Numerical Investigation of a PEC-Backed PVDF/MWCNT/Fe₃O₄ Nanocomposite Microwave Absorber in the X–Ku Band Using HFSS Floquet-Port Simulation

Abstract

Growing electromagnetic interference (EMI) and radar-signature concerns in the X and Ku microwave bands (8-18 GHz) have renewed interest in thin, lightweight, absorption-dominated composite materials as an alternative to bulky metallic shields. This work presents a numerical design study of a PVDF/MWCNT/Fe3O4 nanocomposite absorber backed by a perfect electric conductor (PEC) plane. A dispersive material model was built from representative low-frequency electromagnetic data combined with a Fe3O4-driven magnetic resonance placed at 14.5 GHz, and reflection loss was computed using the transmission-line model (TMM), the exact analytical solution for a homogeneous slab at normal incidence. A thickness sweep from 1.0 to 2.5 mm revealed a sharp, narrow band resonance instead of a gradual thickness-dependent trend. The best configuration, at 1.61 mm, reached a minimum reflection loss of -58.6 dB at 11.34 GHz, well beyond the -20 dB (99% absorption) target and deeper than comparable double and triple filler absorbers reported in the literature at similar thicknesses. The resonance arises from quarter-wavelength geometric matching coinciding with a loss tangent already elevated on approach to the assumed magnetic resonance, and it proved highly sensitive to thickness, with minimum reflection loss (RL_min) varying by over 30 dB across a 0.4 mm window, a finding with direct implications for manufacturing tolerance. These results were cross checked against an initial HFSS Floquet-port simulation, which was found to require a finer mesh before it can serve as independent verification this remains ongoing work, alongside experimental validation of the electromagnetic input data above 12 GHz.