Recent developments in Multiple-Input-Multiple-Output (MIMO) technology include packing a large number of antenna elements in a compact array to access the bandwidth benefits provided by higher mutual coupling (MC). The resulting super-wideband (SW) systems require a circuit-theoretic framework to handle the MC and channel models which span extremely large bands. Hence, in this paper, we make two key contributions. First, we develop a physically-consistent Rician channel model for use with SW systems. Secondly, we express the circuit-theoretic models in terms of a standard MIMO model, so that insights into the effects of antenna layouts, MC, and bandwidth can be made using standard communication theory. For example, we show the bandwidth widening resulting from the new channel model. In addition, we show that MC distorts line-of-sight paths which has beamforming implications. We also highlight the interaction between spatial correlation and MC and show that tight coupling reduces spatial correlations at low frequencies.

翻译：近年来，多输入多输出（MIMO）技术的新进展包括在紧凑阵列中集成大量天线单元，以利用更高互耦（MC）所带来的带宽优势。由此产生的超宽带（SW）系统需要一个基于电路理论的框架来处理互耦以及覆盖极宽频段的信道模型。因此，本文做出了两项关键贡献。首先，我们为超宽带系统开发了一个物理上一致的莱斯信道模型。其次，我们将基于电路理论的模型表达为标准MIMO模型的形式，从而能够利用标准通信理论深入分析天线布局、互耦和带宽的影响。例如，我们展示了新信道模型带来的带宽扩展效应。此外，我们还证明了互耦会扭曲视距路径，这对波束成形具有重要影响。我们也强调了空间相关性与互耦之间的相互作用，并表明在低频段，紧密耦合会降低空间相关性。