Chaaracteristics of passive UHF RFID tags on liquids

Abstract

The characterization of radio frequency (RF) propagation for passive UHF radio frequency identification (RFID) systems has previously garnered much interest in the industry, predominantly due to its efficient utilization in the supply chain environment. The passive tags utilized in this system do not contain a power source, and typically harnesses energy from the reader system, which is an interrogator module. Due to the passivity, and backscatter communication technique used for communication with the reader, the passive UHF RFID tag has been often discussed in the context of metallic, as well as liquid environments [1–3]. These discussions have often resulted in the need for metrics, which would help alleviate the complexities that exist in the tagging of objects in various industries and application, not limited to the supply chain [4]. However, the point that has been often times neglected is the fact that different types of liquid present varying types of issues to the readability of the passive tag. The varying effect can be described due the changes in fundamental dielectric constant parameters, such as the relative permittivity (ɛ r ), relative permeability (μ r ), conductivity (σ), magnetic loss factor (tan δ μ ), and mass density (ϱ), as well as other more fundamental physical characters, such as dimensional constrains and volume.