An Investigation of THz Backscattered Side-Channels Measurement at a Distance

This paper presents the measurement setup and the investigation on the backscatter side-channel signal detected and received, at 300GHz, from an activated FPGA board. First, the ellipsoidal reflector, used as an incident source, with a spot size of 0.7mm is designed and fabricated. Next, a region on the FPGA chip is divided geometrically into various cells with cell dimensions corresponding to reflector spot size. Finally, it was shown that the backscatter side-channel signal can be detected by a diagonal horn antenna placed at a distance from the FPGA board. The received signal behavior is investigated in terms of absolute signal strength, measured noise power level and signal to noise ratio. This provides deeper insight into the detected backscatter side-channel emanating from the FPGA board.