Pseudorandom Time-Modulated Metasurface Cloaked Target Detection Based on Encoded Modulation Sequence Reconstruction

Abstract

Time-modulated metasurfaces (TMMs) encoded by pseudorandom sequences (PSs) present emerging challenges to radar detection by spreading the echo spectrum and defocusing target energy after matched filtering. As a result, the radar receiver fails to reconstruct the correct range profile, severely degrading detection performance. To address this issue, this article proposes a single-channel phase-domain reconstruction framework for noncooperative 1-bit PS-TMM cloaked targets, where the metasurface elements switch between two phase states governed by a pseudorandom binary sequence. Unlike multichannel or high-dimensional solutions, the proposed method requires only one receiving channel, offering low computational complexity, low hardware cost, and ease of implementation, while maintaining high accuracy. For 1-bit PS-TMM cloaked targets with unknown range and velocity, the algorithm compensates for range–velocity coupling terms and reconstructs the encoded modulation sequence directly in the time domain. The effectiveness of the method is validated through theoretical analysis, simulations, and experimental measurements under various conditions. Results demonstrate that the proposed single-channel algorithm can effectively recover the spectral distribution of 1-bit PS-TMM echoes and restore high-resolution range profiles, showing robust performance across different modulation rates, nonideal conditions, and multitarget scenarios.