JP5062338B2 - Helical antenna - Google Patents

Description

  The present invention relates to a helical antenna used for a radio device or the like.

The radiation characteristics of the helical antenna are determined by the radius of one winding of the conductor (helical radius) with respect to the wavelength, the line pitch, and the like.
For example, the excitation mode is a normal mode when the length of one winding of the conductor is sufficiently smaller than the wavelength, and an axial mode in which maximum radiation is obtained in the spiral axial direction when the length of one winding of the conductor is about the same as the wavelength. Become. Further, the resonance characteristics change when the line pitch is changed. The helical antenna is designed so as to obtain desired characteristics from various constants such as a helical radius, a pitch between lines, and the number of turns.

  These constants must be fixed in order to stabilize the antenna characteristics. Therefore, various devices for protecting the antenna element have been tried.

  A helical antenna used for a telephone, a portable radio device, etc. is a cover of a flexible synthetic resin or the like (for example, elastomer) on a spirally wound conductor 41 like a helical antenna 40 shown in FIG. Some are covered with 42.

  The cover 42 is fixed to the cover 44 of the power supply connector 43 with an adhesive or the like. The helical antenna 40 has a gap (0.1 to 0.3 mm) between the cover 42 and the conductor 41. When the helical antenna 40 receives external vibration or impact, the conductor 41 moves inside the cover 42. End up.

If the conductor 1 moves, the helical radius of the conductor 1 and the pitch between lines will change. In the helical antenna 40, if the helical radius and the pitch are changed, the voltage standing wave ratio is changed, and the characteristics as the antenna are not stabilized.
Further, when the cover 42 and the conductor 41 collide with each other due to vibration or impact, an unpleasant noise is generated and the quality of the product is deteriorated.

  For this reason, in such a helical antenna used for a telephone, a portable radio, etc., as shown in FIG. 4B, the cover 42 and the conductor 41 are fixed using an adhesive.

  However, when the cover 42 and the conductor 41 are bonded, the movement of the portion of the conductor 41 where the adhesive is adhered is restricted more than necessary due to the solidification of the adhesive, and the bending performance of the antenna is degraded. In addition, the elasticity of the antenna falls. Furthermore, in the assembling process, care must be taken not to attach various adhesives to unnecessary places, so that the work performance deteriorates.

  Further, when the conductor 41 is incorporated into the cover 42, the inside of the cover 42 is sealed. For this reason, it is necessary to use a type of adhesive that does not contain a solvent, and in general, a two-component epoxy type adhesive is used. For example, however, the mixing of the two liquids is performed in the assembly process, so that the mixing ratio varies, and as a result, the bonding strength varies. In addition, since the effect starts to appear at the moment of mixing, it is difficult to manage the adhesive itself.

  As described above, in the fixing method using the adhesive, it is difficult to fix the conductor 41 wound spirally to the cover 42. In addition, the performance of the fixed antenna may vary. Furthermore, it is difficult to remove the cover from the helical antenna, and it is difficult to cope with a failure or the like.

  In view of these problems, a helical antenna is known in which the shape of the inner side wall of the cover is uneven, and the conductor wound in a spiral shape is suppressed by a convex portion (for example, Patent Document 1).

JP-A-5-34709

  The helical antenna disclosed in Patent Document 1 is difficult to manufacture because it is difficult to process the cover, in particular, to adjust the thickness of the convex portion provided on the back surface. Further, the antenna performance may vary or play may occur due to variations in the height or shape of the protrusions. Furthermore, it is difficult to remove the cover from the helical antenna, and it is difficult to cope with a failure.

The present invention has been made in view of such a conventional problem, and an object thereof is to provide a helical antenna having a structure in which a spirally wound conductor can be easily fixed inside a cover.
Another object of the present invention is to provide a helical antenna having a structure in which a cover can be easily detached.

In order to achieve the above object, the helical antenna of the present invention comprises:
A spirally wound conductor,
A cover over the conductor;
An elastic member disposed in a gap between the conductor and the cover;
With
The cover is covered from the tip of the conductor,
The elastic member includes a first part located outside the spiral of the conductor, a second part located inside the spiral of the conductor, and a third part located closer to the tip of the cover than the tip of the conductor. And having a portion of

For example, the elastic member is a cushion material, and the cushion material is embedded in the spiral of the conductor and protrudes from the spiral of the conductor, and the portion of the cushion material protrudes from the spiral of the conductor The first portion and the third portion are configured by the above .

  By adopting such a configuration, the conductor is easily fixed inside the cover by the elastic member filling the space between the cover and the conductor.

It is a figure which shows the helical antenna which concerns on the 1st Embodiment of this invention. It is a figure which shows the helical antenna which concerns on the 2nd Embodiment of this invention. It is a figure which shows the helical antenna which concerns on the 3rd Embodiment of this invention. It is a figure which shows the conventional helical antenna.

(First embodiment)
Hereinafter, a helical antenna according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1 (a), the helical antenna 10 according to the first embodiment of the present invention includes a spirally wound conductor 1, a cover 2, a power supply connector 3, a support portion 4, And a ribbon-like nonwoven fabric 15.

  A power supply connector 3 is connected to one end of the spirally wound conductor 1. The power supply connector 3 supplies power to the conductor 1. The cover 2 is covered so as to cover the entire conductor 1 in order to protect the conductor 1. A support portion 4 is formed on the power supply connector 3. When the cover 2 is placed on the conductor 1, the support portion 4 is fitted to the inner surface of the base portion of the cover 2 to seal the inside of the cover 2.

  The non-woven fabric 15 is disposed in the gap between the tip of the conductor 1 and the inner wall of the cover 2 and has elasticity, and by pressing the inner wall of the cover 2 and the conductor 1, the friction force causes the conductor 1 to The tip is fixed to the cover 2. The nonwoven fabric 15 is thicker than “the difference between the inner diameter of the cover 2 and the outer diameter of the spiral conductor 1”, and the conductor 1 is pressed against the inner wall of the cover 2 to fix the conductor 1.

  One end of the nonwoven fabric 15 is fixed to the tip of the conductor 1 with an adhesive such as a double-sided tape. This is to prevent the nonwoven fabric 15 from shifting when the conductor 1 is pushed into the cover 2. The length of the non-woven fabric 15 only needs to be long enough to hold down the tip of the conductor 1 inside the cover 2. For example, the length of the non-woven fabric 15 may be about 5 pitches of the spiral.

In such a configuration, as shown in FIG. 1A, the inside of the front end portion of the cover 2 is in a state in which the nonwoven fabric 15 presses the conductor 1 and the inner wall of the cover 2 with a pressing force, so-called backlash is prevented. ing. Since the nonwoven fabric 15 is elastic, it is not pressed so much as to deform the conductor 1. For this reason, the radius planned for the conductor 1 and the pitch between the lines do not greatly deviate from the designed values, and the characteristics of the antenna are not affected.
Further, the cover 2 does not easily come off the conductor 1 due to the frictional force between the cover 2 and the conductor 1 due to the pressing force of the nonwoven fabric 15 and the frictional force between the cover 2 and the nonwoven fabric 15 and between the nonwoven fabric 15 and the conductor 1. Yes. Furthermore, since the nonwoven fabric 15 is a soft material, it does not affect the bending performance of the antenna itself.

  When the helical antenna 10 receives an impact from the outside, the nonwoven fabric 15 acts as a cushion and reduces the impact while holding the conductor 1 inside the cover 2 while ensuring the spiral shape of the conductor 1. Therefore, the antenna characteristics are stable. Furthermore, no abnormal noise is generated due to the conductor 1 colliding with the inner wall of the cover 2.

A method for assembling the helical antenna 10 will be described with reference to the drawings.
As shown in FIG. 1 (b), one end of the nonwoven fabric 15 is attached to the tip of the conductor 1 with an adhesive such as a double-sided tape. The portions other than the one end portion of the nonwoven fabric 15 are kept in a state along the outside of the spiral of the conductor 1 without using an adhesive or the like. Then, as shown in FIG. 1C, the conductor 1 wound in a spiral shape is inserted into the cover 2 while maintaining this state. The nonwoven fabric 15 is accommodated in the cover 2 in a state where the nonwoven fabric 15 is pulled to the tip of the conductor 1 by the adhesive.

Then, as shown to Fig.1 (a), it will be in the state by which the nonwoven fabric 15 was pinched | interposed between the cover 2 and the conductor 1 wound spirally. The nonwoven fabric 15 is sandwiched between the cover 2 and the conductor 1 so that the nonwoven fabric 15, the cover 2, and the conductor 1 are held together, the conductor 1 is fixed inside the cover 2, and the cover 2 can be easily detached. It will not be. The support portion 4 is fitted to the inner surface of the base portion of the cover 2 to seal the inside of the cover 2 and fix the base portion of the conductor 1.
Since the cover 2 is attached to the conductor 1 by pressing force without using an adhesive or the like, the cover 2 is pulled out with the support portion 4 (base portion of the conductor 1) held down. Removal is possible.

  In this way, the cover 2 can be fixed to the conductor 1 wound spirally by the nonwoven fabric 15. Since the nonwoven fabric 15 is fixed by pressing, fluctuations in the pitch between the conductors 1 can be avoided, the voltage standing wave ratio is stabilized, and as a result, the performance as an antenna is stabilized.

Further, there is no abnormal noise due to the conductor 1 wound in a spiral shape due to external vibration or impact colliding with the wall surface of the cover 2.
Furthermore, the adhesive is used only at a part of the tip of the conductor 1, and the conductor 1 and the nonwoven fabric 15 do not suppress the movement of each other. For this reason, there is almost no influence on the flexibility of the helical antenna 10 itself.

  Furthermore, when it is necessary to remove the cover 2 from the conductor 1 due to a failure or the like, the cover 2 can be pulled out by holding the support portion 4 (base portion of the conductor 1), and can be easily corrected.

  As described above, according to the present embodiment, the helically wound conductor 1 can be easily fixed inside the cover 2 to realize a helical antenna with higher operational characteristics and higher quality.

  It should be noted that the present invention is not limited to the above embodiment.

  The nonwoven fabric 15 is not limited to a single sheet, and a plurality of sheets may be used, or the shape may be changed such as a cylindrical shape. In addition, any material that can achieve the same effect may be used instead. For example, the same effect can be obtained with a material having elasticity such as a resin sheet or a rubber sheet. Furthermore, a plurality of locations including one end of the nonwoven fabric 15 may be fixed to the conductor 1.

(Second Embodiment)
As shown in FIG. 2A, a heat shrinkable tube 25 can be used instead of the nonwoven fabric 15.

  A helical antenna 20 shown in FIG. 2A includes a conductor 1 wound in a spiral shape, a cover 2, a power feeding connector 3, a heat shrinkable tube 25, and a support portion 4.

  The size of the heat-shrinkable tube 25 is slightly larger than the outer diameter of the conductor 1 wound in a spiral shape before being contracted. Further, the thickness of the heat-shrinkable tube 25 is a thickness suitable for filling the gap between the cover 2 and the conductor 1 in a contracted state. The outer diameter of the conductor 1 wound on the outer periphery of the conductor 1) / 2} ± α2].

  When assembling the antenna, the heat shrinkable tube 25 is attached to the tip of the conductor 1 as shown in FIG. Subsequently, the heat shrinkable tube 25 is shrunk by heat. Subsequently, as shown in FIG. 2 (c), the cover 2 is put on the conductor 1 to which the heat shrinkable tube 25 is attached.

  Then, as shown in FIG. 2A, the heat shrinkable tube 25 fills the gap between the conductor 1 and the cover 2 and fixes the conductor 1 inside the cover 2 while preventing backlash.

  Thus, the use of the heat-shrinkable tube 25 also makes it easy to manufacture and stable operating characteristics, and can realize a high-quality helical antenna.

(Third embodiment)
A helical antenna 30 shown in FIG. 3A includes a conductor 1 wound spirally, a cover 2, a power supply connector 3, a cushion material 35, and a support portion 4.

As shown in FIG. 3B, the cushion material 35 is embedded in the spiral formed by the conductor 1.
The cushion material 35 is a soft material that does not affect the helical radius and the line pitch of the conductor 1.
The size and the flexibility of the cushion material 35 are such that the protruding portion of the cushion material 35 fills the gap between the cover 2 and the conductor 1 in the state of being incorporated in the conductor 1 as shown in FIG. [{(Inner diameter of cover 2−outer diameter of spiral drawn by conductor 1) / 2} + α3].
As shown in FIG. 3 (a), the helical antenna 30 is filled with a gap between the cover 2 and the conductor 1 at a portion protruding from the conductor 1 of the cushion material 35 to prevent backlash, and the position of the conductor 1 The same effect as the case where the nonwoven fabric 15 or the heat shrinkable tube 25 described above is used can be obtained.

  In the above embodiment, the elastic member is disposed at the tip of the conductor 1 wound spirally. As a result, the tip of the cover 2 is fixed to the tip of the conductor 1. On the other hand, the base portion of the cover 2 is fixed to the base portion of the conductor 1 by the support portion 4. Therefore, the entire cover 2 can be fixed to the conductor 1 even though the elastic member is arranged only in part.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the example in which the diameter of the helix drawn by the conductor 1 is constant is shown, but the diameter of the helix drawn by the conductor 1 may be changed. For example, the diameter of the spiral may be tapered.
Further, the elastic member does not need to press the inner surface of the cover 2, and it may be sufficient to suppress the rattling or vibration by filling the gap in the cover 2 and fixing the position of the conductor 1.

  As described above, according to the present invention, it is possible to provide a helical antenna that can easily fix a spirally wound conductor inside a cover, has stable operating characteristics, and has high quality.

DESCRIPTION OF SYMBOLS 1 Conductor 2 Cover 3 Power supply connector 4 Support part 15 Nonwoven fabric 25 Heat shrinkable tube 35 Cushion material

Claims (2)

A spirally wound conductor,
A cover over the conductor;
An elastic member disposed in a gap between the conductor and the cover;
With
The cover is covered from the tip of the conductor,
The elastic member includes a first part located outside the spiral of the conductor, a second part located inside the spiral of the conductor, and a third part located closer to the tip of the cover than the tip of the conductor. And a helical antenna. The elastic member is a cushion material, and the cushion material is embedded in the spiral of the conductor and protrudes from the spiral of the conductor, and the portion of the cushion material protrudes from the spiral of the conductor. The helical antenna according to claim 1, wherein the first portion and the third portion are configured .

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