How to design an EMC power line coupler for a power line carrier PLC?

The EMC design of power line couplers for power line carrier PLCs must balance signal coupling efficiency and electromagnetic compatibility performance. A high-frequency transformer coupling method should be used, with an electrostatic shielding layer between the primary and secondary windings, wrapped with copper foil or conductive cloth and grounded at one end. High-permeability ferrite core material such as PC40 should be selected, and the operating frequency should cover the carrier band. At the coupler input, a common-mode inductor CMZ2012A-900T is connected in series, and a safety Y capacitor (2.2nF/250VAC) is connected in parallel to suppress common-mode noise. For differential-mode interference, an LC filter network is deployed before and after the coupling point, using a power inductor PWR6045R6R8M0T and a CBB capacitor. The coupler housing uses a metal shield and multiple grounding points. In the PCB layout, the coupled signal lines are kept away from the power lines, and a microstrip line design is used to control the characteristic impedance, thereby ensuring coupling efficiency while meeting EMC requirements.