A transmitting coil with a tumbler structure is presented to improve lateral misalignment tolerance of a wireless power transfer (WPT) system with a planar receiver. The tumbler is made of an acrylic ball and soil. A planar spiral receiving coil wound by Litz wire is centered by Nd-Fe-B magnets. A spherical cap transmitting coil centered also by Nd-Fe-B magnets sticks on the inner surface of the acrylic ball. When lateral misalignment occurs, the transmitting and receiving coils can achieve self-align with the action of magnetic force, and thus the transfer efficiency is improved. A WPT system consisting of two coils with 6 cm outer radii resonated at 107 kHz is studied. A concise theoretical analysis based on circuit model is given first, and then experimental data are reported. The positive correlation between magnetic force and tracking range is given by comparison. Especially, when the transfer distance is 1.5 cm, the WPT system has a 75.5% peak efficiency and a 3.52 W load power at zero lateral misalignment and the tracking range is from 0 to 8.5 cm; In the tracking range the WPT system has a 70.0% average efficiency and the load power maintains over 94.7% of the peak load power. With the increase of transfer distance, the improvements of transfer efficiency and the tracking range both decrease gradually, and the efficiency loss within the tracking range also increases gradually.
In this paper, a dual-mode dual band bandpass filter using stubloaded stepped-impedance resonators is proposed. Two short stub-loaded resonators are combined together in parallel manner with a common deformation of T-shaped feed line in order to design and analyze two resonators separately. The filter has two passbands centered at 2.45 GHz and 5.33 GHz with the respective fractional bandwidths of 7.7% and 7.1%. Moreover, to the needs of miniaturization, the proposed filter has very compact sizes of 0.15λg × 0.09λ g , where the λ g is the guided wavelength at the center frequency of the first passband. The group delay responses of the filter meet the requirement of the wireless communication system.
In this study, a kind of strapped resonator is proposed to deal with high power wireless power transfer (WPT) in microwave regimes. In many specific applications, such as high power microwave wireless power transfer system (WPT), a coil resonator is not suitable due to the frequency limitations. The high cost of the high-permittivity dielectric resonators also limits their application. As a high Q resonator, the strapped resonator is often used in the anode structure of a magnetron. The field distribution of π and π + 1 modes allow the system to operate in dual-frequency mode. Numerical simulation and experimental validation show that with a certain distance, the system provides power transfer efficiency of more than 80% and 70% at 630 MHz and 970 MHz, respectively. Compared to the system based on dielectric resonators, the proposed system has higher power capacity. The leakage and radiation loss of the system is also discussed using numerical methods.
Based on the equivalent dielectric model of the periodic metal wire array, the analytical expression of time reversal EM wave in the metal wire array is derived using transmission line method. Then, the influence of metal wire radius, metal wire array period and the amount of layers on time reversal EM wave focusing property is discussed within the equivalent dielectric model. This structure can be used to focus time reversal EM wave in the far field, at the same time, it provides an engineering reference for time reversal technique.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.