pcb螺旋电感及线圈电感的计算，在低频RFID线圈天线中有着广泛的应用，经典频率125khz，13.56Mhz(pcb spiral inductors and coil inductance calculation of a wide range of applications in the low-frequency RFID coil antenna, the classical frequency 125khz, 13.56Mhz)