Physical Model and Experimental Validation for Thermal Noise Wireless Communication Using Microwave Brightness Temperature

This article explores physical-layer security through thermal noise communication, leveraging its inherent covertness and anti-interference characteristics. We propose a novel approach by employing a microwave radiometer as the core receiver for thermal noise communication systems, based on an equivalent brightness temperature physical model. This model provides a clear and intuitive framework for describing the wireless transmission process of thermal noise, enabling precise analysis of signal generation, propagation, and detection. Theoretical analysis includes deriving the bit error probability (BEP) and investigating the relationships between system parameters and communication performance. Using this model, we separately analyzed the performance of the existing passive thermal noise communication and the active thermal noise communication with additional radio frequency (RF) amplification. Furthermore, we demonstrate a practical covert thermal noise communication system operating at 220 GHz, achieving a transmission distance of 7.7 km at a data rate of 20 kbps. Experimental results validate the theoretical models and highlight the potential of thermal noise communication for high-covertness applications in scenarios such as ground-to-ground, satellite, and uncrewed aerial vehicle communications. This work bridges microwave remote sensing techniques with communication engineering, offering a new paradigm for secure and low-power wireless systems.