Analysis and application of metasurfaces to improve parameters of microstrip antennas
Microstrip antennas; metasurfaces; bandwidth; polarization; spurious radiation
The microstrip antennas are object of study in several fields of research due to their advantages such as: small thickness, reduced weight and facilities of integration to electronic circuits. Similarly, the evolution observed in the development of microstrip antennas was also noticed in relation to metasurfaces, a two-dimensional version of a metamaterial. Metasurfaces are artificial materials that are not found in nature and have unconventional electromagnetic characteristics, such as the refractive index and the coefficients of negative electrical permeability and magnetic permeability, besides, they have the capacity of use in planar structures, such as the microstrip, without interfering in its traditional geometry. The objective of this work is to develop new configurations of metasurfaces that coupled to microstrip antennas are able to realize improvements to the bandwidth, to realize the polarization change from linear to circular and vice versa and contribute to the elimination of spurious radiation. The simulated results are obtained with the commercial software ANSYS HFSS, used for the analysis of the electromagnetic behavior of the antennas, using the Finite Element Method (FEM) and compared to the results measured for validation. The antennas developed are capable of being used in mobile communication devices and wireless networks and were built using fiberglass (FR-4) as a dielectric substrate, making them simple and inexpensive. For that, in this thesis, an analysis on antennas types, with emphasis on microstrip antennas, has previously been carried out. Afterwards an analysis is made on the metasurfaces and their properties. This work also presents a bibliographical analysis on the main methods to obtain improvements / modifications in the merit figures previously mentioned.