EMI Optimization of a Wi-Fi-Enabled Relay Module for Smart Home Application Using ESP8266/N76E003

Modern smart home devices integrate wireless communication and power switching functions on compact printed circuit boards (PCBs), making them vulnerable to electromagnetic interference (EMI). This work investigates the optimization of a Wi-Fi-enabled relay module based on the ESP8266 and N76E003 microcontroller. The approach combines finite element modeling in Ansys SIwave with PCB-level design countermeasures. Key optimizations included improved decoupling, via stitching, and stack-up refinement. Simulation and validation results show significant reductions in power distribution network resonances and transient emissions, ensuring compliance with CISPR Class B. The study demonstrates that systematic PCB design improvements effectively enhance the electromagnetic compatibility of IoT modules.