Wireless communication at millimeter wave frequencies has attracted considerable attention for the delivery of high-bit-rate connectivity to unmanned aerial vehicles (UAVs). However, conducting the channel measurements necessary to assess communication at these frequencies has been challenging due to the severe payload and power restrictions in commercial UAVs. This work presents a novel lightweight (approximately 1.3 kg) channel measurement system at 28 GHz installed on a commercially available UAV. A ground transmitter equipped with a horn antenna conveys sounding signals to a UAV equipped with a lightweight spectrum analyzer. We demonstrate that the measurements can be highly influenced by the antenna pattern as shaped by the UAV's frame. A calibration procedure is presented to correct for the resulting angular variations in antenna gain. The measurement setup is then validated on real flights from an airstrip at distances in excess of 300m.
Three methods suitable for on-site window and wall penetration loss measurements are presented and compared. The methods are (i) outdoor-to-indoor channel measurement, (ii) far-field penetration loss measurement, and (iii) near-field penetration loss measurement. It is shown that the different methods give similar penetration loss results. The measured window exhibits bandstop characteristics due to the internal reflections in the periodic structure of the triple-layer window. The brick wall has penetration loss that increases as a function of the frequency.
European Space Agency is developing EMS (European Mobile System) land mobile system for voice and data communications. Two different antenna concepts have been realised for a mobile terminal. The first one is a rotating antenna consisting of two radiating elements. The second one is an electronic array antenna in which 12 radiating elements locate on the facets of a truncated pyramid. Several field trials have been performed in order to optimise the tracking software and to evaluate the behaviour of the antenna in different environmental conditions. The results show that the developed antenna is feasible from the cost and performance point of view for this application.
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