Evaluation of the Radiated Emission of a Printed Circuit Board Attached with Cables

An electronic product has to comply with a myriad of EMC requirements before it can be marketed globally. Radiated Emission is one of the EMC requirements which constantly poses a challenge to many circuit designer due to the ever increasing speed of PCB clocks. Consequently, in the product it is essential to investigate, identify, model and predict the PCB radiated emission before compliance test is performed for cost and time saving. In this paper, a simple double layer PCB board is fabricated to investigate the PCB radiated emission. Three PCB configurations are investigated for the level of emissions and to correlate with the common-mode currents. These configurations are PCB without attached cables, with one attached cable and with two attached cables. The radiated emission from each configuration is measured in a semi-anechoic chamber at open circuit and 50 ohm loads. It can be shown that the cables are the major sources of radiated emission due to the common-mode currents flowing through it.