It should work fine. The most important thing you can do for best decoding is to feed a clean audio signal. A direction connection via a cable is best, I have some info on building or buying one here:
http://www.blackcatsystems.com/ipad/iPad_iPhone_iPod_Touch_Microphone_Wiring.htmlIf you do not use a cable, you want to position the iPad mic very close to your radio's speaker, or better yet, plug earphones/headphones into the radio, and put the iPad mic next to one of the ear pieces.
Of course proper tuning of the station is essential, with a strong signal, minimal interference, etc.