Influence Factors of Frequency Response Characteristics for a Novel Velvet Frequency Selective Fabric

In this paper, a novel three-dimension (3D) frequency selective fabric (FSF) based on U-shaped velvet, using metallic yarns as the conductive unit material via cluster velvet weaving method, is prepared. U-shaped unit structure is formed by two ending points of the dipole unit extending into the space Z-direction. By testing and analyzing transmission coefficient of specimens, frequency response characteristics are studied. Compared to FSF with dipole unit structure, the new velvet fabrics with the same unit length have double-frequency resonance at 2 -18GHz. With an increase of inclination angle of velvet, the resonance frequency is changed slightly, accompanied by a trend of decreasing first and then stabilizing. The density of conductive yarns is enlarged, and the resonance frequency moves slowly to higher frequency. If the total length of U-shaped unit on the bottom is greater, the resonance frequency will go to lower frequency. The number of connected U type rarely affects the resonance frequency with the same bottom length. And this work shows that U-shaped velvet FSFs can be designed with more parameters comparing with planar FSF. What’s more, they also have a multi-frequency response character.

Keywords: U-shaped velvet fabric; Frequency selective surface; Influence factors; Frequency response characteristics