<p>Unmanned aerial vehicles (UAVs) have attracted attention as aerial platforms for uplink data collection from ground devices. However, UAV communications are vulnerable to jamming interference, which degrades communication reliability and increases the overall mission time. This paper proposes a trajectory planning method for UAV-assisted data collection with directional antenna control under jamming environments. The proposed method jointly optimizes the UAV hovering positions and antenna directivity using particle swarm optimization in order to balance communication efficiency and mobility cost. By adaptively adjusting the antenna beamwidth, the UAV can suppress interference from jammers while maintaining reliable communication with legitimate ground terminals. In addition, a trajectory refinement strategy is employed to construct an efficient flight path that minimizes unnecessary movement. Through simulation experiments, we show that the proposed method effectively reduces the total mission time while ensuring reliable data collection in the presence of jammers.</p>