Gain enhancement methods for printed circuit antennas through multiple superstrates

Reciprocity and a transmission line model are used to determine the radiation properties of printed circuit antennas (PCA's) in a multilayered material configuration. It is demonstrated that extremely high directive gain may result at any scan angle, with practical materials, if the thickness of the substrate and multiple superstrate layers is chosen properly. This model is also used to analyze the radiation characteristics of printed circuit antennas in inhomogeneous substrates.