Greta Johnsen has joined the Public Affairs Department of Chicago Public Media as a new weekend host, handling on-air duties on WBEZ-FM 91.5 from 7 a.m. to noon Saturday and Sunday mornings. She comes to WBEZ from KUAC 89.9, the NPR affiliate station in Fairbanks, Alaska. She spent four years there, most recently as operations manager and "Morning Edition" host. She began her career as a broadcast engineer for WCAL Classical 89.3 in Northfield, Minn., while in college. Johnsen, 26, has a bachelor's degree from St. Olaf College and is pursuing a master's at the Medill School of Journalism at Northwestern University.