Abstract:

Objective Fiber-reinforced composites have been widely investigated as electromagnetic wave （EMW） absorbing materials because of their excellent mechanical properties and structural designability. However， achieving efficient absorption in low-frequency radar bands below 8 GHz remains a challenge because dielectric loss and impedance matching are difficult to balance. In this study， the C-band （4-8 GHz） was selected as the representative frequency range， and a hybrid woven periodic structure composed of silicon carbide fibers （SiC_f） and glass fibers （GF） was designed to optimize EMW absorption performance.

Method A fundamental model of the SiC_f/GF hybrid woven periodic structure was established based on the intrinsic permittivity of SiC_f and GF with different orientations and the geometric characteristics of the woven structure. A genetic algorithm （GA） combined with three-dimensional electromagnetic simulation using CST Microwave Studio （CST MWS） was employed to optimize the key structural parameters， including fiber ratio， weaving pattern， and thickness， thereby improving the EMW absorption performance of the hybrid woven periodic structure in the 4-8 GHz frequency range.

Results The dielectric properties showed that SiC_f/epoxy exhibited much higher complex permittivity when the fibers were aligned parallel to the electric field than when they were perpendicular to it. For the parallel orientation， the real part （ε'）， imaginary part （ε″）， and dielectric loss tangent （tanδ） were 13.86， 21.76， and 1.56， respectively， whereas the corresponding values for the perpendicular orientation were 4.08， 0.15， and 0.03. In contrast， GF/epoxy exhibited relatively low complex permittivity under both fiber orientations. For GF aligned parallel to the electric field， ε'， ε″， and tanδ were 4.53， 0.46， and 0.10， respectively， while the corresponding values for the perpendicular orientation were 3.95， 0.13， and 0.03. The calculated reflection loss （RL） results showed that the unidirectional SiC_f/epoxy and GF/epoxy composites exhibited poor absorption performance within the thickness range of 2-9 mm， with RL values higher than -5 dB， owing to either poor impedance matching or insufficient electromagnetic attenuation capability. Based on these results， a SiC_f/GF hybrid woven periodic structure was designed to combine the high loss capability of SiC_f with the favorable impedance-matching characteristics of GF. The optimized hybrid woven periodic structure exhibited an average RL below -10.8 dB within the 4-8 GHz frequency range， the measured average RL reached -11.9 dB over the same frequency range， showing good agreement with the simulated results and supporting the validity of the optimized design. The enhanced EMW absorption performance was mainly attributed to the synergistic effect of favorable impedance matching and the conduction loss and polarization loss associated with SiC_f.

Conclusion Composites fabricated from SiC_f/GF hybrid woven periodic structures not only exhibit excellent EMW absorption performance in the low-frequency band， but the incorporation of GF also significantly reduces material cost while maintaining comparable performance， thereby providing a cost-effective solution for practical applications. Consequently， the composites combine high-efficiency low-frequency absorption with cost advantages， making them promising candidates for applications in radar stealth， electromagnetic shielding， and lightweight structural components in aerospace and defense fields. Further optimization of the hybrid woven structures and layer design is expected to extend the effective absorption bandwidth of the composites from the C-band to a broader frequency range.

Key words: silicon carbide fiber, glass fiber, hybrid woven periodic structure, electromagnetic wave absorbing material, simulation optimization, fiber-reinforced composite, inorganic fiber