Bio-Inspired Ceramic Design for Tunable Electromagnetic Filtering

The rapid evolution of modern communication systems and the growing demand for spectrum efficiency necessitate electromagnetic filters with inherent frequency selectivity to ensure accurate signal transmission in complex interference environments. Herein, we present a novel design inspired by the hierarchical architecture of bamboo fiber bundles, consisting of dielectric-semiconductor core-shell fibers. The bamboo-inspired structure integrates Fabry-Perot constructive interference, arising from multi-interface reflections, and Bragg grating resonance, induced by the periodic alignment of the fibers, providing the composites with distinctive bandpass microwave filtering characteristics. Additionally, the periodic dielectric-semiconductor interfaces create intrinsic RC-type units, enabling tunable passband regulation analogous to metamaterial unit cells. Comparisons among three FMSCs with different interfacial phases reveal distinct, interface-dependent filtering behaviors, with FMSC-SiO₂ demonstrating superior performance. Specifically, it achieves a reflectivity below 0.56%, a transmissivity of up to 84.9%, and a tunable Ku-band passband coverage of 83.3% within a thickness variation of just 1 mm. This work demonstrates a bio-inspired, material-structure-synergistic strategy for creating miniaturized, low-loss, and tunable ceramic electromagnetic filters, holding potential for precision signal transmission in advanced communication systems, including high-frequency electronic applications.