Does power line impedance mismatch in power line carrier PLC affect EMC?

Impedance mismatch in power line carrier PLCs can lead to increased signal reflection and radiation, impacting EMC performance. Impedance mismatch increases the VSWR, preventing complete signal power transmission and causing ringing and radiation due to energy reflection. The solution is to use an impedance matching network: a matching resistor (e.g., 50Ω) is connected in series at the carrier coupling point, or a transformer is used for impedance transformation. The characteristic impedance of the power line (typically 50-600Ω) is calculated through simulation, and the matching network is designed to ensure a return loss greater than 14dB. In actual testing, the S11 parameter is measured using a network analyzer and should be less than -14dB in the carrier frequency band. Impedance matching can reduce radiated emissions by 10dB and conducted interference by 6dB, improving system EMC performance.