This paper proposes a dual-band reconfigurable antenna array (DBRAA), enabling wireless capabilities in both sub-6 GHz (sub-6G) and millimeter wave (mmWave) bands using a single array. For the sub-6G band, we propose a reconfigurable antenna selection structure, where each sub-6G antenna is formed by multiplexing several mmWave antennas, with its position dynamically adjusted using PIN diodes. For the mmWave band, we develop a reconfigurable hybrid beamforming structure that connects radio frequency chains to the antennas via phase shifters and a reconfigurable switch network. We then investigate integrated sensing and communications (ISAC) in sub-6G and mmWave bands using the proposed DBRAA and formulate a dual-band ISAC beamforming design problem. This problem aims at maximizing the mmWave communication sum-rate subject to the constraints of sub-6G communication quality of service and sensing beamforming gain requirements. The dual-band ISAC beamforming design is decoupled into sub-6G beamforming design and mmWave beamforming design. For the sub-6G beamforming design, we develop a fast search-based joint beamforming and antenna selection algorithm. For the mmWave beamforming design, we develop an alternating direction method of multipliers-based reconfigurable hybrid beamforming algorithm. Simulation results demonstrate the effectiveness of the proposed methods.

翻译：本文提出了一种双频段可重构天线阵列（DBRAA），能够利用单一阵列实现Sub-6 GHz（sub-6G）与毫米波（mmWave）频段的无线能力。针对sub-6G频段，我们提出了一种可重构天线选择结构，其中每个sub-6G天线通过复用多个毫米波天线构成，并利用PIN二极管动态调整其位置。针对毫米波频段，我们开发了一种可重构混合波束成形结构，通过移相器与可重构开关网络将射频链连接至天线。随后，我们利用所提出的DBRAA研究了sub-6G与毫米波频段中的集成感知与通信（ISAC），并构建了一个双频段ISAC波束成形设计问题。该问题旨在最大化毫米波通信的和速率，同时满足sub-6G通信服务质量与感知波束成形增益要求的约束。双频段ISAC波束成形设计被解耦为sub-6G波束成形设计与毫米波波束成形设计两部分。针对sub-6G波束成形设计，我们提出了一种基于快速搜索的联合波束成形与天线选择算法。针对毫米波波束成形设计，我们开发了一种基于交替方向乘子法的可重构混合波束成形算法。仿真结果验证了所提方法的有效性。