Electromagnetic coil for an electromagnetic air-core coil or a receiver antenna consists of a compact disk/DVD with a spiral-shaped notching/groove on an aluminum/gold/silver layer.

摘要

A coil consists of a compact disk (CD)/DVD disk (1) with spiral/multi-circular notching/grooving on an aluminum/silver/gold coating (2) insulated electrically. Only two windings/grooves are needed as a radio antenna (3), or spiral grooves can be very long and represent a coil (4) with many windings. A thin needle can cut grooves (5) in the disk, or a CD burner can cut a type of groove in the CD.