Invention:
The system uses orthogonal antennas and rotation of the beam about its axis to preserve the primary coupling while changing the target coupling. The beam may be either vertical or horizontal. The prototype system currently has a dynamic range of 134 dB, with an expected increase to over 200 dB when a TX moment comparable to that of current commercial systems is used. With the larger TX moment, similar to that of current commercial systems, the ATAC system should be able to detect a standard 2" pipe target at a depth of 9m, i.e. 6X deeper than current systems. When paired with the related procedure for separating target responses from residual errors due to the background earth, this extraordinarily high sensitivity system is applicable to practical exploration problems.
Background:
A major limitation of existing subsurface sensing technology is sensor drift during the course of measurements. For example, commercial instruments can show drift rates of several hundred ppm over typical survey times. To address this problem, the Laboratory for Advanced Subsurface Imaging and the Department of Electrical and Computer Engineering developed Alternating Target Antenna Coupling (ATAC) for making very high-sensitivity measurements with greatly reduced drift.
Applications:
- Nondestructive testing
- Medical diagnostic imaging
- Security monitoring though walls and foliage
- Geophysical exploration
Advantages:
- Higher sensitivity, allowing detection of smaller and deeper targets
- Reduced drift (< 1 ppm), allowing stable scans over longer times
Status: issued U.S. patents #7,994,963 and #RE47,622
