I'm using a Metz AM/FM
antenna mounted outside on my eaves. It's the same thing as the Magnum-Dynalab ST-2 or Fanfare FM-2G (The Magnum is actually a rebadged Metz, don't know whether the Fanfare is too).
This pulls in all the local FM and, surprisingly, all the local AM HD signals in the near suburbs of NYC. I run it through a standard 2-way splitter to both sets of antenna terminals. I'm up on a hill without any nearby high-rise buildings so multipath isn't really a problem. I also tried the Terk AM Advantage antenna which worked fine but was unsightly on top of my cabinet and prone to more electrical interference from indoor sources than the outdoor whip.