| dc.description.abstract | To facilitate a X-band ground-based radar scattering measurements, in this thesis, we design a scattering phased array reflector antenna system, with eight adjustable incidence angles to measure backscattering coefficient. The antenna system composes of feed antenna array, beam-former, and a parabolic reflector. By properly changing the phase difference among array elements, a number of different beam incident angles can be formed. The electronically steering incident angle is superior to the mechanical ones in setting the angle accuracy and easy operation. As for the feed antenna array element, a Quasi Yagi–Uda antenna is chosen for its simple structure, easy feeding, and implementable on microstrip circuit. In doing so, the size and weight of the antenna element can be greatly reduced, about 40-50% frequency bandwidth can be achieved. Its high gain, high directivity of the single-ended (end-fire) radiation pattern is well suited to scattering coefficient measurement with wide bandwidth coverage. Then it comes to the beam-forming. It is realized that the Butler matrix network bears high precision of phase and leveling, simple structure, and easily implemented by type of microstrip lines. Finally, a parabolic reflector is used to focus the antenna beam to produce high output gain, while improve the half-power beam width (3-dB beamwidth).
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