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1. (WO1993019497) ANTENNE A REFLECTEUR A LENTILLE DE FRESNEL POUR HYPERFREQUENCES
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique
Claims:

1. A Fresnel-lens reflecting antenna (2) for receiving signals impinging the antenna essentially as a plane wave having a wavelength λ, said antenna (2) comprising

- a reflecting structure formed by zones (5) situated within each other, or parts thereof, capable of focusing the wave to the focal point (1) of the antenna (2),

characterized in that

- said zones (5) are designed into planar stepped zone sequences (6, 7, 11) whose height increases toward the edge areas of the antenna (2), each sequence having an inner rim (9) and an outer rim (10) so that

- each stepped zone sequence (6, 7, 11) has a total height substantially equal to a half-wavelength for the purpose of equalizing the travel path difference between the wave components reflected from the inner rim (9) and the outer rim (10) of the stepped zone sequence so as to add at the focal point (1) of the antenna,

- the step height (d) of the stepped zone sequence (6, 7, 11) fulfills the design rule d ≈ λ/(N*2) where N is the number of zones in each stepped sequence (6, 7, 11), and

- each stepped zone sequence (6, 7, 11) is situated in the depth direction so as to start from the same level (9) or a level which is shifted by essentially an integer multiple of half-wavelengths from the common reference plane (9).

2. An antenna (2) as defined in claim 1, characterized in that each stepped zone sequence (6, 7, 11) comprises eight zones (5).

3. An antenna (2) as defined in claim 1, characterized in that each stepped zone sequence (6, 7, 11) is formed by adding onto a polymer workpiece having a stepped contour a conducting layer made through vacuum evaporation, sputtering, chemical or galvanic electrodeposition, printing with a conducting ink, spraying or any other suitable metallization technique.

4. An antenna (2) as defined in claim 1, characterized in that the number (N) of zones in each stepped zone sequence (6, 7, 11) is varied.