基于RIS的可控波束成形天线及近场本征模馈源
RIS-Based Steerable Beamforming Antenna with Near-Field Eigenmode Feeder
AI总结：
提出一种利用AMAF到RIS近场传播矩阵本征模的高效天线系统，通过仅在AMAF处进行有源放大，在保持波束成形性能的同时实现了比传统相控阵更高的功率效率和更低的硬件复杂度。
摘要：
我们提出了一种新颖的、功率和硬件高效的天线系统，该系统利用从有源多天线馈源（AMAF）到大型反射智能超表面（RIS）的空中传播矩阵的本征模，两者均配置为标准线性阵列并放置在彼此的近场中。我们通过展示其能够生成适用于多种应用的辐射方向图来证明所提架构的灵活性，例如用于空分多址通信的具有低旁瓣的极窄波束、用于短距离汽车感知和扇区信标的宽角波束，以及用于雷达角度跟踪的单脉冲方向图。我们设计中的一个关键参数是AMAF-RIS距离，该距离必须进行优化，且通常远小于瑞利距离。对于给定的AMAF孔径，最佳AMAF-RIS距离随着RIS尺寸的增加而增加。AMAF-RIS的损耗几乎完全被RIS更大的孔径增益所补偿，使得随着RIS尺寸增加，RIS增益几乎保持恒定。这使得能够选择具有相同中心波束增益的不同波束角度选择性。有源射频放大仅在AMAF处进行，因此在具有相同波束成形性能的情况下，比传统相控阵具有更高的功率效率和更低的硬件复杂度。
英文摘要：
We present a novel, power and hardware efficient, antenna system leveraging the eigenmodes of the over-the-air propagation matrix from an active multi-antenna feeder (AMAF) to a large reflective intelligent surface (RIS), both configured as standard linear arrays and placed in the near field of each other. We demonstrate the flexibility of the proposed architecture by showing that it is capable of generating radiation patterns for multiple applications such as very narrow beams with low side lobes for space-division multiple access communications, wide-angle beams for short range automotive sensing and sectorial beaconing, and monopulse patterns for radar angular tracking. A key parameter in our design is the AMAF-RIS distance which must be optimized and it is generally much less than the Rayleigh distance. For a given AMAF aperture, the optimal AMAF-RIS distance increases as a function of the RIS size. The AMAF-RIS loss is compensated almost exactly by the larger aperture gain of the RIS leading to almost constant RIS gain with increasing RIS sizes. This allows to choose different beam angular selectivities with the same center beam gain. Active RF amplification is done at the AMAF only, thus resulting in a much higher power efficiency and much lower hardware complexity than conventional phased arrays with same beamforming performance.
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