Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
2000-10-17
2001-11-27
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Wave guide type
C343S772000
Reexamination Certificate
active
06323816
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sector beam antenna with a scattering component, which has a desired radiation pattern.
DESCRIPTION OF THE RELATED ART
At a sector beam antenna, forming a sector beam having a desired radiation pattern is one of the important elements. In order to achieve this, generally, the desired radiation pattern is formed by using flares. In this case, the sector beam antenna must provide a sufficient wide directivity in a state that the flares are not attached.
However, in case that the electric field of a radio wave is parallel to parallel plates of the sector beam antenna, there is a problem that the beam is made to be already narrow in the state that the flares are not attached. At this time, the half power beam width is about 60 degrees. The reason why the beam is made to be narrow is explained. In case that the electric field direction of a radio wave propagating between the parallel plates is perpendicular to the parallel plates, the distance “h” between the parallel plates can be made to be an arbitrary distance being less than a half wavelength. Therefore, the shorter the distance “h” is, the smaller an aperture of the sector beam antenna is, and the radio wave propagating through the aperture have a wide directivity. Therefore, when the flares are used, the radiation pattern can be adjusted relatively freely.
On the other hand, in case that the electric field direction of the radio wave propagating between the parallel plates is parallel to the parallel plates, there is a condition that the distance “h” between the parallel plates must be longer than the half wavelength. Further, in order not to propagate a radio wave being a higher mode, the wavelength must be shorter than one wavelength. Based on these conditions mentioned above, it is necessary that the aperture width needs at minimum the half wavelength. In this case, as mentioned above, the radiation pattern becomes about 60 degrees, and it is difficult that a sector beam having more than 60 degrees is formed.
Propagating conditions of the radio wave in both cases that the electric field directions are parallel and perpendicular to the parallel plates at the antenna used parallel plates are described in “Microwave Antenna Theory and Design” edited by S. Silver, published by McGraw-Hill Book Company, Inc., pp. 459, 1949.
However, at the conventional propagating conditions mentioned above, only the conditions propagating the radio wave between the parallel plates are described, and it is not described that what kind of directivity (radiation pattern) can be obtained from this antenna. Even an antenna satisfied these conditions is actually manufactured, there is a problem that it is difficult to obtain a desired wide sector beam by only using flares.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a sector beam antenna with a scattering component, in which a desired radiation pattern can be obtained.
According to a first aspect of the present invention for achieving the object mentioned above, there is provided a sector beam antenna with a scattering component, which forms a sector beam. The sector beam antenna with the scattering component provides parallel plates composed of two conductive plates disposed in parallel in which the distance between the parallel plates is longer than a half wavelength and shorter than one wavelength of a using wavelength, a primary radiator block having an H bend function disposed between the parallel plates, an input port opened at one of the parallel plates in order to supply power to the primary radiator block, and a scattering component made of a conductive material and disposed in parallel to an aperture being an opening end of the parallel plates in a state that a designated distance exists between the scattering component and the aperture.
According to a second aspect of the present invention, in the first aspect, the scattering component is made of a thin pole shaped conductive material or a thin plate shaped conductive material.
According to a third aspect of the present invention, in the first aspect, the sector beam antenna with the scattering component, which forms a sector beam, further provides scattering component fixing components for fixing the scattering component to the parallel plates, flares for forming a beam, and radio wave absorbing materials for absorbing a part of a radio wave disposed at the ends and inside bent surfaces of the flares
According to a fourth aspect of the present invention, in the first aspect, a radio wave, in which the electric field of the radio wave is parallel to the parallel plates, is generated.
According to a fifth aspect of the present invention, in the first aspect, the sector beam antenna with the scattering component, which forms a sector beam, further provides a reflection block for making phases of beams radiating from the aperture equal or for making phases of beams radiating from the aperture not equal at the upper part and the lower part of the aperture.
According to a sixth aspect of the present invention, in the fifth aspect, the reflection block has a parabolic shape or a shape combined plural curve surfaces.
REFERENCES:
patent: 4482898 (1984-11-01), Dragone et al.
patent: 5579021 (1996-11-01), Lee
Microwave Antenna Theory and Design—pp. 459, McGraw-Hill Book Company, Inc. (1949).
Le Hoang-anh
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
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