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...http://www.google.com.tw/patents/US6714153?utm_source=gb-gplus-share專利 US6714153 - Device for electromagnetic detection of geological properties in a well
