JP3155683B2 - Antenna with angle reflector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna with a reflex reflector used as an antenna for a base station of a mobile phone or a mobile phone.

[0002]

2. Description of the Related Art An antenna installed in a base station of an automobile telephone or a portable telephone requires a vertically polarized beam and a beam having a sharp vertical plane directivity, and the horizontal plane directivity has a half-power width of 30 to 180 degrees. It is required that an arbitrary value of the degree can be set. Such an antenna is a so-called fan beam antenna, and an array antenna having a plurality of antenna elements arranged in a vertical direction is used to obtain such an antenna. In this case, when the half-power width in the horizontal direction is 120 degrees or more, a dipole antenna with a reflector obtained by attaching a reflector B to a dipole antenna A as shown in FIG. 3 may be used as each antenna element of the array antenna. In addition, the opening angle Φ of the reflection plate B is set to an angle wider than 180 degrees. The half-power width indicates the directivity of the antenna, and is a width that is 1 / 軸 2 (approximately 70%) lower than the gain of the antenna in the main axis direction by voltage. The smaller this value is, the sharper the directivity is. Become.

In general, the following specifications are required for an antenna used as a base station antenna. 1. In the horizontal plane directivity, the power value radiated to the rear of the antenna with respect to the power radiated in front of the antenna in addition to the half power width (front-back ratio: hereinafter referred to as F / B value)
Is small. 2. The antenna is small (particularly narrow in width) in terms of wind pressure load.

[0004]

In the case of an antenna with a reflex reflector, for example, a dipole antenna with a reflex reflector, reducing the size of the antenna reduces the length L of the reflector B. The size of B affects the half-power width and the F / B value. In particular, the F / B value takes a larger value as the length of the reflector B (smaller width) becomes smaller, that is, the rearward. It will increase the radiation. Therefore, in view of wind pressure load, reducing the antenna (smaller width) and improving the F / B value are mutually contradictory requirements.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna with an angle reflector which does not increase backward radiation even when the angle reflector is made thinner.

[0006]

According to the present invention, as shown in FIG. 1, an antenna provided with a reflex reflector according to claim 1 includes a reflex reflector 2 having an aperture angle .PHI. Wider than 180 degrees. In the attached antenna with a reflex reflector, two sides parallel to the ridge of the corner of the reflex reflector 2 are connected by a back plate 3 so as not to be electrically opened. .

As shown in FIG. 2, the antenna with the reflex reflector according to the second aspect of the present invention has a reflex reflector 2 and a back plate 3.
Is a desired curvature.

[0008]

According to the antenna with the reflex reflector according to the first aspect of the present invention, the two end faces of the reflex reflector 2 are connected by the back plate 3 so as not to be electrically opened. In addition, the current excited between the end faces is less likely to be radiated backward by the back plate 3, and for example, even if the length L of the reflex reflector 2 is reduced, an increase in the F / B value is suppressed.

In the antenna with a reflex reflector according to the second aspect of the present invention, the connecting portion between the reflex reflector 2 and the back plate 3 has a desired curvature. It plays the role of reducing the diffraction, and as a result, it is possible to prevent a state that adversely affects the backward radiation (for example, the diffracted waves become in phase with the backward radiation and strengthen the radio waves), and the F / B value can be reduced. The increase is suppressed.

[0010]

Embodiment 1 FIG. 1 shows an embodiment of an antenna with a reflex reflector according to the present invention, wherein 1 is an antenna (in this case, a dipole antenna), 2 is a reflex reflector,
3 is a back plate.

As the dipole antenna 1, various types of dipole antennas conventionally used in reflector-equipped dipole antennas can be used. In this embodiment, a printed dipole antenna formed by printing a thin film conductor on a dielectric substrate is used. Use

The reflex reflector 2 is formed by forming a rectangular metal conductor plate with a corner angle Φ (Φ> 180 degrees), and the ridge line bb of the corner portion of the reflex reflector 2 is formed. The dipole antenna 1 can be arranged at the center of the '. The reflex reflector 2 may be composed of a single metal conductor plate, or a metal blind may be used. However, in order to obtain a reflection characteristic equivalent to a metal conductor plate using a metal blind, the interval between the metal blinds is set to 1/1 of the used wavelength.
Must be 0 or less.

The back plate 3 is a rectangular metal conductor plate.
The sides (cc ′ and the corresponding side on the a side) are electrically connected to each other. The end faces of the reflex reflector 2 are connected by the back plate 3 so as not to be electrically opened .

In this embodiment, in order to accommodate the whole antenna in a circular radome, the rear plate 3 is curved with the same curvature as the inner diameter of the radome as shown in FIG. However, the rear plate 3 may be a flat plate, and the rear plate 3 may be formed of a metal blind or the like, similarly to the reflex reflector 2.

When the directivity in the horizontal plane (in the magnetic field plane) of the antenna with a reflex reflector (the beam antenna having a half-power width of 180 °) of FIG. 1 described above was measured, a directivity diagram as shown in FIG. 4 was obtained. Was done. In addition, when the same measurement was performed using a conventional type antenna with a reflex reflector having the same size as that of the antenna with a reflex reflector of FIG. 1, a directivity diagram as shown in FIG. 5 was obtained. Comparing the directivity diagrams of FIGS. 4 and 5, the F / B value of the conventional type antenna was 15 dB (maximum value), whereas the F / B value of the antenna of FIG. 1 was improved to approximately 20 dB. It was recognized that. That is, if the F / B value is set to 15 dB, the antenna of the present invention can make the size of the reflex reflector 2 smaller than that of the conventional type.

Further, in the antenna with a reflex reflector of the present invention, the joint between the reflex reflector 2 and the back plate 3 may have a structure having a curvature (R) as shown in FIG. In this case, the backward diffraction of the wave radiated from the dipole antenna 1 can be reduced, and the improvement of the F / B value can be further improved as compared with the antenna with the reflex reflector shown in FIG.

[0017]

According to the antenna with a reflex reflector of the present invention,
An antenna which is very suitable as a base station antenna or the like having a small angle reflector and a small F / B value can be obtained.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of an antenna with a reflex reflector according to the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a side view, and FIG.
FIG.

FIG. 2 is an enlarged view of another embodiment of the antenna with a reflex reflector of the present invention, in which a reflector and a back plate are joined.

FIG. 3 is an example of a conventional antenna with a reflex reflector;
(A) is a plan view, (b) is a side view.

FIG. 4 is a directivity diagram showing horizontal plane directivity by the antenna with a reflex reflector of the present invention.

FIG. 5 is a directivity diagram showing horizontal plane directivity by a conventional antenna with a reflex reflector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 Angle reflector 3 Back plate

Claims (2)

(57) [Claims] 1. An antenna with a reflex reflector having a reflex reflector (2) having an opening angle Φ wider than 180 degrees attached to the antenna (1) .
An antenna with a reflex reflector, wherein two sides parallel to the ridge line of the corner portion are connected by a back plate (3) so as not to be electrically opened . 2. An antenna with an angle reflector according to claim 1, wherein the connecting portion between the angle reflector and the back plate has a desired curvature.