The broadcast antenna used by WRUW-FM, the educational radio station of Case Western Reserve University, Cleveland, Ohio, USA, broadcasting on 91.1 MHz at 15 kW EIRP. This is a view looking up the tower. The antenna consists of four stacked "bays" of specialized dipole driven elements. Those on the right are called "crossed dipoles" and radiate circularly polarized radio waves. Circular polarization is used for FM broadcasting because it is not sensitive to the orientation of the receiver's antenna.