BC stations tried 5/8 wavelength antennas to maximize their groundwave coverage. Unfortunately, the high angle lobe produced a skywave that caused severe interference fading at night out in their desired coverage area.
Most 50 kW, 24/7, omnidirectional MW broadcast stations such as WJR, KMOX etc use a radiator height close to 195 degrees, which produces almost as much groundwave field as a 5/8-wave, but without the high-angle lobe centered at about 60 degrees elevation.
It was this high-angle lobe that produced self-interference when the skywave radiation from it arrived out of phase with the groundwave, at the edges of the groundwave coverage area.
RF
_________________ Topband Reflector
