Plasma frequency selective surfaces

Plasma frequency selective surfaces (FSS) [1]-[2] use plasma instead of metal for the FSS elements. Frequency selective surfaces have been used for filtering electromagnetic waves and Munk [3] wrote a comprehensive book on the subject. In conventional metal FSS, each layer has to be modeled using numerical methods and the layers are stacked in such a way to create the desired filtering. Genetic algorithms are sometimes used to determine the stacking needed for the desired filtering. This is a complicated and numerically expensive process. The plasma frequency selective surfaces can be tuned to a desired filtering by varying any or all of the density, size, shape, and spacing of the plasma elements.