JP2007036422A - Transmission coil antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission coil antenna system having the conformity of the number of turns of coils in the transmission coil antenna system, a core material, and an AC power supply to improve the characteristics of the transmission coil antenna system. <P>SOLUTION: In the transmission coil antenna system, an AC power supply 2 is connected in parallel with an LC series element, where a core 4 and a coil 1 in which winding 5 is wound, and then a tuning capacitor 3 are connected in series. In the transmission coil antenna system, the number of turns of coils is set within a range of one to two times larger than that when effective relative permeability reaches the maximum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmission coil antenna system used for transmission of a radio signal in a low and medium wave band, and more particularly to a transmission coil antenna system suitable for transmission of a radio signal in a frequency range of 10 kHz to 20 MHz.

  Conventionally, when transmitting and receiving a radio signal in a low and medium wave band, various transmission devices and transmission systems or terminals have been used and proposed. For example, an AM radio is one of typical receiving apparatuses, and a radio clock is one of transmitting / receiving apparatuses. Other recent transmission / reception systems to be noted include an automobile immobilizer, an automobile or residential remote keyless entry system, or an RF-ID system.

  As disclosed in Patent Document 1, examples of the magnetic core material for the receiving coil antenna system within a frequency range of 10 kHz to 20 MHz include a sintered ferrite core, a laminated core made of an amorphous alloy thin film, and a ferrite. There are various magnetic core materials composed of plastic mixed materials, powdered or flaky metal and plastic mixed materials.

  Also, as an example of a low / middle-band transmission / reception antenna system, as disclosed in Patent Document 2, an antenna unit that includes a transmission coil and a reception coil, and that configures a resonance circuit and a tuning circuit in combination with capacitors, respectively. A transmitting / receiving coil antenna system is known.

JP 2001-337181 A Japanese Utility Model Publication No. 07-002987

  However, the configuration described in Patent Document 2 is similar to the present invention in which an AC power source is connected in parallel to an LC series element in which a coil and a tuning capacitor are connected in series. The number of times, the compatibility with the magnetic core material and the AC power supply have not been sufficiently studied, and the design of the transmission coil antenna system characteristics (hereinafter referred to as the balance of the electronic circuit) has been lost because the design has not been adequately and optimally designed. , Expressed as “transmission characteristics”).

  Here, the transmission characteristic refers to the magnitude of the electric field generated from the transmission coil antenna system, and the transmission characteristic is better as the electric field is larger. In addition to the magnitude of the electric field itself, the transmission characteristics can be sufficiently evaluated by the voltage of the reception loop antenna, the voltage of the reception coil antenna, and the like. Furthermore, in an arbitrary receiving antenna system in which a receiving coil antenna or a receiving loop antenna is combined with an electronic circuit, the distance can be expressed as a transmission characteristic by obtaining a transmittable distance. However, the electric field generated by the transmitting antenna system must be less than the magnitude of the electric field defined in the Radio Law.

  In order to improve the characteristics of the transmission coil antenna system, the present invention provides a transmission coil antenna system with an optimal number of coil turns, a magnetic core material adapted to the field, consistency with an AC power source corresponding to frequency changes, and electrical An object of the present invention is to provide a transmission coil antenna system having a circuit balance.

  In order to solve the above problems, the present invention provides a magnetic core, a coil in which a winding is wound around the magnetic core, an LC series element in which a tuning capacitor is connected in series, and a transmission coil in which an AC power source is connected in parallel In the antenna system, the number of coil turns is set within a range of 1 to 2 times the number of coil turns when the effective relative permeability is maximized.

  Furthermore, the AC power supply is a constant voltage AC power supply, and the transmission coil antenna system is characterized in that it is a constant voltage AC power supply.

  Therefore, according to the present invention, in the transmission coil antenna system, the optimal number of coil turns, the magnetic core material adapted to the field, the compatibility with the AC power source corresponding to the frequency change, and the balance of the electric circuit are transmitted. Since it becomes possible to provide a coil antenna system, an optimal and favorable transmission coil antenna system can be configured when various magnetic core materials and AC power supplies are used according to the situation.

  FIG. 1 is a configuration diagram shown for explaining a transmission coil antenna system according to an embodiment of the present invention. Embodiments of the present invention will be described with reference to the drawings. An AC power supply 2 for obtaining a rectangular wave output is connected in parallel to an LC series element in which a coil 1 having a winding and a tuning capacitor 3 are connected in series, and in an RF-ID LF wave band of 120 kHz to 135 kHz. Then, a predetermined frequency is tuned and a predetermined voltage is applied.

  FIG. 2 is a configuration diagram shown for explaining the coil 1 according to the embodiment of the present invention. The coil 1 winds a polyurethane winding 5 (polyurethane-coated copper wire) around a plate-shaped magnetic core 4 made of metal powder and plastic a predetermined number of times.

  In actual measurement, the number of turns of the winding 5 of the coil 1 is changed, and the tuning capacitor is changed every time so as to be tuned to a predetermined frequency to obtain the relationship between the effective relative permeability and the transmission characteristics. Here, the transmission characteristic of the transmission coil antenna system is determined as a transmission characteristic by obtaining a distance that can be transmitted by a reception antenna system in which a predetermined reception LC parallel circuit and electronic circuit are combined. Thus, the setting of the optimal number of turns is difficult to perform numerical analysis because the transmission coil antenna system is a bar antenna, and varies depending on the shape of the magnetic core 4 and the AC power source 2. For this reason, the optimum number of turns is simple to obtain by experiment and has high accuracy from the relationship between the effective relative permeability and the transmission characteristics.

  Although depending on the scale of the transmission coil antenna system, a current of several hundred mA to several A is often passed through the transmission coil antenna system. For this reason, in the case of a constant current source, the AC power supply operates until a predetermined current is reached. If the circuit of the coil and the tuning antenna is cut and the power is leaked from the AC power supply, it is assumed that there is a danger to the human body. If the AC power source is a constant voltage circuit, even if a human body or the like is in contact with the AC power source, it is relatively safe if it is a low AC voltage source of 5 V to 10 V, and the AC power source is preferably a constant voltage AC power source.

  Next, the transmission coil antenna system of the present invention will be described in more detail by giving specific examples. The magnetic core 4 of the coil 1 in FIG. 2 is made of Fe—Al—Si alloy (Sendust) powder and plastic, and the magnetic core 4 has a square shape and a size of 3 × 3 × 100 mm. A polyurethane winding 5 (polyurethane-coated copper wire) is wound 90 to 250 times.

  FIG. 3 shows the relationship between effective relative permeability and transmission characteristics when the number of turns of the winding in Example 1 of the present invention is changed and the tuning capacitor is changed every time to tune to 125 kHz and the AC power supply is 5V. FIG. From FIG. 3, the effective relative permeability and the transmission characteristics have a correlation, and the maximum value is 110 turns. When the number of turns was small, the effective relative permeability of the coil decreased rapidly, and the transmission characteristics also decreased rapidly. On the other hand, when the number of windings was large, the effective relative permeability decreased gradually, and the transmission characteristics also decreased gradually.

  As described above, there is an appropriate design value for the number of turns, and in order to stabilize the transmission characteristics, a method of winding more turns than the optimum value when the effective relative permeability is maximum is effective. . Therefore, in consideration of the fact that the appropriate value of the number of windings varies by about ± 50% due to variations in the dimensions of the magnetic core of the coil, variations in the physical properties of the magnetic core material, variations in the capacitor constant, etc. Taking into account that the number of times does not fall, it is desirable to set it to 1 to 2 times the optimum value. Therefore, when the AC power supply is 5 V with the coil set this time, the optimum number of turns is 110, and therefore the appropriate value of the number of turns was 110 to 220. In addition, the tuning capacitor constant at 110 turns was 7,300 pF.

  Next, other specific examples will be given to describe the transmission coil antenna system of the present invention in more detail. FIG. 4 is a diagram showing the relationship between the effective relative permeability and the transmission characteristics when the number of turns of the winding in Example 2 of the present invention is changed. The magnetic core 4 is made of Fe—Al—Si alloy (Sendust) powder and plastic, and the magnetic core 4 has a square shape, a size of 6 × 6 × 80 mm, and a winding 5 made of polyurethane. (Polyurethane-coated copper wire) is wound 10 to 100 times.

  When the number of winding turns was changed and the tuning capacitor was changed every time to tune to 125 kHz. When the AC power supply was 10 V, the optimum value of the effective relative permeability that was the maximum was 30 turns. Therefore, the appropriate value of the number of turns was 30 to 60, and the tuning capacitor constant at the time of 30 turns was 25,000 pF.

  The transmission coil antenna system of the present invention is applicable to a radio transmission and reception system capable of transmitting and receiving a radio signal of 10 kHz to 20 MHz. Moreover, in a remote keyless entry system, it can also be used as an antenna for transmitting a user identification signal transmitted to a receiving antenna system carried by a user. In particular, when the remote keyless entry system is employed in an automobile, the transmission coil antenna system system of the present invention may be mounted on a part of the automobile. More specifically, it may be provided on the door handle of an automobile.

The block diagram shown in order to demonstrate the transmission coil antenna system concerning embodiment of this invention. Sectional drawing shown in order to demonstrate the coil concerning embodiment of this invention. The figure which shows the relationship between the effective relative magnetic permeability in Example 1 of this invention, and transmission characteristics. The figure which shows the relationship between the effective relative magnetic permeability in Example 2 of this invention, and transmission characteristics.

Explanation of symbols

1 Coil 2 AC power supply 3 Tuning capacitor 4 Magnetic core 5 Winding

Claims (2)

  In a transmission coil antenna system in which a magnetic core, a coil having a winding wound around the magnetic core, an LC series element in which a tuning capacitor is connected in series, and an AC power source are connected in parallel, the number of coil turns is an effective ratio. A transmission coil antenna system, wherein the transmission coil antenna system is set in a range of 1 to 2 times the number of coil turns when the magnetic permeability is maximum.   The transmission coil antenna system according to claim 1, wherein the AC power source is a constant voltage AC power source.

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