Scalar and Tensor Holographic Time Reversal Mirror with Consideration of Obstacles

This paper proposes a holographic time reversal mirror capable of near-field beam focusing in the presence of obstacles. First, a scalar holographic time reversal mirror is introduced by reinterpreting holographic modulation in terms of time-reversal using a point source as the object wave. The concept is validated through theoretical calculation, simulation, and prototype measurement. To expand this concept, a tensor holographic time reversal mirror is derived from the previous framework by using a dipole source as the object wave, allowing for the reconstruction of the dipole source. A dipole recording technique, which imports the phase distortion of the object wave caused by a dielectric prism, demonstrates the reconstruction of the dipole source despite the obstacle via a full wave simulation. To confirm the proposed method, a holographic metasurface with dimensions of 12λ0 × 12λ0 is simulated at operating frequency 24.5 GHz, with a dielectric prism placed in the propagation path to create a non-line-of-sight (NLOS) environment. Despite the presence of the obstacle, the beam is focused on the intended focal point (0,0, 5λ0) with 45° polarization.