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The present work investigated design simulation of single and multi-layer microwave absorber based on mono-phase (polyaniline) and dual—phase (polyaniline-expanded graphite) dielectric composite material. The work is the extension of author’s earlier work on carbon–based material using the unique behavior of polyaniline and highly conducting Expanded Graphite as fillers. The dual phase composites of polyaniline/Expanded Graphite prepared by in situ polymerization of aniline with different EG concentration of (0.00, 0.15 and 0.25 wt.%) were mixed with Novolac Phenolic Resin (NPR) in (10, 20 and 30 wt.%) to form (PA1-PA3 & PG1-PG3, PG4-PG6). Based on microwave characterization results and employing transmission line model, a theoretical analysis has been qualitatively done on four layer design simulation of absorber to achieve high performance absorption peak and bandwidth and subsequently fabrication of the designed structure for X-band microwave absorption. A calculated reflection loss ∼−80 dB is observed at 10.69 GHz for PG1-PG3-PG5-PA3 four layer designs having overall thickness of 8.6 mm and promising measured reflection loss ∼−63 dB at 10.66 GHz near the central frequency of the experimental frequency range. High performance absorption is interpreted as impedance matching behavior at the layer interface of the multilayer structure.

Graphene oxide obtained by Hummer's method is used to synthesize reduced graphene oxide (RGO) using chemical and thermal treatment method. Flexible composites of RGO-Silicon carbide (SiC)-Low density polyethylene (LLDPE) in different wt.% ratios of fillers are characterized for complex permittivity and permeability in X-band. A metamaterial design of ring shaped with four stripe structure is designed on developed substrate as well as standard FR4 substrate and simulated using EM simulator, CST Microwave Studio. Simulated results showed shifting of resonant peak frequency from C-band frequency for FR4 substrate to X-band for developed substrates signifying a role of microwave constitutive properties of the dielectric spacer. The fabricated metamaterial structure on RGO-SiC-LLDPE composite of thickness 0.7 mm shows a S11 ∼ −25 dB at 10.7 GHz with maximum absorption of 96.7%. Thus, the developed meta-material design showing a potential application in microwave applications.