The problem is not new. Starlink is licensed for Ka and Ku bands now and eventually will utilize the V band. So there's plenty of real world use and engineering from which to draw. A typical in-flight aircraft system might support 400Mbps and the antennas are already steerable, electronically and mechanically. They are using VSATs and not BGAN so the requirements for aiming aren't exactly for following a satellite and jumping from beam to beam. None-the-less antennas have been a problem for years. They can be small, like a Hughes 9202 L-band Iridium/Inmarsat type, but the throughput isn't 1Gbps. Those relatively small portable terminals support 128Kbps. It's going to be interesting to watch now with OneWeb having gone bankrupt and their plan wasn't nearly as ambitious. They were a couple of years ahead in hardware but still had fairly sizable antennas. It's a balancing act since the link is duplex, asymmetrical but still you have to have either or both antenna gain or amplifier power for reliablity and high bandwidth. Neither being easy to miniaturize. Your phone only needs to work over a couple of miles while in the lowered orbits Starlink was approved for initial launches it's still 340 miles out to 820 miles at their highest orbit.
