A thought occurred to me, and I wondered if it could be made practical...

This video talks about the possibility of electrical battery powered planes, and in short, while it may be practical to build small aircraft using battery power, unless batteries get an energy storage density about ten times greater than what we have today, making commercial airliners using them never will. But what if the airliners were powered by ground-based microwave transmitters? We've apparently managed to get the transmission losses to less than 20%, so how practical would it be to build relays of airplane power transmitters along land-based flight routes and use them to power fully electrical airliners?