I ran the AR-1A thing for a while and used a larsen NMO mount CB antenna for both CB and AM/FM. If you listen to AM/FM at all don't do it. reception SUCKS. Maybe it is the way I had it setup... I did it by the book though.
I run that same Larsen 5/8 wave antenna that Hulk is referencing and like it a lot. It seems very branch resistant and was cheap. Also seems to work well.