Fig. 1. Schematic of the smart SSPP-LWA system. The RS-camera automatically detects the moving target - a model car or a target user (e.g., a horn here) in the environment. The position information of the target is sent to the control system, the supply voltage (via a FPGA) or input frequency (via a signal generator) is fed back in a few milliseconds, and the working status of SSPP-LWA is altered or the beam tracking are realized.

Fig. 2. Smart SSPP-LWA operation architecture. There are four main components in the operation cycle. The depth camera is used for capturing picture information. Through the control system based on YOLOv4-tiny pre-training module, the target detection task is completed. Two devices, the FPGA and the signal generator, are used to control the voltage and input frequency signal to control the reconfigurable SSPP-LWA. Finally, the smart SSPP-LWA can realize the adaptive real-time switching between the radiation and the non-radiation of EM waves and beam tracking.

Fig. 3. Dispersion curves of space harmonics.

Fig. 4. (a) Schematic of the proposed reconfigurable SSPP-LWA. (b) Transition structure diagram for connecting welding free fixtures. (c) Enlarged view of unit cells, where the period l₁ = 3.05 mm, l₂ = 1.04 mm, a = 10.0 mm, b = 4.3 mm, c = 1.0 mm, d = 3.925 mm, h = 0.762 mm, p_d = 1.1 mm, p_h = 2.85 mm, w₁ = 3.0 mm, w₂ = 0.4 mm, and w₃ = 0.3 mm. (d) Evolution process of the proposed radiation patch.

Fig. 5. Performance of the reconfigurable SSPP-LWA. (a) Simulated and (b) measured S-parameter of the reconfigurable SSPP-LWA at different working states. The local current distributions of the antenna in two working states, the coupling part and radiation unit during (c) radiation state and (d) non-radiation state at 11 GHz. When the diode is “ON” or “OFF”, the (e−h) simulated and (i−l) measured field distributions of the integral structure in the radiating state and the non-radiating state at 9 GHz and 12 GHz.

Fig. 6. Simulated 3D radiation patterns and amplitude distributions of electric fields at different beam scanning angles for the reconfigurable SSPP-LWA. (a) 9.5 GHz. (b) 11 GHz. (c) 12.5 GHz. Simulated far-field radiation patterns of the proposed SSPP-LWA of (d) radiation and (e) transmission states at different frequencies. (f) Gains and (g) radiation power of the proposed reconfigurable SSPP-LWA.

Fig. 7. (a) Prototype of the reconfigurable SSPP-LWA in a microwave anechoic chamber. Enlarged part of the (b) front and (c) back of the antenna. Measured radiation pattern of (d) radiation and (e) transmission states with co-polarization. Measured radiation pattern of (f) radiation and (g) transmission states with cross-polarization. Measured gain with (h) co-polarization and (i) cross-polarization.

Fig. 8. The position of the moving car is processed in the control system, and all bias voltages are instantly calculated and supplied to the smart SSPP-LWA. The working state is tested by a VNA. (a) Test scenarios, please see Supplementary Section 6 for details. (b) A picture of the externally perceivable SSPP-LWA system. The results of two test scenarios in which the target (c) appears or (d) disappears.

Fig. 9. (a) Test scenarios of beam tracking, in which a broadband horn antenna moves on the slide rail as the target user, and the RS-Camera captures the position information of the target user, as shown below. It then feeds back to the computer and sends frequency instructions to the signal generator. (b) Detailed connection process of the experimental device. (c) Experimental results of picture frames at three different positions of the target user on the moving path.

Fig. 10. The received power of the target user corresponds to different frequencies during the movement. The blue pentagon is marked as the received power of the target user with vision aid.