JP2012147295A - Antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that in a multi-turn loop antenna, antenna gain is changed depending on a distance between the loop antenna and a conductor, such as a metal plate and human body, even when balanced feeding is carried out.SOLUTION: One end 10 of a first loop element 7 is connected to a first balanced feed terminal 5, and the other end 11 of the first loop element 7 is connected to one end 14 of a third loop element 9. Further, one end 12 of a second loop element 8 is connected to the other end 15 of a third loop element 9, and the other end 13 of the second loop element 8 is connected to a second balanced feed terminal 6. Thus, the loop antenna employs the structure in which the loop elements adjacent to each other are alternately connected to each other without connecting them in order.

Description

  The present invention relates to an antenna.

  A loop antenna whose total length of the loop is sufficiently smaller than one wavelength is called a micro loop antenna. The micro loop antenna is widely used in a portable wireless communication device such as a pager. Here, since the input resistance of the micro loop antenna is generally extremely small, a multi-turn micro loop antenna having a multi-winding structure and increasing the input resistance has been devised. It is known that a minute loop antenna operates as a magnetic current antenna, and good antenna gain characteristics can be obtained even when a metal plate or a human body approaches. (For example, see Patent Documents 1 to 3).

  In other words, the loop antenna has the characteristic that the fluctuation of the antenna gain due to the distance to the human body and conductor is small, so it can be used to measure the distance to the other device by measuring the received electric field level when communicating between devices It is also suitable for the configuration. Here, due to the power radiation from the antenna, a high-frequency current may flow in the casing of the device itself, and the antenna gain may fluctuate (having a property as a current antenna). To avoid this, a loop antenna may be used. It is effective to adopt a power supply form in which balanced power is supplied from both ends of the.

Japanese Patent Laid-Open No. 11-136020 International Publication No. 2004/070879 JP 2000-244219 A

  However, the conventional loop antenna having a multi-winding structure has a problem that the antenna gain varies depending on the distance from a conductor such as a metal plate or a human body even when balanced feeding is performed as described above.

  A multi-winding structure is used to improve the antenna gain of the loop antenna. However, when the multi-winding structure is adopted, the length of the loop antenna in the loop axis direction becomes large, and the properties as a current antenna are produced in addition to the properties as an original magnetic current antenna. A high-frequency current flows through the housing of the device itself. The high-frequency current flowing through the housing greatly varies depending on the distance between the housing or the antenna and a conductor such as a metal plate or a human body. As a result, the gain of the antenna is changed, and there is a problem that the distance detection accuracy is deteriorated when the antenna is used for the purpose of measuring the distance to the other party as described above.

  An object of the present invention is to solve the above problems and provide an antenna device having a smaller variation in antenna gain than a conventional loop antenna regardless of the distance between the conductor and the antenna, and a wireless communication device using the antenna device There is to do.

In order to solve the above-described conventional problems, an antenna according to the present invention includes a dielectric substrate, and a first loop element, a second loop element, and a third loop element that are formed perpendicular to the dielectric substrate. Install the loop element, the second loop element, and the third loop element so that they are adjacent to each other in order, and connect the end points of the first and third loop elements that are not adjacent to each other. A place is provided.

  As described above, according to the present invention, when a multi-turn loop antenna configuration is used, it is possible to suppress a high-frequency current from flowing through the housing of the wireless device, so that it is close to a conductor such as a metal surface or a human body. The change in antenna gain is very small whether it is far or away. Therefore, by measuring the signal reception level from the counterpart device, the error when detecting the distance to the counterpart device can be reduced. Furthermore, according to the present invention, the above features can be realized with an inexpensive configuration.

The perspective view of the antenna in this Embodiment The perspective view of the antenna in this Embodiment The perspective view of the antenna in this Embodiment Another perspective view of the antenna for comparison with the antenna in this embodiment

  According to a first aspect of the present invention, there is provided an antenna including a dielectric substrate and a first loop element, a second loop element, and a third loop element formed perpendicular to the dielectric substrate. The third loop elements are arranged so as to be adjacent to each other in order, and are arranged so as to face each other, and at least a place for connecting the end points of the first loop element and the third loop element that are not adjacent to each other is provided. .

  In a second aspect of the invention, particularly in the first aspect of the invention, the dielectric substrate includes two or more conductor layers, and the first loop adjacent to the layer connecting the end points of the first loop element and the third loop element. The layers connecting the end points of the element and the second loop element or the second loop element and the third loop element are different layers.

  According to a third invention, particularly in the second invention, the dielectric substrate comprising two or more conductor layers has a through-hole structure.

  According to a fourth aspect of the present invention, in the third aspect of the invention, the first loop element, the second loop element, and the third loop element are formed by bending a linear metal material.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Similar components are denoted by the same reference numerals, and detailed description thereof is omitted. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a perspective view showing a configuration of an antenna 101 according to the first embodiment of the present invention. In FIG. 1, an antenna 101 according to the first embodiment is characterized by a winding structure of a three-turn loop antenna.

  In FIG. 1, a radio circuit 3, a balun 4, a first balanced power supply terminal 5, and a second balanced power supply terminal 6 are formed on the surface of a dielectric substrate 1. A ground pattern 2 is formed on the back surface of the dielectric substrate 1. Here, the dielectric substrate 1 is composed of two or more conductor layers and has a through-hole structure.

The high frequency input / output terminal of the wireless circuit 3 is connected to the input terminal of the balun 4, and the balanced output terminal of the balun 4 is connected to the first balanced power supply terminal 5 and the second balanced power supply terminal 6. Here, the balun 4 is a circuit that converts an unbalanced signal and a balanced signal, and converts the unbalanced signal of the wireless circuit 3 into a balanced signal output. Specifically, the balun 4 can be configured with a +90 degree and -90 degree phase shifter, a spectacle balun structure made of a ferrite material and a coil, and the like. A circuit that performs conversion can be used.

  One end of the loop antenna 101 is connected to the first balanced power supply terminal 5, and the other end of the loop antenna 101 is connected to the second balanced power supply terminal 6. Here, the reason why the balanced signal that is the output of the balun 4 is input to the loop antenna 101 is to prevent a high-frequency signal from flowing through the casing of the wireless device, that is, the dielectric substrate 1. By performing balanced feeding, all the high-frequency current flowing out from the first balanced feeding terminal 5 flows into the second balanced feeding terminal 6. Or vice versa. Therefore, it is possible to suppress a high-frequency current from flowing through the dielectric substrate 1.

  As shown in FIG. 1, in the loop antenna 101, the first loop element 7, the second loop element 8, and the third loop element 9 are arranged in a line. Here, the loop element does not have a closed loop structure as shown in FIG. 1, but has an open loop structure in which both ends are opened. The axes of the loop elements (shown by broken lines in FIG. 1) are arranged so as to be aligned with each other.

  In the loop antenna 101, a three-turn loop antenna is formed by connecting a first loop element 7, a second loop element 8, and a third loop element 9 formed by bending a linear metal material in series. The connection method is characteristic.

  That is, one end 10 of the first loop element 7 is connected to the first balanced power supply terminal 5, and the other end 11 of the first loop element 7 is connected to one end 14 of the third loop element 9. Furthermore, one end 12 of the second loop element 8 is connected to the other end 15 of the third loop element 9, and the other end 13 of the second loop element 8 is connected to the second balanced power supply terminal 6. In this way, the adjacent loop elements are not connected in order, but are connected by skipping one by one.

  Further, in FIG. 1, the connection wirings of the loop elements intersect in the vicinity of one plane, and the ends of the loop elements are on the same plane or in the vicinity of the same plane, and the wirings intersect in this plane.

  Here, FIG. 4 is shown as a comparative example. The loop antenna 401 shown in FIG. 4 connects adjacent loop elements in order, and is connected to the second balanced power supply terminal from the tip of the antenna (third loop element). Considering the symmetry with respect to the axis of the loop of the loop structure, it can be seen that the configuration of FIG. This is because the wiring length from the first balanced power supply terminal 5 to the first loop element is relatively short, whereas the wiring length from the second balanced power supply terminal 6 to the third loop element is long.

  On the other hand, in the configuration of FIG. 1, the difference between the wiring length from the first balanced power supply terminal 5 to the first loop element 7 and the wiring length from the second balanced power supply terminal 6 to the second loop element 8 is small. . The wiring structure at other connection points is also symmetrically routed with respect to the axis of the loop element in FIG. 1, and the difference in wiring length is smaller. With such a structure, the collapse of the equilibrium state (increase in the unbalanced component) can be suppressed, thereby preventing an unnecessary high-frequency current from flowing through the dielectric substrate 1.

  In addition, the connection wiring of each loop element intersects in the vicinity of one plane, and the ends of each loop element are on the same plane or in the vicinity of the same plane. Cost reduction is possible.

  In the present embodiment, the loop antenna 101 is an example of a three-turn loop antenna obtained by connecting the first loop element 7, the second loop element 8, and the third loop element 9 in series. As shown in FIG. 2, a loop antenna having three or more turns may be used.

[About 2 turns]
In the loop antenna 201 shown in FIG. 2, a fourth loop element 16 is further provided as compared with FIG. 1, and one end 12 of the second loop element 8 is connected to the other end 18 of the fourth loop element 16. The other end 15 of the loop element 9 is connected to one end 17 of the fourth loop element 16.

  By adopting the connection method described above, the connection wiring of each loop element becomes symmetrical or nearly symmetrical with respect to the axis of the loop element, so that the occurrence of an unbalanced component can be avoided, and the conductor distance Therefore, the antenna gain can be prevented from changing, and the antenna gain can be kept constant.

[About 3 turns]
Further, the loop antenna 301 shown in FIG. 3 is further provided with a fifth loop element 17 as compared with FIG. 2, and the connection method shown in FIG. The loop antenna can be formed with a 5-turn while avoiding the generation of an unbalanced component.

[About N turns]
Finally, a connection method of each loop element when the number of turns of the loop antenna is N will be described. Therefore, N loop elements are arranged in the horizontal direction with respect to the surface of the dielectric substrate 1 so that the axes of the loop elements are substantially in a straight line, and the first balanced feed terminal 5 and the second balanced feed. A loop element arranged at a position closest to the terminal 6 is assumed to be a first loop element, and a mode is assumed in which the N-th loop element is arranged from the second loop element as it is further away. Further, one end of the n-th loop element (n = 1, 2, 3,... N) is expressed as Tn-1, and the multi-end is expressed as Tn-2.

  First, one end T <b> 1-1 of the first loop element is connected to the first balanced power supply terminal 5. Also, the second loop element one end T <b> 2-1 is connected to the second balanced power supply terminal 6. For other loop elements, the connection method changes depending on whether n is an odd number or an even number.

  First, when n is an odd number, one end Tn-1 of the n-th loop element is connected to the multi-end T (n-2) -2 of the (n-2) -th loop element, and the multi-end Tn-- of the n-th loop element is connected. 2 is connected to one end T (n + 2) −1 of the (n + 2) th loop element.

  When n is an even number, one end Tn-1 of the n-th loop element is connected to the multi-end T (n + 2) -2 of the (n + 2) -th loop element, and the multi-end Tn-2 of the n-th loop element is connected to the ( n-2) Connect to one end T (n-2) -1 of the loop element.

  However, as an exception to the above, for the n-th loop element in which n = N-1, one end Tn-1 is connected to the multi-end TN-2 of the N-th loop element. Alternatively, for the n-th loop element in which n = N-1, the multi-end Tn-2 is connected to one end TN-1 of the N-th loop element.

  By connecting the loop elements according to the above rules, a loop antenna can be configured without breaking the symmetry of the loop structure.

  It should be noted that the intersection of the connection wirings of the respective loop elements is configured in the same plane or in the vicinity of the same plane regardless of the number of windings, thereby simplifying the loop structure and reducing the cost.

  In addition, by providing the wireless communication device with the antenna described in this embodiment, the degree of influence on a conductor such as a metal surface or a human body is reduced, and stable wireless communication can be performed.

  As described above, according to the antenna and the wireless communication apparatus using the antenna according to the present invention, the degree of influence on a conductor such as a metal surface or a human body is reduced, and stable wireless communication can be performed.

DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Ground pattern 3 Wireless circuit 4 Balun 5 1st balanced power supply terminal 6 2nd balanced power supply terminal 7 1st loop element 8 2nd loop element 9 3rd loop element 16 4th loop element 19 5th loop element

Claims (4)

In an antenna including a dielectric substrate and a first loop element, a second loop element, and a third loop element formed perpendicular to the dielectric substrate,
The first loop element, the second loop element, and the third loop element are installed so as to be adjacent to each other in this order, and are installed so as to face each other.
The antenna which provided the location which connects the end point of the said 1st loop element and said 3rd loop element which are not adjacent at least. The dielectric substrate includes two or more conductor layers,
A layer connecting end points of the first loop element and the third loop element;
2. The antenna according to claim 1, wherein layers that connect end points of the adjacent first loop element and the second loop element or the second loop element and the third loop element are different layers. 3. The antenna according to claim 2, wherein the dielectric substrate composed of the two or more conductive layers has a through-hole structure. The antenna according to claim 3, wherein the first loop element, the second loop element, and the third loop element are formed by bending a linear metal material.

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