There's a second theory paper in that press release that discusses the range and verifies the model experimentally: http://www.mit.edu/~fadel/papers/PAB-theory-

There's a second theory paper in that press release that discusses the range and verifies the model experimentally: http://www.mit.edu/~fadel/papers/PAB-theory-paper.pdf http://www.mit.edu/~fadel/papers/PAB-theory-paper.pdf This isn't a product that's already on the market, so what matters is how far it can get if actually commercialized - which is pretty impressive at such low power.