Meta-sheets open up new opportunities in the design of radomes for microwave antennas. A meta-sheet typically consists of a periodic array of small resonators embedded in a thin dielectric layer. The smallness of unit cells and the large electrical size of microwave radomes significantly complicate full-wave numerical simulations as a very fine sampling over a large area is required. This paper proposes an efficient simulation approach, which combines Physical Optics and Finite Element methods.