Techniques for focusing an energy radiated by a wireless power transmitting unit are described. An example power transmitting unit includes a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area. The power transmitting unit also includes a power generating circuitry to deliver a current to the transmit coil to generate the magnetic field. The power transmitting unit also includes a patch array disposed in parallel with the transmit coil to reduce a strength of the magnetic field at frequencies outside of the operating frequency during operation of the power transmitting unit.