A surface method of moment (MoM)-based computational electromagnetics solver utilizing the fast multipole method combined with the fast Fourier transform (FMM-FFT) is applied to the analysis of antenna co-site interference problems on realistically large and complex platforms. The code is hardware-accelerated by parallelizing and vectorizing the computational bottlenecks to take advantage of the abundance of multi-core CPUs and graphics processing units (GPUs). Antenna coupling data are validated using measured data, and scaling results are presented.