The mechanism of a universal serial bus 3.0 connector caused radio frequency interference (RFI) to a nearby antenna is studied. The connector radiation is modeled by an equivalent stripline-fed slot antenna, based on the analysis of the common mode current path on the connector structure. With the proposed connector model, the original connector radiation source can be replaced by an equivalent magnetic dipole source, which is directly correlated with the physical quantity on the connector. Applying reciprocity theorem, the equivalent dipole source can be applied to predict the coupled noise power to the antenna. The proposed connector radiation mechanism and model are validated through full-wave simulation and measurement. The application of the magnetic dipole source for RFI estimation is demonstrated in a real laptop system.