Your router's signal strength is subject to the inverse square law. If you are 30' from your router, the router would have to use some very high wattage to get enough power to your phone to charge its battery. Besides the inefficiency of that (since less than a tenth of a percent of the broadcast energy would actually hit your phone), at some point, you will run into FCC limits on broadcast levels. Those limits are there for two main reasons: 1) your safety, and 2) interference with neighboring transmitters. I think this is "pie in the sky".