Characterization of UHF RFID Signal Attenuation in Fluid-Contained Smart Refrigerators

Radio-frequency (RF) signal transmission is highly susceptible to environmental factors such as the properties of materials. This paper presents an analysis of an ultra-high frequency (UHF) radio-frequency identification (RFID) system under various conditions, primarily focusing on signal quality in the presence of different materials and fluid levels. Multiple scenarios are analyzed using Ansys High Frequency Structure Simulator (HFSS) software, which utilizes the finite element method (FEM) for analysis. Scattering parameters (S-parameters) are key metrics to assess RF signal quality. The study shows that RF signal absorption is significantly influenced by the relative position of RFID tags to the water level, and the amount of water further aggravates signal attenuation. Furthermore, there is a clear trend of scattering parameter minimum shifting as the water level arises. Additionally, signal absorption is also affected by the container material, both PVC plastic and aluminum containers are analyzed in this paper. The results show that metal materials effectively reduce RF signal attenuation caused by water inside containers. This study offers valuable insights for improving RFID system performance in smart refrigerators and other complex environments.