JP3464280B2 - Antenna for small radio receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an antenna of a small portable radio, and more particularly, a radio paging receiver such as pager.

[0002]

2. Description of the Related Art FIG. 1 is a partial perspective view of a receiver to which a conventional antenna is attached. A small radio paging receiver such as a pager uses a small loop antenna as shown in FIG. In the figure, 1 is a circuit board of a receiver, 2 is an antenna, and 3 is a battery. Printed wiring conductors are provided on both sides of the circuit board 1, and circuit components of the receiver are mounted on both front and back sides, but not shown. The antenna 2 is a small loop antenna, and the antenna element 2-1 on the upper side of the circuit board 1 and the antenna element 2-2 on the lower side are integrally formed. 1 (b) and 1 (c) are partial perspective views showing the details of the mounting structure of the antenna 2 on the circuit board 1. As shown in FIG. The portions A and C are soldered to the lands of the wiring conductors having a slight gap from above and below the circuit board 1 to become excitation portions (feed points). The portion B is soldered to the printed conductor while sandwiching the edge portion of the circuit board 1 as shown in FIG.

Such a small loop antenna is, in comparison with a whip antenna used in a mobile phone or the like,
In free space, it is an antenna with extremely low radiation efficiency. For example, the maximum antenna gain of a pager in the 280 MHz band is -20 dBd. However, the pager is often used in a shirt or a pocket of a suitcase. In this case, the gain of the whip antenna is significantly deteriorated by the human body, while the small loop antenna is a mirror image antenna generated when the human body approaches the human body. As a result, the gain is improved by 5 to 6 dB at the maximum. FIG. 2 is a diagram showing an example of sensitivity characteristics of a receiver showing an example of this human body effect. by the way,
The effect of improving the gain when worn on the human body is remarkable when the maximum gain of the antenna directional characteristic in free space is obtained at 0 degree. This is obtained when the loop surface becomes perpendicular to the human body.

[0004]

However, in the conventional pager antenna, even if the antenna 1 is arranged such that the loop surface is perpendicular to the circuit board 1 as shown in FIG. 1, the antenna directivity characteristic of FIG. As shown, the maximum radiation direction is shifted by 30 degrees. It is considered that this is affected by the arrangement of the ground conductor pattern of the circuit board 1 and the circuit components. This is a very inconvenient phenomenon for a small loop antenna for a pager that expects a human body effect.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an antenna for a small radio receiver in which the antenna gain is increased by the human body effect.

[0006]

In the antenna for a small radio receiver of the present invention, a circuit board is located in the middle of a rectangular loop, and is fixed to the circuit board at a feeding end and a connecting end facing the feeding end. In a small radio receiver antenna composed of an upper antenna element and a lower antenna element of the circuit board, one or both of the upper antenna element and the lower antenna element is the circuit. It is characterized in that it is arranged with an inclination angle of 30 ° to 60 ° with respect to the substrate. Further, the antenna element is a plate-shaped loop antenna or a rod-shaped loop antenna.

[0007]

FIG. 4 is a perspective view showing a first embodiment of the present invention, in which the upper element 2-3 of the loop antenna 2 is mounted on the circuit board 1 in a tilted manner. The attachment to the circuit board 1 is the same as that shown in FIGS.
-3 may be individually made and attached, or may be integrally attached. As a result, the directional characteristic of the antenna of the first embodiment is as shown in FIG. 5, and the maximum gain direction is oriented at 0 degree. In this embodiment, the inclination angle of the upper antenna element 2-3 with respect to the circuit board 1 is about 45 degrees, but a range of 30 degrees to 60 degrees is preferable. As a result, when the receiver is mounted, the human body and the loop surface are effectively at a right angle, and the gain improvement effect of the human body is sufficiently obtained.

FIG. 6 is a perspective view showing a second embodiment of the present invention. In order to obtain the same human body effect as in the above-described first embodiment, an example in which a loop antenna in which an upper element 2-4 and a lower element 2-5 are integrally formed is attached to the circuit board 1 while being inclined. is there. The inclination angle is preferably in the range of 30 to 60 degrees as in the first embodiment.

FIG. 7 is a perspective view showing a third embodiment of the present invention, in which a plate-shaped antenna element is replaced with a rod-shaped antenna element 2.
This is an example of -6. The second embodiment described above is also the same as the third embodiment.
The embodiment described above also provides the human body effect shown in FIG.

[0010]

By implementing the present invention, it is possible to obtain the antenna directivity characteristic in which the gain is improved by the human body effect without increasing the number of parts, and it is extremely effective in practical use as an antenna for a small radio receiver.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conventional loop antenna structure.

FIG. 2 is a diagram showing an example of actual measurement of sensitivity of a pager using a conventional loop antenna.

FIG. 3 is a diagram showing an example of directional characteristics of a conventional pager antenna.

FIG. 4 is a perspective view showing a first embodiment of the present invention.

FIG. 5 is a characteristic improvement example diagram according to the present invention.

FIG. 6 is a perspective view showing a second embodiment of the present invention.

FIG. 7 is a perspective view showing a third embodiment of the present invention.

[Explanation of symbols]

1 circuit board 2 antenna 3 batteries

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikuni Makino 3-14-20 Higashi-Nakano, Nakano-ku, Tokyo Kokusai Electric Co., Ltd. (72) Inventor Hiroshi Suzuki 3-14-20 Higashi-Nakano, Nakano-ku, Tokyo Kokusai Kokusai Electric Co., Ltd. (56) Reference JP-A-5-183317 (JP, A) JP-A-6-97713 (JP, A) Actual development JP-A-115309 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 1/24 H01Q 7/00

Claims (3)

(57) [Claims] 1. A circuit board is located in the middle of a rectangular loop, and is fixed to the circuit board at a feeding end and a connecting end facing the feeding end, and an antenna element above the circuit board and an antenna element below the circuit board. In the antenna for a small radio receiver, the antenna element for the upper side and the antenna element for the lower side, or both of them are provided with respect to the circuit board.
An antenna for a small radio receiver, which is arranged with an inclination angle of 60 ° to 60 °. 2. The antenna for a small radio receiver according to claim 1, wherein the antenna element is a plate-shaped loop antenna. 3. The antenna for a small radio receiver according to claim 1, wherein the antenna element is a rod-shaped loop antenna.