JPH0631206U - Antenna for portable induction radio - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an antenna for a portable induction wireless device, which is suitable for an induction wireless device to be carried and is highly efficient and stable. [Structure] A plurality of antenna coils (8) formed by winding a conductive wire around a ferromagnetic core are attached to a safety helmet (7) so that their directivity directions are different from each other, and the plurality of antenna coils (8) are aligned. It connects to the inductive radio (9) via the circuit (11).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an antenna for a portable induction wireless device used in a portable induction wireless device using an induction wireless system.

[0002]

[Prior art]

 Conventionally, as an antenna of a portable radio device, a conductor rod whose electric length is λ / 4 (λ is a wave length) of an operating frequency or an integral multiple thereof is attached to the main body of the radio device or is placed at a shoulder position of a shoulder belt. Often set up and used. This is because the radio waves are sent to a wider space and the radio wave energy in a certain space is effectively derived, and this method is used when the communication range is relatively wide.

On the other hand, the guided wireless system is widely used when the communication range is limited to a specific place or when communication is limited to the inside of a building.

As shown in FIG. 3, the inductive wireless system is a relatively low frequency band in the pair of conductor lines 1 and 2, for example, LF (low frequency 30 kHz / 300 kHz) or higher MF (medium wave 300 kHz / 3 MHz). ) A carrier having a frequency band signal of about 4), which is modulated by various information signals and communicates between the portable wireless device 3 and the master device 4 which move along the conductor line, or between these portable wireless devices. Is. As shown in Fig. 4 (a), for example, an antenna used in such a portable wireless device is generally one in which a conductor 6 is wound around a ferromagnetic core 5 such as ferrite to form a coil having a required inductance. When mounting on the portable wireless device, it was mounted inside the induction wireless device 3 as shown in Fig. 2 (b), or mounted on the outside of its upper end as shown in Fig. 3 (c).

[0005]

[Problems to be solved by the device]

 However, these wireless devices have become smaller in size in recent years, and it has become possible to store them in a chest pocket or attach them to a waist belt to improve the workability of the wearer.

However, the above-mentioned guide lines 1 and 2 are usually installed at a position higher than the human body such as the ceiling of the building or its vicinity, and the guide magnetic field from the guide line is proportional to the square of the distance from the guide line. And then decay. Therefore, the antenna coil used in the conventional induction wireless device as described above and the method of mounting the antenna coil not only weaken the connection with the induction line laid high above the head, but also cause the induction wireless device to be worn on the waist belt. When it is used in close contact with the human body, there is a drawback in that the antenna efficiency is further reduced due to the influence of the human body, and the directionality of the coil is unidirectional, which makes communication impossible due to changes in work posture. It also had drawbacks such as falling.

Therefore, an object of the present invention is to provide an antenna for a portable induction wireless device, which is suitable for an induction wireless device to be carried and is capable of stable communication with extremely high efficiency.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention mounts a plurality of antenna coils formed by winding a conductive wire around a ferromagnetic core on a safety helmet so that the directions of the antenna coils are different from each other. It is characterized in that it is connected to an induction radio device via a matching circuit.

[0009]

[Action]

 Since the present invention is configured as described above, the antenna coil is always located at the highest part of the human body, and the coupling between the antenna coil and the induction line laid at a high place can be kept tight. It is also possible to make the overall directional characteristics omnidirectional by combining multiple antenna coils with different directivities. The binding of can be always stable.

[0010]

【Example】

 Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a side view showing an embodiment of the present invention. In the figure, reference numeral 7 is a helmet which has an antenna coil 8 fixed to the side surface thereof and which is connected to an induction radio 9 by a coaxial cable 10. It should be noted that FIG. 1 conceptually shows the present invention. Actually, the helmet 7 is provided with a plurality of antenna coils having different directing directions, and the plurality of antenna coils are combined by a matching circuit or the like to form a coaxial cable. Guided to Le 10.

With such a configuration, the antenna coil can be always positioned at the highest part of the human body even when the induction radio main body 9 is stored in the chest pocket or mounted on the waist belt.

FIG. 2 shows an embodiment of the present invention constructed by using two antenna coils. In the embodiment shown in FIG. 2, two antenna coils are provided on both sides of the helmet 7, one antenna is fixed vertically and the other is fixed horizontally, and the input / output signals of both are combined by the matching circuit 11 and And the wireless device are connected via the coaxial cable 10.

By doing so, the directivity of one antenna coil is usually maximum in the x-axis direction and minimum in the y-axis and z-axis directions, as shown in FIG. 4 (a). However, according to the above-described embodiment, the combined directivity can have the same sensitivity in two orthogonal directions.

Further, although not shown, a third antenna coil is fixed to the back or front of the helmet with directivity in a direction different from the others so as to obtain a combined directivity of these three antenna coils. If formed, it is possible to realize an antenna with uniform directivity in the three-dimensional space above, below, left, and right.

[0016]

[Effect of device]

 Since the present invention is configured as described above, it is effective in providing a stable antenna with high pole efficiency suitable for an inductive radio to be carried and used.

[Brief description of drawings]

FIG. 1 is a side view conceptually showing the present invention.

FIG. 2 is a side view showing an embodiment of the present invention.

FIG. 3 is a diagram showing a principle of guided radio.

FIG. 4 shows an example of an antenna used in a portable wireless device, (a) is a diagram showing a magnetic field direction of an antenna coil, (b)
And (c) are diagrams showing an example of a conventional antenna coil.

[Explanation of symbols]

 1, 2 Conductor line 3, 9 Portable induction radio 5 Core 6 Coil 7 Helmet 8 Antenna coil 10 Coaxial cable 11 Matching circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideo Yasuda Hideo Yasuda 7-3-16, Kikuna, Kohoku-ku, Yokohama, Kanagawa Oi Electric Co., Ltd. Machine Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A plurality of antenna coils formed by winding a conductive wire around a ferromagnetic core are attached to a safety helmet so that the directivity directions are different from each other, and the plurality of antenna coils are guided by a matching circuit. An antenna for a portable induction radio, characterized by being connected to.