Source reconstruction methods have many applications such as antenna diagnosis, calculating far-field radiated emissions, and identifying incompatible sources on integrated circuits or printed circuit boards. In this paper, the Gerchberg-Saxton algorithm is used to retrieve the phase of the transverse magnetic near-field data measured on two parallel plates above the equipment under test (EUT). Then, the method of moments using roof-top basis functions is applied to reconstruct the horizontal electric current densities for the EUT. The proposed method is validated by comparing its results to full-wave simulations obtained using the CST-MWS software.