This paper discusses the architecture of an adaptive transmitting microstrip array that allows highly flexible beamsteering and beamshaping. The antenna array is digitally controlled by a field programmable gate array (FPGA) board. The power and phase of the excitation signals delivered to the array elements are optimized using an algorithm based on particle swarm optimization (PSO), which includes all electromagnetic effects such as mutual coupling and installed performance. Further, the efficiency of the proposed approach is validated by synthesizing various beam patterns, including side lobe level control and beam shaping for cosecant squared and isoflux contours. Very good agreement between simulated and measured results is thereby observed. The paper also addresses implementation aspects that are not reported in detail in literature, such as the compensation for the faulty antennas or transmitting channels, as well as the calibration procedure applied for the experimental validation of the proposed architecture.INDEX TERMS Active element pattern, beamforming, mutual coupling, optimization methods, particle swarm optimization, antenna measurement.
The difficulty of detecting non-technical losses by electric energy concessionaires has been a great and constant challenge. Inspecting consumer units located in rural areas demands excessive time and expenses on the part of concessionaires, due to the distance from urban centers and the difficulty of access, without there being a previous technical indication of the occurrence of Non-Technical Losses. This work aims to present a methodology for estimating electricity consumption for rice crops that use flood irrigation, in the city of Uruguaiana, Rio Grande do Sul, implementing classification using artificial intelligence techniques (clustering, kmeans and random forest), and with the help of indicators, report cases of possible non-technical losses.Resumo: A dificuldade de detecção de perdas não técnicas por parte das concessionárias de energia elétrica, tem se mostrado um grande e constante desafio. Inspecionar unidades consumidoras localizadas em zonas rurais, demanda tempo e gastos excessivos por parte das concessionárias, em função da distância dos centros urbanos e da dificuldade de acesso, sem que haja um prévio indicativo técnico de ocorrência de PNT (Perdas Não Técnicas). Este trabalho tem o objetivo de apresentar uma metodologia de estimativa do consumo de energia elétrica para lavouras de arroz que utilizam irrigação por inundação, no município de Uruguaiana, Rio Grande do Sul, implementar classificação dos mesmos por meio de técnicas de inteligência artificial (clustering, k-means e random forest), e com auxilio de indicadores, informar casos de possível PNT.
This article describes the design of a dual-wideband annular slot antenna. The proposed structure has been optimized to operate in the typical bands of mobile communication systems (0.824-0.960 GHz and 1.710-2.165 GHz). The antenna is designed considering two independent ports with high isolation, one for each operation band, yielding an antenna that exhibits diplexing feature. The final measured results show that the designed antenna exhibits stable radiation pattern over the frequency in both desired bands. The designed antenna has been used to compose a dual-band linear array. Simulation results indicate good performance in both bands for mobile communication systems. Index Terms-dual-band antenna arrays, multi-band antennas, printed antennas, slot antennas. I. INTRODUCTION Dual-band antennas find applications in several areas, such as in mobile communications and satellite navigation systems. The antenna configuration to achieve multiband behavior can be in stacked or coplanar form [1]. Stacked patches have been used in several antenna designs [2]-[5] and have the advantage of allowing broadband or dual-band behavior. The drawback is the need of a multilayer structure for the assembly, which makes the design and fabrication more complex, hence increasing the fabrication costs. Dual-band operation can be achieved as well with coplanar microstrip structures, whereby a canonical patch geometry is generally modified by the inclusion of slots [6]-[12] or by employing fractal-based geometries [13], [14]. Mobile communication is an example of a system based on multi-band operation. A significant number of printed antennas for radio-base stations have been developed and are reported in the literature. The antenna proposed in [15] is a compact dual-feed dual-polarized patch antenna with bands centered at 0.9 GHz and 1.8 GHz. The antenna has a stacked arrangement and its integration into an array is difficult due to the complex feeding system necessary for dual-band operation. Similarly, the antennas presented in [16]-[18] have also a stacked arrangement. They exhibit good performance, but are not well-suited for low-cost solutions. Alternatively to antennas implemented in microstrip configuration, printed slot antennas have been studied and can be assumed as a solution with lower cost compared to the stacked configuration. In [19], a dual-band annular slot antenna has been studied. It exhibits bidirectional pattern and narrow-band behavior, hence it is not
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