Broadband macromodeling of large multiport systems by vector fitting can be time consuming and resource de- manding when all elements of the system matrix share a common set of poles. This letter presents a robust approach which removes the sparsity of the block-structured least-squares equations by a direct application of the QR decomposition. A 60-port printed cir- cuit board example illustrates that considerable savings in terms of computation time and memory requirements are obtained.