Use a magnetic antenna (coil+core) and low frequency (125kHz etc). To check for attenuation use a sturdy garbage can or plastic drum filled with water. Body attenuation is nearly the same as saline solution (~= ocean sea water) for low frequency RF. Peter P. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist