CIRCULAR LEAKWAVE ANTENNA FOR BEAM IDENTIFICATION

Abstract

This disclosure relates to a circular antenna comprising a coaxial probe for feeding the circular antenna with leakage waves and a substrate on one face of which is arranged an array of metallic strips and on the other face of which is arranged a ground plane. The metallic strips are disjointed from one another, and each metallic strip forms at least part of a ring. The position of a geometric axis connecting the coaxial probe to the center of the circular antenna is selectable from several possible positions, such that from one position to another among the possible positions, the circular antenna exhibits a different periodicity, where the periodicity is equal to the sum of the widths of the gaps between successive metallic strips and the widths of said metallic strips along the selected geometric axis. Figure to be published with the abstract: Fig. 1a

Claims

Demands

1. Circular antenna comprising a coaxial probe, called the coaxial feed probe, intended for feeding the circular antenna with leakage waves and a substrate on one face of which is arranged an array of metal strips and on the other face of which is arranged a ground plane, the metal strips being disjointed from each other and each metal strip forming at least part of a ring, the position of a geometric axis connecting the coaxial feed probe to the center of the circular antenna being selectable from a plurality of possible positions, characterized in that from one position to another among said plurality of possible positions, the circular antenna exhibits a different periodicity, where the periodicity is equal to the sum of the width of the slits between successive metal strips and the width of said metal strips along the selected geometric axis.

2. Circular antenna according to claim 1, characterized in that the circular antenna comprises several coaxial probes, called available coaxial probes, which are angularly equidistributed around the center of the circular antenna, and for each possible coaxial probe, the periodicity exhibited by the circular antenna is different, and in that the periodicity exhibited by the circular antenna is selected by activating the feed coaxial probe among said available coaxial probes.

3. Circular antenna according to claim 2, characterized in that the circular antenna is divided into several angular sectors, each angular sector comprising a said coaxial probe available, the periodicity exhibited by the circular antenna being different from one angular sector to another.

4. Circular antenna according to claim 3, characterized in that each angular sector is delimited by a metallic reflector passing through the substrate.

5. Circular antenna according to claim 3 or 4, characterized in that the circular antenna is divided into six angular sectors of the same angle.

6. Circular antenna according to claim 1, characterized in that each metal band forms a ring, and the periodicity exhibited by the circular antenna varies continuously between a value maximum and a minimum value by traversing angularly the circular antenna around its center, and in that the circular antenna is composed of two concentric substrates separated by a space so as to be able to rotate independently of each other and without friction: - a first substrate having a circular crown shape having a hollow center and comprising the network of metal strips, and - a second substrate, mounted movable in rotation concentrically with respect to the first substrate, and containing the coaxial feed probe, the second substrate being included in the hollow center of the first substrate.

7. Circular antenna according to claim 6, characterized in that the second substrate comprises a metallic reflector passing through the second substrate, so as to partially surround the coaxial feed probe while leaving free the geometric axis connecting the coaxial feed probe to the center of the circular antenna in one direction.

8. Circular antenna according to claim 7, characterized in that, on the same side of the circular antenna as the array of metal strips, the second substrate is covered with metal to prevent it from radiating.

9. Circular antenna according to any one of claims 6 to 8, characterized in that the first substrate further comprises several metal strips bent in the direction with minimum periodicity in order to increase the number of radiating slits in that direction.

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