Might not be quite in the same league with some of the more expensive antennea, but Rat Shack has an FM-only 70" outdoor antenna ($23!!)that may fit nicely in your attic. Because it's not that big, it's not that directional. (Generally, the larger a boom antenna is, the more directional it is.) DO NOT get a combo TV-FM antenna if you want to maximize performance as the TV portion can interfere with the FM portion.
My experience is limited but, when I investigated it, my next choice was the ASP-9, but it would likely require a rotor.
My experience is limited but, when I investigated it, my next choice was the ASP-9, but it would likely require a rotor.