High Quality Content by WIKIPEDIA articles! Resonant inductive coupling or electrodynamic induction is the near field wireless transmission of electrical energy between two coils that are tuned to resonate at the same frequency. The equipment to do this is sometimes called a resonant or resonance transformer. While many transformers employ resonance, this type has a high Q and is often air cored to avoid `iron` losses. The two coils may exist as a single piece of equipment or comprise two separate pieces of equipment.