What output levels per antenna are possible with passive UHF RFID readers that have multiple ports supporting multiple antennas?
Each country regulates RF devices differently. In the United States, the Federal Communication Commission (FCC) limits the maximum transmitter power to 1 watt for systems that frequency-hop across at least 50 channels, which most ultrahigh-frequency (UHF) EPC Gen 2 RFID readers do. For a 1-watt reader transmitter, the maximum antenna gain is 6 decibels (6 dBI). I reached out to Sanjiv Due, the president of training and consulting firm RFID4U, to ask about readers with multiple antennas. According to Sanjiv, since every antenna in a multiport reader fires separately, thanks to multiplexing within that reader, each antenna can still have a gain of 6 dBI.
—Mark Roberti, Founder and Editor, RFID Journal
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