Characterization of RFID Strap Using Single-Ended Probe

Radio frequency identification (RFID) strap attachment modality is more reliable, low cost, and easy to assemble, and therefore, it becomes increasingly more popular in RFID tag designs. This paper presents a single-ended probe method with power transmission coefficient compensation for the characterization of RFID straps. Approximate identification of the Read/Write threshold power and impedance is based on the charge status of voltage multipliers and charge pumps instead of on the Read/Write-modulated commands. For comparison purposes, the conventional source-pull system is also briefly reviewed and applied to verify the measurement results of absorbing power and impedance of RFID straps using the presented method. An enhanced source-pull system, named RFID source-pull system, for an RFID strap that can accurately measure the threshold power and impedance for Read/Write-modulated commands is also constructed for verifying the presented method. Alien and Texas Instruments (TI) straps are used for measurement examples in this paper. It is found that the measurement results of both RFID straps obtained by the presented method agree well with those by the conventional source-pull system and the RFID source-pull system. The single-ended probe method can measure the approximate Read/Write threshold power and impedance of the RFID strap with minimum operating procedures; furthermore, the complicated radio frequency (RF) facilities are not required. Obtaining the Read/Write threshold power and impedance of RFID straps allows designers to estimate the maximum read range of the designed RFID tag in advance. Therefore, the implemented cost and design cycle times can substantially be reduced.