Leonardo Lorenzo Bravo Roger

This study presents a portable, compact, and cost-effective in situ monitoring device designed to monitor leaf water status through a terahertz (THz) source, THz sensor, and infrared array sensor. The innovation in the proposed device is the use of Resonant Tunnelling Diodes (RTD) within THz sources and detectors operating at ~0.28 THz and using a low-cost system’s architecture that consists of an integrated signal generator and scope, coupled with associated hardware connected to a computer. This configuration enables signal acquisition and subsequent Fast Fourier Transform (FFT) processing to extract peak power values to determine the plant leaf’s water content and the leaf surface’s temperature using an infrared array sensor. Experimental analysis demonstrates that the proposed THz system exhibits a substantial correlation, with an R-squared value of approximately 0.97, when compared to moisture loss measurements obtained using a moisture analyzer. Furthermore, it effectively detects moisture loss within the range of 25% to 85% and utilizes thermal images from an infrared sensor array to identify potential health issues in plants. Therefore, the device proposed in this work demonstrates a portable, in situ, non-destructive, and cost-effective solution tool for directly assessing water stress or drought conditions within a plant.

To solve problems related to Radio Frequency Identification, as well as to develop new technologies and applications with chipless RFID tags, this article describes the development of an innovative reader system based on Software-Defined Radios. Called SpuR, the system proposes a method of reading the spectral signature of RFID tags chipless, using general purpose hardware, reconfigurable by software, and operating in a wide frequency range without the need to change the reading equipment. This approach allows the accurate reading and identification of different types of chipless tags, using a classification procedure, by Euclidean distance, comparing them with a previously stored database.

Sensors for detecting wear particles in fluid lubricants have been widely studied owing to their ability to diagnose mechanical machine conditions and to help in preventing mechanical failures caused by wear particles or contamination particles. The proposed novelty sensor was fabricated using photolithography to make the complementary split ring resonator (CSSR) on PCB and it utilized neodymium magnets at the center of the CSRR structure to attract ferrous wear particles. The proposed sensor was tested, and we found that it is highly sensitive and could detect 50 ppm of ferrous wear particles larger than 10 μm dissolved in mineral white oil ISO VG 15. The sensor of this article has a low-cost and can be used in different situations to measure the ferrous wear particles while monitoring the real-time mechanical equipment wear, as it can be easily integrated into them. The sensor offers good accuracy, and is insensitive to fluid transparency and bubble formation, unlike other sensors for detection of wear particles. Therefore, the proposed novelty sensor of this work is in line with Industry 4.0, which requires many low-cost sensors for continuous monitoring to apply predictive maintenance techniques for extending the lifespan of infrastructures.

In this study are analyzed horn antennas to operating at X band (8 – 12 GHz) and manufactured by additive manufacturing method (AM). To construct the antennas using AM method was necessary made the structure with acrylonitrile butadiene styrene (ABS) thermoplastic using a 3D printer, and then coated the antennas with conductive surfaces. Were fabricated three antennas with different coated techniques: the first antenna with conductive silver paint, the second antenna using copper tape and the third antenna using copper plated. It is investigated the performances of these antennas in terms of the input reflection coefficient, gain, radiation pattern, weight and compared with the conventional aluminum horn antenna with same dimensions.

This work presents the design of a compact antenna using microstrip patch based on a fractal model for use in Internet-of-Things (IoT) wireless communication in sub-GHz bands. The proposed antenna was implemented on a low cost FR-4 substrate and work in the 433 MHz and 915 MHz or 868 MHz frequencies that are ISM bands used in the IoT networks. The suggested antenna has been manufactured and experimentally characterized, showing a good agreement with the expected simulated results.

This paper presents a design and simulation of a low noise amplifiers (LNA) with all passives elements embedded on low temperature co-fired ceramic (LTCC) substrate. Simulation results in ANSYS Designer and CST Studio Suite reveal that the proposed LNA has a flat-gain of 23.34 dB from 300 to 500 MHz, a noise figure below 0.73 dB and a compact size of 16.7 mm x 8.5 mm.

Este trabalho de iniciação científica tem por finalidade realizar estudo dos efeitos de acoplamento entre os ressonadores FSS, avaliar como afetam o comportamento da atenuação, o desempenho eletromagnético e fator de qualidade em diferentes geometrias HFSS aplicadas a RFID como geometria... Evento destinado a todos os alunos de graduação da UNICAMP que desenvolvem projetos de Iniciação Científica, com financiamento de alguma agência de fomento ou de maneira voluntária.