JP2005236858A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized antenna which is used in frequency bands lower than AM bands and includes a high gain and impulse resistance as well as is rich in flexibility and elasticity. <P>SOLUTION: The small-sized antenna is an AM band antenna to be used for an additional function radio of a portable phone, in which a core material composed of a soft magnetic substance power and an organic binder and rich in flexibility and rubber elasticity is used as a material of a core 11 for antenna, said core material is disposed at both sides of a strap 13, and a winding 12 is applied. Furthermore, the soft magnetic substance powder is flattened and/or needle-shaped and insulating coating is applied to its surface. Moreover, the antenna uses the organic binder composed of a polyurethane resin or the like and a curing agent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antenna used in an AM band or a lower frequency band.

  As an antenna for an AM band radio, in the case of a single radio, there is an antenna having a sintered ferrite core as shown in a perspective view in FIG. In the figure, 61 is a sintered ferrite core, and 62 is a winding.

  As an example, Patent Document 1 discloses an antenna in which a magnetic core (core) formed by molding Mn—Zn ferrite into a rod shape or a plate shape is wound.

  Today, there is a demand for mounting a radio as an additional function in a mobile phone that is in a remarkable development stage as a communication terminal, and an FM band radio is also being installed. Among them, for AM band radio, the mobile phone has a noise source in the AM band, and the bar antenna using sintered ferrite generally used in the AM band clears the small size and impact resistance. It is difficult and has not been realized.

Japanese Patent Laid-Open No. 10-270232

  Sintered ferrite bar antennas need to be large in order to ensure sensitivity, and in the case of sintered ferrite bar antennas that are designed to be small enough to be placed in mobile phones, the radio sensitivity decreases. Further, since it is closer to a noise source, the S / N ratio is also deteriorated. Also, when placed outside like a strap, the size restriction and the effect of internal noise are reduced, but it is rugged and hard, it is vulnerable to shocks such as dropping, and the ferrite of the antenna will break The problem will occur. Rod antennas and coil antennas are difficult to mount due to their design and size. Even with plastic ferrite bar antennas, the impact resistance has been improved to some extent, but pursuing characteristics for antennas (permeability μ60 or more) requires increasing the ferrite filling rate, which is similar to sintered ferrite. The same problem occurred.

  In this situation, an object of the present invention is to provide a small antenna that is used in a frequency band lower than the AM band and has not only high gain and impact resistance but also high flexibility and elasticity.

  Therefore, in order to solve these problems, by using a core made of soft magnetic powder and an elastomer or plastomer as an organic binder as the core material of the bar antenna, the impact resistance is rich in flexibility and elasticity. This makes it possible to manufacture an AM band antenna suitable for mobile phones and the like with improved performance.

  That is, the antenna of the present invention is used in a frequency band lower than the AM band, and includes an antenna including a core made of soft magnetic powder and an organic binder, and a winding. The soft magnetic powder is made of an iron aluminum silicon alloy. , Iron-nickel alloy, iron-cobalt alloy, iron-cobalt-silicon alloy, iron-silicon vanadium alloy, iron-cobalt boron alloy, cobalt-based amorphous alloy, iron-based amorphous alloy, oxide magnetic powder, carbonyl iron, molybdenum permalloy, and pure iron compact The soft magnetic powder is flat and / or needle-shaped, and at least a part of the soft magnetic powder is an oxide film or a polymer material. The organic binder is polyester resin, polyvinyl chloride resin, polyvinyl butyral resin. Thermoplastic resins such as polyurethane resins, cellulose resins, nitrile-butadiene rubbers, styrene-butadiene rubbers or copolymers thereof, epoxy resins, phenol resins, amide resins, imide resins, It is characterized by comprising at least one selected from a halide as an organic flame retardant and a brominated polymer as an organic flame retardant.

  The antenna of the present invention is formed integrally with a strap attached to a mobile phone and can operate as an AM band antenna.

  The antenna of the present invention can be used for RFID in a frequency band lower than the AM band.

  When the antenna of the present invention is used for an AM band antenna for a mobile phone, a core material rich in flexibility and rubber elasticity is used. Therefore, an antenna having good functionality and design can be provided as a strap for a mobile phone. it can. In addition, the core used in the present invention can be manufactured from a thin object such as FPC (flexible printed wiring) to a few centimeters, and can be cut with a blade tool, a press die, a cutter tool, or the like. Molding is also possible by selecting an organic binder. Further, it is possible to cope with more complicated shapes by stacking.

  The antenna according to the first embodiment of the present invention is an AM band antenna used for an additional function radio of a cellular phone, and is composed of a soft magnetic powder and an organic binder in an antenna core, and has flexibility and rubber elasticity. It is a bar antenna using a rich core material.

  This soft magnetic powder is an iron aluminum silicon alloy (Sendust (registered trademark)), an iron nickel alloy (Permalloy (registered trademark)), an iron cobalt alloy, an iron cobalt silicon alloy, an iron silicon vanadium alloy having a high frequency magnetic permeability. , Iron-cobalt boron alloy, cobalt-based amorphous alloy, iron-based amorphous alloy, oxide magnetic powder (ferrite), carbonyl iron, molybdenum permalloy, pure iron powder, or a combination thereof. In addition, since only one kind of oxide magnetic powder (ferrite) has insufficient radio sensitivity, it is used by mixing with other high magnetic permeability soft magnetic powder.

  The organic binder is a polyester resin, a polyvinyl chloride resin, a polyvinyl butyral resin, a polyurethane resin, a cellulose resin, a nitrile-butadiene rubber, a thermoplastic resin such as a styrene-butadiene rubber, or a copolymer thereof. It consists of a thermosetting resin such as an epoxy resin, a phenol resin, an amide resin or an imide resin, or a halide or brominated polymer which is an organic flame retardant, or a combination thereof.

  The soft magnetic powder is a flat powder, a needle powder, or a mixed powder thereof. In addition, at least one material of the soft magnetic powder is subjected to an insulating coating with a polymer material such as an oxide film or an organic binder to prevent the generation of eddy currents.

  When such a core material is disposed on a strap externally attached to a mobile phone and formed integrally, an AM band antenna that can be used even when bent and can be received even when bent is obtained.

  The antenna according to the second embodiment of the present invention is a bar antenna used for RFID (Radio Frequency Identification) that uses radio waves in the medium wave band below the AM band. Even in the case of RFID, because of the core material used in the present invention, the antenna has high gain, impact resistance, flexibility, and rubber elasticity.

  The antenna of the present invention was fabricated as an AM band antenna for a mobile phone, and the characteristics were compared with those of a conventional sintered ferrite bar antenna.

  FIG. 1 is a perspective view showing an antenna according to Embodiment 1 of the present invention. FIG. 2 is a perspective view showing bending flexibility when the antenna of the first embodiment is used as an AM band antenna for a mobile phone. 11 is a core, 12 is a winding, 13 is a strap, and 14 is a connecting and fixing part.

  For the core of the prototype bar antenna, a core material formed with a thickness of 1 mm using an organic binder made of a polyurethane resin and a curing agent is used as the soft magnetic fine powder, Fe-Al-Si alloy powder. . Two sheets were prepared by cutting the core size into 11 × 50 × 1 mm. Next, as shown in FIG. 1, an antenna core was produced by sandwiching the flexible band of the strap 13 between two core members, and a polyurethane wire winding 12 was applied. The magnetic permeability of the core material was μ = 70 or more.

  FIG. 3 shows the gain curve (frequency dependence) of this antenna.

  On the other hand, FIG. 4 shows a gain curve of a conventional sintered ferrite bar antenna. The structure at that time is the same as that of FIG. 6 already described, and the core size is φ10 × 60 mm.

  FIG. 5 shows a gain curve in a small-sized sintered ferrite bar antenna. The core size at this time is φ3.5 × 20 mm.

  That is, FIGS. 3 to 5 show data obtained by comparing and measuring the gain of the AM band antenna for mobile phones of the present invention and the gain of the conventional sintered ferrite bar antenna and the small-sized sintered ferrite bar antenna. Indicates. Table 1 summarizes the results.

  As shown in Table 1, the antenna of the present invention has good characteristics in terms of both gain and Q as compared with a small-sized sintered ferrite bar antenna. The conventional sintered ferrite bar antenna does not reach the characteristics, but can be sufficiently adapted for general use by adjusting the AGC (Automatic Gain Control) circuit, and is shown in FIG. 1 of the present invention. The radio wave reception state of the AM station in the shape was as good as that of the conventional sintered ferrite. Also, the sensitivity was good even in the shape where the core was bent as shown in FIG.

1 is a perspective view showing an antenna of Example 1. FIG. The perspective view which shows the bending flexibility of the antenna of Example 1. FIG. The gain curve of the antenna of Example 1. FIG. Gain curve of a conventional sintered ferrite bar antenna. Gain curve of a sintered ferrite bar antenna with a small design. The perspective view which shows the bar antenna using the conventional sintered ferrite.

Explanation of symbols

11 Core 12, 62 Winding 13 Strap
14 Connection fixing part 61 Sintered ferrite core

Claims (3)

  In an antenna that is used in a frequency band lower than the AM band and includes a core made of soft magnetic powder and an organic binder and a winding, the soft magnetic powder is made of iron aluminum silicon alloy, iron nickel alloy, iron cobalt alloy. , Iron cobalt silicon alloy, iron silicon vanadium alloy, iron cobalt boron alloy, cobalt amorphous alloy, iron amorphous alloy, oxide magnetic powder, carbonyl iron, molybdenum permalloy, and pure iron powder compact Or a combination thereof, and the shape of the soft magnetic powder is flat and / or needle-shaped, and at least a part of the soft magnetic powder is insulated with an oxide film or a polymer material, and the organic bond The agent is polyester resin, polyvinyl chloride resin, polyvinyl butyral resin, polyurethane resin, cellulose Resin, Thermoplastic resins such as nitrile-butadiene rubber, styrene-butadiene rubber or their copolymers, epoxy resins, phenol resins, amide resins, imide resins, etc., organic flame retardants An antenna comprising at least one selected from a certain halide and a brominated polymer which is an organic flame retardant.   The antenna according to claim 1, wherein the antenna is formed integrally with a strap attached to the mobile phone and operates as an AM band antenna.   The antenna according to claim 1, wherein the antenna is used for an RFID having a frequency band lower than an AM band.

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