The performance of the Vertical Cavity Surface Emitting Laser (VCSEL) for hybrid optical links SMF/FSO based on different data rates and MIMO configuration techniques was obtained using OptiSystemTM which is close to the results of the experimental system. The developed system was tested with various transmission distances: 20, 30, 40, and 50 km, and in the existence of many configuration kinds and modulations. In addition to that the hybrid system was estimated with different weather cases: clear, rain, and snow. The results state that the performance of the OOK-NRZ system reveals better performance than OOK-RZ system under the same conditions. Also, the performance of the free space link is better than the fiber link formost of the link ranges considered and configurations. For OOK-NRZ of the fiber link, it was found that the MIMO 8×8 technique has better system performance than other configurations, and the Q-factor = 11.39 and BER = 5.4×10-30 for a length of 50 Km while for the FSO link, it was found that MIMO 8×8 indicates a high performance for Q-factor = 12.7 and BER = 1.8×10-37. The maximum FSO link distances under different weather conditions and coupling ratios were found. For BER≤10−9, in NRZ format for SMF 50 km utilizing MISO8×1 technology in clear weather for 10 Gbps, 15 Gbps, and 20 Gbps for FSO links, the maximum accessible lengths are 0.6 Km, 0.51 Km, and 0.43 Km, respectively. The process is expanded to include snow conditions for data rates of 10 Gbps, 15 Gbps, and 20 Gbps for FSO links with lengths of 0.4 Km, 0.3 Km, and 0.26 Km, respectively.
This paper presents a novel design of Compact Notched Wide Band Antenna that has dual notches in the band of Wireless Local Area Network (5.15 GHz-5.825 GHz) and X-band Satellite Communication (8 GHz-12 GHz). The proposed antenna has a defective ground structure (DGS) to operate the antenna for wide band applications. Notch bands are achieved by inserting slots on the radiating patch and feed line. A horizontal S-shaped slot on patch is responsible for the notch in the band of wireless local area network, and an inverted U slot is used in feed line to get a notch in the band of Satellite Communication. The proposed antenna is fabricated using FR4 substrate of size 26 x 26 x 1.6 mm3 and tested using Vector Network Analyzer MS2037C. Although the measured results are slightly changed in comparison with simulated, they agree reasonably well. The measured result also reveals that the prototype antenna is in compact size and resonated from 4.24 GHz-12.59 GHz with two notch bands centered at 5.8 GHz and 10.3 GHz.
In order to reduce the cogging torque and improve the back electromotive force (EMF) performance of the motor, a three-phase permanent magnet (PM) synchronous motor with magnetic pole eccentricity and slotting design is proposed in this paper. Firstly, the analytical expression for the cogging torque of the motor is derived based on the energy method, and the factors influencing cogging torque are analyzed. Subsequently, taking the cogging torque and the amplitude of the back EMF as the optimization objectives, the response surface method (RSM) and multi-objective genetic algorithm (MOGA) are combined to obtain the optimal values for the eccentricity distance of the PMs, slotting radius, and slot position. Finally, a finite element model is established for simulation comparison. The results show that compared with the traditional model, the optimized model effectively reduces the cogging torque while slightly sacrificing the back-EMF amplitude, and improves the sine degree of the no-load back-EMF.
The rapid advancement of communication technology has led to an increase in electromagnetic interference (EMI), or electromagnetic (EM) pollution. This is a cause for concern, as EMI can disrupt communication services, damage electronic equipment, and pose health risks. Regulatory bodies are working to develop standards for the safe use of wireless devices, but the problem of EMI is likely to continue to grow as the number of Internet of Thing (IoT) devices continues to increase. To address this issue, this study investigated the effectiveness of carbon-coated cobalt ferrite nanoparticles as a potential material for electromagnetic shielding. The synthesis of cobalt ferrite (CoFe2O4) nanoparticles was successfully achieved using the co-precipitation method. Subsequently, a carbon coating was applied to the nanoparticles through a hydrothermal process using a 200 mL autoclave made of teflon-lined stainless steel. This process was carried out at a temperature of 180˚C for a duration of 12 hours, with a heating rate of 8˚C per minute. This study examined both uncoated and carbon-coated CoFe2O4 nanoparticles at various ratios of glucose to CoFe2O4 (1:1, 2:1, and 3:1) using techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and higher resolution transmission electron microscopy (HRTEM) analysis. The XRD analysis revealed distinct and well-defined peaks corresponding to CoFe2O4, indicating the successful synthesis of the nanoparticles. The crystallite size of the uncoated CoFe2O4 nanoparticles was measured to be 11.47 nm, while for the carbon-coated CoFe2O4, the average crystallite size was determined to be 14.15 nm through XRD analysis. The results obtained from the FTIR analysis were consistent with previous reports and confirmed the formation of spinel CoFe2O4 nanoparticles, as suggested by published data. The morphological and structural properties of the prepared samples were further characterized using FESEM and HRTEM analysis, which demonstrated uniformity in both particle size distribution and morphology. Overall, the research findings indicated that the structure and properties of CoFe2O4 nanoparticles were significantly influenced by the carbon coating process. Notably, the optimum ratio of carbon to CoFe2O4 was found to be 2:1, which resulted in the highest carbon thickness. The electromagnetic properties of the samples were evaluated using a vector network analyzer (VNA) and measured S-parameters in the frequency range of 8.2 to 12.4 GHz, known as the x-band region, suitable for radar applications. The sample with a carbon ratio of 2:1 exhibited the highest total shielding effectiveness (SE) of -17 dB at approximately 10 GHz. As a conclusion, the carbon-coated CoFe2O4 nanoparticles showed promising potential as an effective material for shielding against electromagnetic wave pollution, particularly when the carbon coating and filler composition reached an optimal point. Additionally, the shielding effectiveness performance of the sample could be further enhanced by incorporating a conductive polymer as an auxiliary material.