In this article, we propose a deep neural network (DNN)- for the radiation pattern synthesis of an antenna. The DNN utilizes the radiation patterns as inputs and the amplitude and phase of the antenna elements as outputs. Consequently, the radiation patterns of the array antenna can be easily obtained from the outputs of the trained DNN, which are amplitude and phase of the antenna elements. However, it is difficult to determine the amplitude and phase of each antenna element from the desired pattern in an environment where inter-element coupling exists. For this purpose, 6,859 radiation pattern samples for a $4 \times 1$ array patch antenna were generated by changing the phases of the antenna elements, and those patterns were leveraged to train the proposed DNN with low complexity. The radiation patterns of the ideal square and triangular array shapes, which are practically infeasible to implement, were used as inputs to the DNN. It was confirmed that the radiation pattern generated from the output signals of the DNN was very similar to the input radiation pattern.

We propose a deep neural network (DNN) to determine the matching circuit parameters for antenna impedance matching. The DNN determines the element values of the matching circuit without requiring a mathematical description of matching methods, and it approximates feasible solutions even for unimplementable inputs. For matching, the magnitude and phase of impedance should be known in general. In contrast, the element values of the matching circuit can be determined only using the impedance magnitude using the proposed DNN. A gamma-matching circuit consisting of a series capacitor and a parallel capacitor was applied to a conventional inverted-F antenna for impedance matching. For learning, the magnitude of input impedance S₁₁ of the antenna was extracted according to the element values of the matching circuit. A total of 377 training samples and 66 validation samples were obtained. The DNN was then constructed considering the magnitude of impedance S₁₁ as the input and the element values of the matching circuit as the output. During training, the loss converged as the number of epochs increased. In addition, the desired matching values for unlearned square and triangular waves were obtained during testing.

Conventional contact-based train power transfer systems have high maintenance costs and safety issues and cause noise and additional aerodynamic drag. Instead of the conventional system, a loosely coupled online wireless power transfer (WPT) system for a train is proposed in this paper. The operating frequency of the proposed design is 60 kHz to ensure a low flux density and a high-efficiency system with a large air gap. In addition, a new transmitter track and pick-up geometry for 60 kHz operation are designed using finite element analysis (FEA). The proposed design is evaluated theoretically and experimentally. By using the simulated results, a new 180 kW, 15 m test-bed for a tram is constructed. The total power transfer efficiency is greater than 85% at the rated output power, and the loss distribution in the system is identified. Electromagnetic field (EMF) radiation and the voltage induction at the rail are measured for safety evaluation. The measured EMF satisfied international guidelines.

In this study, we present a 1 MW-class wireless power transfer (WPT) system and test the operational data by applying it to an actual light-rail system for over 40,000 km. The data demonstrate that there are no reliability issues when applying the WPT system to light-rail systems. The power capacity of the WPT system was designed based on actual operating scenarios of light-rail systems. We propose a suitable transmitter and pick-up structure for real vehicle operation, and analyze the input/output voltages, current, power, and efficiency of the WPT system during operation. The applied WPT system achieved a maximum efficiency of 89%, which is considered high. The one-year operation data are expected to provide significant assistance in the future commercialization of wireless charging applications for railways.

The high-power wireless power transfer (WPT) system in railways does not require physical contact to transfer electrical power, is electrically safe, and reduces maintenance costs from wear and tear. However, a high-power system generates a strong magnetic field that can result in problems of electromagnetic field (EMF) exposure and electromagnetic interference (EMI). In this study, EMF and EMI were measured at various positions under in-motion environment conditions for a 1-MW WPT light rail transit system. The measured maximum EMF was 2.41 μT, which is lower than the international guideline of 6.25 μT for the various locations with a potential presence of passengers. The measured EMI also satisfied international standards in the frequency range of 150 kHz–1 GHz.

In this letter, the shape of metal plate is proposed in a way to maximize the transmission efficiency when a metal plate is placed between transmitter and receiver in wireless power transfer system. In case of the metal plate having slots, electromagnetic waves can penetrate into the metal plate if the direction of the slots is same as the polarization direction of the magnetic field. Unit cell simulation is performed to investigate the relation between the transmission coefficient and the slot width. As a result, electromagnetic waves demonstrated it can penetrate through a very small slot of 0.1 mm. Based on the simulation results, a metal plate with slots in same direction as the polarization of magnetic field generated by the receiving coil is designed. The efficiency of the wireless power transfer system is increased in line with the increase in slot width of the metal plate. Two types of slot width 0.1 mm and 1 mm are fabricated, and the efficiencies are measured. As a result, the efficiencies are 71% at 6.78 MHz and 81%, respectively.