Dual-Stream Backscatter Transmission Using Tags with 3-Load

Backscatter communication (BackCom) enables low-power wireless transmission by modulating reflected radio-frequency signals rather than actively generating a carrier. However, conventional 2-load tag architectures inherently produce strongly coupled upper and lower sidebands, limiting the flexible utilization of sideband spectral resources. This paper presents a 3-load backscatter tag for independent dual-stream transmissions by exploiting the positive and negative first-order sidebands. By introducing one additional reflection state and jointly controlling the switching sequence and duty allocation, the proposed BackCom tag enables decoupled magnitude-domain shaping of the two mirror sidebands, allowing them to serve as separately addressable spectral resources for data transmission to independent users. Theoretical analyses demonstrate enhanced sideband-shaping flexibility over conventional 2-load modulation through an enlarged achievable sideband-magnitude region. Furthermore, a proof-of-concept dual-stream On-Off Keying (OOK) transmission is implemented using a cable-based setup, where four distinguishable spectral states corresponding to the two OOK dimensions are experimentally demonstrated.