Figure 17.

Realizing Harmonic Beam Steering Using a Binary Particle Swarm Optimization (BPSO) Algorithm

(A–C) Harmonic beam steering based on the space-time-coding digital metamaterial.

(A) The BPSO-optimized space-time-coding matrix.

(B and C) The corresponding scattering-pattern cuts at ϕ = 90°, and 3D scattering patterns at different harmonic frequencies.

(D–G) Nonreciprocal reflection effects enabled by the space-time-coding digital metamaterial.

(D and E) Scattering patterns in the forward scenario (excitation from port 1 at $f_c$ and ${\theta }_i=60°$).

(F and G) Scattering patterns in the time-reversal scenario (excitation from port 2 at $f_c+f_0$ and ${\theta }_i=20.3°$).