fit in a proper way in the available space of the launching vehicle. A square array with a size of 2 m by 2 m seems to fulfill all these requirements. Phased arrays of this order of size already exist for these low frequency bands. INMARS AT-2 is equipped with alm phased array operating at 1.6 GHz. Matra Marconi is developing an Advanced Synthetic Aperture Radar (ASAR) using a 10 m by 1 m phased array operating at 5.3 GHz. The power per element in these two applications is only slightly lower than the proposed power beaming experiment, giving confidence about the availability of solid-state components. As their linearity constraints could be relaxed for this application, it should be possible to slightly increase power. The innovation of this proposed demonstration is the increased number of independently controlled elements, and the steerability of the beam. The accuracy requirements for the two applications mentioned above are not critical, so that a quite rough steerability was acceptable. On the contrary, the pointing accuracy requirements for future power beaming systems are very important, so that this demonstration should proceed in that direction. One of the results of this experiment will then be a better understanding of the technological requirements, trade-offs and limitations for future systems. Phased Array General Characteristics The following phased array general characteristics are shown in Figure 10.2.5: • Frequency: 2.45 GHz • Wavelength: 0.1224 m • Array size: 2 m by 2 m • Elements spacing: A/2 = 0.0612 m • Number of elements: 32 x 32 = 1024 A pointing accuracy better than 0.5 degrees, and a beam deflection angle of more than +/- 30 degrees should be achieved. The array will be designed in two parts for mechanical assembly purposes. Figure 10.2.5 Phased Array Antenna. Phased Array Electrical Characteristics The word “segment” will refer to an element of the array and its electronic device which generates its signal. The generation of these various signals can be broken down in the following operations:
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