Fig. 1. The proposed framework for the RASM.

Fig. 2. Schematic diagram of the meta-atom structure. (a) 3D structural diagram, h1=3.248  mm, h2=0.2  mm, h3=0.5  mm. (b) The front view of the meta-atom. The optimized geometrical parameters are as follows: p=25  mm, l1=10  mm, l2=6  mm, l3=3  mm, l4=7.4  mm, l5=2  mm, w1=4  mm, w2=5  mm, w3=1.9  mm, w4=3.4  mm, g1=0.7  mm, g2=0.1  mm, g3=0.1  mm, k1=0.2  mm, r1=0.8  mm. (c) The phase shift network. The biasing layer for (d) varactors and (e) PIN diodes.

Fig. 3. The simulated surface currents at 6.4 GHz. (a) Vx=0 and Vy=−v0. (b) Vx=0 and Vy=v0. (c) Vx=−v0 and Vy=0. (d) Vx=v0 and Vy=0. (e) V1=−v1. (f) V1=+v1.

Fig. 4. The simulated performance of the meta-atom. (a) The simulated S11 in four states. (b) The realized gain and phase varying with frequency. The simulated radiation pattern in four states: (c) realized gain and (d) phase. The measured (e) S11 and (f) realized gain and phase varying with frequency for y-polarization when all meta-atoms maintain the same state.

Fig. 5. (a) The bottom power division network and PSN. (b) The detailed structure of the power division network, and d1=1.9  mm, d2=0.75  mm, d3=1.6  mm, d4=1.734  mm, d5=1.06  mm, q1=2.94  mm, q2=4  mm, q3=12.3  mm. (c) S11 and (d) S21 and S31 of the power division network.

Fig. 6. (a) The ideal phase distribution corresponding to the scanning angle. (b) The ideal amplitude distribution for different SLLs. (c) The amplitude difference between the actual generated amplitude and the target amplitude for different L. (d) The phase difference between the actual generated phase and the target phase for different L.

Fig. 7. MAX(SBL) that varies with L.

Fig. 8. The time-coding sequences for θ=10° with (a) SLL=−13  dB and (c) SLL=−30  dB. The simulated radiation patterns with (b) SLL=−13  dB and (d) SLL=−30  dB.

Fig. 9. (a) Power spectrum corresponding to stochastic and sequential distributions of time-coding sequences. (b) The power spectrum for modulation periods τq=[1+0.09(q−1)]  μs and τq=1  μs. (c) The power spectrum for SLL=−13.5  dB and SLL=−30  dB. (d) Power spectrum for L=50 and L=1000.

Fig. 10. The (a) front and (b) back of the prototype. (c) The measurement setup.

Fig. 11. Measured beams scanning at (a) 6.2 GHz, (b) 6.4 GHz, and (c) 6.6 GHz for SLL=−13.5  dB. Measured time-modulated power spectrum of the prototype with SLL=−13.5  dB, θ=10°, and L=1000 at (d) 6.2 GHz, (e) 6.4 GHz, and (f) 6.6 GHz.

Fig. 12. The simulated (a) S₁₁ and (b) realized gain and phase varying with frequency for x-polarization. (c) Measured beam scanning at 6.4 GHz for x-polarization with SLL=−13.5  dB. (d) Measured time-modulated power spectrum of the prototype for x-polarization with SLL=−13.5  dB and θ=10°.

Fig. 13. The equivalent amplitude varying with the number of “none” states.