Analysis and Fabrication of a Frequency-Selective Helix Layer

Inhalt:
We investigate a layer composed of periodically placed copper helices. Thereby, left- and right-turned helices form a chessboard-like pattern. In this manner, cross-polarized field components which are inherent to helical particles cancel out. According to theory, this setup features nearly full reflection at resonance. The single-scatterer resonance of a representative number of particles is examined experimentally in order to assess manufacturing tolerances. The latter are taken into account by a numerical scattering approach being able to determine reflection and transmission characteristics. For experimental verification, the scatterers are mounted in commercially available plastic foam. To reduce the effect of manufacturing tolerances, smallstructured profiles are cut out by means of a laser beam. A fabricated sample consisting of a total of 3600 helices is characterized by means of a free-space measurement setup.