星载差动毫米波辐射计的研究

Study of Spaceborne Differential Millimeter Wave Radiometer

研究了欧空局普朗克计划低频设备中一30 GHz的差动毫米波辐射计,该辐射计由前端模型(FEM)和后端模型(BEM)组成,FEM工作在20 K的低温下,降低系统噪声温度以获得极高的灵敏度,同时利用相移开关构成差动结构,具有比迪克辐射计更良好的稳定性。BEM工作在常温下,对FEM输出的射频信号进行放大、滤波、检波并放大输出直流电压信号。利用ADS软件,对该辐射计BEM的带通滤波器和平方律检波器进行了设计仿真,在20%的有效带宽内,滤波器的S参数,检波器的灵敏度均达到系统要求,为先进的高灵敏度毫米波辐射计系统的研制打下基础。

A differential millimeter wave radiometer at 30 GHz for the Planck-LFI instrument of ESA was studied in this paper. This radiometer is composed of a Front-End Module（FEM） and a Back-End Module（BEM）, The FEM is cooled at 20 K in Qrder to obtain a receiver with a very low noise temperature and a very high sensitivity. One phase switch is placed in each FEM branch to have better stability than Dicke radiometer. The BEM provides further amplification, defines the band and detects the signal. Finally, a commercial software named ADS is used to realize the BPF and the square-law detector with a 20G of effective bandwidth for BEM, the S-parameter of BPF and the sensitivity of detector can meet well the system requirement. This dissertation makes a good foundation for the further researches on the advanced millimeter wave radiometer.