An analagous analysis, carried out for the frequency range 35 - 38 GHz, shows that losses due to clouds amount to 0.01 db, while under consitioiis of dense mist and slight rains the losses equal 0.8 db. In it necessary to note that greater decay of up to 12 db can appear in dense cumulus-rain clouds and heavy rain, although these conditions only occur at middle latitudes during 2% of rainfall. Taking into account that it rains on average only 0.1% of the time one can calculate the effects on the possibility of energy transmission through the Earth’s atmosphere at these frequencies. There also exist a number of measures which can be taken to lower the influence of rain and clouds, such as placing the receiving ground antenna, in a region with few overcast or rainy days, using several reserve antennas in different regions separated by sufficient distance—which takes into account the fact that rain and clouds are usually local phenomena—and also by seeding rain clouds to provoke precipitation. With all this, losses of microwave energy at 35 - 38 GHz can be estimated to be 8% - 11%. This is only 1.5-2 times worse than the case at 2.5 - 3 GHz. Since the energy lost by beam transportation is only an insignificant part of the total energy losses in such projects, it can be said that degrading the efficiency of energy transfer by using a millimeter wavelength is quite acceptable. The point is that under fixed values of Ap L, and G greater than 100-fold decrease of the orbital transmitting antenna area at is possible. It is obvious that this must considerably decrease the mass and overall dimensions of an orbital power station. Factors which hamper the practical use of this proposed 35 - 38 GHz frequency range, include the limited choice of powerful and highly efficent microwave radiation sources in this range. However, the use of such microwave energy converters as gyrotrons, masers, and free electron lasers permits hope for overcoming these technical difficulties in the near future. There exist other “radiowindows” in the Earth’s atmosphere, particularly more short-wave “radiowindows” in the range of 140 GHz and 220GHz, but the use of these can probably only be exploited further on in the future.
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