Abstract: A microstrip structure comprising a conductive layer whose width varies in such a way as to obtain an effective dielectric constant, which presents a sinusoidal shape modulation. The propagation of electromagnetic waves in materials with electromagnetic properties, which varies along their propagation direction having desirable characteristics, such as the presence of frequency bands in which the propagation is allowed and of bands in which the electromagnetic waves are stopped.

Abstract: An antenna comprising a plurality of re-radiating elements arranged in at least one plane being parallel to a fixed surface. The arrangement is adapted such that electromagnetic radiation emitted from the re-radiating elements in response to electromagnetic radiation arriving from a predetermined direction interferes constructively at a feed location. Additionally, the antenna comprises a feed provided at the feed location. In a method of manufacturing an antenna, the arrangement of the plurality of re-radiating elements may be calculated and the re-radiating elements can be provided in the at least one plane substantially parallel to the substrate. An apparatus for manufacturing an antenna may comprise a data processor adapted to calculate the arrangement of the plurality of re-radiating elements and means for forming the plurality of re-radiating elements.