Hybrid Pinching Antenna Systems: Architecture and Beamforming Design

Pinching antennas (PAs), a special class of leaky-wave antennas (LWAs), have recently emerged as a promising technology to mitigate blockage and reduce large-scale path loss. However, PAs suffer from performance limitations due to their passive radiation characteristics and mechanical actuation. To overcome these limitations, we introduce reconfigurable LWAs (RLWAs), which enable RLWA beamforming through electronic control of both radiation amplitudes and phases. By integrating RLWAs into the existing PA systems (PASS), we propose a hybrid PASS (H-PASS) architecture, which combines mechanically reconfigurable PA beamforming with electronically reconfigurable RLWA beamforming. Given that PAs in H-PASS can be deployed in discrete-position or continuous-position manners, H-PASS comes in two variants accordingly, and we formulate weighted sum-rate maximization problems for them, respectively. For the discrete-position case, we propose a penalty-based two-loop joint analog and digital beamforming algorithm. For the continuous-position case, we propose an alternating-minimization-based joint position optimization and beamforming algorithm. Simulation results demonstrate that H-PASS can increase the sum-rate of the existing PASS by up to 33%, reduce the performance loss caused by phase quantization in discrete-position PAs by up to 69%, and mitigate the performance loss caused by position errors in continuous-position PAs by up to 90%. Overall, H-PASS significantly improves the performance of existing PASS by leveraging the strengths of RLWAs while mitigating the limitations of PAs.