Frequency-Selective Beamforming and Single-Shot Beam Training With Dynamic Metasurface Antennas

Dynamic metasurface antennas (DMAs) are leaky-wave antennas with frequency-reconfigurable slots. While resonant frequency of individual slots on the DMA can be independently configured in a wide frequency range, the DMA’s beamforming performance across different operating frequencies in the available range has not been studied yet. We show that the dominant beam direction and the operating frequency of a DMA are interdependent. Using this observation, we derive a closed-form expression for line-of-sight (LOS) beamforming gain maximization to jointly configure the operating frequency and per-slot resonant frequency configuration of the DMA. A benefit of this approach in the LOS channel case is that all slots are tuned to the same resonant frequency, eliminating the need for a computationally expensive search across all feasible resonant frequency configurations. We also apply this approach to mitigate beam training overhead in large arrays by proposing a single-shot beam training algorithm that estimates the optimal resonant frequency configuration through simultaneous probing of multiple angular directions across frequencies. Simulation results show that our proposed approach offers a comparable achievable rate to true-time-delay (TTD) based systems, but with lower power consumption and hardware cost.