Metallic zone plates for sectoral horns

Fresnel zone plates are planar devices with lens-like focusing properties. The planar structure makes a zone plate easy to construct and provides lower absorption loss and weight. This paper reports on the Fresnel zone plates to be constructed from metal. Typically in the past, zone plates have been fabricated from dielectric material. In addition to the advantages mentioned earlier, metallic zone plates can be machined or cast directly into sectoral horns.