Proposal of a New Multifractal Structure with Low Sensitivity of Resonance Frequency with Relation to Periodicity
Frequency selective surface, Fractal Geometry and Periodicity insensitive
Frequency selective surfaces have received great attention from researchers around the world, due to their filtering characteristics. These structures evolved in terms of manufacturing. Thus, the geometries used, initially, were yarns in the form of a grid and later, several types of new geometries such as: rectangular, square, circular, rings, square coils, etc. were used. Recently, fractals and, more recently, multifractal elements have been employed. The use of these geometries is done in order to obtain a specific frequency response. Important parameters such as bandwidth and resonant frequency are met from the use of a given geometry. This work proposes a multifractal geometry with double similarity, which has as main characteristic low sensitivity to the variation of the periodicity with respect to the resonance frequency. This specificity will bring gain with regard to the elaboration of the project, because the control of the bandwidth is made only with the change of periodicity. Several simulations were implemented in the ANSOFT DESIGNER, for demonstration purposes, traditional structures were simulated, aiming at demonstrating the effect of periodicity on resonance frequency, and then two prototypes were constructed and measurements were made to experimentally validate the simulations.