With the development of wireless communication systems, the integration of unmanned aerial vehicles (UAVs) for wireless power transfer (WPT) has emerged as a promising solution to extend the operational range and longevity of ground-based sensor networks. This chapter delves into the joint design of such a UAV-assisted WPT network, where the UAV is equipped with a uniform linear array (ULA) directional antenna. Our objective is to enhance the minimum energy collected by all sensor nodes (SNs) by jointly optimizing the UAV trajectory and the directional antenna orientation. To accurately capture real-world dynamics, we employ a non-linear model for energy harvesting (EH). The difficulties of the original problem, arising from the complex patterns of analog beamforming and the non-linearity of the energy harvesting model, are addressed by introducing an approximate model for the antenna’s radiation pattern and discretizing the UAV trajectory. Capitalizing on the convex properties of the energy harvesting model, we develop a robust convex approximation for the modified problem and devise an efficient computational method to solve it. Simulation results validate the algorithm’s convergence and its capability to significantly boost the system’s performance.