The Design and Implementation of Receiver Modules for a 36.5 GHz Microwave Radiometer

• Main Authors: Shih-Chieh Wang, 王詩傑
• Other Authors: Yuei-An Liou
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/51121964056005085742

碩士 === 國立中央大學 === 電機工程研究所 === 91 === In the thesis,the 36.5 GHz Microwave Total Power Digital Radiometer is designed,implemented and simulated. Include RF front end, analog to digital converter and digital correlator. The superheterodyne structure is applied on the design of receiver frond end. The 36.5 GHz RF signal is then downconverted to 500 MHz IF signal using a mixer-preamplifier. The gain of the IF amplifier are determined in the measurement to achieve the full-scale input of analog-to-digital converter. The flash analog to digital converter digitizes full scale input into 6-bit digital words at an update rate of 1 Giga Sample Per Second (GSPS) . It not only results in the required sensitivity of the radiometer, it also makes the system possibly extended in the future using the direct-sampling approach. Two statistical model of noise signal in digital radiometer are also studied. The narrow band noise signal is modeled as a Gaussian random process. A computer program is developed to help understand the relationship between Noise-Equivalent sensitivity and quantization resolution. Finally the prototype of 36.5 GHz Microwave Total Power Digital Radiometer is presented. Future works will involve realizing the digital correlator to verify the sensitivity predicted by statistical models.