Specific absorption rates in muscle tissues for passive UHF RFID tag backscatter

In this paper, we describe the specific absorption rates for RF propagation in muscle tissues and present an evaluative study for radiation reflected by a passive UHF radio frequency identification (RFID) tag. A derivation of UHF RFID tag backscatter theory is presented. This theory is merged with the biological effects of RF propagation in muscle tissues to form a general theory. This general theory is then used to analyze the workings of a passive tag operating on human muscle tissues. Enhanced theoretical as well as analytical evaluations are performed to exemplify the field penetration due to the skin effect and the specific absorption rate (SAR) in human muscle tissues. It is shown that the SAR in muscle tissues for a passive UHF RFID tag in the near-field, is less than two orders of magnitude than the FCC limitation for safe RF exposure on tissues.