inductance The inductance L represents the inherent characteristics of the coil itself and is independent of the current. Except for special inductance coils (color code inductors), the inductance quantity is not usually marked on the coils but by a specific name. impedance The size of inductance coil to the ac current blocking effect is called inductive reactance XL, the unit is ohm. The relation between it and inductance L and ac frequency f is XL=2πfL The quality factor Quality factor Q is a physical quantity representing coil quality,Q is the ratio of inductive reactance XL to its equivalent resistance, that is,Q =XL/R. The higher the Q value of the coil, the aller the loss of the loop. The Q value of the coil is related to the DC resistance of the wire, the dielectric loss of the skeleton, the loss caused by the shield or iron core, and the influence of the skin effect of high frequency. Coil Q values are usually tens to hundreds. Distributed capacitance The capacitance between turns of the coil, between the coil and the shield, and between the coil and the base plate is called distributed capacitance. The existence of distributed capacitance reduces the Q value of the coil and deteriorates its stability, so the aller the distributed capacitance of the coil, the better.