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Method for locating underground anomalies by diffraction of electromagnetic waves passing between spaced boreholes

Patent ·
OSTI ID:863385
 [1];  [1];  [2];  [1]
  1. Livermore, CA
  2. Alamo, CA
+ Show Author Affiliations
Underground anomalies or discontinuities, such as holes, tunnels, and caverns, are located by lowering an electromagnetic signal transmitting antenna down one borehole and a receiving antenna down another, the ground to be surveyed for anomalies being situated between the boreholes. Electronic transmitting and receiving equipment associated with the antennas is activated and the antennas are lowered in unison at the same rate down their respective boreholes a plurality of times, each time with the receiving antenna at a different level with respect to the transmitting antenna. The transmitted electromagnetic waves diffract at each edge of an anomaly. This causes minimal signal reception at the receiving antenna. Triangulation of the straight lines between the antennas for the depths at which the signal minimums are detected precisely locates the anomaly. Alternatively, phase shifts of the transmitted waves may be detected to locate an anomaly, the phase shift being distinctive for the waves directed at the anomaly.
Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
DOE Contract Number:
W-7405-ENG-48
Assignee:
United States of America as represented by United States (Washington, DC)
Patent Number(s):
US 4161687
OSTI ID:
863385
Country of Publication:
United States
Language:
English

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