All receivers, regardless of their type need a good antenna to deliver their best performance. You could have the bestest, mostest expensive tuner in the world and hobble it with a piss poor antenna and the guy next store with a mediocre tuner and a good antenna will whup yer butt any day.
Your antenna needs depend on where you are, where the stations you want to listen to are geographically in relation to you, and the terrain and buildings between you and the them.
My experience with little powered antennas has not been good and I'm in a good signal area. You're generally better off with something like
this or a pair of rabbit ears that were made for TV reception.
In all cases, the higher up you can mount it, the better off you will be. FM is basically a line of site medium and mountains or buildings between you and the station can have detrimental effects on your reception.
If, like me, you are blessed to be in an area rich in stations in all directions and fairly close by, you can do well with an inexpensive omnidirectional antenna.
This is similar to the one I use.
If you're in the boonies and your nearest station is a looooooong distance (35 miles +) you'll probably want a directional antenna, which has greater range but only in the one direction that it is aimed.
Here's an example of one of those
To compound this, if the stations are far away and in all directions, you'll probably want a rotator so you can aim the antenna at whatever station tickles your fancy at that moment.
Granted, there are bigger, more powerful antennas available but these two are fairly representative of what's out there. I use one similar to the one on the bottom. That, and an inexpensive amp, is driving three FM tuners with virtually no noise. When I only had two FM's, I didn't need the amp but, each time you split the signal it gets weaker and, at some point, the camel's back breaks.
RatShack used to offer antennas similar to these, both in performance and pricing. You might want to start your shopping there. You might want to see what else they (and antennacraft for that matter) have to offer as far as antenna stuff goes BUT keep in mind that those monstorous combination VHF/UHF/FM antennas will most likely not work as well as a cheap FM only antenna. Only a few elements are dedicated to FM while on the dedicated FM antennas, they are designed for ONLY FM.
Good luck...
P.S..
Here's a fun toy to play with.
Check out the advanced options, zip code and state.