A rarely used reconnaissance resistivity method in which an array of three inline electrodes emplaced along the traverse line forms two consecutive grounded electric dipoles, with the central electrode in common. Signals from the two dipoles are filtered about a band of high geomagnetic activity (e.g., periods of the order of 20 s) to yield amplitude ratio and phase difference. The array is leap-frogged along the survey line to obtain continuous relative electric-field intensity ratios. When successively multiplied together, the ratios yield a relative amplitude profile of the component of the electric field in the traverse line direction. Exploration depth varies inversely with frequency and usually two or more frequencies are recorded and analyzed. Also known as inline tellurics or E-field-ratio tellurics. See Beyer (1977).