Glad that I was able to give you some additional insight.
There are cases where a stronger signal is available at a lower height, just as the report indicates. This is when the signal reflected from the ground or other horizontal surface adds to the direct signal in phase. This is called "ground bounce."
or ground gain
http://www.qsl.net/oz1rh/gndgain/gnd_gain_eme_2002.htm
http://www.hdtvexpert.com/classic-pe...fringe-082009/