JPH11261327A - Antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna in which a helical coil and a sleeve are jointed to each other excellently and which is easily manufactured. SOLUTION: The antenna used for a portable radio device is provided with a helical coil 1 inside an antenna top 7. This helical coil 1 has its specific part joined with the sleeve 2 as a feed part. The winding pitch is less at the specific part than at other parts and the number of turns is at least one turn less. The specific part is wound preferably closely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an antenna used for a communication device such as a portable telephone and a portable radio.

[0002]

2. Description of the Related Art An example of the structure of this type of antenna will be described with reference to FIGS. In this antenna, a helical joint 21 and a coil stopper flange 22 are provided on a sleeve 2 serving as a power supply unit. Further, an integral coil guide 41 is formed on the antenna top side with a non-conductive material such as nylon resin. At the same time, an insulator 4 for passing the inside of the sleeve 2 and mechanically fixing the whip antenna to the other end of the sleeve 2 is formed. After that, a wire diameter of 0.5 mm that functions as a helical antenna
The coil spring-shaped helical coil 1 is screwed along the coil guide 41 as shown in FIG. At that time, the helical coil 1 is brought into contact with the helical coupling portion 21 of the sleeve 2 to make it electrically conductive. Thereafter, the antenna top 7 is molded with resin in order to protect the antenna and improve the design. The antenna top 7 may be of a cap type.

[0003]

However, the helical coil 1 is screwed into the coil guide 41 and the sleeve 2
When the pitch of the helical coil 1 is wider,
The helical coil 1 is deformed so as to be forcibly pressed in the horizontal direction, and may come into partial contact with the helical joint 21 at several points as shown in FIG. 8, the contact impedance increases, and the characteristics deteriorate. Or become unstable.

If the helical joint is greatly deformed when the antenna top 7 is formed, the pressure of the molding resin causes the helical coil 1 to pass over the coil stopper flange 22 of the sleeve 2 so that the appearance can be confirmed. In some cases, causing serious problems in yield and electrical characteristics.

[0005] Therefore, an object of the present invention is to provide an antenna in which the helical coil and the sleeve can be favorably joined together and can be easily manufactured.

[0006]

According to the present invention, an antenna used in a portable radio has a helical coil in an antenna top portion, and the helical coil has a specific portion joined to a sleeve serving as a feeding portion. An antenna characterized in that

[0007] Preferably, the specific portion has a smaller winding pitch than other portions and has at least one winding.

Preferably, the specific portion is tightly wound.

[0009] An angle or a round groove slightly wider than a wire diameter of the helical coil may be spirally provided at a portion where the specific portion of the sleeve is joined.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an antenna according to an embodiment of the present invention will be described.

As shown in FIG. 1, the sleeve 2 has a helical coupling portion 21 and a coil stopper flange 22. The helical coupling portion 21 is a portion to which the helical coil 1 is joined to obtain electrical conduction, and has a cylindrical and smooth outer peripheral surface. The coil fixing flange 22 is a portion for positioning the helical coil 1. The helical coil 1 has a winding pitch smaller than that of a portion joined to the sleeve 2, that is, a specific portion near one axial end of the helical coil 1, which is the other portion that functions as a helical antenna, and has several windings. As described above, the specific portion of the helical coil 1 is tightly wound, and is press-fitted into the helical coupling portion 21 of the sleeve 2 by being pushed into the helical coupling portion 21 in the axial direction without screwing as in the related art, and is joined and coupled.

After attaching the helical coil 1 to the sleeve 2, a separate coil guide 3 is screwed into the helical coil 1 as shown in FIG. 2 to obtain the structure shown in FIG. The coil guide 3 is formed of a non-conductive material such as a nylon resin. The helical coil 1 may be deformed due to some external force at the time of forming the antenna top or working in the process up to attaching the cap, or the pressure of the molding resin at the time of forming the antenna top.
However, the coil guide 3 is provided for the purpose of avoiding the positional deviation and the deformation. That is, the coil guide 3 serves to prevent the helical coil 1 from being displaced or deformed. Therefore, the coil guide 3 may be called a coil support.

Further, as shown in FIG.
The antenna top 7 is molded with resin so that the antenna top 7 is included together with the helical coil 1. Thus, a helical coil portion is formed.

An insulator 4 separately formed of a non-conductive material connects the sleeve 2 and the whip antenna 5 and further arranges a tube 6 on the outer periphery so as to protect the whip antenna 5. Get.

According to the above-described structure, the helical coil 1 functioning as a helical antenna and the sleeve 2 serving as a power feeding portion when the antenna is housed can be easily joined, and the deformation due to the attachment is small. As a result, it is possible to provide an antenna that is electrically stable, has low contact impedance, and does not cause any trouble even when the antenna top 7 is formed.
In addition, since the coil guide 3 does not receive a strong external force due to the mounting of the helical coil 1, the coil guide 3 can be formed in an air core, and the coil stopper flange 22 of the sleeve 2 can have a minimum necessary size. . as a result,
Lightening is possible.

In the above description, the helical coupling portion 21 of the sleeve 2 has a cylindrical and smooth outer peripheral surface, but the outer peripheral surface of the helical coupling portion 21 has a wire of the helical coil 1 as shown in FIG. A spiral corner or round groove 21a slightly larger than the diameter may be provided.

[0017]

As described above, according to the present invention,
Since the coil guide is separated and the helical coil and the sleeve joint are structured to stabilize the electrical connection, deformation when the helical coil is attached is eliminated, and therefore the antenna top is electrically stable and has a small contact impedance. It has become possible to provide a helical antenna that does not cause any trouble during molding.

[Brief description of the drawings]

FIG. 1 is an explanatory external view for explaining a process of assembling a helical coil and a sleeve when manufacturing an antenna according to an embodiment of the present invention.

FIG. 2 is an explanatory external view for explaining a step of assembling a coil guide to an assembly of a helical coil and a sleeve when manufacturing an antenna according to an embodiment of the present invention.

FIG. 3 is an external view of a semi-finished antenna according to an embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a separated antenna as an antenna according to one embodiment of the present invention.

FIG. 5 is an external view showing a sleeve used for an antenna according to another embodiment of the present invention.

FIG. 6 is an explanatory external view for explaining a process of assembling a helical coil and a sleeve when manufacturing a conventional antenna.

FIG. 7 is a partial sectional view of a helical antenna portion of a conventional antenna.

FIG. 8 is an enlarged detailed view of a joint between a helical coil and a sleeve in a conventional antenna, as viewed from an axial direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Helical coil (helical antenna) 2 Sleeve 21 Helical joint 22 Coil fixing flange 3 Coil guide 4 Insulator 41 Coil guide 5 Whip antenna 6 Tube 7 Antenna top

Claims (4)

[Claims] 1. An antenna used for a portable wireless device, wherein a helical coil is provided in an antenna top portion, and the helical coil has a specific portion joined to a sleeve serving as a power feeding portion. 2. The antenna according to claim 1, wherein the specific portion has a smaller winding pitch than the other portions and has at least one winding. 3. The antenna according to claim 2, wherein the specific portion is tightly wound. 4. The antenna according to claim 2, wherein a corner or a round groove slightly wider than a wire diameter of the helical coil is spirally provided at a portion of the sleeve that joins the specific portion.