Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
2002-02-12
2004-07-06
Clinger, James (Department: 2821)
Communications: radio wave antennas
Antennas
Wave guide type
C343S840000
Reexamination Certificate
active
06759992
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to sectorized cellular communication systems and, more particularly, to antennas for use in such systems.
BACKGROUND OF THE INVENTION
Pyramidal horns having corrugated interior surfaces have been known for use in microwave systems for many years.
Sectorized cellular communication systems have also been known for many years, and are in widespread commercial use. Sectorized cellular systems typically use directional antennas to separate signals radiated at similar frequencies. In theory, the antenna for each sector has a specified azimuthal beamwidth to reduce interference from both customer equipment and cell-site equipment in other cells. However, interference can increase if the antennas serving the sectors do not produce azimuth-plane patterns that drop off sharply at the edges of their respective sectors, and patterns that do not have large sidelobes and backlobes. Producing such patterns becomes more challenging as the number of sectors in a cell is increased and the sector sizes become smaller, e.g., from three 120° sectors to nine 40° sectors, or to twelve 30° sectors.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an antenna for use in a sectorized cellular communication system, the antenna comprising a wide-flare pyramidal horn having two pairs of opposed flared side walls, at least one of the two pairs of opposed walls having corrugated interior surfaces, the length of the horn and the flare angle of the walls having the corrugated interior surfaces being selected to produce a ratio &Dgr;
e
/&lgr; greater than 1.5, where
&Dgr;
e
=[a/2/&lgr;] tan (&agr;
e
/2) is the spherical-wave error of said horn, &lgr; is the free space wavelength of the microwave signals to be transmitted by said antenna, a is the aperture width and &agr;
e
is the horizontal half-angle of the horn.
The azimuthal pattern has a half-power beam width that is substantially as wide as the azimuthal width of the specified sector and drops sharply at both azimuthal edges of that sector. In the elevation plane, The elevation pattern is substantially free of nulls across a specified elevation-plane beam width (typically ±25°).
When used in a sectorized cellular communication system, this antenna is capable of producing specified patterns in both the azimuth and elevation planes of a specified azimuthal sector with a specified ground range within a cell.
REFERENCES:
patent: 2659817 (1953-11-01), Cutler
patent: 2912695 (1959-11-01), Cutler
patent: 3611396 (1971-10-01), Jones, Jr.
patent: 3631502 (1971-12-01), Peters, Jr. et al.
patent: 3924237 (1975-12-01), Fletcher et al.
patent: 4301456 (1981-11-01), Lovick, Jr.
patent: 4477816 (1984-10-01), Cho
patent: 4658258 (1987-04-01), Wilson
PROC. IEE. vol. 116. No. 2 Feb. 1969, G.H. Bryant,Propagation in Corrugated Waveguides, 1968.
Richard C. Johnson,Antenna Engineering Handbook 3rdEdition, McGraw-Hill, Inc., New York, 1993, Ch. 15 pp. 1-54, par. 37, 45.
Knop Charles M.
Orseno Greg
Soliman Nabil
Andrew Corporation
Clinger James
Jenkens & Gilchrist
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