Multi Time-Scale Modulated Metasurface-Based Electromagnetic Tags for Cooperative Target Identification

Non-contact target identification technology serves as a critical requirement for intelligent microwave sensing systems. In this article, we propose a novel electromagnetic (EM) tag for cooperative target identification based on a multi time-scale modulated metasurface (MTM-MTS). The modulation scheme of the metasurface involves pseudorandom modulation on the fast-time scale and periodic modulation on the slow-time scale. The detector can identify the target in the delay-frequency domain by using correlation operation and Fourier transform on the fast/slow-time scale, respectively. The primary advantage of this approach lies in the security of cooperative target identification and the flexibility of the EM tag encoding. To verify the proposed EM tag, we design and fabricate a reconfigurable metasurface operating at the Ka band. The experimental accuracy of target identification exceeds 0.9 in the monostatic case, demonstrating the effectiveness and reliability of the proposed tag.