Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-09-22
2001-11-20
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S824000
Reexamination Certificate
active
06320542
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a patch antenna apparatus, and more particularly, a patch antenna apparatus mainly for use in an antenna apparatus for a base station of mobile communication systems.
2. Description of the Prior Art
FIG. 29
is a perspective view showing a configuration of a prior art patch antenna apparatus.
FIGS. 30
to
32
are pattern diagrams each showing an example of the projection directional pattern of the patch antenna apparatus of FIG.
29
.
Referring to
FIG. 29
, a dielectric substrate
90
has a top surface and a bottom surface which are parallel to each other, and a grounding conductor
91
is formed on the bottom surface of the dielectric substrate
90
. On the top surface of the dielectric substrate
90
is formed a square-shaped conductor patch
92
having a square which has one side having a length of half a wavelength of a resonance frequency when the dielectric constant of the dielectric substrate
90
is taken into consideration. For example, the conductor patch
92
is formed so that, on an X-Y plane having the origin located in the center of the dielectric substrate
90
, sides of the square of the conductor patch
92
which cross each other so as to be perpendicular to each other are parallel to the X-axis and Y-axis, respectively, and the center of the conductor patch
92
is positioned at the origin of the X-Y plane. Further, a feeding point
93
is positioned on the X-axis, namely, is located on the perpendicular bisector of one side in the Y-axis direction of the square of the conductor patch
92
. When a radio signal having the above-mentioned resonance frequency is fed to the feeding point
93
, the patch antenna apparatus resonates in parallel with the X-axis. Consequently, the radio signal is projected, as a linearly polarized radio wave having the exciting or driving direction parallel to the X-axis including the feeding point
93
, in the Z-axis direction which is perpendicular to the X-Y plane and opposite to the grounding conductor
91
.
As shown in
FIGS. 30
to
32
, the radio wave projected from the patch antenna apparatus of
FIG. 29
has a main polarization which is a linear polarization having the exciting or driving direction parallel to the X-axis. The radio wave is projected so that its projection intensity becomes the maximum in the Z direction which is the front direction of the patch antenna apparatus.
However, the prior art patch antenna apparatus shown in
FIG. 29
can project the linearly polarized radio wave which is parallel to the X-axis but cannot project a linear polarization parallel to the Y-axis which is perpendicular to the X-axis. Although the patch antenna apparatus can strongly project the radio wave in the Z direction which is the front direction of the antenna apparatus, the patch antenna apparatus cannot strongly project the radio wave in the horizontal direction of the antenna apparatus and an upper direction inclined with a low elevation angle.
For example, in the case of projecting the radio wave in a space such as a room or the like whose height is small and which has a broadening in the horizontal direction, it can be considered that the antenna apparatus is provided on a ceiling or a wall surface. In consideration of the view or the like, however, it is desirable to install the antenna apparatus on the ceiling which is not usually seen. In the case of suspending the antenna apparatus from the ceiling, in order to efficiently project the radio wave, it is preferable to horizontally suspend the antenna apparatus from the ceiling so that the plane of the dielectric substrate
90
is parallel to the surface of the ceiling (hereinafter, this installing method will be referred to as a ceiling installing method). In this case, the radio wave projected from the patch antenna apparatus has only a polarization which is parallel with the X-axis. Mainly, a vertical polarized radio wave is used in mobile communication systems. In the ceiling installing method, however, the intensity of the vertical polarized radio wave in radio waves projected from the antenna apparatus is the strongest on the X-axis and no vertical polarized radio wave exists in radio waves projected from the antenna apparatus on the Y-axis.
In the case of a space such as a room or the like whose height is small and which has a broadening in the horizontal direction, in order to realize a broader projection area, it is desirable that the radio wave is strongly projected from the antenna apparatus in the horizontal direction of the antenna apparatus and an upper direction inclined with a low elevation angle.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a patch antenna apparatus having a simple structure and being capable of controlling a projection area so as to obtain a desired projection area in accordance with a projection space.
Also, a second object of the present invention is to provide a patch antenna apparatus having a simple structure and being capable of obtaining a projection area broader than that of the prior art.
Further, a third object of the present invention is to provide a patch antenna apparatus having a simple structure and being capable of maximizing projection of the radio wave in the direction with a low elevation angle.
Still further, a fourth object of the present invention is to provide a patch antenna apparatus having a simple structure, having a gain higher than that of the prior art, and being capable of obtaining a projection beam narrower than that of the prior art.
According to the first aspect of the present invention, there is provided a patch antenna apparatus comprising:
a dielectric substrate having a first axis and a second axis which cross each other to be perpendicular to each other, and having a first surface and a second surface which are parallel to each other;
a grounding conductor formed on the first surface;
at least one conductor patch formed on the second surface, the conductor patch having a first feeding point for producing resonance in parallel to the first axis at a predetermined resonance frequency, and having a second feeding point for producing resonance in parallel to the second axis at the resonance frequency; and
control means for controlling each of radio signals of the resonance frequency fed to the first and second feeding points, so as to change at least one of an amplitude and a phase thereof,
thereby, upon feeding the radio signals of the resonance frequency to the first and second feeding points, projecting radio waves having two linear polarizations which are parallel to the first and second axes and which cross each other to be perpendicular to each other, with a projection directional pattern corresponding to the control for the radio signals by the control means.
In the above-mentioned patch antenna apparatus, there is preferably provided at least two of the conductor patches, where two conductor patches selected from the at least two conductor patches are arranged so as to be symmetrical to each other with respect to the first axis, and the control means controls the radio signals so as to feed the radio signals having the same phases to either one of each of the first feeding points and each of the second feeding points of the two conductor patches arranged so as to be symmetrical to each other with respect to the first axis.
Further, in the above-mentioned patch antenna apparatus, there is preferably provided at least four of the conductor patches, where each pair of the conductor patches selected from the at least four conductor patches is arranged so as to be symmetrical to each other with respect to the first axis, and the control means controls the radio signals so as to feed the radio signals having phases opposite to each other to either one of each of the first feeding points and each of the second feeding points of the each pair of the conductor patches arranged so as to be symmetrical to each other with respect to the first axis.
According to the second aspect of the
Matsuyoshi Toshimitsu
Ogawa Koichi
Yamamoto Atsushi
Clinger James
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
Wong Don
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