Design and Optimization of a Triple-Band Fractal Antenna with AMC backing for Wearable sub-6 GHz Applications

This paper presents a compact triple-band fractal antenna integrated with an artificial magnetic conductor (AMC) reflector for wearable and mobile sub-6 GHz communication systems. The antenna operates at 1.82, 2.42, and 5.1 GHz. The radiating element is designed using a two-iteration Sierpinski carpet fractal geometry, which increases the effective current path and enables multiband resonance within a compact footprint. To improve body-centric performance, an AMC ground plane is positioned below the radiator to provide in-phase reflection, suppress backward radiation toward the human body, and enhance forward-directed radiation. Full-wave simulations and measurements show that the AMC-backed configuration improves the realized gain from 2.14–2.90 dBi to 3.52–3.85 dBi across the three operating bands, while maintaining radiation efficiency above 85%. Specific absorption rate (SAR) analysis verifies compliance with international exposure limits. The localized SAR1g values are 0.135, 0.128, and 0.119 W/kg at 1.8, 2.4, and 5.0 GHz, respectively, with SAR10g values below 0.118 W/kg. Additional body-location studies confirm stable and safe operation for practical wearable placements.