Exploration of Convergence Point Characteristics in Near-Sea-Surface Wireless Power Transfer

This study investigates the enhancement of long-distance microwave wireless power transfer (WPT) performance by utilizing naturally formed evaporation ducts near the sea surface. The parabolic equation method is applied to analyze how emission height, frequency, evaporation duct height and receiving aperture influence multiple convergence points and power distribution. Results show that increasing emission height transforms the power pattern from a single- to a multi-layer structure, improving spatial coverage and providing additional transmission options while slightly reducing near-surface power concentration. Higher frequencies strengthen beam confinement, with the power ratio Pe at 12 GHz, about 2.7 times higher than that at 8 GHz. Furthermore, a higher EDH enhances power trapping, leading to a more complex vertical field structure and increased field strength. A larger receiving aperture also improves performance, with a 3 m aperture at 12 GHz achieving 2.5 times the power ratio of a 1 m aperture. Optimizing these parameters facilitates consistent and efficient power delivery over long distances. The findings provide theoretical support for developing sustainable wireless power transmission systems, particularly for offshore platforms, maritime vessels, and remote-area power networks.