Study on characteristics of resonant frequency of wireless power transmission based on PCB coil

With the development of science and technology, the application of implantable biomedical electronic devices which play an important role in biological research and medical diagnostics becomes increasingly popular[1]. Nowadays wireless energy transfer is one of the most popular research field, it can penetrate the skin to supply electric energy to implantable biomedical electronic devices steady, so it is more and more used in the biomedical field. The main constraints restrict for wireless charging technology to realize miniaturization and portability is that the volume of the transmission coil is difficult to reduce. The production process of the PCB(printed circuit board) coil is simple, and its width, thickness, line spacing and other parameters can be precisely controlled, mass production of PCB coils have same parameters, meanwhile, PCB coil is easy to integrate with external circuit. In order to improve the efficiency of the radio transmission system fundamentally, by comparing the test methods, we study the PCB coil width and wire spacing, analyze the impact of these two factors on the resonant frequency. And we reach the following conclusion: The resonant frequency is negative correlated to the number of turns when the wire spacing is fixed. When the number of turns is constant, the wire spacing of the coil and the resonant frequency are positively correlated.