JP6030991B2 - Reversed phase double loop antenna - Google Patents

Description

  The present invention relates to an antenna technology using a magnetic field.

  There is a demand for wireless communication in which a communication area is intentionally limited. About this, using the electric field communication system of patent document 1 is also considered. However, since the electric field distribution in the vicinity of the communication area is strongly influenced by the surroundings (the influence of noise due to conductors and dielectrics), it is difficult to realize wireless communication with high stability and reliability.

  On the other hand, a low frequency magnetic field of about 10 MHz or less is used as a communication medium for wireless communication because its interaction with the surroundings is significantly lower than that of an electric field. Therefore, in order to realize the above-described wireless communication, there is a demand for an antenna that can generate a “sharp magnetic field distribution” in which the magnetic field strength sharply attenuates at the boundary between the communication area and the non-communication area.

There is an anti-phase double loop antenna as such an antenna. FIG. 10 shows a circuit configuration of a conventional antiphase double loop antenna. Two loop antennas 10 and 20 having different diameters are arranged concentrically, and currents I ₁ and I ₂ flowing through the two loop antennas 10 and 20 respectively proceed in the opposite directions.

  In general, the magnetic field strength generated far away by the loop antenna is proportional to the magnetic moment m, which is the product of the area S in the loop surrounded by the loop antenna and the current I flowing through the loop antenna.

The traveling directions of the currents I ₁ and I ₂ flowing through the two loop antennas 10 and 20 arranged on the same plane are opposite to each other, and the magnitudes of the magnetic moments m ₁ and m ₂ of the loop antennas 10 and 20 are the same. In this case, the magnetic moments m ₁ and m ₂ cancel each other, so that the magnetic field strength in the distance is extremely small.

On the other hand, the magnetic field strength in the vicinity of the center is strongly influenced by the current I ₂ flowing through the inner loop antenna 20, so that the magnetic moments m ₁ and m _{2 of the} two loop antennas 10 and 20 cancel each other. Even if this is the case, the magnetic field in the vicinity of the center point will not be reduced.

  As a result, as shown in FIG. 11, the antiphase double loop antenna can attenuate the magnetic field strength in the distance more rapidly than the case where a single loop antenna is used.

If the ratio of the absolute values of the magnetic moments m ₁ and m ₂ is γ = | m ₂ | / | m ₁ |, the ratio of the currents flowing through the two loop antennas 10 and 20 is changed, thereby changing the communication area. The position of the boundary can be controlled.

For example, as shown in FIG. 10, when the radius of the outer loop antenna 10 is twice the inner radius, the resistance value of the variable resistor R ₃ is adjusted to be I ₁ : I ₂ = 1: 4, and γ If = 1, an attenuation factor of 100 dB / dec can be obtained at a distance as shown in FIG. For example, if I ₁ : I ₂ = 1: 2, the magnetic field distribution characteristic represented by the curve of γ = 0.5 in FIG. 11 can be obtained.

JP 2007-174570 A JP 2005-33587 A JP 2001-16025 A

  However, according to the conventional antiphase double loop antenna shown in FIG. 10, since the two loop antennas 10 and 20 are connected in parallel to the signal source 100, the magnetic field strength near the antenna is reduced to a single value. To maintain the same level as when a loop antenna is used, the current consumption becomes large.

  This invention is made | formed in view of the said situation, and it aims at reducing the power consumption of a negative phase double loop antenna.

The anti-phase double loop antenna according to claim 1, wherein the outer loop first loop antenna is wound once or a plurality of times, is wound once or a plurality of times, and is arranged concentrically with the first loop antenna. It is connected in series with the first loop antenna, and an inner second loop antenna current flows in the opposite direction to the traveling direction of the current input to the first loop antenna, across the second loop antenna A connected resistor and a current that is connected in parallel to the first loop antenna and the second loop antenna, is contained in the second loop antenna or contains the second loop antenna, and flows through the second loop antenna. And a third loop antenna through which a current flows in the same direction as the traveling direction of .

According to the present invention, since the two concentric loop antennas in which currents flow in the opposite directions are connected in series, the power consumption of the antiphase double loop antenna can be reduced. Further, according to the present invention, since the resistor is connected between both ends of the inner loop antenna, the ratio of the current of the outer loop antenna and the current of the inner loop antenna can be changed. Furthermore, according to the present invention, a loop antenna that is connected in parallel to the outer loop antenna and the inner loop antenna and in which a current flows in the same direction as the current flowing in the inner loop antenna is included in the inner loop antenna. In addition, since the inner loop antenna is included, the current flowing through the inner loop antenna is increased, so that a magnetic field strength equivalent to a large current amount can be obtained with a small amount of current.

The negative phase double loop antenna according to claim 2 is the negative phase double loop antenna according to claim 1, further comprising a resistor connected in series with the third loop antenna .

The antiphase double loop antenna according to claim 3 is the antiphase double loop antenna according to claim 1 or 2, wherein the first loop antenna and the second loop antenna have a number of turns and a center to the loop antenna. The gist is that two integrated values obtained by integrating the square of the distance are equal.

According to the present invention, since the two integrated values obtained by integrating the number of turns and the square of the distance from the center to the loop antenna for the first loop antenna and the second loop antenna are equal, An attenuation factor of 100 dB / dec can be obtained.

  According to the present invention, it is possible to reduce the power consumption of the antiphase double loop antenna.

It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 1st Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 2nd Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 3rd Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 4th Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 5th Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 6th Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 6th Embodiment. It is a figure which shows the circuit structure of the negative phase double loop antenna which concerns on 7th Embodiment. It is a figure which shows the circuit structure of the anti | reverse | negative phase double loop antenna which concerns on 8th Embodiment. It is a figure which shows the circuit structure of the conventional reverse phase double loop antenna. It is a figure which shows electric field strength distribution.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram showing a circuit configuration of an antiphase double loop antenna according to the present embodiment. The reverse-phase dual-loop antenna is composed of two loop antennas 10 and 20, three feed lines 30, 40, 50, one of the resistor _{R 1.}

The two loop antennas 10 and 20 are configured and formed by winding a conducting wire once in a ring shape with different diameters, and are arranged concentrically on the same plane, and one signal source 100 or current input terminal T They are connected in series to the _in.

Specifically, the winding starting end of the large outer loop antenna 10 diameter, connected to a current input terminal T _in using the first feed line 30, the winding finish end, a second feed line 40 is used to connect to the winding start end of the inner loop antenna 20. Then, the winding end of the inner loop antenna 20 is connected to the current output terminal T _gnd connected to the ground using the third feed line 50.

Between the current output terminal T _gnd (unconnected ends of the inner loop antenna 20) a third end of the feed line 50, connecting the resistor R ₁ inserted to. The resistor R ₁ is for adjusting the value of the current I _T flows to the two loop antennas 10 and 20 connected in series. A combination of a capacitor, an inductor, or a resistor may be used.

Next, the current flowing through the antiphase double loop antenna will be described. When the signal source 100 to between the current input terminal T _in the current output terminal T _gnd is connected, the current I _T output from the signal source 100, to branch via a first feed line 30 Instead, it is fed to the outer loop antenna 10 and flows clockwise as viewed from above.

Then, the current I _T in which the outer loop antenna 10 1 lap are fed via a second feed line 40 to the inside of the loop antenna 20, opposite direction to the traveling direction of the current in the outer loop antenna 10 of the Flows counterclockwise.

Then, via a third feed line 50, back to the signal source 100 through the resistor R ₁ of the current adjustment.

  As described above, according to the present embodiment, since the two concentric loop antennas 10 and 20 in which currents flow in the opposite directions are connected in series, the power consumption of the antiphase double loop antenna can be reduced. That is, compared with the conventional antiphase double loop antenna shown in FIG. 10, the same magnetic field strength can be obtained with a small current.

[Second Embodiment]
FIG. 2 is a diagram showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. In this antiphase double loop antenna, the number of turns of the inner loop antenna 20 is increased from 1 to 4 times. The rest is the same as the first embodiment.

As described above, the magnetic field distribution of the antiphase double loop antenna changes according to the ratio γ = | m ₂ | / | m ₁ | of the magnetic moments m ₁ and m ₂ of the two loop antennas 10 and 20. Therefore, it is necessary to appropriately design the γ value in accordance with the application using the antiphase double loop antenna.

  In the present embodiment, as one method for increasing the γ value, only the inner ring current flowing through the inner loop antenna 20 is increased without increasing the outer ring current flowing through the outer loop antenna 10.

Specifically, only the inner loop antenna 20 is spirally wound four times to increase the inner ring current equivalently. Thus, since the inner ring current increases 4I _T from equivalently I _T, it is possible to increase the γ value.

  As described above, according to the present embodiment, since only the inner loop antenna 20 is wound a plurality of times, the γ value can be increased by an equivalent increase in the inner ring current, which is equivalent to a large amount of current with a small amount of current. Magnetic field strength can be obtained.

[Third Embodiment]
FIG. 3 is a diagram showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. In this reversed-phase double loop antenna, the number of turns of the outer loop antenna 10 is increased from 1 to 2, and the number of turns of the inner loop antenna 20 is increased from 1 to 8. The rest is the same as the first embodiment.

  In the present embodiment, as another method for increasing the γ value, both the outer ring current flowing through the outer loop antenna 10 and the inner ring current flowing through the inner loop antenna 20 are increased.

Specifically, the outer loop antenna 10 is wound twice in a spiral to increase the outer ring current equivalently. The inner loop current 20 is equivalently increased by winding the inner loop antenna 20 in a spiral shape eight times. Thus, the outer ring current is increased from I _T to 2I _T, for increasing values of the inner ring current is greater than (increased from I _T to 8I _T), can increase the γ value.

  As described above, according to the present embodiment, the outer loop antenna 10 is wound twice and the inner loop antenna 20 is wound eight times, so that the γ value can be increased by an equivalent increase in the inner ring current, A magnetic field strength equivalent to a large current amount can be obtained with a small current amount.

  The number of turns of each loop antenna 10, 20 described in the present embodiment or the second embodiment is an example. It is also possible to design the γ value to be decreased by making the number of turns of the outer loop antenna 10 smaller than the number of turns of the inner loop antenna 20.

[Fourth Embodiment]
FIG. 4 is a diagram showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. In this antiphase double loop antenna, the radius a ₁ of the outer loop antenna 10 is 10 cm, and the mean square radius a ₂ of the inner loop antenna 20 is 5 cm. The rest is the same as in the second embodiment.

Since the number of turns N of the inner loop antenna 20 is four, at this time, a ₁ ² = Na ₂ ² is established. That is, since the magnetic moments m ₁ and m ₂ of the two loop antennas 10 and 20 are equal and the γ value is 1, as described above, an attenuation factor of 100 dB / dec can be obtained far away.

As described above, according to the present embodiment, an integrated value obtained by integrating the value obtained by squaring the radius a ₁ of the outer loop antenna 10, the number of turns N of the inner loop antenna 20, and the square of the mean square radius a ₂ thereof. Therefore, an attenuation factor of 100 dB / dec can be obtained far away from the antiphase double loop antenna.

The radius a ₁ of the outer loop antenna 10, the number N of turns of the inner loop antenna 20, and the root mean square radius a ₂ described in the present embodiment are examples. If a ₁ ² = Na ₂ ² is established, the γ value becomes 1 even if the value of each radius and the number of turns are arbitrarily designed, and an attenuation factor of 100 dB / dec can be obtained at a distance.

[Fifth Embodiment]
FIG. 5 is a diagram showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. In this antiphase double loop antenna, the mean square radius a ₁ of the outer loop antenna 10 is 10 cm, and the mean square radius a ₂ of the inner loop antenna 20 is 5 cm. The rest is the same as in the third embodiment.

Since the number M of turns of the outer loop antenna 10 is two and the number of turns N of the inner loop antenna 20 is eight, Ma ₁ ² = Na ₂ ² is established at this time. That is, since the magnetic moments m ₁ and m ₂ of the two loop antennas 10 and 20 are equal and the γ value is 1, an attenuation factor of 100 dB / dec is obtained at a distance as in the fourth embodiment. be able to.

As described above, according to the present embodiment, the integrated value obtained by integrating the number of turns M of the outer loop antenna 10 and the square of the mean square radius a ₁ thereof, the number of turns N of the inner loop antenna 20, and the mean square thereof. Since the integrated value obtained by integrating the square of the radius a ₂ is equal, an attenuation factor of 100 dB / dec can be obtained far away from the antiphase double loop antenna.

Note that the number N of turns of the outer loop antenna 10 and its mean square radius a ₁ and the number of turns N of the inner loop antenna 20 and its mean square radius a ₂ described in the present embodiment are examples. If Ma ₁ ² = Na ₂ ² holds, the γ value is 1 even if the value of each radius and the number of turns are arbitrarily designed, and an attenuation factor of 100 dB / dec can be obtained at a distance.

[Sixth Embodiment]
6 and 7 are diagrams showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. These anti-phase double loop antennas further include a resistor R ₂ connected between the winding end of the outer loop antenna 10 and an arbitrary contact on the third feed line 50. The rest is the same as the second embodiment and the third embodiment.

  In the previous embodiments, the outer ring current flowing in the outer loop antenna 10 and the inner ring current flowing in the inner loop antenna 20 are necessarily equal, and the ratio of the outer ring current and the inner ring current is continuously set. It is difficult to change. However, depending on the application, it is necessary to precisely or continuously control the boundaries of the communication area.

Therefore, in the present embodiment, the resistor R ₂ is connected between the winding end of the outer loop antenna 10 and the arbitrary contact on the third feed line 50. Thus, the inner ring current, it becomes possible to current ΔI fraction smaller branching to the resistor R _2, it is possible to change the ratio of the inner and outer ring current.

According to more, the embodiment above, since the resistor R ₂ between any contacts on the winding termination end and the third feed line 50 of the outer loop antenna 10 is connected, outside the ring current And each current value of the inner ring current can be adjusted, and the current ratio can be changed.

The method of connecting the resistor R ₂ described in this embodiment is an example. Since it is sufficient that the inner ring current can be made smaller than the outer ring current, it is only necessary to be connected between the winding start end and the winding end end of the inner loop antenna 20. For example, you may connect between the arbitrary contact on the 2nd feed line 40, and the arbitrary contact on the 3rd feed line 50. FIG.

[Seventh Embodiment]
FIG. 8 is a diagram showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. This anti-phase double loop antenna is connected so that the branched loop antenna 60 branched from the first feed line 30 is included in the inner loop antenna 20.

  The branched loop antenna 60 is concentrically arranged on the same plane as the two loop antennas 10 and 20, is included in the inner loop antenna 20, and has a current in the same direction as the direction of current flowing through the inner loop antenna 20. Are connected in parallel to the outer loop antenna 10 and the inner loop antenna 20.

Specifically, the branch loop antenna 60 is arranged inside the inner loop antenna 20, and its winding start end is connected to the winding start end of the outer loop antenna 10 using the fourth feed line 70. The winding end is _connected to the current output terminal T _gnd using the fifth feed line 80. Between the current output terminal T _gnd (unconnected end of the branch loop antenna 60) at one end of the fifth feed line 80, connected by inserting a variable resistor R ₃ for current adjustment.

In the case of the present embodiment, the current supplied from the signal source 100 is branched into two parallel connection paths, and one current I ₁ flows through the outer loop antenna 10 and the inner loop antenna 20, and the other current I _2. Flows through the branch loop antenna 60. The current I _{2 that} has circulated through the branch loop antenna 60 passes through the variable resistor R ₃ and then merges with the current I _1, and returns to the signal source 100 together.

  As described above, according to the present embodiment, the branch loop antenna 60 in which the current flows in the same direction as the traveling direction of the current flowing in the inner loop antenna 20 is included in the inner loop antenna. Since this acts on an increase in the current flowing through 20, it is possible to obtain a large γ value without increasing the number of turns of the inner loop antenna 20.

[Eighth Embodiment]
FIG. 9 is a diagram showing a circuit configuration of the antiphase double loop antenna according to the present embodiment. This reverse phase double loop antenna is connected so that a branched loop antenna 60 branched from the first feed line 30 includes the inner loop antenna 20. The rest is the same as in the seventh embodiment.

  As described above, according to the present embodiment, the branch loop antenna 60 in which the current flows in the same direction as the traveling direction of the current flowing in the inner loop antenna 20 includes the inner loop antenna. Since this acts on an increase in the current flowing through 20, it is possible to obtain a large γ value without increasing the number of turns of the inner loop antenna 20.

  Finally, effects common to all the embodiments will be described again. According to each embodiment, two concentric loop antennas 10 and 20 having different diameters are connected in series, and currents flow in the opposite directions. Therefore, a reverse phase capable of generating a sharp magnetic field distribution with a small current consumption. A dual loop antenna can be provided.

  In each embodiment, a circular loop antenna has been described as an example. However, in addition to such a circular loop antenna, a regular dodecagonal antenna that is nearly circular, or a square that is not so circular. Even when the rectangular loop antennas are arranged concentrically, the same effect can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Outer loop antenna 20 ... Inner loop antenna 30 ... 1st feed line 40 ... 2nd feed line 50 ... 3rd feed line 60 ... Branch loop antenna 70 ... 4th feed line 80 ... 5th Feed lines R ₁ , R ₂ ... resistor R ₃ ... variable resistor

Claims (3)

An outer first loop antenna wound once or multiple times;
Wound one or more times wound, is disposed on the first loop antenna and concentric, connected in series with said first loop antenna, the traveling direction of the current input to the first loop antenna in opposite direction An inner second loop antenna through which current flows,
A resistor connected between both ends of the second loop antenna;
Connected in parallel to the first loop antenna and the second loop antenna, included in the second loop antenna or included in the second loop antenna, and in the same direction as the traveling direction of the current flowing through the second loop antenna A third loop antenna through which current flows,
An antiphase double loop antenna characterized by comprising: The antiphase double loop antenna according to claim 1, further comprising a resistor connected in series to the third loop antenna. 3. The reverse phase according to claim 1, wherein two integrated values obtained by integrating the number of turns and the square of the distance from the center to the loop antenna for the first loop antenna and the second loop antenna are equal to each other. Double loop antenna.

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