I know dry sand is transparent to microwave but wouldn't damp earth shield against radio frequencies? In the utility industries, with what are known as “out-of-sight” terminations, a device is buried which can be located with a detector. Wet soil or not. It’s spring, and so my mind can’t remember how this works exactly. Not quite the same as locating buried cables, which requires a signal to be applied to the cable. So it would be possible. (If not slightly ridiculous; I would have to buy thousands of devices.) Bob Nold Denver, Colorado, USA _______________________________________________ pbs mailing list pbs@lists.ibiblio.org http://pacificbulbsociety.org/list.php http://pacificbulbsociety.org/pbswiki/