For the Physics of radio, see Faraday, Maxwell, Heaviside, and Hertz. http://en.wikipedia.org/wiki/Electromagnetism is a good a place as any to start. Pointy cap & wand optional :) Jack -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist