Técnica de detecção da polarização de ondas eletromagnéticas em ambiente aberto.

Abstract

This work presents a new technique for polarization measurements of electromagnetic waves, which allows for a simplification if compared to other known methods. A circuit with cascated Wilkinson power dividers is developed to perform division, phase-shifting and sum operations of input signals, in order to allow the main parameters of the po- larization to be determined from amplitude measurements only, in which two linearly polarized antennas are used for reception. The use of this circuit simplifies the overall system, since a phase-shifting device is no more needed, besides avoiding the procedure of antenna rotation as seen in some methods. The structure of the proposed circuit, its S-parameters and its operation are analyzed. Circularly polarized antennas of planar and helical-type are described, and their simulated and measured reflection coefficients are presented. Experiments with different measurement methods, such as linear component method and vector network analyzer method, are described in order to validate the pro- posed technique. Results for phase difference, axial ratio and tilt angle measurements are presented for the different methods and different antennas. Comparisons between the results are made, which allows to verify the agreement between results and to validate the proposed technique.