Robson H. C. Maniçoba

Wide stop-band cascaded frequency selective surfaces with Koch fractal elements

Numerical and experimental investigations are presented for a cascaded frequency selective surface (FSS) with Koch fractal conducting patch elements. The work is developed in two steps. In the first step two Koch fractal FSS screens are designed using the Ansoft Designer™ software. In the second step these FSS are cascaded and separated by an air gap layer to improve the bandwidth behavior. The structures are cascaded using Teflon spacers and screws to obtain the air gap. Thereafter, a numerical cascading technique is used to analyze the effect of the air gap between the cascading structures.

A Minkowski fractal Frequency Selective Surface with high angular stability

An investigation on the properties of Frequency Selective Surfaces (FSSs) with fractal patch elements is presented. Particularly, the main objective of this work is to design a high angular stability FSS band reject filter using a simple fractal element shape based on Minkowski fractal curves. The chosen FSS geometry is composed of a periodic array of conducting patches on a dielectric layer. Simulation and design are performed using Ansoft Designer commercial software for several wave incidence angles. Prototypes are built and measured to validate the study. Good agreement is observed between simulated and measured results.

Improving stop-band properties of frequency selective surfaces with Koch fractal elements

Design and experimental investigations are presented for a cascaded frequency selective surface (FSS) with perfectly conducting Koch fractal patch elements. The work was developed in two steps. In the first step two Koch fractal FSS screens were designed using the software Ansoft Design¿ and several prototypes were built. In the second step these FSS screens were cascaded and separated by an air gap layer to improve the bandwidth behaviour. The structures are cascaded using Teflon spacers and screws to obtain the air gap. The FSSs were built on a RT-Duroid 3010 substrate. Good agreement was observed between simulated and measured results.

Experimental investigation of FSS cascading with fractal elements

This paper presents experimental investigations of cascaded Frequency Selective Surfaces (FSS) with perfectly conducting fractal patch elements. Fractal FSS screens, each one using a type of fractal element, were cascaded and separated by an air gap layer. The structures are cascaded using Teflon spacers and screws to obtain the air gap. In this work three types of fractal elements were used, such as Koch, Minkowski, and Dürers pentagon patches.

Software for project and analysis of frequency selective surfaces

In this paper, a software for design and analysis of frequency selective surfaces (FSS) based on the equivalent circuit model is presented, with emphasis on teaching students in the interaction between FSS parameters. Tools to design FSSs and a tutorial with theoretical elements of the equivalent circuit method, applied to FSS, compose this software. The software can be used at FSS analysis and design course to consolidate the first theoretical and illustrated concepts.