Low‐Frequency, Ultra‐Thin and Ultra‐Wideband Meta‐Absorber via Resonance Enhancement Harnessing Magnetic Material

ABSTRACT Achieving efficient, ultra‐thin, and broadband absorption in the low‐frequency regime (e.g., P to S bands, 0.23–4 GHz) remains a significant challenge due to the inherent limitations of conventional materials and designs. To address this, we propose a composite metamaterial absorber that synergistically integrates a three‐layer metasurface absorber (TLMA) with a top‐loaded magnetic material (MM) layer. The standalone TLMA achieves perfect absorption (> 90%) but within a narrow 300 MHz band around 0.77 GHz. The introduction of the MM layer drastically enhances and broadens the resonant response through magnetic loss and optimized coupling, yielding an ultra‐wide absorption bandwidth from 0.5 to 3.8 GHz, which effectively covers the P, L, and S bands. The final optimized structure exhibits a remarkable overall thickness of only 41.0 mm (0.068 λ at the lowest frequency) and a fractional bandwidth of 153.5%. The working mechanism, elucidated through surface current and equivalent impedance analysis, is attributed to magnetic‐material‐assisted resonance optimization. This work provides a practical and effective strategy for developing high‐performance, ultra‐thin absorbers for advanced low‐frequency applications.