A Unified Approach to the Calculation of Self- and Mutual-Inductance for Coaxial Coils in Air

This paper extends a previous formula for the mutual inductance between single-turn coils to include all coils in air with rectangular cross sections, without any restrictions on the dimensions (including overlapping coils). The formula is compared with a wide spectrum of examples from the literature and agreement is excellent in every case. Experimental results are presented to validate the formula for both solenoid and disk coils. The formula is relevant to coreless transformers, inductive coupling, wireless power transfer, and leakage inductance in resonant converters.