radio recption on my 525

[prsprd1]

I have a 2001 BMW 525i. We bought the car used and it has been great. We took it on a long road trip this weekend before we left the radio worked fine. We used CDs during the whole trip as we were out of range from our regular radio stations. When we tried to use the radio when we got back all we got was static. Does anyone know what the cause is? I am thinking antenna but earlier posts don't help a whole lot. Dealer wants arm and leg just to look at it so want to tries to do this on my own and low $$