JPH07231213A - Antenna for small radio receiver - Google Patents

Abstract

PURPOSE:To allow an antenna to be suitably applied to the mobile radio receiver by obtaining a composite antenna sensing magnetic field and electric field components with a simple configuration of extension of an end of a small loop antenna so as to provide a directivity without unevenness in every direction. CONSTITUTION:The antenna is provided with two ends 20, 21 to connect to a radio frequency amplifier, capacitive reactance parts 23, 24 forming a receiver input circuit to connect to the radio frequency amplifier, a capacitive reactance part 22 connected between the end 21 and a reference earthing, and an extension part 25 extended from the end 21. Through the constitution above, antenna conductors 26, 27, 28 including the ends 20, 21 form a magnetic field sensing loop antenna, the extension 25 acts like a very small dipole element to allow the antenna to act like a composite antenna comprising the loop antenna and the dipole antenna, and the reactance part 22 is resonated to a reception frequency. Thus, the unevenness in the directivity is decreased or eliminated in every direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna for a small radio device, and more particularly to an antenna for a portable radio receiver.

[0002]

2. Description of the Related Art As a small radio receiver antenna that is worn on a waist belt or in a pocket, a loop antenna that uses an electromagnetic field property in which a magnetic field component becomes strong near the human body is often used and has a high sensitivity characteristic. Has been obtained. FIG. 5 shows an example thereof.

[0003]

However, the radio receiver is not only used in the vicinity of the human body such as in a pocket, but also in a state close to a free space such as in a bag, in a car or on a desk. used. The loop antenna that is sensitive to the magnetic field component shows good characteristics in the vicinity of the human body, but the reception directional pattern in free space is in the shape of a figure 8 as shown in Fig. 6, and the reception characteristics may be extremely high depending on the usage state of the radio. It has the drawback of decreasing.

The object of the present invention is to solve the above problems.
(EN) An antenna for a small radio receiver in which an antenna is configured to be sensitive to both magnetic field and electric field components, and a good reception pattern can be obtained by synthesizing patterns of both components.

[0005]

The present invention provides a plate-shaped or rod-shaped loop antenna used for a small radio receiver for the above-mentioned purpose, the loop antenna having two ends of the loop antenna.
A first end is connected to the receiver input circuit, a capacitive reactance is connected between the second end and the receiver reference ground,
By extending the second end in an arbitrary direction on a spherical surface having an arbitrary radius centered on the second end, a good reception pattern can be obtained as compared with the conventional loop antenna. It is composed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the main body will be described below with reference to the drawings. FIG. 1 is a diagram showing a basic shape of an antenna according to the present invention, in which 20 and 21 are two ends, 23 and 24 are capacitive reactances constituting a receiver input circuit connected to a radio frequency amplifier, 22 is a capacitive reactance connected between the end 21 and the reference ground. 25 is the second
It is an extension from the end of. Next, the operation will be described. In the above configuration, the antenna conductor portions 26, 27 and 28 including the first end portion 20 and the second end portion constitute a magnetic field sensitive loop antenna, and the extension conductor 25 operates as a fine dipole element. And a dipole antenna, which makes the capacitive reactance 22 resonate with the reception frequency and operates.

Next, the directivity of the antenna shown in FIG. 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram showing a state in which the antenna is placed perpendicular to the XY plane. FIG. 3 shows the directivity of the present antenna on the XY plane for vertically polarized waves.
FIG. 6 shows the directional characteristics of the conventional loop antenna shown in FIG. According to the configuration of the present antenna as shown in FIG. 3, an antenna having a small dip in directivity in all directions can be obtained.

In another embodiment shown in FIG. 4, it was confirmed that similar directivity can be obtained even in an antenna configuration in which the ends 20 and 21 are bent.

[0009]

As described above, according to the present invention, it is possible to construct a composite antenna sensitive to magnetic field and electric field components by a simple antenna configuration in which the end portion of a small loop antenna is extended. As for the directivity, good characteristics with little drop in all directions can be obtained. Therefore, the antenna configuration is extremely effective as an antenna of a mobile radio receiver that is required to be omnidirectional in use.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining the directivity of an antenna according to the present invention.

FIG. 3 is a directional characteristic diagram of an antenna according to the present invention.

FIG. 4 is a perspective view for explaining another embodiment of the present invention.

FIG. 5 is a perspective view showing a structural example of a conventional antenna for a small radio device.

FIG. 6 is a directional characteristic diagram of the antenna of FIG.

[Explanation of symbols]

 20, 21 Antenna end 22, 23, 24 Capacitive reactance 25 Extension 26, 27, 28 Antenna conductor

Claims (1)

[Claims] 1. A plate-shaped or rod-shaped loop antenna used in a small radio receiver, wherein a first end of the two ends is connected to a receiver input circuit, and a second end is connected to the receiver input circuit. An antenna in which a capacitive reactance is connected between the base and a receiver reference ground, the second end is extended in an arbitrary direction on a spherical surface having an arbitrary radius with the second end as a center. An antenna for a small radio receiver characterized by the following.