Propagation environment assessment using UAV electromagnetic sensors

In this thesis, we attempt to build a picture of local propagation conditions by measuring signal transmission losses that allows naval operators to better understand the performance of their electromagnetic systems. By comparing the collected data against those of known baseline conditions, we can reliably determine the presence of atmospheric ducts as well as their ceiling heights, which include the detection of elevated ducts. Another function of the post-processing analysis of the collected data is to estimate κ, which is a parameter of the atmospheric refractivity. Knowledge of κ allows us to estimate the radar horizon, which is the maximum distance that a transmitter and receiver can be separated and remain within the propagation line-of-sight, despite the curvature of the Earth. This important information allows operators to choose the optimal settings for the maximum detection range of their radar and radio systems. We also investigate the measurement system requirements and operational scenarios such as the number of unmanned aerial vehicles and the total time needed to collect sufficient data. Two different types of flight patterns were studied, and our findings show that the vertical flight pattern using a rotary platform is more efficient. Furthermore, our simulation results suggest that the optimal operating frequency for the system is in the S Band.http://archive.org/details/propagationenvir1094558353Major, Republic of Singapore Air ForceApproved for public release; distribution is unlimited