A simple method for predicting common-mode radiation from a cable attached to a conducting enclosure

Common-mode (CM) radiation from a cable attached to a conducting enclosure is typically a dipole-type antenna structure, in which an equivalent noise voltage source located at the connector excites the attached cable against the enclosure to produce radiated emissions. A simple method for predicting the CM radiation from the cable/enclosure structure was proposed in this paper. The method combines an equivalent dipole approximation with sinusoidal current distribution and CM current measurement at a specified location on the cable. The predicted resonance frequencies and CM radiation levels were validated with engineering accuracy, i.e., within 30 MHz and 6 dB, respectively, from the measured and FDTD-modeled results in the frequencies above 130 MHz