Not Sure, Try Adapter
They make an adapter that will hook to your vehicle FM antenna that will split the signal from your antenna to your radio and then also to your scanner.. I'm not sure about any on glass scanner antenna but I might try that also. I don't know how good they are or how hard they are to install but if you don't want any unsightly antennas on the car then that is just a suggestion. I know they make them I have found them before...It's been awhile thought but I figure you can still find one somewhere, Ebay or radioshack, etc. but it's supposed to split your antenna on your FM radio to your radio and to your scanner...Just a suggestion, About All I know To Do, Someone else might have more but I don't, Sorry I couldn't suggest more...