Digital Multi-Channel Microwave Radiometry : Achievable Accuracy, System Architecture and Measurement Based Verification

Microwave radiometry is a crucial tool in various scientific and technical fields. Thanks to the continuous improvement of analog-to-digital converters, there is the possibility to implement core components of these radiometer systems in the digital domain. This work focuses on these so-called digital microwave radiometers.
The thesis deals with radiometric resolution while considering influences such as phase noise, receiver gain variations, and quantization noise. The Cramér-Rao inequality is used to analyze the achievable resolution. Furthermore, the statistical moments of a non-ideal estimator are determined to assess the performance of an estimator in real scenarios.
Also the concept of array gain and its impact on radiometric resolution is analyzed in the theoretical part of this work.
In the practical part, the setup of the realized radiometer is explained. This digital two-channel microwave radiometer uses a low-noise block converter, commonly used in K-band satellite communication, as the core of the analog hardware. Signal processing is performed in both dedicated digital hardware and software developed for this application.
Finally, the measurement results are presented. To validate channel coherence, correlation and phase difference measurements were conducted. In addition, performance and sensitivity measurements are presented, providing insights into the actual performance of the radiometer.