A Simple Method of Estimating the Radiated Emission From a Cable Attached to a Mobile Device

When a mobile device is connected to cables for charging power or transmitting data, the radiated emission from the attached cables, which are typically effective electromagnetic interference (EMI) antennae at certain frequencies, can cause serious system-level EMI problems. The measurement of system-level radiation during compliance and precompliance tests is not only a time-consuming task, but also requires expensive facilities such as a semianechoic chamber. This paper proposes a simple method of predicting far-field radiation from cables attached to mobile devices at the early stage of the design and development phase without using an EMI chamber. The method combines radiation characterization of a simple box-source-cable geometry using full-wave simulations with the measurement of the real common-mode current flowing through the cable. The proposed method was applied to mobile phones to estimate the far-field radiated emissions, which were compared with the measurement results. The accuracy of the predicted results was evaluated using the feature selective validation technique, indicating good agreement and correlation.