JP3193561B2 - Cross loop antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross-loop antenna for generating both horizontal and vertical polarizations, and more particularly to a cross-loop antenna incorporated in a circuit board.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a principle configuration of a cross-loop antenna for generating both horizontal and vertical polarizations. In the figure, reference numeral 101 denotes a horizontal polarization loop (element), and reference numeral 102 denotes a vertical polarization. A loop 103 is a feeding point, and has a structure in which a horizontal polarization loop 101 and a vertical polarization loop 102 are crossed and integrated as shown in the figure. It is known that loop antennas can be widely used from long waves to very short waves and for reception and transmission.
In addition to the loop in which the electric wire is wound in a coil shape, FIG.
In some cases, the loop is formed by a strip line as shown in FIG. In recent years, cross-loop antennas have been used as antennas for remote control keys for locking and unlocking the keys of automobiles and the like by remote control using wireless communication. In this case, it is necessary to make the portable terminal as convenient as possible. It is necessary to reduce the size and flatness of the circuit board because it is integrated into the circuit board and incorporated in the key ring.

FIG. 4A is a perspective view showing an example of the structure of a conventional cross-loop antenna incorporated in the above-mentioned circuit board. In the figure, reference numeral 200 denotes a circuit board, and 201 denotes, for example, a horizontal polarized wave. A first loop 202 is, for example, a second loop for vertical polarization, and 203 is a feed point. FIG.
The cross-loop antenna shown in FIG.
Loop 201 and second loop 20 across front and back
2 are held so as to be orthogonal on the plane of the circuit board 200, and have a structure that generates two orthogonal polarized waves, horizontal and vertical. However, in this structure, the first loop 201 and the second loop 202 are completely independent,
Two sets of feeding points must be provided. FIG. 4B is a perspective view showing another example of the structure of the conventional cross-loop antenna incorporated in the circuit board described above.
201a and 201b are, for example, each half of an element constituting a horizontal polarization loop, 202a and 202b are each a half of elements constituting a vertical polarization loop, for example, and 203 is a feeding point. As shown in FIG. 4B, this cross-loop antenna connects the first loop and the second loop, and has a single feeding point 203, and is provided on the surface (upper surface) of the circuit board 200. Is element 2
A horizontal polarization loop is formed by 01a and 201b, a vertical polarization loop is formed by the elements 202a and 202b over the front and back surfaces, and a feeding point 203 is provided on each of the front and back surfaces. The elements 202a and 202b
The reason why the area surrounded by the vertical polarization loop constituted by the above is smaller is that an electronic component (not shown) is mounted on the circuit board 200 and the strip lines (elements) 202a and 202b are laid on the electronic component (not shown). Even if it is used, it is required to be as thin and as small as possible when used for remote control keys and the like.

[0004]

The above-described cross-loop antenna incorporated in the conventional circuit board shown in FIG. 4 is constructed as described above. In the cross-loop antenna shown in FIG. Are completely independent,
Since two sets of feeding points must be provided, there are many structural wastes, which hinders miniaturization. In the cross-loop antenna shown in FIG. 4B, the intensity of the received electric field from a loop formed on the substrate surface (horizontal polarization loop in the example shown in FIG. 4B) is affected by the shape of the circuit board. Is stronger than the loop formed over the front and back surfaces of the circuit board (vertical polarization loop in the example shown in FIG. 4B), and the radiation characteristics are shifted. In addition, the size of the loop formed over the front and back surfaces of the circuit board is inevitably smaller than that of the loop formed on the surface of the circuit board for planarization and miniaturization. There was a problem of becoming large.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a cross-loop antenna which prevents deviation of radiation characteristics due to a difference between a circuit board shape and a loop shape. .

[0006]

A cross-loop antenna according to the present invention is held on one surface of a circuit board or the like among two loops for generating both horizontal and vertical polarizations incorporated in the circuit board and the like. The thickness of the element forming one loop and the thickness of the element forming the other loop held over the front and back surfaces of a circuit board or the like are made different to adjust the balance of radiation intensity. . In addition, the width of the element forming the other one loop is made wider than the width of the element forming the one loop to adjust the balance of the radiation intensity. Further, the element forming the one loop held on one surface of the circuit board or the like is positioned at the outer peripheral end of the circuit board or the like.

[0007]

In the cross-loop antenna of the present invention, one of the two loops, which are incorporated in a circuit board or the like and generates both horizontal and vertical polarizations, is held on one surface of the circuit board or the like. Element thickness and
Since the thickness of the other element constituting the other loop, such as a circuit board, held over the front and back surfaces is made different, the power distribution ratio to the two loops is adjusted while miniaturizing and flattening. Deviation of the radiation characteristics can be prevented.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing one embodiment of the present invention, in which 10 is a circuit board, 11a, 11b, 12a, 1
Reference numeral 2b denotes an element. In this embodiment, a loop surrounded by the elements 11a and 11b constitutes a loop antenna for horizontal polarization, and a loop surrounded by the elements 12a and 12b constitutes a loop antenna for vertical polarization. Reference numeral 13 denotes a feeding point. And the elements 12a,
The width (thickness) D2 of the element 12b is made wider (thicker) than the width (thickness) D1 of the elements 11a and 11b, and
a, element 1 from the power sent to 11b
The power distribution ratio is set so that the power transmitted to 2a and 12b becomes stronger.

Therefore, when the power distribution ratios are the same, the radiation characteristics are offset due to the asymmetry of the shape and loop shape of the circuit board 10, that is, the elements 11a, 11
The electric field intensity radiated from the element 12a, 1
It is possible to configure an antenna capable of uniformly radiating two orthogonal polarization components by canceling out the radiation characteristic of being stronger than the electric field intensity radiated from 2b.

FIG. 2 is a perspective view showing another embodiment of the present invention. In this embodiment, horizontal polarization elements 11a and 11a are used.
11b is provided at the outer peripheral end of the circuit board 10. In the present embodiment, the elements 11a and 11b can be made relatively thin, so that such a configuration is also possible. The structure can easily hold the element. In the above embodiment, the circuit board 1
Although the case of incorporating into 0 is described, it goes without saying that the present invention can be applied to all cases of incorporating into a similar shape.

[0011]

As described above, the cross-roof antenna of the present invention is held on one surface of a circuit board or the like among two loops for generating both horizontal and vertical polarizations incorporated in the circuit board and the like. The thickness of the element forming one loop and the thickness of the element forming the other loop held over the front and back surfaces of a circuit board or the like are made different to adjust the balance of radiation intensity. So
By using an asymmetrical cross loop incorporated on a circuit board, it is possible to obtain an antenna having a uniform radiation characteristic that uniformly radiates two orthogonal polarization components while miniaturizing and planarizing. Further, by forming the inside of the case by etching or the like, there is an effect that the cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing another embodiment of the present invention.

FIG. 3 is a diagram showing a principle configuration of a loop antenna that generates both horizontal and vertical polarizations.

FIG. 4 is a perspective view showing the structure of a cross-loop antenna incorporated in a conventional circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Circuit board 11a, 11b, 12a, 12b Element 13 Feeding point

Continuation of the front page (56) References JP-A-2-84824 (JP, A) JP-A-59-186401 (JP, A) JP-A-4-20717 (JP, U) JP-A-57-34733 (JP, A) , U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01Q 7/00 H01Q 21/24

Claims (3)

(57) [Claims] The thickness of an element constituting one of the two loops, which are incorporated in a circuit board or the like and generate both horizontal and vertical polarizations, held on one surface of a circuit board or the like, and A cross-loop antenna having a structure that adjusts the balance of radiation intensity by varying the thickness of another element constituting another loop held over the front and back surfaces of a substrate or the like. 2. The cross-loop antenna according to claim 1,
There are, the width of the elements constituting the other one of the loops held over the front and back surfaces, such as the circuit board (thickness), the one loop being held on one side, such as the circuit board A cross-loop antenna characterized by being wider (thicker) than the width (thickness) of the elements that constitute. 3. The cross-loop device according to claim 1, wherein
A container, cross loop antenna, characterized in that the elements constituting the said one loop held on one side, such as the circuit board is positioned on the outer edge, such as the circuit board.