This book focuses on the propagation characterization and channel modeling of Unmanned Aerial Vehicle (UAV) communications. Currently, there are no books that cover this specific topic. The authors fill in this void by elaborating accurate yet easy-to-use UAV channel models. The authors also present such topics as propagation characteristics of  UAV communications, a time stationary regular-shaped geometry-based stochastic model (RS-GBSM) for UAV narrowband channels. It also introduces a time non-stationary RS-GBSM for UAV narrowband channels, a time non-stationary RS-GBSM for UAV wideband channels, a time-space non-stationary irregular-shaped geometry-based stochastic model (IS-GBSM) for UAV wideband channels and more. Finally, this book closes up with some promising directions, hoping to promote future research outcomes in the field of  UAV channel modeling. As the UAV technology matures rapidly, UAV communications are shifting from military development to civilian and commercial sectors. The UAV communication is widely considered as a significant and indispensable component of wireless communications. It is well known that an accurate yet easy-to-use UAV channel model is the foundation of designing a proper UAV communication system and evaluating its performance. This book also provides valuable suggestions for the design of UAV communication systems by adequately presenting the UAV propagation characterization and channel modeling. This book is mainly written for researchers and professionals working in wireless communications. Advanced-level students majoring in computer science or electrical engineering may also find the content useful as a secondary textbook.