Determining the far-field radiation pattern of an antenna from measurements of its near field is a common task in the field of antenna characterization. Near-field measurements performed on-site are of great interest, as they can considerably extend the capabilities of traditional antenna characterization in anechoic chambers.

This thesis deals with the measurement and transformation of modulated electromagnetic fields that are recorded on-site with the help of uncrewed aerial vehicles. A corresponding near-field measurement setup is presented, measurements are examined and a comprehensive error analysis of the measurement setup is given. Furthermore, approaches for the measurement of modulated field signals are discussed and their applicability is demonstrated by numerical simulations and measurements in an anechoic chamber and on a flight navigation system.