Dave, We have the Furuno FA150 AIS unit and use a Digital AIS antenna. The antenna is only 4' long and only has a 4.5 DB gain but we regularly get over 25 mile reception from targets. Just as an aside, last summer we were making the crossing from California to Hawaii. Half way across, we got into some weird VHF propagation circumstances or skipping. We could still hear the LA Coast Guard transmissions although they could not hear us. At the same time, I got AIS target data on a couple of ships back in Long Beach Harbor 1200 miles away. Phil Eslinger Flat Earth N50 Ko Olina, Hi