how can you tell if an ota signal is multipathing? my cbs station is about 60 mi. from me so i didn't expect to pull it in but...i was playing with the antenna and could get a 50 to 60 siganl strength, then it would jump to 81-85, just for a second or two, then go back to 50. is this caused by multipathing? how do you keep it from doing that?