Abstract-A novel double-higher-order large-domain Galerkin-type method of moments based on higher order geometrical modeling and higher order current modeling is proposed for analysis of composite dielectric and metallic radiation/scattering structures combining the volume integral
equation (VIE) approach for dielectric parts and the surface integral equation (SIE) approach for metallic parts of the structure. The technique employs Lagrange-type interpolation generalized hexahedra and quadrilaterals of arbitrary geometrical-mapping orders for the approximation of geometry and hierarchical divergence-conforming polynomial vector basis functions of arbitrary expansion orders for the approximation of currents within the elements. The double-higher-order VSIE (VIE-SIE) method is extensively validated and evaluated against the analytical solutions and the numerical results obtained by alternative higher order methods.Index Terms-Electromagnetic analysis, numerical techniques, method of moments, volume integral equations, higher order modeling, curved parametric elements, polynomial basis functions, wire-plate-dielectric structures, antennas, scattering.