Communications: radio wave antennas – Antennas – Balanced doublet - centerfed
Reexamination Certificate
1999-01-20
2002-02-05
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
Balanced doublet - centerfed
C343S878000, C343S886000
Reexamination Certificate
active
06344822
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
“Not applicable”
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
“Not applicable”
REFERENCE TO A MICROFICHE APPENDIX
“Not applicable”
BACKGROUND OF THE INVENTION
This invention relates to an improvement in the Instrument Landing System (ILS) for aircraft, in particular, the glide slope component thereof, employing an antenna system of the earth-image type, such as described in Butts, H. H., U.S. Pat. No. 3,325,812, Jun. 13, 1967, Capture Effect Glide Slope System, (Ref.1).
The standard antenna usually is mounted on a steel tower located several hundred feet to one side of the runway, considered a safe distance to avoid being struck by an airplane. This invention, however, is an antenna using wide aperture slotted cable elements, such as described in U.S. Pat. No. 4,464,665, Aug. 7, 1984, Watts, Jr., (Ref.2), or in co-pending application “Improvement in Slotted Cable Antenna Structure.” Frangible construction permits it to be located safely much closer to the runway. These characteristics allow for a guidance radiation pattern having narrow azimuthal coverage, resulting in improved glide slope performance in the vertical plane, together with fly-up signal to both sides as well as below path.
BRIEF SUMMARY OF THE INVENTION
The invention is an improvement on standard ILS image-type glide slope antenna arrays. It replaces the usual antenna elements with wide aperture slotted cables. Mounted on a frangible support, the antenna array can be located safely much closer to the runway. The closer spacing, with the wide aperture, provides for a vertical guidance pattern that is narrower in azimuth, resulting in improved quality of guidance. An additional slotted cable, fed only with clearance signal, provides fly-up indication, both sides, over a wider azimuth sector.
REFERENCES:
patent: 1747008 (1930-02-01), Jacobson
patent: 4464665 (1984-08-01), Watts
Johnson John Henry
Watts, Jr. Chester B.
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