A novel directional borehole radar system using optical electric field sensors

Motoyuki Sato, Takuya Takayama

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

A directional borehole radar system using an array antenna connected to passive optical electric field sensors was developed and evaluated by laboratory and field experiments. This system uses a single dipole antenna for a transmitter and a four-dipole element circular array for a receiver. The received signals are transmitted through optical fibers from optical electric field sensors. The receiver array measures the phase differences between four dipole antennas and estimates the azimuth direction of the incoming reflection wave. The accuracy of the phase measurement was first evaluated in a laboratory test and then tested in a field experiment. To compensate for the sensitivity differences among the sensors, we propose an in situ calibration technique. The dominant operating frequency of the system is 70 MHz. Subsequently, we used borehole radar for subsurface measurements in a vertical borehole in granite. Estimation of the azimuth orientations of subsurface fractures was successfully demonstrated.

Original languageEnglish
Pages (from-to)2529-2535
Number of pages7
JournalIEEE Transactions on Geoscience and Remote Sensing
Volume45
Issue number8
DOIs
Publication statusPublished - 2007 Aug

Keywords

  • Adcock antenna
  • Antenna array
  • Direction finding
  • Directional borehole radar
  • Ground-penetrating radar (GPR)
  • Optical electric field sensor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Earth and Planetary Sciences(all)

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