Radio Link Budgets for UHF RFID on Multipath Environments

Radio frequency identification (RFID) applications are growing rapidly, especially in the UHF frequency band, which is being used in inventory management. Passive UHF tags are preferred for this application. However, the read range is often overestimated using free space calculations. This paper presents a method to estimate the read range in multipath environments. Other effects with a direct impact on read range as the effect of materials on tag performance are also addressed. Using the proposed model and the ray trace method a RFID system simulator is presented.