Abstract Surface Plasmon Polaritons (SPPs) are evanescent surface electromagnetic waves that propagate along a dielectric-metal interface. They allow propagating modes in waveguides with dimensions smaller than the diffraction limit. By arranging slits of different widths along a metallic film, it is possible to design plasmonic lenses through phase modulation at the slits output. The distance of energy concentration, obtained by these lenses, its called focus and is of the order of one wavelength (λ). Lenses of this type allow light coming from a micrometric waveguide, such as optical fibers, for example, to be coupled to structures such as nanometric waveguides, at short distances, reducing considerably the coupling area. In this work, by using the Finite Element Method (FEM) was simulated the energy coupling between a light source and a plasmonic waveguide using plasmonic lens operating at wavelengths of 650 nm.

Abstract Visible-light communication (VLC) is a technique that employs light-emitting diodes (LEDs) and photodiodes to enable communication in indoor scenarios. VLC has gathered increasing attention due to its potential for data transmission across a broad unregulated spectrum (430-790 THz). One of VLC’s primary objectives is to utilize pre-existing LED infrastructures as access points. In this investigation, we assess the performance of an indoor VLC link by measuring the illumination characteristics of commercial LED luminaire. The results are utilized to design an electronic transmission and reception circuit. An analysis was conducted to identify the optimal operating point that ensures adequate lighting and reliable communication. The designed circuits exhibited a bandwidth of 50 MHz at -3 dB. Characterization of the luminaire demonstrated that a single luminaire provided the illumination (486 lx) within the recommended range at 1.6 m. For data transmission, the variable pulse position modulation (VPPM) and the orthogonal frequency-division multiplexing (OFDM) were employed in different configurations. The bit error rate (BER) results, with a threshold of ≤ 10-3, revealed that VPPM performed best at a distance of 1.9 m with a rate of 12.5 Mbps. Conversely, OFDM modulation achieved optimal performance at 1.75 m, providing a transmission rate of 30 Mbps.

Abstract This paper presents an eyebolt structural fault detection system, based on the analysis of multiple electromagnetic parameters through a random forest classifier trained by both measurements and high-fidelity simulated signals. The proposed methodology is completely noninvasive and does not require the disassembly of the electrical infrastructure, allowing the live-line working. The obtained results show that the proposed multi-parameter strategy achieves high accuracy and increases the system’s capability of detecting faults, improving the efficiency of the operator’s preventive maintenance routines and, consequently, increasing the reliability of the power supply and energy distribution systems. system highfidelity fidelity signals infrastructure liveline live line working multiparameter multi parameter systems s faults operators operator consequently

Abstract This article describes the use of a low-cost softwaredefined radio applied to an Electromagnetic Compatibility (EMC) test. The proposed system is indicated for cases when an autonomous instrument is better suited, i.e., when there is no need for external signal or power connections. As a proof of concept, a metallic cavity has its shielding parameter measured, and the obtained results illustrate the kind of outputs the instrument can provide. Details concerning the hardware and software utilized are mentioned, alongside observed pitfalls and trade-offs. It is an affordable and versatile method, which can replace the traditional use of spectrum analyzers and receivers, especially in precompliance tasks. lowcost low cost EMC (EMC test suited ie i e i.e. connections concept measured provide mentioned tradeoffs. tradeoffs trade offs. offs trade-offs method receivers tasks i.e

Abstract This paper suggests a slotted ground ‘S’-shaped low profile planar microstrip patch antenna for wideband and high gain operation. The suggested antenna has physical dimensions of 20mm×14mm×1.6mm having a fractional bandwidth of 111% having the operating impedance bandwidth 22.55GHz (9.12 GHz to 31.67 GHz). At 19 GHz, maximum gain of 3.9 dBi is attained. An equivalent circuit model corresponding to suggested antenna is designed by ADS software and assessed with the simulated and measured antenna results. Frequency Selective Surface (FSS) of single layer has been placed at optimum position at a distance of 15 mm below the antenna for further improvement of the overall gain of the suggested antenna. Combination of suggested antenna and 6×6 FSS configuration increases peak gain to 9.4 dBi maintaining the same antenna bandwidth. The FSS unit cell of dimension 6.5mm×6.5mm×1.6mm is used. Design of the antenna is done using commercially available electromagnetic simulator (CST Microwave Studio), and the simulated results are verified by suitable antenna measurement technique using standard microwave test bench. Given FSS integrated antenna has an overall physical volume of 39mm×39mm×15mm which makes it ideally suited for high-gain long-range applications.

Abstract This paper presents a study of a segmented waveguide where the layers are distributed following the Fibonacci sequence and aims to diminish the scattering losses usually caused by imperfections in the core boundaries of the waveguide. This phenomenon normally happens in structures which present a high contrast between the refractive index of the core and the refractive index of the clad. The analyses were obtained through observations of wave fields that propagates along the waveguide, how the effective refractive index (neff) varies along the z-direction and the study of its normalized power. The simulation of this photonic component was accomplished with the help of the Vectorial Beam Propagation Method (VBPM).

Abstract This paper presents a radiopropagation algorithm based on a Ray Tracing (RT) technique that combines a modified multipath model for constant refractivity gradient profiles and the Uniform Theory of Diffraction (UTD). A novel formulation is proposed by the authors for calculation and ground-reflection analysis of ray paths depending on atmospheric refractivity. The algorithm introduced herein was evaluated in a mixed scenario and in two more realistic case studies, under conditions of constant refractivity gradient and lossy terrain profiles. Pathloss results are obtained and compared with Parabolic Equation (PE) numerical solution results at 2.0 GHz, 3.5 GHz and 5.4 GHz. In such conditions, the modified radiopropagation multipath algorithm with atmospheric refractivity introduced herein showed satisfactory results.

Abstract This paper presents a model that uses bio-inspired optimization algorithms to control of the mutual coupling (MC) in Multiple-Input Multiple-Output (MIMO) systems. The method promotes an increase in the channel throughput and a reduction in the distance among the array elements, searching values less than a half wavelength. A microstrip antenna design, at the frequency of 26 GHz, is used as a prototype for MIMO system testing and performance analysis. Genetic Algorithm (GA) is used to optimize, to determine the antenna physical parameters and to improve its performance. The mutual impedance concept is used to model the MC. The particle swarm optimization (PSO) algorithm is used to optimize the channel throughput and to reduce the distance between the elements. Simulation results show that it is possible to obtain a MIMO system performance improvement of 11.1% in channel throughput, the microstrip width is reduced by 14.5% and the distance among the elements can be reduced by 23.7%, considering the MC.

Abstract This paper presents a feasibility study of a singlylayered dual-band reflectarray for space applications. The data links should operate simultaneously at K-band downlink frequency band 17.7-20.2 GHz with left-hand circular polarization (LHCP) and at Ka-band uplink frequency band 27-30 GHz with right-hand circular polarization (RHCP). The main aim is to present how a reflectarray can be designed so as to allow reconfigurability of its radiation pattern, especially in terms of beam steering to two different directions. The design is automated by means of a computational tool developed in MATLAB environment interfaced with the electromagnetic simulator CST Studio Suite by means of Visual Basic scripts. Simulation results are presented to demonstrate the efficiency of the proposed computational tool and reconfiguration strategy.

Abstract This work presents an adaptive hybrid signal precoding strategy for Cell-Free (CF) Massive multiple-input multiple-output (MIMO) systems. The proposed solution exploits the advantages of both distributed and centralized signal processing schemes to perform precoding. In our proposal, some access points (APs) are dynamically configured to be used in a centralized precoding scheme, whereas others are adjusted to employ a distributed method. Simulation results show that it is possible to achieve a good compromise between spectral efficiency (SE) and computational complexity (CC) in CF Massive MIMO systems finding a sensible balance between APs utilized in centralized and distributed precoding. To the best of our knowledge, prior-art solutions have not addressed an adaptive hybrid precoding method itself, they have only proposed a specific solution for each architecture, i.e., distributed or centralized.

Abstract In this work, a theoretical model for the transmittance in a left-handed metamaterial of different geometries is presented. The proposed unit cells are a combination of conducting wires of rectangular cross-section with square-ring and hexagonal resonators. In this new dielectric compound, dependence of transmittance on the thickness of the resonators are analyzed for the particular case of normal incidence in the GHz range. It is found that the transmittance for the hexagonal resonator shows a significant increase compared to the square geometry resonator. work lefthanded left handed presented crosssection cross section squarering ring compound range

Abstract In this article an innovative method of studying and removing the resonances, inherently exhibit by some waveguide to microstrip transitions, is presented. By modeling an equivalent circuit, this new approach allows to obtain the constructive parameters of a finline to microstrip transition, only using the values of the resistance and capacitance components of the equivalent circuit. This procedure will allow small microwave design Companies to realize these transitions only implementing circuit analysis software, and not having to afford electromagnetic analysis software, which are very expensive and time-consuming. A full 3D electromagnetic analysis confirms that the simulation results are in excellent agreement with the results obtained by the new equations discussed in this work. resonances presented transition software timeconsuming. timeconsuming time consuming. consuming time-consuming D work

Abstract This paper is regarding the statistical coexistence analysis between a cluster of International Mobile Telecommunication 2020 (IMT-2020) Base Stations and an Aircraft Earth Station (AES) operating during flight time in the L Band on a final approach. We assess the cumulative distribution function (CDF) of interference-over-noise ratio (INR) considering the fuselage attenuation contribution and compare it with the AES protection criteria. Our coexistence analysis approach considers the use of a high gain AES commercial antenna model, for an aircraft at two different altitudes, 187 m and 83 m, for 3600 m and 1600 m of horizontal distance from the runway threshold, respectively. Therefore, considering the IMT-2020 suburban scenario near the airport, simulation results presented an INR that met the protection criteria for 100% and 99.95% of the time for the distances of 3600 m and 1600 m from the runway, respectively, making the spectrum sharing feasible between systems. To the best of our knowledge, this is the first time in the literature that fuselage attenuation considering part of the plane, in the L-band is presented in a statistical coexistence analysis.

Abstract This work presents the development of a reconfigurable frequency selective surface (RFSS) for application in the 2400-2483.5 MHz band, standard IEEE 802.11b/g/n (Wi-Fi). The proposed RFSS is based on the four-arms star geometry and PIN diodes were used as switching elements. In the initial design, numerical and measured results, especially for y polarization, PIN diode on-state, shown a difference of 15% for the resonant frequency. To overcome this drawback, a scaling factor was adopted and RFSS was redesigned and characterized, achieving the desired frequency response. The RFSS reconfigurability is confirmed, with a variation of at least 15 dB, when switching the states of the PIN diode. Moreover, the signal strength was measured directly on a notebook, confirming the reconfiguration of the RFSS. Finally, for the y polarization, it was found that for this polarization the frequency response remains virtually unchanged, even for angles of incidence up to 45°. In addition to the Wi-Fi signal control, the observed features make the developed RFSS especially attractive for reconfigurable antennas applications.

Abstract Frequency Selective Surfaces (FSS) are increasingly being used in telecommunications systems due to the numerous advantages presented by this sort of structure, among them low cost, ease of fabrication, and low profile stand out. This work reports the design, fabrication, and characterization of a multilayer frequency-selective absorber (FSA) for broadband operation. The proposed structure shows an absorption performance (operating in the frequency range between 2 GHz and 6 GHz) within the transmission band. The absorber consists of cascaded frequency selective surfaces, which are composed of both conductive square loops, which reflect incident signals, and resistive ones, which act as an absorbing layer. To verify the absorbing structure performance, full-wave numerical simulations and measurements are presented. The measured results are in good agreement with the numerical ones and show that the design performs absorption above 80% within the range of 2.48 GHz to 6.13 GHz, which verifies the project properties. Besides that, numerical results show that the proposed absorber has a proper response under oblique incidence up to 30°.