Low cost and easily scalable microwave absorbing material based on three-layer honeycomb sandwich structures

The present work describes a new three-layer structure for developing lightweight and low-cost microwave absorbing material using available honeycomb (HC) structures sandwiched by high density polyethylene (HDPE) composites loaded with a 3% of hybrid mixture of carbon black (CB) and graphite (GF) as dielectric filler (HDPE/HB) or 5% of granitic quarry waste (HDPE/GQW) as magnetic material. The microwave absorbing properties was studied in the X-band frequency range, which is useful for military purpose. Uncoated HC structure presented reasonable microwave absorbing properties, which could be improved by a proper choice of the thickness and cell size. The three-layer structure constituted by HC (4 mm thick) sandwiched by HDPE composites (1 mm thick) with HDPE/GQW composite as the matching layer resulted in minimum reflection loss of − 30.0 dB, which corresponds to electromagnetic wave attenuation higher than 99.9%. The present work illustrates the possibility of developing low cost and lightweight microwave absorbing material with easy and scalable fabrication procedures, for applications in both civil and military fields. The results also provide useful application of the waste generated from crushed gneiss rock during the production of fine aggregates, which is important for the environmental sustainability purpose.