Origami tunable frequency selective fabric and its tuning mechanism

The tunable frequency selective surface can change its resonant frequency to better meet the complex and changeable electromagnetic (EM) environment. The traditional metal frequency selective surface (FSS) has high precision, but it is hard, making it not easy to bend and adapt to the surface. In this paper, an origami tunable frequency selective fabric (oTFSF) is proposed, which is thin, flexible, and bendable with precise resonant frequency adjustment function. The oTFSF is made by folding and ironing a single layer of FSF with a special three-dimensional spatial structure. By changing its state, the angle of the EM wave interacting with conductive units of the oTFSF can be altered to realize the precise adjustment of the resonant frequency. When the folding trace is parallel to the electric field, the three-dimensional structure of the oTFSF can be equivalent to the projected plane structure through simulation. Therefore, multiple oblique incidence situations can be converted into vertical incidence situations. The equivalent EM parameters of the oTFSF can be obtained by particle swarm optimization algorithm (PSO) to analyze the influence of unit size change on oTFSF. The results show that when the folding angle increases, the equivalent inductance (L) decreases, and the equivalent capacitance (C) increases. The oTFSF can be used to prepare intelligent EM functional materials with characteristics of broadband, lightweight, flexible, and adjustable frequency.