核磁共振技术在核矩的测量、物质结构分析以及计量标准等许多方面,已经得到广泛的应用.在这些应用当中,人们往在希望得到一个灵敏的核磁共振探头.在较大范围内可变频率的核磁共振探头通常采用边缘振荡线路[1-3].这种探头除了做核磁共振实验之外,特别适用于磁场的精密测量.最近 Nuclear magnetic resonance (NMR) has been widely used in many aspects, such as the measurement of the nuclear moment, the analysis of the material structure and the measurement standard, etc. In these applications, people are looking forward to obtaining a sensitive NMR probe. Within a large range of variable frequency Of the NMR probe is usually the edge of the oscillation circuit [1-3]. In addition to doing this kind of NMR experiments, the probe is particularly suitable for the precision measurement of the magnetic field. Recently