JP4218044B2 - 3D antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional antenna that can be particularly suitably used for a contactless IC card such as a tag attached to an article, a small portable communication terminal, and the like.
[0002]
[Prior art]
In a distribution system, inventory management system, etc., contactless IC card type tags used on items to identify the type and destination of the item, small portable communication terminals, etc. A suitable antenna is incorporated.
[0003]
A conventional antenna is formed in a two-dimensional coil shape, functions as a loop antenna, and is combined with a communication IC module to receive incoming radio waves from outside and supply operating power to the IC module. In addition, radio waves for information transmission can be transmitted to and received from external devices.
[0004]
[Problems to be solved by the invention]
According to such a conventional technique, since the antenna functions as a loop antenna, there is a problem that the directivity is sharp, the transmission / reception direction of radio waves is limited to be narrow, and the stability of communication may be lacking.
[0005]
Therefore, in view of the problems of the prior art, an object of the present invention is to combine the first, second, and third coils arranged in the X-axis direction, the Y-axis direction, and the Z-axis direction, so that the entire three-dimensional space can be obtained. An object of the present invention is to provide a three-dimensional antenna that can easily realize a good omnidirectional characteristic with respect to a direction.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the configuration of the present invention is such that the first, second, and third coils arranged in the X-axis direction, the Y-axis direction, and the Z-axis direction serve as antenna elements, Each of the coils 2 is an individual cylindrical cored coil, the third coil is a disk-shaped coil whose axial length is shorter than the winding diameter, and each core is formed of ferrite. The gist of the first, second, and third coils is that they are connected in series in random order and connected to a common communication IC module.
[0008]
The first, second, and third coils may be mounted on a common substrate, and the third coil core has an axial length of each of the first and second coil cores. The same diameter may be set.
[0009]
[Action]
According to such a configuration of the invention, the first, second, and third coils are arranged in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, and in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively. Since it operates as an antenna element having directional characteristics, the directional characteristics can be combined by combining them to realize a good omnidirectional characteristic in all directions in the three-dimensional space as a whole.
[0010]
The first, second, and third coils can be connected in series to increase the overall inductance, easily resonate with the operating frequency, and easily match with the external circuit. Note that the first, second, and third coils may be connected in series in any order.
[0011]
Each of the first, second, and third coils can be further increased in inductance as a cored coil. Note that the core at this time is preferably formed of a low-loss, high-magnetic material containing ferrite.
[0012]
The relative positions of the first, second, and third coils mounted on the common substrate can be correctly positioned via the substrate, and can be easily connected via the pattern on the substrate. However, an insulating printed board can be used as the board.
[0013]
If the axial length of the third coil is set to be equivalent to the diameter of the first and second coils, when the third coil is installed on the XY plane including the first and second coils, It does not protrude excessively up and down, and the overall thickness can be minimized.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
The three-dimensional antenna AT is configured by arranging the first, second, and third coils Lx, Ly, and Lz in the X-axis direction, the Y-axis direction, and the Z-axis direction (FIGS. 1 and 2). However, the X axis, the Y axis, and the Z axis are virtual axes in an appropriate three-dimensional space. The first, second, and third coils Lx, Ly, and Lz are mounted on the common substrate 11.
[0016]
The substrate 11 is formed from a suitable insulating printed circuit board, and linear patterns 11a and 11b and lands 11c are formed. The first and second coils Lx and Ly are inserted into individual cylindrical cores CAx and CAy, respectively, and are formed into core-containing coils having a diameter Dx = Dy. The third coil Lz is held by a disk-shaped core CAz with upper and lower flanges. The disk-shaped core CAz has an axial length Hz shorter than the winding diameter and is set to an axial length Hz≈Dx = Dy. One flange of the core CAz has an IC module for communication. M is mounted.
[0017]
In the IC module M, capacitors for resonance and impedance matching C1 and C2 and a communication IC chip M1 are integrated (FIGS. 1 and 3). The IC module M is directly connected to one end of the third coil Lz, and is connected to one end of the second coil Ly through the pattern 11b on the substrate 11. The other end of the third coil Lz is connected to one end of the first coil Lx via the pattern 11a on the substrate 11, and the other end of the first coil Lx is connected to the first coil 11 via the land 11c on the substrate 11. The other end of the second coil Ly is connected. That is, the first, second, and third coils Lx, Ly, and Lz are connected in series via the patterns 11a and 11b and the land 11c. The first, second, and third coils Lx, Ly, and Lz are set to have substantially the same inductance, and are fixed on the substrate 11 together with the IC module M through an appropriate sealing material SL. (FIG. 2).
[0018]
An example of transmission / reception sensitivity test data of the three-dimensional antenna AT is shown in FIG. However, as shown in FIG. 4 (B), when the three-dimensional antenna AT and the reader / writer T that transmits and receives the radio wave S having a frequency of 125 kHz are moved relative to each other in the lateral direction, as shown in FIG. The communicable range is illustrated by a horizontal distance Lh and a vertical distance Lv. In addition, the dashed-dotted line of FIG. 4 (A) is the comparison data by only the 3rd coil Lz.
[0019]
That is, according to FIG. 4A, although the three-dimensional antenna AT is slightly inferior in vertical transmission / reception sensitivity as compared with the case of only the third coil Lz (the dashed line in the figure), It can be seen that the stable communicable range can be expanded to a range of about 30% increase, and good communication performance can be maintained over a wide range of the horizontal distance Lh unless the vertical distance Lv is excessive.
[0020]
FIG. 5 shows other transmission / reception sensitivity test data. In FIG. 5A, as shown in FIG. 5B, the reader / writer T similar to that in FIG. 4 is moved in the direction of the relative angle θ with respect to the three-dimensional antenna AT, and the stable communicable range between the two is set as the transmission / reception distance. It is illustrated as Ls, horizontal distance Lh, and vertical distance Lv. According to FIG. 5A, in the three-dimensional antenna AT, the transmission / reception distance Ls is reduced by about 10% at the relative angle θ = 90 ° as compared with the case of only the third coil Lz (the dashed line in the figure). However, at the relative angle θ = 60 °, the transmission / reception distance Ls is substantially the same, and at the relative angles θ = 45 ° and θ = 30 °, the transmission / reception distance Ls is increased by about 50% and about 75%, respectively. It can be seen that a transmission / reception distance Ls of about 200% can be obtained at the relative angle θ = 0 °.
[0021]
That is, the three-dimensional antenna AT can realize good omnidirectional characteristics in all directions of the three-dimensional space including the X-axis direction, the Y-axis direction, and the Z-axis direction.
[0022]
The three-dimensional antenna AT according to the present invention is a non-contact type that is incorporated together with a communication IC module M in a commuter pass, a commuter pass, an identification card for verifying the identity of a carrier, a tag attached to an article, etc. With this IC card, it is possible to ensure good communication performance with the corresponding reader / writer T regardless of the moving direction or posture thereof. The same applies to portable communication terminals that communicate with external devices.
[0023]
【The invention's effect】
As described above, according to the present invention, the first, second, and third coils arranged in the X-axis direction, the Y-axis direction, and the Z-axis direction are used as antenna elements. The second and third coils synthesize the respective directional characteristics, and as a whole, can realize good omnidirectional characteristics in all directions of the three-dimensional space. When applied to a portable communication terminal or the like, there is no restriction on the transmission / reception direction of radio waves, and there is an excellent effect that the stability of communication can be greatly improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of the overall configuration. FIG. 2 is an enlarged cross-sectional view corresponding to the line AA in FIG. 1. FIG. 3 is an equivalent circuit diagram.
[Fig.5] Directional characteristic explanatory diagram (2)
[Explanation of symbols]
Dx, Dy ... diameter Hz ... length Lx ... first coil Ly ... second coil Lz ... third coil CAx, CAy, CAz ... core 11 ... substrate

Claims (3)

The first, second, and third coils arranged in the X-axis direction, the Y-axis direction, and the Z-axis direction are antenna elements, respectively, and the first and second coils are respectively individual cylindrical cores. And the third coil is a coil with a disk- like core whose axial length is shorter than the winding diameter. Each core is formed of ferrite, and the first, second, second The three coils are connected in series in random order and connected to a common communication IC module. Said first, second, third coils, three-dimensional antenna of claim 1 Symbol mounting, characterized in that mounted on a common substrate. Core for the third coil, the axial direction the length first, according to claim 1 or claim 2, wherein the set to the same diameter equivalent of each core for the second coil 3D antenna.

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