The results of modelling antennas installed near electrically large platforms using a hybrid method-of-moments/physical optics (MoM/PO) code are reported. A half-wavelength wire monopole driven by a delta-gap voltage source was positioned in two locations on a representative ship on a ground plane. All parts of the model were perfectly electrically conducing although the antenna was insulated from its mechanical support by a small air gap. The model was divided into physical optics and moment method domains and radiation pattern calculations were made using the hybrid method.