Gentlemen (and ladies if there are any present)

I have somewhat of a newbie question regarding antenna placement. I've been flying for quite a while now, so you'd think I should know this. Oh well....

Anyway, on all the models that I've flown, the antenna wire was for the most part outside the plane. Off the top of my head, most if not all other models that I've seen the wire has be exposed also. I'm just wondering if there's a big reason for this? If one were to run most of the wire inside the plane, and just have it exit at the rear, would this be a problem? I'm just wondering if it cuts down your range at all? Just curious I guess.

Thanks

- Paul