Refletor de bragg impresso em 3D para aumentar o ganho e a diretividade de antenas de ondas centimétricas e milimétricas

Abstract

The emergence of new applications that use wireless communication technologies re present a significant development in telecommunications systems. However, the lack of appropriated mechanisms to manipulate the radiation patterns, in order to avoid signal transmission to undesired regions, still constitutes an important drawback. Ex ploiting the Bragg mechanism for reflecting used by photonic structures, we design and developed a quasi-cylindrical reflector with an aperture for improved directivity of readily available centimeter and millimeter wave antennas, i.e., without changing any feature of the antenna. In particular, we used a Bragg structure built by three bilayers, which are made of transparent materials, to analyze the behavior of an electromagnetic field with normal incidence on the surface of each bilayer of this structure. This analy sis verified that the layers thickness according to Bragg law, the structure offers high reflectivity. The aperture has a triangular geometry that resembles the idea of a highly directional horn-like antenna. The design was developed to work at conventional WiFi frequencies based on the IEEE802.11 standards to adjust the signal coverage into the residence. Numerical analyses based in simulations were made using the ANSYS HFSS®software, in terms of reflection coefficient, radiation pattern, directivity and gain. The simulations shown the transparent layers performance together with an an tenna designed for operating frequency at the exact same design frequency, 5,7 GHz. Lastly, the dielectric reflector in almost cylindrical shape was manufactured using 3D printing and experimentally analysed. Comparisons between the results obtained in the numerical and experimental characterization are presented. Remarkably, we observed an improved directionality of the radiation pattern, in excellent agreement with nume rical simulations. Gain enhancements of more than 400% are reported in relation to the antenna gain without the Bragg structure. Significantly, the proposal is an economic and easy-to-build structure, which works with WiFi applications. Therefore, we hope our proposal can be easily implemented by non-specialists, just being placed around the antenna to improve the directivity and gain of the signal.