Backscatter Beamforming: A Transponder for Novel MIMO RFID Transmission Schemes

In this paper, a proof-of-concept two-antenna backscatter transponder for a frequency of 5.8 GHz is presented, based on four IQ modulator ICs and a Raspberry Pi control circuit. Allowing for the free adjustment of the full signaling matrix, novel multiple-input multiple-output backscatter transmission schemes for prospective radio frequency identification-based communication systems are facilitated. The transponder's capabilities are verified by its characterization in terms of time-varying scattering parameters and its backscatter radiation pattern. In this context, the concept of backscatter beamforming is introduced for the first time.