Advances and mechanistic insights into low-frequency (Sub-8 GHz) microwave-absorbing materials: A critical review bridging conventional architectures and emerging frontiers.

The rapid proliferation of 1-8 GHz electromagnetic waves (EMW) in modern communication systems has intensified the need for advanced low-frequency microwave absorbers. This review highlights the evolution of sub-8 GHz absorption materials, transitioning from traditional magnetic systems (e.g., ferrites, metallic powders) limited by high density, narrow bandwidth, and environmental instability to next-generation multifunctional composites. Innovations in carbon-based hybrids (e.g., carbon nanotubes, graphene), magnetic-dielectric heterostructures, and emerging nanomaterials (e.g., MXenes, metamaterials) have enabled lightweight, broadband, and tunable absorption through compositional optimization and structural engineering. Key electromagnetic parameters, including complex permittivity, permeability, and impedance matching, are systematically analyzed to elucidate absorption mechanisms such as interfacial polarization and multi-scale structural effects. Recent advancements demonstrate enhanced performance, yet challenges remain in translating laboratory-scale innovations to practical applications due to issues in cost, durability, and scalability. This review critically evaluates these challenges and proposes forward-looking solutions, such as machine learning-assisted material design and scalable fabrication techniques. By bridging fundamental research with application-driven insights, this work provides a comprehensive understanding of material evolution and design principles, offering a roadmap for future research in low-frequency microwave absorption. The findings aim to inspire the development of next-generation absorbers with tailored performance for emerging technological demands.