Design of Four Layer Microwave Absorber Based on Polyaniline-Expanded Graphite Composites: Role of Layer Interfaces in Impedance Matching

Abstract

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.