Computer Networks and Communications, Electrical and Electronic Engineering
4
Scopus Publications
Scopus Publications
Impact of Receiver Coil Displacement and Orientation on the Efficiency of Resonant WPT Systems Maurício D Almeida, Ursula Resende, Silvia C Albuquerque 2025 SBMO IEEE MTT S International Microwave and Optoelectronics Conference Imoc 2025, 2025 This work presents a comprehensive simulation-based analysis of a wireless power transfer system employing resonant magnetic coupling between coils. A circuit-based model was developed to evaluate the behavior of the system, incorporating lumped parameters to represent the transmitting and receiving coils. This model was validated through comparison with simulations performed using Advanced Design System (ADS) software, showing strong agreement in input resistance, scattering parameters, and load current. Once validated, the circuit model was used for all subsequent analyses. The study investigates how the spatial positioning of the receiver coil—specifically alignment, lateral misalignment, and angular tilt—affects key performance metrics such as input resistance, scattering parameters (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{S}_{11}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{S}_{21}$</tex>), load current, mutual inductance, and overall system efficiency. Parametric sweeps were conducted for distance (0–100 mm), lateral offset (0–100 mm), and tilt angle <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(0^{\circ}-180^{\circ})$</tex>, with simulation results revealing the sensitivity of energy transfer to coil positioning. Notably, lateral misalignment caused significant impedance mismatch and efficiency reduction, while angular tilt led to symmetric efficiency behavior around <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$90^{\circ}$</tex>, where mutual inductance approached zero. The results identify operational windows outside ideal alignment and emphasize the substantial impact of mutual inductance variations due to spatial factors.
High-Performance Thin PTFE-Ni Metamaterial Absorber for Ultra-Broadband Applications Camilla C. Moro Carmo, Úrsula C. Resende, Sílvia C. Albuquerque, Maurício D. Almeida IEEE Access, 2025 This study presents a high-performance, ultra-thin metamaterial absorber consisting of nickel resonator disks arranged in a 4 × 4 matrix on a polytetrafluoroethylene (PTFE) substrate. The novelty of the design lies in the integration of nickel—a cost-effective alternative to noble metals—and PTFE, whose excellent thermal stability enhances the overall performance of the metamaterial. Additionally, the simplified unit cell structure enables scalability and offers a practical alternative to conventional absorbers. The proposed metamaterial absorber achieves broadband absorption across the ultraviolet, visible, and infrared spectra. A systematic parametric analysis was conducted to optimize the structural parameters, maximizing absorption efficiency while maintaining minimal thickness. Numerical simulations performed in CST Studio Suite<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> validated the optimized design, demonstrating an average absorption of 99.00% and a peak absorption of 99.36% within the 375–850 nm range. Given the elevated absorption rates achieved, the analysis range was extended to 300–3000 nm, and a genetic algorithm was employed to refine the geometric parameters. This optimization resulted in a stable absorption profile with an average efficiency of 98.98%, and a peak of 99.96%. This structurally simple design offers an advantage by combining cost-effective material selection with high broadband absorption performance.
Optimized Wireless Power Transfer From Unmanned Aerial Vehicle to Internet of Things Devices Sílvia C. Albuquerque, Úrsula C. Resende, Maurício M. Almeida, Camilla C. Moro Carmo, Icaro V. Soares 2025 IEEE Wireless Power Technology Conference and Expo Wptce 2025 Proceedings, 2025 The concept of Wireless Power Transfer has gained prominence as an effective method for powering devices without physical connections, enabling a variety of applications, particularly for devices with limited battery capacity or those situated in remote areas. Thus, this study proposes an innovative Wireless Power Transfer system using resonant coils to power Internet of Things devices through an Unmanned Aerial Vehicle acting as energy carrier and transmitter. The proposed geometry of the system and resonance frequency were optimized to achieve high energy transfer efficiency while ensuring compatibility with commercially available capacitors. The optimization process proposed is based on a circuital approximation of the system, designed to maximize its efficiency, and implemented in the Julia programming language. The numerical results obtained through the proposed modelling approach were validated using computational simulations in CST Studio Suite and experimental laboratory measurements. These results demonstrated an efficiency exceeding 98 percent at the resonant frequency without observing the splitting effect, highlighting the potential of the designed system for the proposed wireless energy transfer application.
Design of a Dual-Band MIMO Rectenna with Class-E Rectifier for Wireless Power Transfer Fagner Fernandes Santos Ramalho, Ursula Resende, Silvia C Albuquerque, Lucas Silva Lima, Igor Oliveira Souza, Daniel Augusto da Costa Oliveira 2025 SBMO IEEE MTT S International Microwave and Optoelectronics Conference Imoc 2025, 2025 This work investigates the design and simulation of a SWIPT (Simultaneous Wireless Information and Power Transfer) rectenna system proposed for IoT applications. The proposed architecture integrates a single-port dual-band MIMO microstrip antenna, a dual-band asymmetric Wilkinson power divider, and a Class-E resonant half-wave rectifier. The antenna was specifically designed to operate at the frequencies of 915 MHz and 2.45 GHz and was modeled and optimized using CST Studio Suite. It was designed on two different substrates, FR4 and Rogers RO3210, to enable a comparative analysis of how the dielectric properties affect key performance parameters such as impedance matching, bandwidth, and radiation characteristics. The Wilkinson power divider was designed and simulated in Advanced Design System (ADS) with the goal of achieving an asymmetric 4:1 power split between its output ports, while maintaining low insertion loss and high isolation over both frequency bands. Additionally, the Class-E resonant half-wave rectifier was designed and optimized in ADS for operation at 2.45 GHz on an FR4 substrate. The rectifier achieved an input impedance close to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$53.41-\mathrm{j} 0.0011 \Omega$</tex> and a reflection coefficient (S11) of –32.16 dB, indicating excellent impedance matching. The simulation results demonstrate the effective performance of each individual component and confirm their compatibility when integrated. These results suggest that the proposed rectenna components are well suited for use in SWIPT-based IoT sensor nodes, supporting both power harvesting and wireless information transfer functions efficiently.
