Superfícies seletivas em frequência do tipo absorve/transmite banda larga

Abstract

Frequency Selective Surfaces (FSS) are increasingly being used in telecommunications systems due to the numerous advantages presented by this type of structure, among them the low cost, ease of fabrication and low profile. As well as frequency selective surfaces, electromagnetic wave absorbers have also been widely used, mainly with the objective of solving the problem of multipath. Absorbers are structures that aim to absorb electromagnetic waves in a certain frequency range, while allowing the passage of waves outside it. Thus, this work proposes to investigate the use of FSS, for the design of multilayer absorbers, to obtain broadband absorption. The study consists of the application of resistive-type FSS combined with conductive-type FSS, which use square loops as unit cell geometry, to design an absorb/transmit structure with broadband-type frequency response. The proposed structure operates in the frequency range between 2 GHz and 6 GHz. An extensive parametric analysis was performed to optimize the desired response. At the end of this analysis, two resistive and two conductive FSS were designed and cascaded to obtain the desired bandwidth. The analyzes showed that the broadband absorber has polarization independence and angular stability up to 30º. Furthermore, experimental results show that the proposed structure can absorb signals in a frequency range from 2.4 to 6.13 GHz. Absorption above 80% occurs over the entire proposed frequency range. The structure can absorb signals for the entire ISM band (2.4 – 2.4835 GHz), 5G at 3.5 GHz and UNII (5 – 6 GHz), without blocking the other frequencies, avoiding multipath in the proximity of the absorber it’s installed.