Transmitter assembly and methods for making and using the same

Transmitter assemblies and methods for making and using the same. The transmitter assembly can be used for magnetic power transfer. The transmitter assembly can include a primary inductor configured to produce an electromagnetic field. The transmitter assembly can include a back shield unit including a primary back shield that has a first surface proximal to the primary inductor and a second surface opposite to the first surface. The primary back shield is at least partially made of a ferromagnetic material and has a property that is non-uniformly distributed from a center region of the primary back shield to an outer perimeter region of the primary back shield. The property includes a thickness, a magnetic property, or a combination thereof. When used in wireless charging, the transmitter assembly results in improved coupling factor, misalignment tolerance, efficiency, magnetic emissions and z-height coupling distance of a magnetic power transfer profile.