Hotspot Estimation for Antenna-Less Backscatter Communication Using Excited Impedance Analysis

This paper proposes a novel method for determining the optimal mounting position of nonlinear components for antenna-less backscatter communication using ground (GND) plane patterns on printed circuit boards (PCB). By analyzing the excited impedance of GND planes in conjunction with the on-off characteristics of a nonlinear GaAs pHEMT, the proposed method identifies the optimal location of the transistor on the GND plane to maximize the backscattering ratio between its on and off states. To validate the method, a test PCB is fabricated. The maximum return loss ratio is found to be 29.68 dB on switching the transistor at the hotspot location at 1.745 GHz. Furthermore, in the time domain, the backscattered signal clearly exhibits good antenna-less backscattering performance.