  Unmanned Aerial Vehicle (UAV) networks can provide a resilient communication
infrastructure to enhance terrestrial networks in case of traffic spikes or
disaster scenarios. However, to be able to do so, they need to be based on
high-bandwidth wireless technologies for both radio access and backhaul. With
this respect, the millimeter wave (mmWave) spectrum represents an enticing
solution, since it provides large chunks of untapped spectrum that can enable
ultra-high data-rates for aerial platforms. Aerial mmWave channels, however,
experience characteristics that are significantly different from terrestrial
deployments in the same frequency bands. As of today, mmWave aerial channels
have not been extensively studied and modeled. Specifically, the combination of
UAV micro-mobility (because of imprecisions in the control loop, and external
factors including wind) and the highly directional mmWave transmissions require
ad hoc models to accurately capture the performance of UAV deployments. To fill
this gap, we propose an empirical propagation loss model for UAV-to-UAV
communications at 60 GHz, based on an extensive aerial measurement campaign
conducted with the Facebook Terragraph channel sounders. We compare it with
3GPP channel models and make the measurement dataset publicly available.
