Illumination Tapers Synthesis for Adaptive Microwave Power Transmission Systems with Variable Distance Between the Antennas A.A. ZAPOROZHETS SUMMARY Adaptive microwave power transmission systems prevented power output from fluctuating in the case of variable distance between antennas. In this system both the peak power density at the receiving antenna and the power received are maintained due to phase distribution tuning. An antenna optimization method is proposed. The tapers generated allow the distance change rate to be maximized or more power to be transmitted while range is fixed. Introduction Microwave power transmission from low-orbit space power satellites to the Earth and from one space vehicle to another are now considered as first steps to future large scale applications of this technology [1-3]. But there is a problem - variable distance between the transmitting antenna and the receiving one - that must be taken into account. For example, let us consider the operation of a conventional power transmission system (Fig.l). Assume that the characteristics of such a system are optimized for the position B of the transmitting antenna. The level of microwave power density at the receiving antenna (rectenna) depends on the distance between antennas. The high level (position C) may cause breakdown of rectenna rectifying elements. On the other hand, the rectenna conversion efficiency may be greatly decreased at a low level of microwave power density (position A). Moreover, in position A the rectenna intercepts microwave power only at the center of the beam. In position* C only the center of the rectenna operates. Thus, the power output of such a system depends strongly on the distance between antennas. It is possible to change the beam angular size by an appropriate change of the phase distribution over the transmitting antenna. The purpose of this paper is to describe a technique to maintain both the peak power density at the rectenna and the power intercepted by the rectenna (power received) by phase distribution tuning in the case of variable distance between the antennas. A synthesis method has been proposed which generates the optimal antenna illumination tapers for such an adaptive system. The tapers generated allow the range of distance changes allowable to be maximized or more power to be transmitted while range is fixed. Physics Department, Moscow State University, Moscow, 119899, Russian Republic.
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