Diplexer-Free Dual-Band Backscatter with Tag-Side FDDvia Impedance-Tuner State Synthesis

We demonstrate a diplexer-free dual-band backscatter tag with tag-side FDD behavior at 868 MHz and 1300 MHz using a single RF path and impedance-tuner state synthesis. By measuring the tag reflection response across discrete tuner states, we synthesize state pairs that provide strong modulation in both bands and state pairs that modulate one band while minimally disturbing the other. Hardware measurements under dual-carrier excitation show four resolvable tag-side envelope levels for 2-bit signaling, and receiver-side time-domain measurements confirm band-selective operation. The results demonstrate dual-band backscatter and duplex-capable band separation without external RF filtering.