Unmanned aerial vehicles (UAVs), also known as drones, are proliferating. Applications such as surveillance, disaster management, and drone racing place high requirements on the communication with the drones in terms of throughout, reliability and latency. Existing wireless technologies, notably WiFi, that are currently used for drone connectivity are limited to short ranges and low-mobility situations. A new, scalable technology is needed to meet future demands on long connectivity ranges, support for fast-moving drones, and the possibility to simultaneously communicate with entire swarms of drones. Massive multiple-input and multiple-output (MIMO), a main technology component of emerging 5G standards, has the potential to meet these requirements.