Fig. 3: Modulation and constellation plots.
From: A frequency-agile retrodirective tag for large-scale sub-terahertz data backscattering
a An illustration showing the phase and amplitude modulation inside the waveguide cavity. We employ an electrostatic MEMS mirror to modulate the trajectory of guided waves; thereby, changing the effective leakage aperture and the amount of out-coupled power, consequently. For phase modulation, we employ a piezo actuator in the cavity and change the trajectory length of the guided waves by a fraction of wavelength to enable the phase shift of interest. b Example constellation plots for multiple leaky-wave backscatters operating at different frequency regimes. Depending on its angular location, each leaky-wave backscatter modulates a portion of the incident broadband signal. The external receiver can recover the data sent by all 3 backscatter tags and simultaneously localize them by mapping the received center frequency to angular locations.
