From Turabian Style Manual - Chicago Style Manual does not tell how to cite radio.
See examples below:
1st Footnote or Endnote
15. "Bumps on the Road Back to Work," Tamara Keith, All Things Considered,
aired September 5, 2011, on NPR. http://www.loc.gov/ammem/papr/nychome.html.
Usually not cited in bibliography.
1st Parenthetical Note
(All Things Considered 2011)
All Things Considered. 2011. "Bumps on the Road Back to Work," Tamara Keith.
Aired September 5 on NPR.