Borehole Radar Evaluation Program: Antenna designs for optimal directionality

Technical Report · Wed May 01 04:00:00 EDT 1991

OSTI ID:5721629

Castle, J G; Morris, H E

The thrust of this progress report deals with the significant advances we have made in the past few months toward optimal radiating efficiency and optimal directionality from antenna arrays that fit inside a 5.5 in.-OD tool. The reasons spawning this development effort on antennas are the many uses for underground radar systems that can be built around such high-performance antennas. Targets of interest include large man-made voids, natural voids in strata, fractures zones in hard rock, edges and internal faults in salts domes and glaciers, etc. Recent progress includes observation of the radiation patterns of several dipole arrays which we designed to fit within a 5.5-inch OD borehole tool and to radiate efficiently at wavelengths in the band from 0.4 meter to 2 meters with optimal directionality. Front-to-back ratios of 15 dB are consistently observed in the horizontal plane of these arrays. These antennas are observed to radiate with high efficiencies, less than 1 dB loss, into air at 1.3 meter wavelength. 18 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5721629
• Report Number(s): SAND-90-1050; ON: DE91014322
• Country of Publication: United States
• Language: English

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ANTENNAS
BOREHOLES
CAVITIES
DESIGN
DIPOLES
ELECTRICAL EQUIPMENT
EQUIPMENT
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
MAPPING
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RANGE FINDERS
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