堆叠式流体超表面：互耦感知建模与优化

中文摘要 AI 辅助

堆叠式智能超表面逐层处理透射场，流体天线使每个辐射器的位置成为设计变量。两者结合，可在层内和层间以亚波长间距布置辐射器，而互耦支配着当前模型忽略的物理机制。本文开发了一个耦合一致的流体发射层模型，该层照射一叠无源流体超对角层。任何端口星座的多端口阻抗矩阵被证明是在三维间隔处采样的阻抗核，采用一种闭合球面汉克尔形式，其面内限制为层内耦合，轴向限制取代标量瑞利-索末菲传播子。仅发射器被驱动：层电流被感应，熟悉的级联是单次矩阵求逆的单程极限。在波数域中，光圆仍将辐射与反应分开，现在附有平面波传播子，每个傅里叶模式看到由层加载的传输线，效率恒等式表明堆叠在效率上的代价由其总感应电流范数决定，而非层数。由于负载从未被假定为层对角，互连可连接不同片上的原子，且在每个位点重复的垂直网络在频谱上是局部的。交替优化以闭式梯度设计预编码器、位置和负载。数值上，在$\lambda/8$网格上的流体端口性能在连续可移动端口的几个百分点以内，而基于传统级联模型的设计可能比开路堆叠更差。

英文摘要

Stacked intelligent metasurfaces process the transmitted field layer by layer, and fluid antennas make the position of every radiator a design variable. Combined, they pack radiators at sub-wavelength spacings within and across layers, where mutual coupling governs the physics that current models omit. This paper develops a coupling-consistent model of a fluid transmit layer illuminating a stack of passive fluid beyond-diagonal layers. The multiport impedance matrix of any port constellation is shown to be the impedance kernel sampled at the three-dimensional separations, in one closed spherical-Hankel form whose in-plane restriction is intra-layer coupling and whose axial restriction replaces the scalar Rayleigh--Sommerfeld propagator. Only the transmitter is driven: the layer currents are induced, and the familiar cascade is the single-pass limit of one matrix inversion. In the wavenumber domain the light circle still separates radiation from reaction, now with a plane-wave propagator attached, every Fourier mode sees a transmission line loaded by the layers, and an efficiency identity shows that what the stack costs in efficiency is set by its total induced-current norm, not by its layer count. Because the load is never assumed layer-diagonal, interconnections may join atoms on different sheets, and vertical networks repeated at every site are spectrally local. Alternating optimization designs precoders, positions, and loads with closed-form gradients. Numerically, fluid ports on a $λ/8$ grid perform within a few per cent of continuously movable ones, while a design based on the conventional cascade model can do worse than open-circuiting the stack.

发表机构

• Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg（卢森堡大学安全、可靠与信任跨学科中心）

机构由 AI 辅助整理，请以论文原文为准。