Air Coil Inductors

Air Coil Inductors
Using Any Wire Gauges (Up to AWG #8)

CWS manufactures all types of air coils inductors, from round diameter wires in AWG #36 to AWG#8, and rectangular sizes of 72 mils x 182 mils and 95 mils x 182 mils. In many cases, the windings are done using 200 deg C class wire insulation for high temperature application.

Single layer air coil windings formula and the Q factor can be downloaded from the following .PDF file

CALCULATION OF AIR COIL INDUCTORS INDUCTANCE, NUMBER OF TURNS AND Q

This formula in the above .PDF file is most accurate when the coil length is greater than 0.67 of the radius and the frequency is less than 10 Mhz. As the frequency goes above 10 Mhz, parasitic capacitance causes the formula to be less accurate.

Q changes drastically as a function of frequency. At lower frequency, Q is good as only the DC resistance has an effect. As the frequency increase, Q will increase up to a point when the skin effects and the distributed capacitance begin to dominate. Then, Q will decrease till it reached zero at self resonance frequency.

Q can be increase by decreasing the windings resistance ( using heavy gauge wires), spread the windings to lower distributed capacitance and using a iron or ferrite core to wind over to increase the inductance.

An Air Coil Winding chart can be downloaded from the .PDF file below. This chart shows the air coil inductances with various number of turns, diameter and length.

AIR COIL WINDING CHART

See below for examples of custom coil windings. Please call CWS for your requirements - high quality work at a reasonable tooling cost and low cost volume production.