Development of a borehole directional antenna at VHF

Technical Report · Thu Mar 01 04:00:00 EST 1984

DOI:https://doi.org/10.2172/7145810· OSTI ID:7145810

Chang, H T; Scott, L

The feasibility of constructing a directional VHF (30 MH/sub z/ to 300 MH/sub z/) antenna to physically fit into a small borehole is investigated. The study was carried out in a test chamber containing a 15 cm diameter borehole surrounded by sand which can be moistened with water or brine to adjust the dielectric constant and electrical conductivity. Electric field measurements were made for an eccentrically positioned monopole, a corner reflector and a two-element array for a number of possible configurations. Using an eccentric monopole, the best beamwidth obtained was 78/sup 0/ and the front-to-back ratio was 3.5 db. The front-to-back ratio was increased to 8.5 db when two element arrays were arranged in such a way as to provide the optimum radiation pattern. However, the best results were achieved using a corner reflector: 60/sup 0/ beamwidth and 13 db front-to-back ratio. It is concluded that a directional VHF antenna can be designed for downhole application.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 7145810
• Report Number(s): SAND-84-0254; ON: DE84010746
• Country of Publication: United States
• Language: English

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