Resumo em Inglês:

Abstract This paper proposes a methodology for developing antipodal Vivaldi antennas using RSIW (Ridge Substrate Integrated Waveguide) technology for a specific cut-off frequency. The technique employs metallic-vias and metalized cylindrical posts of reduced sizes inserted in the dielectric substrate. The simulations were performed using the ANSYS® Electronics Desktop software. The antenna RSIW is designed for a resonant frequency of 4 GHz and was fabricated on FR4 (ɛr=4.4 and tanδ=0.02). The structure is compared to an antipodal Vivaldi antenna (AVA) fed by a SIW. The structure proposed had an increase in bandwidth of 4.09 GHz and an increase in gain of 1.41 dBi.

Resumo em Inglês:

Abstract This study examines the characteristics of the lowvoltage MIMO-PLC electric power line channel, which operates within the 2-100 MHz frequency range. The research involved measurements in four different Setups using 2.5 mm copper wires, including phase, neutral, and protective earth wires. These wires were transposed within a conduit, measured in pairs, with variations in the number and lengths of branches, assuming a deterministic modeling behavior of the electric power line. Throughout the experimentation process, essential parameters such as the magnitude of the S21 scattering parameters and VSWR identify frequency ranges suitable for efficient data transmission. The findings suggest remarkable prospects for enhancing PLC communication across MIMO channels. Depending on the combination of cable lines, over 70% of the bandwidth remains available. Additionally, the overall average impedance measured at 77.14 Ω is vital for impedance matching in PLC coupling circuit designs.

Resumo em Inglês:

Abstract Ring shape microstrip antenna designs supported via an altered ground plane profile are proposed for multi-band response with wider bandwidth in each band. The impedance bandwidth of a single ring patch supported via a slot cut ground plane on a substrate having a thickness of ~ 0.1λg, is 45.8% and the broadside gain is 5.6 dBi. By employing additional stack patches, dual and triple-band configurations are obtained. In the respective operative frequency bands, maximum 15% of bandwidth is achieved in the suggested antenna, with a maximum broadside gain of more than 5.5 dBi. Through the acquired antenna features, the proposed configuration fulfills the criteria of E-GSM900/Secondary Surveillance Radar/Aeronautical Radio Navigation Applications.

Resumo em Inglês:

Abstract The equivalent wave impedance circuit model (ECM-WI) is presented for the analysis of frequency selective surfaces (FSS). The development of the analytical model is based on homogenization theory, as well as analogies between wave theory and transmission line theory. The coplanar strip model and the concept of wave impedance are used to scale the Marcuvitz model for periodic strip gratings of conductive strips, as well as to consider the influence of the presence of a lossy dielectric substrate on the frequency response of the FSS. In particular, the model is applied to the analysis of square loop FSSs and considering the normal incidence. The results obtained are presented by comparing full-wave simulations for the two proposed models, obtaining average deviations in absolute values (%) of 2.11 and 0.38 for resonance frequency and 3.45 and 5.49 for bandwidth. The prototype manufactured in FR-4 obtained a deviation of 2.56% for resonance frequency and 2.79% for bandwidth.

Resumo em Inglês:

Abstract This paper presents a novel nature-inspired tri-band frequency selective surface (FSS) characterized by closely spaced bands, angular stability, and polarization independence. The FSS element adopts a segmented Fibonacci spiral geometry. While a single-segmented Fibonacci spiral does not inherently possess polarization independence, the proposed proof of concept achieves this by cascading the same design geometry rotated by 90° between them. Resonant frequencies of 1.63 GHz, 2.46 GHz, and 3.43 GHz are achieved, with minimal separation ratios of 1.5 from the second to the first frequency and 1.4 from the third to the second. Additionally, angular stability is confirmed up to 45°. Simulation of the FSS is conducted using HFSS software, and the simulated results are rigorously validated against experimental data, demonstrating excellent agreement.

Resumo em Inglês:

Abstract This paper focused on the design and practical implementation of a compact arrowhead slot Super Wide Band (SWB) antenna on a semi-flexible substrate for a wide range of applications. A tapered feed circular monopole antenna with an arrowhead-shaped slot structure is designed on RT/Duroid substrate with a compact physical dimension of 22 × 28 × 0.508 mm3. The impedance bandwidth of the proposed antenna is 95.93 GHz (3.1-99.17 GHz) with a peak gain of 6.91 dBi. The proposed antenna has a fractional bandwidth of 187% with a high Bandwidth Dimension Ratio (BDR) of 3049 which makes the proposed antenna suitable for a wide range of applications. The proposed antenna compactness is theoretically verified with the help of the fundamental dimension limit theorem. For wearable IoT applications compactness, conformal and bending capabilities of materials are essential and hence the proposed antenna is also tested under different bending conditions and achieved a minor effect on the antenna performance. Further in order to observe the signal correlation, the time domain analysis using similar antennas in face-to-face and side-to-side scenarios has been also analyzed. The simulated results of the proposed antenna exhibit good agreement with the experimental results of the prototype model antenna.

Resumo em Inglês:

Abstract In this work a broadband Magnetoelectric (ME) dipole antenna for the Global Navigation Satellite System (GNSS) applied to nanosatellites is proposed. The antenna consists of a reflective cavity with open walls containing four gaps to enhance the axial ratio (AR) bandwidth. Additionally, it includes two ME dipoles formed by two pairs of vertical and horizontal copper plates, one of which is trapezoidal and a T-Γ-shaped cross-feeding structure. A prototype was designed and subsequently manufactured and measured. The experimentally obtained results exhibit consistent agreement with simulated outcomes, demonstrating that the antenna has a wide impedance bandwidth of 111.36% from 1.13 GHz to 1.62 GHz for the Voltage Standing Wave Ratio (VSWR) ≤ 2 and a 3 dB AR bandwidth of 120.45% from 1.10 GHz to 1.63 GHz. Within this range, high gain (≥8.5 dBi) and high radiation efficiency (90%) can be achieved. Furthermore, the antenna exhibits right-hand circular polarization (RHCP) and possesses good unidirectional radiation characteristics with a high front-to-back ratio (≥ 20 dB).