The invention is a well radar for detecting, by electromagnetic wave reflection, resistivity horizons in production zones in oil wells. Transmitter and receiver antennas are combined in a tubing string antenna module. Two dipole transmitter antenna are positioned in a first position on either side of the tubing string antenna module. A first directionally sensitive group of four dipole receiver antennas is positioned in a second positioned so that the receiver antennas have even angular separation. Likewise, a second directionally sensitive group of four dipole receiver antennas is positioned in a third position opposite the first directionally sensitive group.