Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
2000-09-15
2002-03-26
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S792500, C343S795000
Reexamination Certificate
active
06362796
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to broadband antennas, and especially to a compact, multiply-polarized log-periodic antenna.
BACKGROUND OF THE INVENTION
Log-periodic broadband antennas are known that consist of four radial antenna arms, 90° apart around a common center, from which antenna elements branch off alternately to left and right of each arm. The lengths of the elements, and the spacings between them, increase logarithmically away from the center. The signal feed is usually at the center, with two opposite arms being combined to provide a linearly polarized antenna, or all four to provide a circularly polarized antenna. In order to handle lower frequencies with a physically small antenna, the antenna elements on adjacent arms are sometimes interleaved.
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided an antenna comprising a dielectric sheet, and a pair of feed stems facing one another on opposite sides of the sheet. A plurality of antenna elements extend away from each feed stem, each antenna element forming a pair with an antenna element on the other feed stem.
According to another aspect of the invention, there is provided an antenna comprising a feed stem and a plurality of antenna elements extending laterally from the feed stem, wherein the antenna elements are of zig-zag form such that the electrical length of each element is greater than the distance between its ends.
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BAE Systems Aerospace Electronics Inc.
Drinker Biddle & Keath LLP
Nguyen Hoang
Wong Don
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