2267279_en-US

CW transmitter is introduced to inject extra energy into the RFID tag

Hello, I have a question regarding the UCODE 8 (U8) passive UHF RFID tag.

According to the datasheet, the tag uses non-coherent demodulation (envelope detection) for ASK-modulated signals from the reader.

When an additional, independent CW transmitter (different frequency as the reader, e.g., 924Mhz v.s. 910Mhz) is introduced to inject extra energy into the tag, it does not increase the backscatter communication range. Sometimes, it even causes unstable communication or reduces the range.

This seems counterintuitive. The extra CW signal provides more energy, but the result is not a longer range.