For decades, the finite-element method (FEM) has been proven to be a versatile approach in modeling complicated materials/systems for its strong adaptability to complex geometries and high numerical accuracy (J.-M. Jin, The Finite Element Method in Electromagnetics. 3rd ed., Hoboken, NJ: Wiley, 2014). Unfortunately, a volumetric discretization, as required by the FEM, would easily yield a linear system with millions or even billions of unknowns for modern engineering applications such as antenna array analysis. The domain decomposition-based FEMs have been therefore developed to enable large-scale electromagnetic (EM) simulations on parallelized computer clusters, among which the dual-primal finite-element tearing and interconnecting (FETI-DP) algorithm for EM analysis is highly powerful because of its numerical stability and scalability (Y.-J. Li and J.-M. Jin, J. Comput. Phys., 228, 3255-3267, 2009).