JP5285731B2 - Parasitic antenna and wireless communication system - Google Patents

Description

  The present invention relates to a parasitic antenna and a wireless communication system used, for example, for extending a communication range of a specific low-power wireless device.

  In recent years, the demand for wireless communication in a relatively narrow service area has increased. As a means for performing this type of wireless communication, for example, a specific low power wireless device is used. Since the specific low-power radio apparatus does not require a radio worker qualification or a radio station license, it can be widely used by general people.

  By the way, the specified low-power radio apparatus is defined by the Radio Law as “not having a feeder and grounding device” (Article 49-14 of Radio Equipment Regulations). Therefore, a parasitic antenna may be used for the specific low-power radio apparatus to extend its communication range (see, for example, Patent Document 1).

  The parasitic antenna described in Patent Document 1 includes a first antenna that is brought close to the antenna of the specific low-power radio apparatus, a support base that supports the first antenna, a feed line connected to the first antenna, And a second antenna connected to the feeder line. With this configuration, the antenna of the specific low-power radio apparatus mounted on the support base and the first antenna are electrostatically coupled. As a result, the parasitic antenna described in Patent Document 1 outputs a radio signal from the second antenna at the time of transmission by the specific low power radio apparatus, and inputs a radio signal from the second antenna at the time of reception by the specific low power radio apparatus. be able to.

JP 2000-216628 A

  However, as a result of examination of the parasitic antenna described in Patent Document 1 by the inventor of the present invention, the coupling loss between the antenna of the specific low-power radio apparatus and the first antenna is relatively large, and further improvement is necessary. It turned out to be.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a parasitic antenna and a wireless communication system that can reduce the coupling loss as compared with the conventional one.

A parasitic antenna according to claim 1 of the present invention is a parasitic antenna (1) that is added to a radio apparatus (2) having radio antennas (21, 22) and transmits / receives radio signals, Electrostatic coupling part (12) to be electrostatically coupled, magnetic coupling part (13) to be magnetically coupled to the radio antenna, conductor patterns (12, 13) provided on a dielectric substrate, and a through hole penetrating the radio antenna A printed circuit board (10) provided with a hole (11), wherein the electrostatic coupling portion is formed of a first conductor pattern (12) provided to face at least a part of the wireless antenna. The magnetic coupling portion has a configuration formed of a second conductor pattern (13) provided on the outer periphery of the through hole .

  With this configuration, the parasitic antenna according to the first aspect of the present invention includes the electrostatic coupling portion and the magnetic coupling portion, so that the coupling loss can be reduced as compared with the conventional one.

Further, this configuration, since parasitic antenna according to claim 1 of the present invention comprises a first conductive pattern and the radio antenna and the second conductor pattern for magnetically coupling for coupling radio antenna and the electrostatic, the conventional As a result, the coupling loss can be reduced.

In the parasitic antenna according to claim 2 of the present invention, the wireless device includes a circuit board (2b) to which one end (22a) of the wireless antenna is connected, and the magnetic coupling portion includes The wireless antenna is provided between an intermediate point from the other end (21a) to the one end to the one end, and the electrostatic coupling portion is provided on the other end side with respect to the magnetic coupling portion. ing.

With this configuration, the parasitic antenna according to claim 2 of the present invention is rationally coupled because it is electrostatically coupled on the side where the voltage of the parasitic antenna is high and magnetically coupled on the side where the magnetic field of the parasitic antenna is strong. Thus, an electrostatic coupling state and a magnetic coupling state can be obtained.

In the parasitic antenna according to claim 3 of the present invention, the wireless antenna has an L-shape, and the magnetic coupling portion is closer to the circuit board than the L-shaped bent portion (25a). The electrostatic coupling portion is provided on the other end side of the wireless antenna with respect to the L-shaped bent portion.

With this configuration, the parasitic antenna according to claim 3 of the present invention is rationally coupled because it is electrostatically coupled on the side where the voltage of the parasitic antenna is high and magnetically coupled on the side where the magnetic field of the parasitic antenna is strong. Thus, an electrostatic coupling state and a magnetic coupling state can be obtained.

A parasitic antenna according to a fourth aspect of the present invention includes a fixing means (32) for fixing the other end of the wireless antenna and the printed circuit board.

With this configuration, in the parasitic antenna according to claim 4 of the present invention, since the other end of the wireless antenna and the printed circuit board are fixed, a stable electrostatic coupling state and a magnetic coupling state can be obtained.

A wireless communication system according to claim 5 of the present invention includes the parasitic antenna according to any one of claims 1 to 5 and the wireless device to which the parasitic antenna can be added. It has the composition provided.

With this configuration, the wireless communication system according to the fifth aspect of the present invention includes the parasitic antenna having the electrostatic coupling unit and the magnetic coupling unit, so that the coupling loss can be reduced as compared with the conventional one.

  The present invention can provide a parasitic antenna and a wireless communication system having an effect that the coupling loss can be reduced as compared with the conventional one.

It is a block diagram in one Embodiment of the parasitic antenna which concerns on this invention. 1 is a configuration cross-sectional view of a printed circuit board and a wireless device antenna in an embodiment of a parasitic antenna according to the present invention. It is a block diagram of the printed circuit board in one Embodiment of the parasitic antenna which concerns on this invention. It is a figure which shows the experimental data regarding the coupling loss in one Embodiment of the parasitic antenna which concerns on this invention. It is a figure which shows the other aspect in one Embodiment of the parasitic antenna which concerns on this invention.

  Hereinafter, an embodiment of a parasitic antenna according to the present invention will be described with reference to the drawings.

  First, the overall configuration of the parasitic antenna according to the present embodiment will be described with reference to FIG. FIG. 1A is a plan view of a wireless device to which a parasitic antenna according to the present embodiment is attached, and FIG. 1B is a diagram viewed from the back side of the wireless device.

  As shown in FIG. 1, the parasitic antenna 1 in this embodiment is attached to a wireless device 2. The wireless device 2 includes a back panel 2 a and an antenna 20. This radio | wireless apparatus 2 operate | moves as a specific low power radio | wireless apparatus, for example. Here, the parasitic antenna 1 and the wireless device 2 constitute a wireless communication system according to the present invention.

  The parasitic antenna 1 includes a printed circuit board 10, a connector 16, a feeder line 17, and an external antenna 18. Here, each characteristic impedance of the connector 16, the feed line 17, and the external antenna 18 is configured to be 50Ω, for example. Although not shown in detail, the connector 16 includes a connector jack (printed circuit board 10 side) and a connector plug (feed line 17 side).

  The printed circuit board 10 is composed of a dielectric substrate, for example. The printed board 10 has a through hole 11 through which the antenna 20 passes. The antenna 20 passes through the through hole 11 and is bent in an L shape. Further, the printed circuit board 10 is fixed to the back panel 2 a by screws 31. Further, the printed circuit board 10 is fixed to the front end side of the antenna 20 by a cap 32. Here, the cap 32 constitutes a fixing means according to the present invention.

  FIG. 2 is a schematic cross-sectional view showing the mounting relationship between the printed circuit board 10 and the antenna 20. As shown in FIG. 2, the antenna 20 includes an antenna element 21, a metal lead wire 22, an antenna cover 23, a holding part 24, a root part 25, and a board connector 26.

  The antenna element 21 is composed of, for example, a rod-shaped metal body or a conductor pattern formed on a printed circuit board, and has a tip portion 21a. The antenna element 21 is electrically connected to one end of the metal lead wire 22.

  The other end of the metal lead wire 22 is connected to a board connector 26 attached to the circuit board 2b of the wireless device 2. The metal lead wire 22 has a tip 22a at the other end.

  In the present embodiment, the antenna length of the antenna 20, that is, the length from the tip portion 21a of the antenna element 21 to the tip portion 22a of the other end of the metal lead wire 22 is ¼ of the wavelength λ of the radio wave to be used. . The antenna element 21 and the metal lead wire 22 constitute a wireless antenna according to the present invention.

  The antenna cover 23 has a configuration that covers the entire antenna element 21, and is inserted and held in the holding portion 24.

  The holding part 24 is connected to the root part 25 via a fulcrum part 25 a of the root part 25. With this fulcrum portion 25a as a fulcrum, the antenna 20 can be positioned at any position within the range from the L shape shown in the figure to the linear shape shown by the broken line. Here, the fulcrum portion 25a corresponds to a bent portion according to the present invention. The antenna 20 also has a mechanism (not shown) that rotates around the central axis of the root portion 25 and can be positioned at an arbitrary rotational position.

  Next, the configuration of the printed circuit board 10 will be described. As shown in FIG. 3, the printed circuit board 10 includes a through hole 11 into which a root portion 25 (see FIG. 2) of the antenna 20 is inserted, conductor patterns 12 and 13 formed on a surface facing the antenna 20, A connector mounting portion 14 to which a connector jack (not shown) constituting the connector 16 (see FIG. 1B) is attached, and a through hole 15 through which a screw 31 (see FIG. 1B) passes.

  The conductor pattern 12 is a linear conductor pattern formed at a position facing the antenna element 21 (see FIG. 2). The distance from the conductor pattern 12 to the antenna element 21 is, for example, several millimeters, and both are electrostatically coupled. That is, the conductor pattern 12 constitutes the electrostatic coupling portion and the first conductor pattern according to the present invention.

  The conductor pattern 13 is provided on the outer periphery of the through hole 11. More specifically, the conductor pattern 13 is formed in a shape surrounding 90% of the entire periphery of the through hole 11. That is, the conductor pattern 13 has a function equivalent to that of a coil wound with 0.9 turns on the metal lead wire 22 (see FIG. 2), and a current corresponding to the magnetic flux generated in the metal lead wire 22 is obtained. Is generated. The conductor pattern 13 constitutes a magnetic coupling portion and a second conductor pattern according to the present invention.

  The pattern shapes of the conductor patterns 12 and 13, the distance between the conductor pattern 12 and the antenna element 21, the shape and position of the antenna element 21, and the like are based on, for example, VSWR (Voltage Standing Wave Ratio) characteristics. The VSWR characteristic is determined to be a shape that provides a practical value of 3 or less, which is a practical value.

  Here, the front end portion 21a of the antenna element 21 to the front end portion 22a of the metal lead wire 22 is referred to as the total length of the antenna, and the end portion 21a side of the antenna element 21 with respect to the middle point is referred to as the front end side of the antenna 20. The tip 22a side of the lead wire 22 is referred to as the root side of the antenna 20. Then, in this embodiment, the conductor pattern 13 as the magnetic coupling portion is closer to the root side than the midpoint of the total length of the antenna and has a length of about 1/3 of the total length of the antenna from the tip portion 22a of the metal lead wire 22. It is provided at a position (on the side of the distal end portion 22a from the fulcrum portion 25a). Then, the conductor pattern 12 as the electrostatic coupling portion is on the tip side from the midpoint of the antenna total length, and the position (fulcrum portion 25a) is approximately 2/3 of the antenna total length from the tip portion 21a of the antenna element 21. Rather than the tip 21a side).

  This configuration conforms to the theory that the tip side of the antenna has a higher voltage and a weaker magnetic field than the base side of the antenna. That is, the parasitic antenna 1 according to the present embodiment electrostatically couples the conductor pattern 12 and the antenna element 21 on the side where the antenna voltage is high, and connects the conductor pattern 13 and the antenna element 21 on the side where the antenna magnetic field is strong. It has the structure to combine. Therefore, in the parasitic antenna 1 according to the present embodiment, a reasonable electrostatic coupling state and magnetic coupling state can be obtained.

  As described above, the parasitic antenna 1 in the present embodiment has a simpler configuration than the conventional one.

  Specifically, when the conventional parasitic antenna described in the background art is applied to the wireless device 2, an antenna that is electrostatically coupled to the antenna 20 is separately required, and a support base that supports the antenna is provided. In addition, it is necessary to adjust the position of the wireless device 2 installed on the support base.

  On the other hand, in the parasitic antenna 1 according to the present embodiment, neither an antenna that is electrostatically coupled to the antenna 20 nor a support base is necessary, and the position adjustment of the wireless device 2 is not necessary. Therefore, the parasitic antenna 1 can be configured more simply than the conventional antenna.

  Furthermore, the parasitic antenna 1 in the present embodiment is configured to perform electrostatic coupling and magnetic coupling by attaching the printed circuit board 10 between the back panel 2a of the wireless device 2 and the antenna 20. Therefore, the parasitic antenna 1 does not give a sense of incongruity to the user of the wireless device 2 even if the printed circuit board 10 or the like is added to the wireless device 2.

  Next, experimental data regarding the coupling loss of the parasitic antenna 1 in the present embodiment will be described with reference to FIG.

  As shown in FIG. 4, in the parasitic antenna 1, the coupling loss is −5.5 dB when only the electrostatic coupling between the conductor pattern 12 and the antenna element 21 is performed. On the other hand, in the parasitic antenna 1, in the configuration in which the magnetic coupling between the conductor pattern 13 and the metal lead wire 22 is added to the electrostatic coupling between the conductor pattern 12 and the antenna element 21, the coupling loss is −4.8 dB. . Therefore, the parasitic antenna 1 according to the present embodiment can improve the coupling loss by 0.7 dB.

  Next, the process of attaching the parasitic antenna 1 to the wireless device 2 in the embodiment will be described with reference to FIGS. It is assumed that the antenna 20 is attached to the wireless device 2 by bending it into an L shape (see FIG. 1).

  First, the printed circuit board 10 in which the connector jack of the connector 16 is attached to the connector attaching portion 14 is prepared. Also, an assembly is prepared in which one end of the power supply line 17 is connected to the external antenna 18 and the connector plug of the connector 16 is connected to the other end of the power supply line 17.

  Next, the antenna 20 is raised in a direction perpendicular to the back panel 2 a, and the antenna 20 is inserted into the through hole 11 of the printed board 10.

  Subsequently, the printed circuit board 10 is fixed to the back panel 2 a using the screws 31. Although screwing is performed at one location, since the root portion 25 of the antenna 20 is inserted into the through hole 11 of the printed circuit board 10, accurate positioning can be easily performed.

  Next, the antenna 20 is bent in an L-shape, and a cap 32 is put on the tip of the antenna 20 to fix the antenna 20 to the printed board 10. Thereby, a stable electrostatic coupling state and a magnetic coupling state are obtained.

  Then, the connector plug of the connector 16 is attached to the connector jack on the printed circuit board 10.

  As described above, the process of attaching the parasitic antenna 1 to the wireless device 2 is very simple. Moreover, the process of removing the parasitic antenna 1 from the wireless device 2 is the reverse of the above process and can be performed very easily.

  Therefore, for example, when a service person visits the user's home of the wireless device 2 and performs an operation of adding the parasitic antenna 1 to the wireless device 2, the service person can easily perform in a short time without requiring special techniques and knowledge. Can be expanded. For example, the same applies to the case where the operator attaches the parasitic antenna 1 to the wireless device 2 when the wireless device 2 is shipped from the factory.

  As described above, the parasitic antenna 1 according to the present embodiment includes the conductor pattern 12 that is electrostatically coupled to the antenna element 21 and the conductor pattern 13 that is magnetically coupled to the antenna element 21. The coupling loss can be reduced with a simpler configuration.

  In the above-described embodiment, the conductor pattern 13 as the magnetic coupling portion has been described with an example in which the conductor pattern 13 is formed in a shape surrounding 90% of the entire periphery of the through hole 11. However, the present invention is not limited to this. Instead, the shape of the conductor pattern 13 can be arbitrarily determined in consideration of the magnetic coupling characteristic and the VSWR characteristic. For example, the conductor pattern 13 may have a shape that surrounds 50% of the entire periphery of the through hole 11. In addition, for example, a multilayer substrate may be used instead of the printed circuit board 10 so that the conductor pattern as the magnetic coupling portion has a function equivalent to that of a coil wound around the metal lead wire 22 with one or more turns. Good.

  Next, another aspect of the present embodiment will be described. In the above-described embodiment, an example in which the parasitic antenna 1 is coupled to the antenna 20 having the L-shape has been described. However, the present invention is not limited to this, and, for example, a linear radio shown in FIG. It can also be applied to an antenna.

  A linear antenna 50 shown in FIG. 5 includes an antenna element 51, a cover portion 52 that covers the antenna element 51, and a metal lead wire 53 that is electrically connected to the antenna element 51. In contrast to this configuration, the parasitic antenna includes printed circuit boards 41 and 42.

  That is, the printed circuit board 41 has a conductor pattern (not shown) that is electrostatically coupled to the printed circuit board 41 and the antenna element 51, similarly to the printed circuit board 10 described above. The printed circuit board 42 includes a through hole 42 a that allows the linear antenna 50 to pass therethrough, and a substrate surface 42 b on which a conductor pattern that is magnetically coupled to the antenna element 51 is formed. The parasitic antenna having this configuration can obtain the same effects as described above. The conductor pattern formed on the substrate surface 42b may be magnetically coupled to the metal lead wire 53.

  As described above, the parasitic antenna and the wireless communication system according to the present invention have an effect that the coupling loss can be reduced as compared with the conventional one, and the parasitic power that extends the communication range of the specific low-power wireless device. It is useful as an antenna and a wireless communication system.

1 Parasitic antenna (wireless communication system)
2 Radio equipment (wireless communication system)
2a Rear panel 2b Circuit board 10, 41, 42 Printed circuit board 11, 15, 42a Through hole 12 Conductor pattern (electrostatic coupling portion, first conductor pattern)
13 Conductor pattern (magnetic coupling part, second conductor pattern)
14 Connector mounting portion 16 Connector 17 Feed line 18 External antenna 20, 50 Antenna 21, 51 Antenna element (wireless antenna)
21a Tip (the other end of the wireless antenna)
22, 53 Metal lead wire (wireless antenna)
22a Tip (one end of the wireless antenna)
23 antenna cover 24 holding part 25 root part 25a fulcrum part (bending part)
26 Board connector 32 Cap (fixing means)
42b Substrate surface

Claims (5)

A parasitic antenna (1) that is attached to a radio device (2) having radio antennas (21, 22) and transmits and receives radio signals,
An electrostatic coupling portion (12) for electrostatic coupling with the wireless antenna;
A magnetic coupling portion (13) magnetically coupled to the wireless antenna;
A printed circuit board (10) provided with a conductor pattern (12, 13) provided on a dielectric substrate and a through hole (11) through which the wireless antenna penetrates;
With
The electrostatic coupling portion is formed of a first conductor pattern (12) provided to face at least a part of the wireless antenna,
The parasitic antenna according to claim 1, wherein the magnetic coupling portion is formed of a second conductor pattern (13) provided on an outer periphery of the through hole . The wireless device includes a circuit board (2b) to which one end (22a) of the wireless antenna is connected,
The magnetic coupling unit is provided between an intermediate point from the other end (21a) of the wireless antenna to the one end to the one end,
The parasitic antenna according to claim 1, wherein the electrostatic coupling portion is provided on the other end side with respect to the magnetic coupling portion . The wireless antenna has an L-shape,
The magnetic coupling portion is provided closer to the circuit board than the L-shaped bent portion (25a),
The parasitic antenna according to claim 2, wherein the electrostatic coupling portion is provided on the other end side of the wireless antenna with respect to the L-shaped bent portion . The parasitic antenna according to any one of claims 1 to 3, further comprising fixing means (32) for fixing the other end of the wireless antenna and the printed circuit board . The parasitic antenna according to any one of claims 1 to 4,
A wireless communication system comprising: the wireless device to which the parasitic antenna can be added.

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