Abstract: An ambient electromagnetic energy collector has a magnetic core of high permeability ferromagnetic material wrapped in an inductor coil for coupling primarily to a magnetic field component of a propagating transverse electromagnetic (TEM) wave. For coupling to electromagnetic waves of a wide range of frequencies and magnitudes, the collector is coupled to a multi-phase transformer connected to a multi-phase diode voltage multiplier to provide a current source output to an associated energy storage device. An output controller supplies output power as needed to the associated energy-using device. Preferred types of ferromagnetic materials include nickel-iron alloys with a small percentage of silicon, molybdenum, or copper. It may be combined with other types of ambient energy collectors, such as acoustic/vibration, thermoelectric, and photovoltaic collectors, in a multi-source device provided with a collector interface for converting the different outputs for storage in a common energy storage device.