Gppcom UFRN

Synthesis of Dual-Band Convoluted FSS Using Radial Basis Function Neural Networks

Resumo: This paper proposes a dual-band frequency selective surface (FSS) synthesized with a radial basis function (RBF) neural network. A convoluted unit cell was optimized to operate at the ISM (2.45 GHz) and UNII (5.5 GHz) bands. A database of simulated responses was used to train the RBF model, which achieved accurate parameter prediction with a root-mean-square error of 0.02. The fabricated prototype showed good agreement with simulations, exhibiting dual-band operation, polarization independence, and angular stability. The results confirm the effectiveness of ANN-based synthesis for rapid and efficient FSS design in wireless communication applications.

Autores:
Francisco Carlos G. da Silva Segundo (Departament of Engineering and Technologies, UFERSA)
Alfredo Gomes Neto (Telecommunications and Applied Electromagnetism Group, IFPB)
Antonio Luiz P. S. Campos (PPgEEC/UFRN)

IEEE 2nd Latin American Conference on Antennas and Propagation (LACAP 2026)

Artigo publicado no IEEE 2nd Latin American Conference on Antennas and Propagation (LACAP 2026).

This work describes a structure that achieves simultaneous tri-band absorption and broadband polarization conversion in a single device. The unit cell consists of three square loops and a square patch with a diagonal split, printed on a grounded dielectric substrate and covered by a superstrate, both FR-4. The proposed design offers absorption peaks of 99.98%, 97.6% and 97.6% at frequencies of 1.87GHz,3.3GHz and 4.8 GHz, respectively, while polarization conversion occurs in the Xband, from 8.22 to 9.26 GHz, with a polarization conversion rate above 90% across the entire band. Furthermore, the structure is compact, with dimensions of 0.1λ×0.1λ (length and width) and a thickness equivalent to λ/50.12 at the lowest frequency of absorption.

Autores:
Thayana Mayrink L. de Sousa (Dep. of Telecommunication Engineering, Fluminense Federal University)

Victor M. M. Albuquerque (Dep. of Electrical Engineering, Federal University of Roraima, Boa Vista)

Francisco Diego M. Nobre (Dep. of Electrical Engineering, Federal University of Roraima)

Antônio L. P. S. Campos (PPgEEC/UFRN)

Maurício W. B. Silva (Dep. of Telecommunication Engineering, Fluminense Federal University, Niterói and São Paulo Federal Institute of Education, Science and Technology, Avaré Campus, Avaré, São Paulo)

Parceira entre a UFRN, a UFRR, a UFF e a IFSP

Novo artigo publicado!

This work presents the design, simulation, and experimental validation of a high-quality factor microwave sensor for measuring the relative permittivity of solid materials. The proposed sensor integrates an interdigital capacitor (IDC) into a rectangular microstrip patch antenna. The sensor achieved a quality factor of 440, a frequency detection resolution (FDR) of 62 MHz, and an average measurement error of only 0.07%. Numerical simulations and equivalent circuit modeling confirm the accuracy of the sensor's behavior, while experimental measurements using five materials under test (MUTs) validate its practical performance.

Autores:
Isau de Sousa Silva (PPgEEC/UFRN)
Ruann V. A. Lira (Department of Engineering and Technology, UFERSA)
Isaac B. T. Da Silva (Department of Engineering and Technology, UFERSA)
Antonio Luiz P. S. Campos (PPgEEC/UFRN)

Veículo: IEEE 2nd Latin American Conference on Antennas and Propagation (LACAP 2026)

This paper extends a previously published proposed approach for estimating worst-case exposure scenarios in buildings using publicly available Base Station (BS) parameters, applying it to a critical case involving a multi-operator shared site. Radiofrequency Electromagnetic Fields (RF-EMF) exposure was assessed on every floor of a 20-story building facing the site, revealing significantly higher levels near the center of the antennas’ estimated vertical zone of interest, with a peak of 31.86 V/m, 23.95 times higher than the street-level peak value. However, due to uncertainties in the input parameters, measurements across all locations within the zone of interest are required to accurately identify the floor of maximum exposure. The results demonstrate the usefulness of the proposed estimation approach and highlight the need for improved methods that consider BS antenna configurations and current technical information to ensure accurate assessments of exposure to RF-EMF.