This letter introduces two concentric open-loop spiral resonators (OLSRs) that are used to improve magnetic field for nonradiative wireless power transfer (WPT) systems. OLSRs are fed through metal-insulator-metal (MIM) capacitive coupling using a 50-Ω microstrip transmission line. First, a single OLSR is designed and implemented for WPT, then two OLSRs are used instead of a single OLSR to emphasize the surface current on the spiral resonators. Therefore, it helps to intensify the electromagnetic field in order to get a high transmission distance or higher efficiency. The proposed WPT system operates at 438.5 MHz with a measured power transfer efficiency (PTE) of 70.8% at a transmission distance of 31 mm and a design area of 576 mm 2 . An equivalent circuit of the proposed WPT system is presented as a heuristic approach to show the electrical behavior of the WPT system.

中文翻译：

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使用两个同心开环螺旋谐振器改善近场 WPT 系统的磁场


这封信介绍了两个同心开环螺旋谐振器 (OLSR)，它们用于改善非辐射无线电力传输 (WPT) 系统的磁场。 OLSR 使用 50Ω 微带传输线通过金属-绝缘体-金属 (MIM) 电容耦合进行馈电。首先，为WPT设计并实现了单个OLSR，然后使用两个OLSR代替单个OLSR来强调螺旋谐振器上的表面电流。因此，它有助于增强电磁场以获得较长的传输距离或更高的效率。所提出的WPT系统工作频率为438.5 MHz，在传输距离为31 mm、设计面积为576 mm 2 时测得的功率传输效率（PTE）为70.8%。所提出的 WPT 系统的等效电路作为启发式方法提出，以显示 WPT 系统的电气行为。