Precious little technical details don't inspire much confidence on the performance of the product. After years of research and controversy we get a demo that sh

Precious little technical details don't inspire much confidence on the performance of the product. After years of research and controversy we get a demo that shows basically very little. To trigger a charge detection on a phone, you only need to apply a sufficient voltage and be able to supply a small current. It will "charge" but may take days to do so. As a minimum, the UBeam receiver must be able to generate 5W of power (1A at 5V) to adequately charge a phone (10W or more would be needed for a faster charge though). Assuming that the technology is 100% efficient in its power transceivers (which is impossible), there is still the matter of exponential attenuation when transmitting ultrasounds through air: at 2m, to produce 5W at the receiver, you need to generate 25W at the transmitter. This gets worse very fast. Even if you assume they magically manage to get extremely efficient, the laws of physic will prevent the technology from being useful beyond a couple of meters without requiring hundreds of watts of transmitted power. And we're not even talking about the actual performance of the transducers, or the fact that the angle between the transmitter and receiver can affect power transmission, as would air humidity levels... UBeam will most probably end up producing something super-niche. On paper and in controlled demos, you can transmit some power through the air using ultrasounds. So maybe they'll manage to have an exhibit in a museum or some technology-of-the-future showrooms and they'll probably continue to have demo at exhibitions for years to come while not answering the difficult questions of efficiency and practicality with actual verifiable numbers. Having an affordable, safe, useful, practical mass-consumer product though? Nah, not a chance. UBeam is one of these companies build on wishful thinking. They sell a dream and get money from people caught in that dream. They can't back down now, so they have to keep up appearances and come up with polished demos from time to time just to keep the buzz and the mystery alive, and the money flowing.