Shared Impedance Noise Coupling in Radio Receivers

Radio sensitivity serves as a commonly used parameter in wireless receiver systems. When excess antenna noise is introduced into the system, it results in a reduction of radiated sensitivity. This phenomenon, referred to as radiated sensitivity desensitization, occurs upon connecting antennas. This paper elucidates a shared impedance noise coupling mechanism, which sheds light on how passive antennas can introduce excess noise into the wireless system. To address this apparent contradiction, the paper introduces the general theory of antenna noise temperature, providing an explanation for the mechanism of noise coupling through a shared impedance path. Additionally, a mathematical expression for radiated sensitivity is presented in this paper. An understanding of this noise coupling mechanism holds significant implications for various fields, including antenna technology, electromagnetic compatibility, radio science, remote sensing, and wireless communication systems.