Self-Capacitance of Single-Layer Inductors With Separation Between Conductor Turns

This letter presents the technique for estimating the self-capacitance of single-layer air-core solenoid inductors with separation between the insulated turns. In single-layer air-core inductors, the self-capacitance is due to the conductor turn-to-turn capacitances. The analytical framework to determine the turn-to-turn capacitances of single-layer air-core inductors with uniformly and nonuniformly separated conductor turns is established. The influence of the wire insulation coating is taken into consideration. A representative design example of a single-layer air-core inductor is presented and its self-capacitance and self-resonant frequency are predicted. The presented analytical approach was tested by experimental measurements on the designed inductor. The derived analytical expressions are useful for designing air-core inductors for high frequency (HF) and very HF applications such as electromagnetic interference/electromagnetic compatibility filters and radio and TV transmitters.