Any oscillating electric current transmits magnetic waves of a certain strength. Certain oscillations at particular frequencies represent radio waves. At lower

Any oscillating electric current transmits magnetic waves of a certain strength. Certain oscillations at particular frequencies represent radio waves. At lower frequencies, one might merely act directly upon the magnetic transducers of a poorly-shielded audio speaker, creating sounds at volumes and within ranges audible to humans. Any segment of electric wire, carrying a current that can change direction, might be used to this effect. Stronger electrical activity over a bigger, better wire has higher chance of sending a signal that can be detected.