Mine both sends and receives. I installed a splitter box, so I use my existing VHF antenna. AIS takes away so much of the anxiety of singlehanding offshore. Not that you can't still get run down at sea, but the odds of not seeing a vessel that is also not using AIS is very, very small. I'm probably more likely to get hit by a bus crossing the street. (Here in Miami, probably much more likely.)

Ron