JPH0715228A - Antenna for radio communication - Google Patents

Abstract

PURPOSE:To unnecessitate forbidden bands over a wide range and to reduce erroneous communication by arranging the opening face of a first loop antenna while facing it to the opening face of a second loop antenna. CONSTITUTION:A transmitted signal from a transmitter/receiver 1 is impressed to loop antenna parts 2 and 3 with the same phase. At such a time, the loop antenna parts 2 and 3 are provided with 8-shaped directivity and the transmitting current of the loop antenna part 2 is provided with the same phase as the transmitting current of the loop antenna part 3 so that the electric field component and magnetic field component of an electromagnetic wave transmitted from the loop antenna part 2 can be provided with the same phase of the electric field component and magnetic field component of an electromagnetic wave transmitted from the loop antenna part 3. As a result, the electric field component and magnetic field component of the electromagnetic wave to be generated are overlapped each other, and a communication area becomes a pillar-shaped area. At such a time, the characteristics of the loop antenna parts 2 and 3 are synthesized inside this area, and the electric field component and magnetic field component of the electromagnetic wave are made stronger in comparison with the peripheral parts. In the case of receiving the electromagnetic wave, reception sensitivity is made higher in comparison with the periphery as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication antenna used for communication using electromagnetic waves as a medium.

[0002]

2. Description of the Related Art As an antenna for wireless communication, for example, FIG.
There is something like. This wireless communication antenna
The loop antenna section 71 is used and is connected to a transmission / reception device 72 for transmitting and receiving radio waves. The loop antenna portion 71 is centered on the opening surface 71A for transmitting and receiving radio waves, and is perpendicular to the opening surface 71A.
As shown in FIG.
Have 3.

As shown in FIG. 9, some wireless communication antennas are provided with loop antenna units 91 and 92 which are connected to the transmitter / receiver 93 and are installed horizontally. The communication area by this wireless communication antenna is
As shown in FIG. 10, an area 94 is obtained by combining the communication areas 73 shown in FIG. Further, as shown in FIG. 11, there is also one in which the loop antenna units 91 and 92 of FIG. 9 are installed in the vertical direction. These wireless communication antennas
A wider communication area can be secured as compared with the wireless communication antenna of FIG. 7.

Such a radio communication antenna has a wide range of applications and is used in various devices.

[0005]

By the way, an antenna for wireless communication as shown in FIG. 7 is used for gate management using a data carrier (not shown) for generating a magnetic field as shown in FIG. 12, for example. Sometimes. here,
The loop antenna unit 71 receives the magnetic field component of electromagnetic waves. In this case, the communication area 73 in the direction perpendicular to the opening surface 71A of the loop antenna unit 71 has a symmetrical 8-shape. Therefore, in order to prevent erroneous communication, there is a detection area around the place where the person 100 to be detected enters, and it is necessary to provide a wide prohibition band for prohibiting the person 100 to be detected from entering.

Also in the radio communication antennas shown in FIGS. 9 and 11, it is necessary to provide a wider forbidden band as the communication area becomes wider.

It is an object of the present invention to provide a radio communication antenna which eliminates such drawbacks, does not require a wide band forbidden band, and can reduce false communication.

[0008]

In order to achieve the object, the present invention has an opening surface for transmitting and receiving electromagnetic waves as a center,
In a wireless communication antenna including a first loop antenna section and a second loop antenna section having a communication area based on the directivity of a figure 8 characteristic, the opening surface of the first loop antenna section faces the opening surface of the second loop antenna section. I arranged them together.

[0009]

With this configuration, the columnar portion from the opening surface of the first loop antenna portion to the opening surface of the second loop antenna portion is used as the communication area. The first loop antenna section and the second loop antenna section are symmetrical with respect to the aperture plane.
It has the directivity of the character. Therefore, in the columnar communication area, the characteristics of the first loop antenna section and the characteristics of the second loop antenna section are combined, so that the communication sensitivity is increased.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. This wireless communication antenna is used by being connected to a transmitter / receiver 1 for transmitting and receiving electromagnetic waves, and includes a loop antenna unit 2 as a first loop antenna unit and a loop antenna unit 3 as a second loop antenna unit.

The loop antenna section 2 has a communication area based on the directivity of an 8-shaped characteristic as shown in FIG. The opening surface 2A of the loop antenna unit 2 has a circular shape.

Like the loop antenna unit 2, the loop antenna unit 3 has a communication area based on the directivity of the figure 8 characteristic and has a circular opening surface 3A. The opening surface 3A of the loop antenna part 3 is arranged so as to face the opening surface 2A of the loop antenna part 2.

The loop antenna section 3 is connected in series to the loop antenna section 2, as shown in FIG. At this time, the capacitor 4 is connected in series to the series circuit of the loop antenna unit 3 and the loop antenna unit 2. The capacitor 4 causes series resonance together with the coiled loop antenna unit 2 and the loop antenna unit 3 to enhance the efficiency of the antenna.

Loop antenna section 3 and loop antenna section 2
Other than the connection shown in FIG. 2, the connection shown in FIG. Here, the loop antenna unit 3 is connected to the loop antenna unit 2 in parallel. Further, a series resonance capacitor 4 is connected in series to the parallel circuit.

A transmitting / receiving device 1 flowing through the loop antenna section 3
Is in phase with the current flowing through the loop antenna unit 2. As a result, the direction of the electric field component or the magnetic field component of the electromagnetic wave transmitted by the loop antenna unit 3 is in phase with the direction of the electric field component or the magnetic field component of the electromagnetic wave generated by the loop antenna unit 2. The winding direction of the loop antenna unit 3 is the same as the winding direction of the loop antenna unit 2. As a result, when the electric field component or the magnetic field component of the electromagnetic wave is received, the phase of the reception current flowing from the loop antenna unit 3 to the transmission / reception device 1 becomes the same phase as the reception current of the loop antenna unit 2.

The operation of the embodiment having such a configuration will be described.

First, in the case of transmitting an electromagnetic wave using the wireless communication antenna of this embodiment, it is as follows. The transmission signal from the transmitter / receiver 1 is applied to the loop antenna unit 2 and the loop antenna unit 3 in phase.

At this time, since the loop antenna units 2 and 3 have the directivity of the figure 8 characteristic as shown in FIG.
The electromagnetic waves transmitted from the loop antenna units 2 and 3 are also in the same state as in FIG. At this time, the loop antenna unit 2
Since the transmission current applied to the loop antenna unit 3 is in phase with the transmission current applied to the loop antenna unit 3, the electric field component and the magnetic field component of the electromagnetic wave transmitted from the loop antenna unit 2 are electromagnetic waves transmitted from the loop antenna unit 3. It has the same phase as the electric field component and magnetic field component of.

As a result, the electric field component and the magnetic field component of the generated electromagnetic waves overlap each other, and the communication area becomes a columnar area 5 as shown in FIG. At this time, in the columnar communication area 5, the characteristics of the loop antenna unit 2 and the characteristics of the loop antenna unit 3 are combined, and the electric field component and the magnetic field component of the electromagnetic wave become stronger than those in the peripheral portion.

Next, when an electromagnetic wave is received using the wireless communication antenna of this embodiment, the following is performed. The directivity of the loop antenna units 2 and 3 when receiving electromagnetic waves is
This is the same as when transmitting electromagnetic waves, and is as shown in FIG. Therefore, the communication area for reception formed by the loop antenna units 2 and 3 has a columnar shape as in FIG.
At this time, since the reception current of the loop antenna unit 2 received and generated in the columnar communication area 5 is in phase with the reception current of the loop antenna unit 3, in the columnar communication area 5, compared to the surroundings, The reception sensitivity is high.

As described above, according to this embodiment, it is possible to form the columnar communication area 5 having a large difference in transmission / reception level compared with the surrounding area.

Although the capacitor 4 for series resonance is used in this embodiment, the capacitor 4 may be omitted. Further, at the time of reception, the capacitor 4 may be switched and used for parallel resonance.

Further, in this embodiment, one transmitting / receiving device 1 is used, but the present invention is not particularly limited to this, and the wireless communication antenna of this embodiment is attached to a transmitting device or a receiving device and used. Good.

Further, although the loop antenna units 2 and 3 are circular in this embodiment, the present invention is not limited to this, and various loop antenna units such as rectangles, squares and triangles may be used. You may use.

FIG. 5 is a diagram showing an example in which the radio communication antenna of this embodiment is applied to gate management using a data carrier (not shown). In this application example, a magnetic field is particularly used.

Here, the loop antenna section 2 and the loop antenna section 3 are arranged so as to sandwich an object such as a person, an animal, or a car, which passes through a gate (not shown), for example, the person 100. Since the magnetic field reception sensitivity is higher in the columnar communication area 5 than in the surrounding area, the person 100 that passes the gate can detect the person 100 regardless of where on the body the data carrier is attached. . In addition, since the receiving sensitivity is low in the peripheral portion other than the columnar communication area 5,
The chance of accessing person 100 who does not pass through the gate is extremely small. Further, since the communication area 5 has a columnar shape, a wide forbidden band is not required, and the place for disposing the loop antenna unit 2 and the loop antenna unit 3 can be made smaller than in the conventional case.

In this application example, the two wires are bundled so that the directions of the currents flowing through the connecting wires from the loop antenna units 2 and 3 to the receiving apparatus 1 are reversed, and the area formed by these wires is reduced. So that the magnetic field component generated in the connection line can be ignored.

FIG. 6 is a diagram showing an example in which the wireless communication antenna of this embodiment is applied to an automatic ticket gate installed in a train station or the like. In this application example, the loop antenna unit 11 is provided above and below a portion through which the user's path 101 passes.
The loop antenna unit 12 is arranged, and the loop antenna units 11 and 12 are connected to the receiving device 13. The loop antenna parts 11 and 12 are long in the passing direction A of the path 101. The communication area 13 formed by the loop antenna units 11 and 12 having such a shape is the path 101.
Of the loop antenna parts 11 and 12
It is possible to reduce the occurrence of erroneous access without providing a wide forbidden zone around the.

[0030]

As described above, according to the present invention, when the columnar portion formed by the first loop antenna section and the second loop antenna section is used as the communication area, the sensitivity of the columnar communication area is improved. , Higher than the surrounding area.
As a result, the communication area can be limited to this columnar portion, a wide band forbidden band is unnecessary, and erroneous communication can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a connection of a loop antenna unit.

FIG. 3 is a diagram showing a connection of a loop antenna unit.

FIG. 4 is a diagram showing a communication area of the embodiment of FIG.

FIG. 5 is a diagram showing a state in which the embodiment of FIG. 1 is applied to gate management.

FIG. 6 is a diagram showing a state in which the embodiment of FIG. 1 is applied to an automatic ticket gate.

FIG. 7 is a diagram showing an example of a conventional wireless communication antenna.

FIG. 8 is a diagram showing a communication area of the wireless communication antenna of FIG.

FIG. 9 is a diagram showing another example of a conventional wireless communication antenna.

FIG. 10 is a diagram showing a communication area of the wireless communication antenna of FIG.

FIG. 11 is a diagram showing another example of a conventional wireless communication antenna.

FIG. 12 is a diagram showing an application example of a conventional wireless communication antenna.

[Explanation of symbols]

 2 Loop antenna part 2A opening face 3 Loop antenna part 3A opening face

Claims (1)

[Claims] 1. A center of an opening for transmitting and receiving electromagnetic waves,
In a wireless communication antenna including a first loop antenna part and a second loop antenna part having a communication area based on a directivity of a figure 8 characteristic, the opening surface of the first loop antenna part is the opening surface of the second loop antenna part. An antenna for wireless communication, which is arranged facing each other.