|
| | Abstract | | In this paper, we investigate influence of radar sonde eccentricity on a direct wave between a transmitting and a receiving antenna in singlehole borehole radar measurement. According to our calculation, at high frequencies above 200 MHz, guided waves play a vital role in the direct wave. We found that the most important pole is HE11 mode one, which is excited only when the antenna is eccentered in a borehole. We show that this causes artificial noise in the moving average subtraction, which is a common signal processing method used to remove the direct wave. In field experiments in granite, we conducted a special experiment, in which location and rotation of the radar sonde was controlled mechanically. We found the excitation of the mode in high frequencies, when the sonde is eccentered by 1.7 cm in a borehole. |
|
|
|
| |
|