8/29/2023 0 Comments Uhf rfid tags![]() ![]() In the standard, the tag sensitivity requirement is defined as –18 dBm, which matches the analysis result quite well. To support the link range at 25 meters as defined in the standard, the tag sensitivity should be better than –18.7 dBm and the reader sensitivity should be better than –70.4 dBm. Forward and reverse link budget calculation. The system link budget shown in Figure 1 is based on the previously described formulas and parameters.įigure 1. The center frequency is 922.5 MHz, so λ = 0.33 m. ƞ mod represents the modulation efficiency of the tag, which depends on the tag antenna matching and the tag impedance shift that occurs during modulation and it is reasonable to assume that ƞ mod = –8 dB. ![]() A tag antenna is usually similar to a dipole and it is reasonable to assume Gtag = 2 dBi. As for Grx, in an electronic identification of motor vehicles application, the reader normally uses the monostatic configuration, whereas a single antenna is used at the reader for both transmission and reception, so Grx = Gtx = 12 dBi. An antenna of 10 dBi to 12 dBi gain is used in the field test, so Gtx is assumed to be 12 dBi. ![]() The forward and reverse link budget formulas 3, 4 are described in Equation 1 through Equation 3:Īs defined in GB/T 35786-2017 section 6.2 and section 6.5.2.2, Ptx is 30 dBm and the feeder cable insertion loss is less than 1 dB, so the real Ptx is around 29 dBm. Passive RFID systems have two fundamental link limits: The forward link normally limited by the minimum RF to dc power to supply the tag electronics and the reverse link limited by the reader receiver sensitivity. Successfully read information in a chip identifier data bank Successfully read information in a chip identifier data bank and vehicle registration data bank Type 2 Reader Key Performance Requirement Item Standards SummaryĪccording to the GB/T 29768-2013 and GB/T 35786-2017 standards relating to the electronic identification of motor vehicles, the key air interface parameters and the performance requirements of high performance Type 2 readers for these applications are summarized in Table 1 through Table 3. Although the RF front end described in this article is application specific, both the analysis method and the front end itself are applicable for general UHF RFID reader solutions. This article focuses on a target application for the electronic identification of motor vehicles in China, which must be compliant with the Chinese standards GB/T 29768-2013 “Information Technology-Radio Frequency Identification-Air Interface Protocol at 800/900 MHz”1 and GB/T 35786-2017 “General Specification for Read-Write Equipment of the Electronic Identification of Motor Vehicles.”2 In comparison to a discrete, two component implementation, this AD9361-based solution greatly decreases design complexity, component count, and board space, with a trade-off of receiver sensitivity degradation. One implementation is based on the ADF9010 and AD9963, while the other is based on the AD9361. This article describes two implementations of an Analog Devices’ signal chain-based UHF RFID reader RF front end. Recently, they have gained attention for use in unmanned supermarket applications and for the electronic identification of motor vehicles. ![]() Ultrahigh frequency radio frequency identification (UHF RFID) systems have been widely adopted for applications like asset management and apparel retail. Developing a UHF RFID Reader RF Front End with an Analog Devices’ Solution ![]()
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