SAR Measurements of UHF RFID Reader Antenna Operating in Close Proximity to a Flat Phantom

This paper presents the results of measurements of the Specific Absorption Rate (SAR) distribution produced by the UHF RFID reader antenna located close to the standard flat phantom. SAR measurements have been carried out by the SPEAG DASY5 system at 918 MHz for the varying distance between the antenna and the phantom. RHCP antenna with 8.5dBic gain connected to the commercial UHF RFID reader operating at Pout=30dBm has been used to irradiate the phantom. Safety levels of 10-g averaged SAR not exceeding the 2W/kg limit have been confirmed by the series of measurements. However, it has been found that the maximum values of SAR distribution inside the phantom are localized in front of the antenna. The results obtained can be used as a benchmark data for the applications of wearable, biomedical and implantable UHF RFID systems.