Electromagnetic Shielding Effectiveness of an Absorber-Like Carbonyl Iron-FeNi Double-Layer Composite

A genetic algorithm was employed as a novel method to determine the best combination of materials for a double-layer electromagnetic shielding composite with good electromagnetic wave absorption efficiency at high frequencies from numerous magnetic materials. A carbonyl iron soft magnetic composite and a flaky FeNi soft magnetic composite were used to form the double-layer composite. The reflection and transmission parameters of the double-layer composite were measured using a vector network analyzer. The electromagnetic shielding effectiveness (SE) of the double-layer composite was calculated and analyzed. The double-layer composite was composed of two shielding materials with different electromagnetic parameters and demonstrated an excellent electromagnetic SE greater than 20 dB above 4 GHz; the ratio of the absorption efficiency (SEA) to SE (SEA/SE) was greater than 0.95, which indicates that more than 95% of the electromagnetic waves at high frequencies were attenuated by the shielding material, rather than being scattered into the surrounding environment. The double-layer composite exhibits excellent performance toward high electromagnetic waves absorption during the EMI shielding process.

Automated summary

A genetic algorithm was used to determine the best combination of magnetic materials for a double-layer electromagnetic shielding composite with good absorption efficiency at high frequencies. The composite, composed of carbonyl iron and flaky FeNi soft magnetic composites, demonstrated an excellent electromagnetic shielding effectiveness (SE) greater than 20 dB above 4 GHz, with absorption efficiency to SE ratio (SEA/SE) exceeding 0.95, indicating a high level of attenuation of high frequency electromagnetic waves.