JP2012169944A - Antenna device, and wireless communication device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiband-adaptive antenna device having an extremely simple configuration without providing a plurality of antenna elements.SOLUTION: In an antenna device in a wireless communication device configured so that a monopole antenna 1 for a predetermined frequency band is fixed to a circuit board 2 by a fixing metal fitting 5, the fixing metal fitting 5 is utilized as an another loop-like antenna having a different band from the frequency band of the monopole antenna 1. Such the configuration enables a multiband-adaptive antenna device without specially providing another antenna.

Description

  The present invention relates to an antenna device and a wireless communication device using the antenna device, and more particularly to an antenna structure used in a wireless communication device that supports multiband.

  Recently, in wireless communication devices such as wireless LAN routers, in order to support a MIMO (Multiple Input Multiple Output) communication method and a WiMAX (Worldwide Interoperability Access) communication method, a plurality of communication methods (multiband). As the number of antennas corresponding to the number increases, it is necessary to devise in the case where these antennas are built in the apparatus.

  As the size of wireless communication devices is reduced, the area for incorporating these antennas into the device has also become narrower. The wireless LAN router may need to be compatible with multimedia broadcasts where services will be started in the future, and thus further antenna miniaturization is required.

  As related techniques, techniques disclosed in Patent Documents 1 to 3 are listed. The technology disclosed in Patent Document 1 provides a shape of a composite planar antenna that can be used for a plurality of communication services with an apparently one antenna.

  Moreover, the technique disclosed in Patent Document 2 is intended to reduce the size of the device by using a part of a metal component provided in the wireless communication device as an antenna. Furthermore, the technique of Patent Document 3 is such that a monopole antenna and a loop antenna are formed on a circuit board, and the operating frequency can be adjusted over a wide range by combining both antennas.

Japanese Patent Application Laid-Open No. 08-237025 JP 2008-1224797 A JP 2010-239246 A

  As described above, in a wireless communication device such as a wireless LAN router, in order to support a plurality of types of communication methods, it is necessary to incorporate an antenna corresponding to each of these communication methods. As a result, the area in which the antenna is built is narrowed and limited. Therefore, a device such as further miniaturization of the antenna is required.

  In the technique of the above-mentioned Patent Document 1, the shape of the composite planar antenna is devised so as to be able to cope with a plurality of communication systems with an apparently single antenna. It is considered as one antenna, and the structure is complicated.

  Moreover, in the technique of Patent Document 2, a part of the metal parts is used as an inverted F antenna or a loop antenna, but it is not multiband compatible with a plurality of communication methods. Furthermore, in the technique of Patent Document 3, two antenna elements, a monopole antenna and a loop antenna, are incorporated on a circuit board and combined to achieve multi-band compatibility. There are a plurality of antenna elements. The number of elements does not decrease.

  Accordingly, an object of the present invention is to provide a multiband antenna device and a wireless communication device using the antenna device with a very simple configuration without providing a plurality of antenna elements.

An antenna device according to the present invention includes:
An antenna device in a wireless communication device in which an antenna for a predetermined frequency band is fixed to a circuit board with a fixing bracket,
The fixing bracket is used as another antenna having a band different from the frequency band of the antenna.

  A wireless communication device according to the present invention is characterized by using the antenna device described above.

  According to the present invention, there is an effect that the number of antenna parts can be reduced by using a fixing bracket for fixing an antenna for a predetermined frequency band as an antenna for another frequency band.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of one embodiment of this invention, (A) is the top perspective view, (B) is a front view including a partial enlarged view. It is a figure which shows the example of the structure of the antenna part of the wireless LAN router which has a monopole antenna relevant to this invention, (A) is the top perspective view, (B) is a front view including a partial enlarged view. It is a figure which shows the simulation result of the antenna apparatus shown in FIG. It is a figure which shows the modification of one embodiment of this invention, and is a front view containing a partial enlarged view. It is a figure which shows the simulation result of the antenna apparatus shown in FIG. It is a figure which shows the other modification of one embodiment of this invention, and is a front view containing a partial enlarged view. It is a figure which shows the simulation result of the antenna apparatus shown in FIG. It is a figure which shows other embodiment of this invention, and is a front view containing a partially expanded view. It is a figure which shows the simulation result of the antenna apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Prior to that, the structure of the antenna portion of a wireless LAN router having a monopole antenna related to the present invention will be described with reference to FIG. explain. 2A and 2B are diagrams showing an example of the antenna structure, in which FIG. 2A is a plan perspective view and FIG. 2B is a front view including a partially enlarged view.

  For example, when a multimedia broadcast antenna using the 200 MHz band is mounted on a wireless LAN router device, it is difficult to incorporate this antenna. Therefore, as shown in FIG. Can be implemented outside the apparatus. In FIG. 2, when the monopole antenna 1 with the coaxial cable 3 is used, a fixing bracket 5 is required to connect the monopole antenna 1 and the GND (ground) of the circuit board 2 of the apparatus.

  In FIG. 2, the monopole antenna 1 is connected to a coaxial connector 4 provided on the circuit board 2 via a coaxial cable 3. A monopole antenna 1 is fixed to the circuit board 2 via a fixing bracket 5 at an upper corner portion of the circuit board 2. The fixing metal 5 includes a pair of leg portions 52 and 53 having one end fixed to the circuit board 2 and an antenna mounting plate portion 51 attached to the other end of the leg portions 52 and 53.

  In the present invention, the fixture 5 of the monopole antenna 1 shown in FIG. 2 is used as an antenna for a wireless LAN or the like. That is, by modifying the shape of the fixture 5 as shown in FIG. 1, it can be used as an antenna for a wireless LAN, etc., and the number of antenna components can be reduced and the antenna area can be reduced. .

  1A and 1B are views showing the structure of an embodiment of the present invention. FIG. 1A is a plan perspective view thereof, and FIG. 1B is a front view including a partially enlarged view. 1, the same parts as those in FIG. 2 are denoted by the same reference numerals.

  Referring to FIG. 1, an antenna portion of a wireless LAN router device having a monopole antenna 1 is shown. In the case of a multimedia broadcast antenna using the 200 MHz band, considering the size of the wireless LAN router, the possibility of mounting a monopole antenna outside the device is high as described above.

  Such a wireless LAN router device includes a monopole antenna 1, a circuit board 2, a coaxial connector 4 that connects a radio circuit for multimedia broadcasting (not shown) and the monopole antenna 1, an antenna GND, and a board GND. It is composed of a fixture 5 for connecting and fixing the monopole antenna 1 and a matching circuit 6 for matching the wireless circuit 7 for wireless LAN.

  In addition to the pair of leg portions 52 and 53 and the antenna mounting plate portion 51 described with reference to FIG. A third leg portion 54 is connected and the other end is connected to the antenna mounting plate portion 51.

  The signal from the wireless circuit 7 for wireless LAN is inputted from the right end leg 53 of the fixing bracket 5 through the matching circuit 6, and the other legs 52 and 54 of the fixing bracket 5 are connected to the circuit. It is connected to the GND of the substrate 2. Note that the wireless circuit 7 for wireless LAN here is well known to those skilled in the art and is not directly related to the present invention, so the description thereof will be omitted.

  Next, the operation as an antenna will be described. A signal from the wireless LAN wireless circuit 7 is fed from the right end leg 53 of the fixture 5 via the matching circuit 6. Here, assuming that the plate portion 51 of the fixture 5 and the (third) leg portion 54 in the center thereof and the circuit board 2 are set so as to have one wavelength in a loop shape, It will operate as a loop antenna at frequency.

  Since the antenna current flows also on the left end leg portion 52 side of the coaxial cable 3 and the fixing bracket 5, an ideal operation cannot be expected, but the influence on the whole is small. Therefore, the required wireless LAN antenna characteristics can be obtained.

  A simulation result of the operation of such a loop antenna is shown in FIG. As shown in FIG. 3, it can be confirmed that the characteristics of the band (2.4 to 2.5 GHz) necessary for the wireless LAN are secured.

  Here, FIG. 5 shows the result of the simulation when the method of routing the coaxial cable 3 is changed as shown in FIG. Moreover, the result of the simulation in the case where the method of routing the coaxial cable 3 is changed as shown in FIG. 6 is shown in FIG. 4 shows an example in which the coaxial cable 3 is routed outside the circuit board 2 instead of being linear as shown in FIG. 1, and FIG. 6 shows an example in which the coaxial cable 3 is routed inside the circuit board 2. It is.

  As is apparent from the simulation results of FIGS. 5 and 7, as shown in FIGS. 4 and 6, it can be confirmed that even if the routing of the coaxial cable 3 is slightly changed, the effect on the loop antenna characteristics is small. Become.

  As described above, in the present invention, the number of antenna components can be reduced by using the monopole antenna fixing bracket 5 as a loop antenna for other frequency bands.

  Considering the case where another antenna is mounted as a wireless LAN antenna, the fixing bracket 5 is regarded as the same as the GND of the circuit board 2 from the antenna, and therefore the antenna and the fixing bracket 5 are mounted with a distance. However, in the present invention, such a region is not required. Therefore, according to the present invention, it is possible to reduce the antenna area and downsize the device itself.

  Next, another embodiment of the present invention will be described with reference to FIG. FIG. 8 is a front view including a partially enlarged view showing the configuration of another embodiment of the present invention, and the same parts as those in FIG.

  As shown in FIG. 8, the shape of the fixture 5 shown in FIG. 1 is modified to add one more loop antenna. That is, a parallel member 55 is added in parallel with the plate portion 51 between the leg portions 53 and 54 of the fixture 5. As a result, a second loop-shaped antenna having one wavelength in the 5 GHz band is added by the leg portion 53, the plate portion 51, the leg portion 54, and the added parallel member 55. .

  Of course, the first loop antenna of the 2.4 GHz band is formed by the leg portion 53, the plate portion 51, the leg portion 54, and the circuit board 2 as in the previous embodiment.

  The simulation result in the embodiment in this case is shown in FIG. As is clear from FIG. 9, in this example, a dual-band antenna capable of supporting not only the 2.4 GHz band but also the 5 GHz band can be formed by using the fixing bracket 5. An effective antenna is obtained.

  In the above embodiment, the wireless LAN router has been described as an example of the wireless communication device. However, the present invention is not limited to this and can be applied to a multiband compatible wireless communication device. In addition, as an antenna element to be fixed to the wireless communication apparatus with a fixing bracket, a monopole antenna is taken as an example. Obviously, various modifications are possible.

1 Monopole antenna
2 Circuit board
3 Coaxial cable
4 Coaxial connector
5 Fixing bracket
6 Matching circuit
7 Wireless circuit for wireless LAN
51 Antenna mounting plate 52, 53, 54 Leg
55 Parallel members

Claims (6)

An antenna device in a wireless communication device in which an antenna for a predetermined frequency band is fixed to a circuit board with a fixing bracket,
An antenna device characterized in that the fixing bracket is used as another antenna having a band different from the frequency band of the antenna.   The antenna device according to claim 1, wherein the another antenna is a loop antenna formed by the fixing metal fitting and the circuit board.   The another antenna is a second loop antenna formed by forming a loop with only the fixing bracket, in addition to the first loop antenna formed by the fixing bracket and the circuit board. The antenna device according to claim 1.   A wireless communication device using the antenna device according to claim 1.   The wireless communication apparatus according to claim 4, wherein the wireless communication apparatus is a wireless LAN router, and the loop antenna is an antenna for a wireless LAN.   6. The wireless communication apparatus according to claim 5, wherein the antenna for the predetermined frequency band is a multimedia monopole antenna.

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