To establish a stable, effective and reliable communication systems between unmanned aerial vehicle (UAV) and mobile vehicles, the propagation characteristics of air-ground (AG) wireless channels need to be better understand. In this paper, a narrowband multi-link channel measurement for UAV to mobile vehicles at 2.4 and 5.9 GHz is presented. Based on the measured data, some essential channel characteristics such as large-scale fading (LSF) including path loss, shadow fading (SF), and small-scale fading (SSF) including fading depth (FD), magnitude distribution and Rician distribution K-factor are analyzed. Then the cross-correlation characteristics of different channel parameters and receiving antenna numbers at 2.4 GHz and 5.9 GHz are systematically investigated. These researches provide some references to optimize antenna design and multi-link channel modeling of UAV to mobile vehicle communication systems in future intelligent transportation system (ITS).