Space Based Solar Power - Path Attenuation
Microwave power from space must contend with atmospheric attenuation. The Space Solar Power Satellite (SSPS) will not be directly overhead a temperate-latitude rectenna; a lower elevation above the horizon increases attenuation.
The attached graph is originally from xxx and duplicated as Figure 2.19 on page 2,48 in the second edition of Radar Handbook by Merrill Skolnik, TK6575.R262 1990.