{'fraction_non_alphanumeric': 0.017299107142857144, 'fraction_numerical': 0.004464285714285714, 'mean_word_length': 5.7406015037593985, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Research on 3D periodic structure velvet fabric and its frequency response characteristics

Frequency selective surfaces (FSSs) based on textile or textile composite materials are increasingly becoming popular due to their textile nature of high flexibility, softness, low-cost, easy fabrication, and other textile characteristics compared to the traditional metal FSS, especially the two-dimensional FSS fabrics. In this study, a three-dimensional (3D) fabric periodic structure with conductive textile fabricated vertically on the common textile substrate, forming a U-shaped array, is proposed. An experimental validation has been conducted to verify whether the 3D frequency selective structure fabric has good frequency response characteristics and great design ability. The model samples of 3D periodic structure based on velvet fabric with different structure or material parameters were fabricated by hand. Through testing and analysis of transmission and reflection coefficients at 2–18 GHz using the shielding chamber method, the results show that the velvet height of the fabric model periodic structure has an obvious effect on the resonant frequency. With an increase in velvet height, the resonant peak will move towards lower frequency. With an increase of vertical velvet spacing, the resonant frequency will also move towards lower frequency. Velvet material has a slight influence on the frequency response characteristics. The frequency response characteristics of this structure are stable under different incident angles. The 3D periodic structure offers more design freedom and possibilities. Significant effects of wave absorption or selective filtering by the periodic structure can be achieved by regulating the structural parameters and material parameters together.