I see these slanted antennas (photo attached) on quite a few commercial buildings built prior to the early 1990's in the area. From the information I've gathered, these antennas were used to receive Muzak which was broadcast on sub-carriers of commercial FM radio stations until the mid-1990's. The antenna slant would make sense due to the polarization of most commercial FM transmissions. Muzak is now distributed via satellite and over the Internet. Can anyone confirm this information, and if that's the case, I'm curious if anyone knows which FM station in Indianapolis the sub-carrier used to be broadcast on.