Hi: The counter measure is called a corner reflector. Three flat surfaces joined at right angles. These can be made from 3 flat sheets forming 8 corner reflectors so you don't need to aim it, just put in a visible place. Any incoming ADS radiation gets sent right back to where it came from. Have Fun, Brooke Clarke -- w/Java http://www.PRC68.com w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml http://www.precisionclock.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist