http://www.verizonwireless.com/support/verizon-familybase-faqs/ https://www.kickstarter.com/projects/1226890823/iota-never-lose-sight-of-whats-important/description http://www.techhive.com/article/2459455/iota-offers-no-fee-gps-tracking-thanks-to-long-range-rf-and-your-neighbors-wi-fi.html http://www.iotera.com/preorder/ https://www.thetileapp.com/ http://www.kensington.com/us/us/4570/proximo™-find-your-phone-items-easily#.U9k2RoBdXTY http://www.hindawi.com/journals/js/2010/450392/ http://www.networkworld.com/article/2170751/tech-primers/location-based-wi-fi-services-can-add-immediate-value-to-wi-fi-deployments.html
http://www.instructables.com/id/Distance-measurement-with-radio-waves/step5/Step-5-Schematic/ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/radar.html http://www.radio-electronics.com/info/propagation/em_waves/electromagnetic_waves.php