Análise do acoplamento de estruturas fractais em antenas monopolo multi-banda para comunicação sem fio

Abstract

This work has as main objective to carry out the study and analysis of different planar microstrip antenna, by employing fractal geometry in the resonator patch and partial removal of the ground plane with coupling. Recent studies show that variations in geometric shapes of the antenna and the ground plane generate changes in current density distribution of the planar structure and consequently the resonant modes and antenna polarization. In developing this thesis presents a new fractal antenna using the technique of insertion slots and fractal shaped defects (gaps) in the ground plane and discontinuities with ¼ wavelength transformer in the transmission line in order to increase the bandwidth and inserting in the feed line to reach specific behaviors in three frequency bandwidth applications. We used the FR-4 substrate with dimensions of 85.0 x 85.0 x 1.57 mm³. In addition, we used different modes of impedance matching in line antenna feed as CPW (Coplanar Wave Guide), to change the width of the transmission line in order to obtain a variation in the current distribution and hence the response bandwidth impedance to S11 ≤ -10dB for C band (3.9 GHz - 6.2 GHz) and S band (2.0 GHz - 4.0 GHz). A comparative analysis of cases with microstrip line and CPW was made, applications in this frequency range require preferably circularly polarized antennas. Good agreement was obtained between measured and simulated results.