Wideband multi-user transmission assisted by reconfigurable holographic surfaces (RHSs) is fundamentally limited by mutual coupling effect among densely packed sub-wavelength radiation elements. This paper develops a coupling-aware wideband RHS model and an efficient joint beamforming framework to maximize the multi-user sum rate under practical feeder power and RHS excitation power constraints. We establish an electromagnetic equivalent model based on magnetic-dipole elements and a physically interpretable coupling decomposition into free space near field coupling and guided surface wave coupling. For optimization, we employ a weighted minimum mean square error (WMMSE)-based block coordinate method with a closed-form digital precoder update and introduce a Jacobian-aided coupling consistent hologram update that preserves coupling sensitivity via a first-order surrogate while keeping the hologram subproblem convex and efficiently solvable by projected first-order methods. Meep experiments verify the correctness of the proposed coupling model, and the simulations for a 28~GHz, 1~GHz-bandwidth RHS downlink prove the effectiveness of Jacobian-aided WMMSE-based method.

翻译：可重构全息表面(RHS)辅助的宽带多用户传输从根本上受到密集亚波长辐射单元间互耦效应的限制。本文建立了一个耦合感知的宽带RHS模型和一个高效的联合波束赋形框架，以在实际馈源功率和RHS激励功率约束下最大化多用户和速率。我们基于磁偶极子单元建立电磁等效模型，并将耦合物理可解释地分解为自由空间近场耦合和导行表面波耦合。在优化方面，我们采用基于加权最小均方误差(WMMSE)的块坐标方法，其中数字预编码器更新具有闭式解，并引入了一种雅可比辅助的耦合一致性全息图更新方法。该方法通过一阶代理函数保持耦合敏感性，同时使全息图子问题保持凸性，并可通过投影一阶方法高效求解。Meep实验验证了所提耦合模型的正确性，针对28 GHz、1 GHz带宽RHS下行链路的仿真证明了基于雅可比辅助WMMSE方法的有效性。