A cavity model well suited for computed-aided design is developed to synthesize the dimensions of patches for a given resonant frequency, an input resistance and a substrate. The antennas which have been investigated are rectangular patches fed with either a microstripline or a coaxial probe.

The Finite-Difference Time-Domain (FDTD) method has been applied to study the scattering characteristics of Fabry-Perot cavities with infinite planar periodic surfaces. Periodic Boundary Conditions (PBC) are used to reduce the analysis to one unit periodic volume. Both dielectric and metallic losses are included in the algorithm using a frequency dependent formalism. This technique is used to study the frequency response of plane parallel Fabry-Perot cavities with square aperture metal mesh mirrors. These cavities are assumed to be illuminated by a normally incident plane wave. After a detailed description of the algorithm, we show theoretically the separate effects of dielectric and metal losses on the transmission coefficient of such cavities. We compare also simulation results to measurements, in the 60 GHz band, of resonant frequencies and Q factors of cavities with various mesh parameters.