A.G. Shubov and V.V. Denisenko

The known most scale project concerning wireless power transmission system (WPT) by means of a microwave beam urged to replace running low natural resources of fuel. Its basic characteristics are resulted. The project provides for power 5 GW and based on solar space power station (SPS) which is located on a geostationary orbit. Solar photo-batteries panel is placed on the platform. In an original project the panel area is equal to 5 km × 10 km. Besides, SPS consists of the transmitting phased array antenna (PAA), and land rectenna. PAA (diameter is about 1 km) focuses a microwave beam (frequency of 2.45 GHz) on the rectenna. It has the area 10 km × 15 km and transforms a microwave energy to a direct current (DC). The demonstrational breadboard model of the industrial SPS (namely SPS 2000) uses low orbit platform under power decreased down to 10 MW. The authors representing Lavochkin Association offer alternative to known projects SPS and SPS 2000. They propose to use a "fleet" of informationally connected spacecrafts as power stations. The idea of this offer consists in replacement of one huge platform with a system of satellites each of them has rather small sizes and the independent power supply from solar batteries as well as PAA subarray creating the contribution in total microwave beam on the rectenna. This offer generates serious problems. It is known that grating lobes (GL) appear in the PAA radiation pattern if the array antenna is rare. With distance between elements increase the quantity of GL and their level are increased. This causes considerable losses of energy and degrades system efficiency. The results of computer simulation of the field in the focus plane are given. The works of other authors, on an example of two-dimensional model, show that methods of array antenna synthesis (the choice of unequal sizes of gaps between subarrays, phase synthesis) provides comprehensible efficiency and raises the power on the rectenna if subarrays are placing closely in the center of the PAA and rare as they leave from it. Thus at edges of PAA the gap between subarrays with uniform excitation reaches approximately the subarray size. In accordance with available publications, ideas of creating optimum WPT with separated PAA subarrays are in a stage of theoretical researches. Engineering recommendations still should be developed. Total number of satellites is defined by the area of panels with solar batteries. For example, to provide radiated power 5 GW, it is necessary to arrange in a geostationary orbit of 20 thousand satellites with the area of panels 500 m2 on each of them. The authors propose to use a millimeter range, but this way only aggravates conditions for growth of parasitic GL in PAA radiation pattern. Besides, considerable losses of energy in atmosphere of the Earth the millimeter range causes of placing rectenna in a stratosphere or in a space. In turn, it creates a problem of direct current transmission from rectenna. The project of using a cable from height of 4000 km for these purposes has no analogues and does not study in any way. It seems that the idea of informationally connected spacecraft application for WPT is rather useful for other important problem, namely WPT between satellites when on one of them the PAA and on other rectenna are placed. Achievements of Lavochkin Association can play a considerable part in this direction.