Obstacle-type artificial dielectrics for microwaves

Artificial dielectrics consisting of arrays of small metallic elements have found widespread employ ment recently, notably in the construction of microwave lens aqtenn Depending on the shape of the obstacles, these media may be conveniently analyzed (1) by an analogy with classical molecular theory, (2) by a consideration of scattering phenomena, or (3) by an analogy with transmission-line theory. A great deal of experimental information is also becoming available. A survey of the analytical and practical techniques now used in the design of artificial dielectrics is presented. Special emphasis is given to a consideration of the similarities and dissimilarities between the behaviour of such media and that of actual dielectrics. The case for artificial dielectrics is discussed in terms of their various advantages over actual dielectrics, such as light weight, good matching properties, and the feasibility of spatial variation of refractive index for Lÿneburg-lens and other applications.