Frequency selective surfaces with time-varying nonlinear loads

An approach to a periodic surface loaded with nonlinear devices is presented which uses an equivalent circuit representation at the load location. This method is applicable to all angles of incidence, and it takes into account the effect of dielectric substrate and superstrate layers. It is also applicable to periodic surfaces with arbitrarily placed loading and arbitrarily shaped array elements. Specifically, a unique development combining the frequency-domain data of a frequency selective surface (FSS) with time-varying loads is demonstrated. It is based on the moment method solution of the spectral domain formulation for variable surface impedance and lumped elements. Nonlinearly loaded surfaces can disperse energy into many scattered frequencies. Applications would include frequency multipliers, frequency modulators, and beam steering.<>