Design of Graphite Silicone and Iron Silicone Structure for Efficient X‐Band EMI Shielding Performance

ABSTRACT Flexible electromagnetic interference (EMI) shielding materials with high attenuation, low weight, and mechanical adaptability are increasingly being recognized for their potential applications in microwave‐frequency electronics. This study examines silicone‐based composites filled with conductive graphite and magnetic iron powders for X‐band EMI shielding. Graphite–silicone (GS) and iron–silicone (IS) composites were fabricated at 20, 40, and 60 vol% filler loading and characterized using a WR‐90 waveguide and vector network analyzer within the WR‐90 X‐band range of 8.2–12.4 GHz. Unlike conventional mixed‐filler formulations, this work employs a staged evaluation framework in which GS and IS composites were first tested individually and subsequently combined as two separate layers. The measured results show that both GS and IS composites exhibit absorption‐dominant shielding behavior and that selected paired configurations provide improved shielding compared to several single composites. The improved shielding response is attributed to the combined effects of conductive network formation, dielectric relaxation, interfacial polarization, and multiple internal reflections within the stacked structure. The GS40–IS40 configuration showed a maximum (SE T ) of approximately 62 dB at 11.2 GHz within the WR‐90 X‐band range of 8.2–12.4 GHz. This value represents a frequency‐dependent peak and should not be interpreted as constant across the entire band. This dual‐composite silicone design concept represents a flexible, scalable, promising option for microwave EMI shielding materials.