The objective of this paper is to explore the potential of integrating three distinct functionalities into a thin, single-layer metasurface. Specifically, the study introduces a metasurface design that combines absorption, polarization conversion, and transmission capabilities. The proposed structure consists of a double square loop disposed on a dielectric substrate, which is covered by a superstrate. In this study, the traditional ground plane was replaced with a periodic array, selectively reflecting frequencies of interest. Then, the absorption and polarization conversion characteristics were achieved by introducing the resonators in the front layer. By introducing asymmetry to the resonators and integrating PIN diodes for control, we demonstrated that the metasurface could efficiently absorb electromagnetic waves (with PIN diodes in the ON state), convert polarization (with PIN diodes in the OFF state), and enable signal transmission in a different frequency range. The numerical results indicated excellent performance in both absorption and polarization conversion. At a frequency of 3.05 GHz, the absorption rate reached 97%, while a polarization conversion rate of 98% was achieved at the resonance frequency of 4.37 GHz. Moreover, the proposed structure exhibited a thickness of λ/30.7 at the absorption peak.

A metasurface-based ultrathin and ultrawideband reflective linear polarization converter is designed and simulated in this research. Through three resonances generated in a periodic array composed of a circular patch cut at 45 degrees and two square slits, a bandwidth expansion is obtained, making it possible to cover almost completely the X-band, entirely the Ku-band and partially the K-band. Simulation results show that the metasurface converts linearly polarized waves into cross polarized waves from 8.32 to 21.82 GHz, with a total bandwidth greater than 13 GHz. Furthermore, efficient cross-polarization conversion is achieved with fractional -10 dB bandwidth of nearly 90% with an average polarization conversion rate of 97%. The proposed cross-polarization converter (CPC) is λ/12.8 in thickness and λ/4.5 in periodicity at the lowest frequency.

A metasurface generally has a single function, as they can only absorb incident energy and, in some cases, in addition to absorbing also transmit, or convert the polarization state of an incident wave. Bringing new breakthroughs, in this manuscript, a multifunctional thin metasurface is presented. The proposed structure is composed of an array of double square loops disposed over a dielectric substrate. In this study, the full ground plane is replaced with a periodic array to reflect only the frequencies of interest. By breaking the symmetry of the resonators and inserting PIN diodes for control, we demonstrate that the structure can efficiently absorb electromagnetic waves (PIN diode ON), convert the polarization (PIN diode OFF) and allow signals to travel in other frequency band. The simulated structure showed good results for both absorption and conversion. For the frequency of 3.05GHz the absorption rate was 97 %, and a conversion ratio of 98 % is obtained for the resonance frequency of 4.37GHz. Furthermore, the proposed structure has a thickness of lambda/30.7 in relation to the absorption peak. Although the operating bands are narrow, the structure has potential applications such as thermal detectors, stealth field, imaging, remote sensors, and radiometers.

Resumo-Neste trabalho é proposta uma estrutura absorvedora baseada em uma superfície multiressonante de alta impedância que pode ser usada como etiqueta em um sistema de identificação por rádio frequência (RFID) sem chip. A célula unitária é composta por espiras circulares com capacidade de absorção de sinal nas faixas S, C e X acima de 90% nas frequências de ressonância de 3,612 GHz, 4,718 GHz, 5,984 GHz, 7,798 GHz e 11,316 GHz. É feita uma análise de codificação de bits a partir da presença ou ausência de elementos. São avaliados os parâmetros de performance da célula proposta como independência sob incidência angular, efeitos de cruzada polarização e fator de seletividade Q da estrutura, com resultados para a RFID proposta com possíveis aplicações em identificação de sistemas de radio enlace e filtragem de sinais.