Natural and artificial dielectrics: Similarities and differences

The concept of "artificial dielectric" is re-examined and its relationship to natural dielectrics is investigated. The mere discrete nature of an artificial dielectric sets an inherent conceptual limit on how closely it can imitate the behaviour of a natural dielectric. Among other things, the difference between the wave propagation in natural and artificial dielectric media are underlined. Also alternative theoretical schemes, that are less familiar in the antenna and microwave community, will be re-introduced to explain such phenomena as "lens effect". It is also argued that an artificial dielectric can be interpreted as a delay medium.