When selecting and using inductors, we must first think of the inspection and measurement of the coil, and then judge the quality of the coil. The accurate detection of inductance and quality factor Q of inductors generally requires special instruments, and the test method is more complicated. In actual work, before testing with the instrument, the on-off check of the coil and the size of the Q value can be performed first.
    
    1. According to the working frequency, select the wire of the coil

    When operating at low frequency voltage, inductors are generally made of enameled wire with insulated conductors. In circuits with operating frequencies higher than tens of thousands of Hertz or less than 2MHZ, multi-strand insulated wires are used to wind the coil, which can effectively increase the surface area of the conductor, thus overcoming the influence of skin effect, so that the Q value is 30% ~ 50% higher than that of the coil wound by a single wire with the same interface agent. The inductor is wound with a single thick conductor wire, and the diameter of the wire is generally 0.3~1.5mm. The use of interwound inductors, commonly wound with silver-plated copper wire, to reduce additional losses, its effect is not as good as a single wire.
    
    2. Select high-quality coil skeleton to reduce dielectric loss.

    At higher frequencies, high frequency dielectric materials should be selected, and interwound winding method should be used.
 
    3. Choose a reasonable coil size to reduce the loss.
 
    4. Reasonably select the diameter of the shield.

    Too small shield will increase the loss of the coil, reduce the Q value, too large will also increase the volume, so we must choose a reasonable diameter size when selecting.

    5. The use of magnetic core can significantly reduce the number of coils.

    Reducing the magnetic core not only reduces the number of turns of the coil and reduces the volume, but also helps to improve the resistance value of the coil and improve the Q value.

    6. Select a larger coil diameter to reduce coil loss.

    The diameter of the coil can be selected larger, which is conducive to increasing the volume and reducing the loss of the coil, the general receiver, the diameter of the single coil can be selected 12-30mm, the multi-layer coil is selected 6-13mm, and the maximum volume should not exceed 20-25mm.

    7. Reduce the distributed capacitance of the wound coil.

    Try to use a frameless winding coil, which can reduce the distributed capacitance by 15%-20%. For multilayer circuit coils, the smaller the diameter and the smaller the winding length, the smaller the distributed capacitance. Therefore, the winding length should be reduced when winding.