A classification of the electromagnetic coil inside the accessory based on its measured field distribution. A Pancake Coil produces a center-dominant field with peak strength at the center and rapid falloff outward. A Donut Coil produces a ring-dominant field with peak strength in a ring around the center and a weaker center. A Loop Coil concentrates energy along the wire path. Coil type is detected automatically from the scan data by comparing ring zone field strength to center field strength. For multi-coil mats (rect shape), single-coil-type detection doesn't apply. Instead the report uses Coil Count, Coil Layout, and Coverage Uniformity to describe the mat's collective behavior.
How the wire is wound sets where the field is strongest. Each profile is a real measured cross-section. A pancake coil is a tight flat spiral, so its field stays strong across a broad center. A donut coil leaves a hole in the middle, so its field peaks in a ring and dips at the center. A loop coil is one large turn, so its field peaks over the wire ring and eases off toward the middle and the rim. Copper dots are the wire seen end-on.
