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7 Platform one GetSat in Israel is developing the first steerable phased array satellite transceiver that can be used in UAVs (writes Nick Flaherty). The system is based around a solid- state steerable phased array flat-panel antenna, and provides a full satellite terminal and modem that weighs less than 1 kg. It will provide a bandwidth of 10 Mbit/s for real-time full-motion video, and can be used on Class 3 UAVs weighing between 10 and 20 kg. GetSat started with an interlaced antenna design where all the radiating elements are interlaced for the Ka satellite band, using the same area of the panel to receive and transmit. It is also developing an antenna for the L band at 500 MHz to 1.5 GHz. “As our terminal is small, we realised there is no small modem on the market so we developed the modem as well. The terminal can be separate or integrated into the modem,” said Oleg Roitberg at GetSat. “We have the modem and the antenna controller using the same board, so we save a lot of space and power consumption. The modem ASIC and antenna controller are separate to support older systems, but they can sit on the same board. “Right now it’s not a bottleneck so Laser communications systems maker Mynaric is adapting its space technology for UAVs in precision agriculture applications (writes Nick Flaherty). It is developing a variant of its air-to- ground terminal that weighs less than 2 kg and can send data at 1 Gbit/s there’s no case for further integration,” he said. “Most of the power on this type of terminal is the transmission, so we are working with high-efficiency gallium nitride amplifiers with integrated solid- state power amplifiers.” The modem itself is software-defined to enable it to handle different protocols, with an RF signal chain for the L-band frequencies and then up-converted to the Ka (27-40 GHz) or Ku (12-18 GHz) bands in the terminal. “As regards the antenna, we are now reaching 60-80% efficiency depending on the band for phased array rather than 10-15% [for existing antennas]. If you have low efficiency you can do nothing with it on the modem except reduce the data throughput. Flat panels and phased array in Ka with high efficiency is the real challenge. The issue is the performance. across distances of up to 10 km. “Incorporating a redesigned micro- laser terminal into a lightweight UAV allows far greater tranches of data to be downloaded and assessed, over much larger tracts of land,” said Dr Markus Knapek at Mynaric. “UAVs flying at 8000 ft can survey 40,000 acres of crops in an hour. That is “The full-duplex antenna panel will have a steering capability – we have already carried out tests on a prototype developed for the Ka band,” he said. “You are transmitting directly to the radiating elements so there are no losses from the power amplifier, and the noise figure on the receive side is much higher than the RF ICs on the market, which have a 5-6 dB noise figure. We are at around 1.1 dB for noise so that gives us almost 10x more bandwidth.” The panel size will be 28 x 9 cm as a basic block, which can then be made any size depending on the performance requirements and space available. “For a smaller UAV this can give you that 10 Mbit/s throughput and even more on the receive side of the panel,” Roitberg said. The first systems will be on the market as full products by the end of 2018. an incredible amount of data to process, and laser communication’s ability to transmit such a lot of data will allow farmers to tailor their use of pesticides, herbicides and fertilisers, and fully use highly complex data gleaned from hyperspectral imaging.” The new terminal will be available in early 2020. Steerable satcom system New field for space tech Communications Airborne vehicles GetSat’s phased array satellite transceiver will be a first for the UAV industry Unmanned Systems Technology | August/September 2018