New Method for Doppler Shift using a Reconfigurable Intelligent Surface

We provide a new method to generate Doppler frequency shifts (DFS) using a reconfigurable intelligent surface (RIS). In conventional methods, the required Doppler shift is acquired by modulating RIS’s reflection phase. However, this method is greatly dependent on the variation of the reflection magnitude and phase of RISs, which are not constant in the frequency band of interest. To alleviate this unwanted dependency, our RIS structure directly transforms the input signal to the target Doppler shift, which is based on sensing the difference between the input and the output signals. Consequently, our RIS can enhance both a conversion loss (CL) and a spurious-free dynamic range (SFDR), simultaneously.