, and the rear end portion of the cylinder 20 may be the cylindrical body 12 in the state where the rod 18 is housed, without being projected.
Any structure may be used as long as it can be fitted to the tip of the to obtain an electrical connection. Further, the power feeding structure for the rod 18 is not limited to the above-described embodiment, but the rod 18
It can be easily understood that any structure may be used if the inner portion of the cylindrical body 12 is used as a feeding point.

[0029]

As described above, since the antenna of the present invention is constructed, the following special effects are 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 for the communication signal frequency but merely functions as a decorative ball. The part where the rod is pulled out from the cylinder acts as an antenna. Therefore, by accurately setting the lead-out dimension to the length of resonance such as ¼ wavelength of the communication signal frequency, the antenna characteristic when the rod is pulled out becomes stable. Also, since the cylinder is fixed to the tip of the rod via the short-circuit plate, it is a structure that fixes a rod-shaped object to a planar object, and has a robust structure compared to fixing the rod-shaped tips to each other. Can
A member that acts as an antenna when the rod is stored can be firmly fixed to the tip of the rod.

Further, the antenna according to claim 2 also functions as an antenna similar to that according to claim 1.

In the antenna according to the third aspect, since the cylinder is integrally formed on the tip of the rod with the dielectric material of the insulating resin, it can be mass-produced with high dimensional accuracy by insert molding or the like, and the rod can be stored. The antenna characteristics will be stable without 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, the reliable electrical connection is maintained regardless of the axial position of the rod. To be done.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of an antenna of the present invention, in which (a) is a rod withdrawn and (b) is a rod housed.

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Housing 12 Cylindrical body 14 Insulation material 16 Inner cylinder 18 Rod 20 Cylindrical 20a Slit 22 Short circuit plate 24 Dielectric material 26 Lantern spring 28 Coaxial power supply cable 28a Center conductor 28b External conductor

Claims (4)

[Claims] 1. A rod made of an electrically conductive material is movably disposed in an axial direction in a casing made of an electrically conductive material, the rod being made of an electrically conductive material. A cylinder having a spiral slit made of a conductive material at the tip of the protruding side of this rod is coaxially arranged without electrical connection, and the tip side of this cylinder and the tip of the rod are connected by a short-circuit plate. Electrical connection is made so that the rear end side of the cylinder contacts the tip of the cylinder to make electrical connection while the rod is housed in the cylinder, and power is supplied to the in-cylinder portion of the rod. An antenna, characterized in that it is a point and the cylindrical body is grounded. 2. The antenna according to claim 1, wherein instead of electrically connecting the cylinder to the rod with the short-circuit plate, the cylinder is coaxially arranged with the rod without being electrically connected. An antenna characterized by being configured as. 3. The antenna according to claim 1 or 2, wherein the cylinder is integrally formed with an insulating resin at the tip of the rod. 4. The antenna according to claim 1 or 2, wherein an inner cylinder made of a conductive material is coaxially arranged in the cylinder through an insulating material, and the inner cylinder and the rod are formed of a conductive spring member. An antenna characterized in that the antenna is electrically connected via a central conductor of a coaxial power feeding cable to the inner cylinder, and an outer conductor of the coaxial power feeding cable is electrically connected to the cylindrical body.