A receiver coil is a component that picks up or receives signals or energy in the form of electromagnetic waves. It is commonly found in technologies like wireless charging systems or inductive coupling communication systems. Full definition
With inductive charging technology, the charge passes between a transmitter and receiver coil placed closely together, usually only separated by the outer casing of the two devices (< 7 mm). (wirelesspowerconsortium.com)
You'll need to cannibalize a wireless conduction receiver coil from another phone, case, or adapter — a charger won't do. (howtogeek.com)
The base station regularly sends a signal out, and when a resonance or capacity change is found because a compatible receiver coil is close enough, the signal is modulated and inductive charging begins. (androidcentral.com)