Design, preparation and electromagnetic characteristics analysis of single, double and three-layer cross-shaped frequency selective fabrics

Abstract

Based on the research basis of single-layer cross-shaped frequency selective fabrics, the electromagnetic transmission characteristics of double-layer and three-layer cross-shaped frequency selective fabrics were explored in this paper. The frequency selective fabrics with different multilayer structures and specific-sized conductive units were designed, and then prepared by the computer engraving method and tested using the free-space method. The results show that the single-layer sample is less affected by the polarization mode of the electromagnetic wave, while the effect of the incidence angle is slightly larger. For the frequency selective fabric samples with the same frequency selective surface layers, the frequency selective characteristics of the double-layer samples are more ideal than those of the single-layer samples, while the electromagnetic loss of the three-layer samples is large and the narrow-band transmission characteristic is weakened. For the frequency selective fabric samples with the complementary frequency selective surface layers, the double-layer sample mainly shows band-pass characteristics and the narrow-band transmission characteristics are better than the single-layer sample. The three-layer sample of ‘patch + aperture + patch’ presents band-pass characteristics, and the ‘aperture + patch + aperture’ sample generates resonance at multiple frequency points, but the resonance peaks are all less than –10.00 dB, meaning that the sample presents full shielding characteristics in the test frequency band. The equivalent circuit model was built to explore the electromagnetic transmission mechanism, revealing the fabric type and structure, and the conductive unit type and size will affect the equivalent impedance of the frequency selective fabrics, thus further influencing the electromagnetic transmission characteristics.