JP2701747B2 - Helical 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 helical antenna, and more particularly to a helical antenna formed using a flexible substrate.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a structure of a conventional helical antenna. In this figure, a flexible substrate 2 having a helical pattern 1 formed on a dielectric cylinder 4 is attached. FIG. 6 is a diagram showing a structure of a conventional helical antenna. In the figure, a helical pattern 1 has two parallel patterns of a predetermined length formed on a flexible substrate 2. In order to wind the flexible substrate 2 around the dielectric cylinder 4, the flexible substrate 2
On the side, four positioning holes 10 to 12 are formed at positions not on the helical pattern 1, and on the dielectric cylinder 5 side, four projections 1 are provided at positions corresponding to the positioning holes.
4 to 17 are formed. When the flexible substrate 2 is wound around a dielectric cylinder, the protrusions 14 to 17 are caulked and fixed.

The above structure is disclosed in, for example, Japanese Utility Model Application No. 4-8518.
There is a description in the publication.

[0004]

In this conventional helical antenna, only the flexible substrate 2 is wound around a dielectric cylinder and the four projections 14 to 17 are fixed by caulking. In an environment where the temperature changes, it is difficult to obtain high durability due to deformation of the flexible substrate, loosening of the fixing, and the like. Also,
Since the helical pattern 1 is printed on the flexible substrate 2, electrical adjustment cannot be easily performed.

[0005]

A helical antenna according to the present invention is a helical antenna in which a plurality of helical patterns are formed on a flexible substrate, and the flexible substrate is wound around a dielectric cylinder. Means for bonding between the cylinders with a double-sided adhesive tape, and connecting the ends of the plurality of helical patterns to each other by penetrating the inside of the cylinder with a thin metal conductor to prevent peeling of the helical pattern. Means for changing the length of the metal conductor to change the length of the helical pattern to perform electrical matching of the helical antenna.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a helical antenna according to one embodiment of the present invention. FIG. 2 is a view showing a structure for attaching the flexible substrate 7 to the dielectric cylinder 4. The flexible substrate 7 has the helical pattern 1 formed thereon, and the flexible substrate 2 shown in FIG.
They have the same shape except that there are no twelve. The flexible substrate 7 on which the helical pattern 1 is formed is adhered to the dielectric cylinder 4 by the double-sided adhesive tape 3. One end above the two-wire helical pattern 1 arranged in parallel is supplied with power directly to the center conductor of the coaxial cable 5 and via the balun 8, thereby forming a balanced two-wire helical antenna.

A metal conductor 6 is connected to the other lower end of the helical pattern 1 to short-circuit two parallel helical patterns. In this case, the metal conductor 6 penetrates through the dielectric cylinder 4 and is soldered in a helical pattern. The structure of the metal conductor 6 has a linear shape as shown in FIG. 3 or a U-shape as shown in FIG. The mechanical role and electrical role of the metal conductor 6 will be described below.

As a mechanical role, the metal conductor 6 is formed by bonding the helical pattern 1 by soldering.
The flexible substrate 2 has a role of preventing the flexible substrate 2 from coming off the dielectric cylinder 4. As a result, the flexible substrate 2 is adhered to the dielectric cylinder 4 by the double-sided adhesive tape 3. It has the role of maintaining its shape.

In addition, as an electrical role, the metal conductor 6
It plays a role in matching the helical antenna. In general, a helical antenna feeds one end of a helical pattern 1 and uses the other end as an open or a short circuit, but when the total length of the helical pattern is less than about 5 wavelengths, the input impedance changes depending on the length of the helical pattern. For this reason, the metal conductor 6 is formed in a U-shape as shown in FIG. 4 and has a role of easily adjusting the electrical matching of the helical antenna by changing the length of the U-shape.

In the embodiment described above, the two-line helical pattern arranged in parallel has a structure in which the formed flexible substrate is bonded onto the dielectric cylinder, but the helical pattern is not limited to this. For example, it is a matter of course that the configuration can be made even when the winding pitch of the helical is changed at a predetermined interval, or by using a helical pattern of two or more polylines.

In this embodiment, the metal conductor 6 is described as having a linear or U-shape. However, the metal conductor 6 may have a linear or U-shape if it has a mechanical role and an electrical role as described above. The shape is not limited to the letter shape.

[0013]

As described above, according to the present invention, the helical pattern is formed by connecting the ends of the helical pattern through the dielectric cylinder, which is a mandrel, with a straight or U-shaped metal conductor. This has the effect of maintaining high durability and facilitating electrical matching.

[Brief description of the drawings]

FIG. 1 is a perspective view of a helical antenna according to one embodiment of the present invention.

FIG. 2 is a partially developed view of the flexible substrate of the embodiment shown in FIG.

FIG. 3 is a sectional view of a helical terminal portion of the embodiment shown in FIG. 1;

FIG. 4 is a sectional view of a helical terminal portion of the embodiment shown in FIG. 1;

FIG. 5 is a perspective view of a conventional helical antenna.

FIG. 6 is a partially developed view of a flexible substrate of a conventional helical antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Helical pattern 2 Flexible board 3 Double-sided adhesive tape 4 Dielectric cylinder 5 Coaxial cable 6 Metal conductor 7 Flexible board 8 Balun 10-13 Positioning hole 14-15 Projection

Continuation of the front page (56) References JP-A-3-274904 (JP, A) JP-A-4-26203 (JP, A) JP-A-3-74906 (JP, A) JP-A-57-99006 (JP) , A) Japanese Utility Model Application 4-110011 (JP, U) Japanese Utility Model Application Showa 64-38006 (JP, U) Japanese Utility Model Application Showa 64-44706 (JP, U) Japanese Utility Model Application Hei 4-8518 (JP, U)

Claims (2)

(57) [Claims] 1. A helical antenna in which a plurality of helical patterns are formed on a flexible substrate and the flexible substrate is wound around a dielectric cylinder, wherein the flexible substrate and the dielectric cylinder are bonded with a double-sided adhesive tape. means for, ends of said plurality of helical patterns
Are connected to each other by passing through the inside of the cylinder with a thin metal conductor
Means for preventing the helical pattern from peeling off,
The length of the helical pattern is changed by changing the length of the metal conductor.
The electrical alignment of the helical antenna
Helical antenna characterized by comprising means for performing focus. 2. The helical antenna according to claim 1, wherein the metal conductor is linear or U-shaped in the axial direction of the helical antenna.