| In this paper, direct-detection radiometer is discussed, which is an attempt of the receiving-model of the radiometer used in space. The system of the radiometer and its principle is researched, and the low-noise-receiving technology which takes a great role in the radiometer is also taken into discuss. A direct-detection radiometer is devised on the basis of the theoretical analysis. Its performance is tested. Its advantages are verified by comparing with a different receiving-model radiometer.The following are the main works of this thesis:(1) The theory of radiometer is discussed.(2) The low-noise-receiving technology is discussed.(3) With some CAD tools, the microwave circuit of the direct-detection radiometer is simulated and designed, and the systemed is integrated and optimized.(4) A direct-detection radiometer at 18GHz is designed, the performance answers for the previous target. Its performance is compared with a different receiving-model radiometer. Its advantages in miniaturization and the improving of the electromagnetic environment are verified. |
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