EEG is represented to referential derivation with ear lobe reference and bipolar derivations for quantitative interpretation. When the ear lobe was activated, referential derivation with ear lobe reference was contaminated by ear lobe artifacts. In this study, the focus and extension of EEG components were estimated based on the cross spectrum of bipolar derivation. A referential derivation was constructed by choosing the electrodes out of the focus and extension area to obtain the distribution of EEG components. The constructed referential derivation can avoid the artifacts of ear lobe activation for quantitative EEG interpretation.