A novel approach to design broadband tunable microwave absorber using expanded graphite on a flexible substrate

This article presents a highly efficient and cost-effective approach to develop tunable broadband microwave absorber. The proposed absorber consists of non-metallic Expanded Graphite (EG) unit cells fabricated on Linear Low-Density Polyethylene (LLDPE) substrate. The tunability of the absorber is achieved by injecting distilled water into the fluidic channel engraved on the LLDPE substrate. The developed absorber shows a bandwidth of 2.10 GHz of -10 dB with > 90% of absorption with air filled channels and can be tuned by 1.10 GHz with the water filled channels. Rigorous numerical calculations and experimental measurements are carried out to establish the efficiency of the absorber. Prior to fabrication process, simulations of the electric and magnetic fields are carried out for different configurations to figure out the physical origin of the absorption property. Being fabricated on a flexible substrate with non-metallic expanded graphite, the absorber caters the advantages of being ultra-thin, flexible, non-corrosive and free from processing conundrums. Current progression of the unit cells in microwave absorber design in modern state of the art communication systems, stealth technology and electromagnetic shielding circuits, indicates offers strong possibilities for future applications of the developed flexible absorber.