On-Body Flexible Energy Harvesting Antenna Design Aided by Characteristic Mode Analysis

This paper introduces an on-body, flexible energy-harvesting antenna, utilizing characteristic mode analysis (CMA) to enhance and predict its design and performance under bending conditions. The initial design features a simple E-shaped patch antenna, with structural modifications implemented by incorporating a U-slot into the E-shaped configuration following CMA evaluation. The antenna's on-body performance is evaluated through cylindrical bending with varying radii, considering the proximity of a human wrist model to the antenna. The final antenna exhibits superior performance after bending, demonstrating robust gain and an expanded bandwidth compared to its initial state. Notably, the antenna achieves a maximum bandwidth of 3.73 GHz to 8.18 GHz under severe bending conditions. Under slight bending scenarios, the antenna attains a peak gain of 10.3 dBi at 5.0 GHz. Of particular significance, the antenna's bandwidth encompasses the ISM 5.8 GHz band, positioning it as a promising candidate for Wireless Energy Harvesting (WEH) applications. Crucially, this paper validates the efficacy of Characteristic Mode Analysis in predicting the impact of bending on antennas, thereby providing valuable insights for the design of flexible and conformal antennas.