Poster

[GP-P-02] Estimation of the direction of an object by directional borehole radar with dipole array for a transmitter and a receiver

*Yuki Tsujikawa¹, Satoshi Ebihara¹, Koki Koyama¹, Tomoya Kako¹, Hisaya Yamamoto¹ (1. Osaka Electro-Communication Univ. (Japan))

We present a directional borehole radar system with dipole array antennas used as a transmitter and a receiver in this paper. This radar can estimate the azimuth direction of a radar target position at both the transmitter and receiver. Thanks to this capability, the radar may precisely estimate the azimuth angle even if the media around the borehole are inhomogeneous. Dipole antenna elements are arranged in a circle at both the transmitter and the receiver. We use the difference in arrival times measured at the dipole antenna elements to estimate an object’s direction. In our prototype borehole radar systems, there are four dipole antenna elements for the transmitter and the same number of elements for the receiver. These antenna elements are packed in an FRP vessel within the length of about one meter. We demonstrated a field experiment with the radar in wet soil. A radar target is an inclined cylindrical conducting cylinder, positioned about one meter from the borehole. The error in the estimated azimuth angles of the conducting cylinder ranged from a few degrees to about 30 degrees. Averaging the calculated values, we evaluated the azimuth direction within an error of 15 degrees. We found the multiple antennas at both the transmitter and receiver improved the estimated azimuth angles in the field experiment data.