本文提出一种高灵敏度的高温超导微波辐射计设计方法,用于海水表面盐度检测.微波辐射计的接收前端由一个高温超导滤波器和一个低噪声放大器(LNA)组成.该接收前端具有极低的噪声系数,并能有效抑制射频干扰(RFI).超导滤波器的中心频率为1.4135GHz,带宽25MHz.实验测量得到滤波器的插入损耗0.15dB,带外陡峭度35dB/MHz,带外抑制大于80dB.在77K温度下测量得到LNA的噪声系数为0.27dB.与其他辐射计相比,我们的器件具有较低的噪声温度.这使得我们的微波辐射计具有更高的测量灵敏度,可以显示更精确的海水表面盐度分布图样,有利于海洋盐度成像.%In this paper,a new high temperature superconducting (HTS)-based microwave radiometer with an improved sensitivity is presented.The proposed microwave radiometer is equipped with a cryogenic receiver front end that consists of a HTS filter and a cryogenic low noise amplifier (LNA).The cryogenic receiver front end shows an ultra-low noise figure and can suppress radio frequency interference (RFI) effectively.The HTS filter works at a center frequency of 1.4135GHz with a bandwidth of 25MHz.The measured mid-band insertion loss,side band steepness and out-of-band attenuation of the HTS filter are 0.15dB,35dB/MHz and 80dB,respectively.The noise figure of the cryogenic LNA is about 0.27dB at a temperature of 77K.Compared with other total power radiometers,the proposed radiometer has a lower receiver noise temperature,which can improve the sensitivity with a short integration time of satellite-based salinity meter,and facihtates the ocean salinity imaging in remote sensing.
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