Here's a nice close-up of that channel 3 bat-wing antenna behind the studios of WISC-TV (3 Madison) at 7025 Raymond Road. I have no idea whether this is still used as a backup or not. (It's not reflected in the FCC's database, but older backups were authorized by letter so this does not necessarily mean that this is not licensed as a backup.)
Copyright 2004, Garrett Wollman. All rights reserved. Photograph taken 2004-10-10.