JP3240251B2 - Small 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 small antenna suitable for a small portable radio.

[0002]

2. Description of the Related Art In portable small radios, loop antennas and monopole antennas are often used. These have directivity. For example, in the case of a monopole antenna, when the antenna is oriented perpendicular to the ground surface, it can efficiently receive vertically polarized waves.

FIG. 4 shows an example of an antenna used in a pager receiver. A quadrilateral conductor plate 1 having A1, B1, C1, and D1 as vertices, and A2, B2, C2, and D2 are shown.
Are placed in parallel with each other, and are connected by wires 3 (A1-A2) and 4 (C1-C2). When the dimensions of the antenna are as shown in the figure, the antenna length (loop length) is about 20 cm. Also, as shown in FIG. 5, when vertical polarization is incident from directions perpendicular to the X, Y, and Z directions shown in FIG. 4, an example of the reception gain when this antenna is rotated in the θ direction. Is shown in FIG.

[0004]

A part of the radio wave transmitted from the transmitting station in the vertical polarization is changed to the horizontal polarization component due to the influence of the surroundings and reaches the receiver. The component arrives several times stronger than the horizontally polarized component. The reception sensitivity difference between the case where the antenna polarization plane of the receiver coincides with the incoming radio wave and the case where the antenna polarization plane does not coincide is remarkably large. For example, taking a monopole antenna as an example, vertical polarization can be received when the antenna is vertical, but vertical polarization cannot be received when the antenna is horizontal.
Also, in the case of the antenna of the pager receiver shown in FIG.
When the vertically polarized wave is incident on the X axis at a right angle (for the polarized wave oscillating in the X axis direction), the sensitivity is relatively good for all angles as shown in the actual characteristic of FIG. When the vertically polarized wave enters the Z axis at a right angle, a large directivity appears.

SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems by maintaining a high reception gain, maintaining the best reception sensitivity regardless of the attitude of the radio, and improving the communication range. An object of the present invention is to provide a small antenna.

[0006]

According to the present invention, there is provided a small antenna having a loop formed by a wire in two opposing surfaces and a wire connecting the two surfaces, wherein the small antenna comprises a loop. The arrangement of the wires in one plane is different from the arrangement of the wires in the other plane, and the electromagnetic fields generated by the two wires on at least one of the two planes are not canceled each other. A small antenna characterized by forming and disposing the wire is disclosed.

Further, the present invention relates to a small-sized antenna comprising a loop formed by wires in two opposing surfaces and a wire connecting the two surfaces, wherein a loop is formed in one of the two surfaces. The arrangement of the wires is different from the arrangement of the wires in the other plane, and the wires are formed and arranged so that the electromagnetic fields generated by the two wires on at least one of the two planes do not cancel each other. A small antenna characterized by the above is disclosed.

[0008]

Embodiments of the present invention will be described below. FIG. 1 shows an embodiment of a small antenna according to the present invention, in which wires E1-F1, F1-G1, G
1-H1, H1-H2, H2-F2, F2-G2, G2
-A loop consisting of E2 and E2-E1 is formed. The end points E1, F1, H1, G1 of the wire are on a first plane, and the end points E2, F2, H2, G2 of the wire are on a second plane. The first and second planes form planes parallel to each other, and a rectangular parallelepiped surrounded by these end points is formed so as to coincide with a housing of a wireless device or the like using the small antenna as a part thereof. You.

This configuration has the following features. One is that the wire arrangement in the first plane is different from the wire arrangement in the second plane. In FIG. 1, wires E1-F1 and H1-G in a first plane are shown.
No wire corresponding to 1 is in the second plane, and conversely, wires H2-F2 and G2-E2 in the second plane are not in the first plane. By adopting such an asymmetric structure, the electric field generated between the two planes is reduced, and a decrease in gain is prevented, and a sharp directivity is prevented from appearing.

Another feature is that a loop is formed so that current directions of parallel wires are always the same. In FIG. 1, a feeding point is provided on the wires E1-E2, and E2 →
At the moment when the current is supplied in the direction of E1, the current flowing in the antenna becomes as shown by the arrow in FIG. 1, and the current directions of the parallel wires H2-F2 and G2-E2, also E1-F1
And the current directions of G1-H1, the wires F1-G1 and F
The current directions of 2-G2 are the same. This configuration has the effect of increasing the equivalent antenna length.

In the example shown in FIG. 1, a loop is formed along the outer surface of the rectangular parallelepiped with two straight wires in a plane parallel to each other and a straight wire connecting the two wires. Even if the two planes are not completely parallel or each wire is not perfectly straight, etc., if the deviation is small, it is clear that the antenna of the present invention has the same effect. is there.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the configuration of FIG. 1, the length of G2-E2 is 80 m.
m, length of G2-H2 50 mm, length of E1-E2 = 5
In the case of a rectangular parallelepiped shape of mm, the antenna length is ２０46 cm, which is much longer than the antenna length of 20 cm of the antenna of the same size shown in the conventional example of FIG. As shown in FIG. 2, when the vertically polarized wave enters from the directions perpendicular to the X, Y, and Z directions in FIG. 1, the reception gain when the antenna in FIG. This is shown in FIG. This figure 3
As shown in FIG. 7, the antenna has a small directivity without significantly reducing the reception gain for the incident wave from either direction.

[0013]

According to the present invention, a small antenna suitable for a portable radio or the like can be realized by increasing the antenna length to increase the reception gain and reducing the directivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a small antenna according to the present invention.

FIG. 2 is an explanatory diagram of a radio wave incident direction.

FIG. 3 is a diagram illustrating reception gain characteristics of the antenna of FIG. 1;

FIG. 4 is a diagram showing an example of a conventional small antenna.

FIG. 5 is an explanatory diagram of a radio wave incident direction.

FIG. 6 is a diagram illustrating reception gain characteristics of the antenna of FIG. 4;

[Explanation of symbols]

E1, E2, F1, F2, G1, G2, H1, H2 Wire end points

Claims (2)

(57) [Claims] 1. A small antenna in which a loop is formed from a wire in two opposing surfaces and a wire connecting the two surfaces, wherein the wire is arranged in one of the two surfaces. And the arrangement of the wires in the other planes are different from each other, and at least one of the two planes
A small antenna, wherein said wires are formed and arranged such that electromagnetic fields generated by said wires do not cancel each other. 2. A small antenna having a loop formed by a straight wire in two opposing parallel planes and a wire connecting between the two planes, wherein the loop is formed in one of the two planes. And the arrangement of the straight wires in the other plane are different from each other, and the straight lines are arranged so that the electromagnetic fields generated by the two straight wires in at least one of the two planes do not cancel each other. A small antenna characterized in that wires are formed and arranged.