This study focuses on developing an electromagnetic device designed to harvest electrical energy from low-speed natural wind, suitable for powering Wireless sensors in Structural Health Monitoring. The device features a tip prism activated by aeroelastic galloping, equipped with magnets to create a concentrated magnetic flux gradient through a coil, eliminating the need for mechanical links. The prototype with magnets optimized from placed in an opposing-pole configuration into dual linear Halbach arrays, was evaluated in a wind tunnel and examined through numerical simulation. At wind speeds of 2.6 m/s, the device starts to generate power, and at 12 m/s, it achieves an average power production of 4.9 mW. Numerical simulation results closely match experimental findings, showing that external electric load resistance greatly impacts the galloping onset wind speed and the oscillation amplitude of the harvester. The simplicity of this design is impressive.