Microstrip Antenna Efficiency and Surface Wave Loss

The efficiency components of a rectangular microstrip antenna (MSA) have been traditionally computed using the cavity model. The MSA cavity model does not include surface wave losses, but has been extended to include them. MSA surface wave losses have been assumed to be TM₀ mode on a shorted dielectric slab, which have no lower cutoff frequency. Here we examine this assumption using full-wave simulation. The nonradiative losses appear inconsistent with the generation of a pure TM₀ mode.