TY - JOUR
T1 - Cross-polarization borehole radar measurements with a slot antenna
AU - Sato, Motoyuki
AU - Ohkubo, Takeshi
AU - Niitsuma, Hiroaki
PY - 1995/1
Y1 - 1995/1
N2 - In this paper we discuss co-polarization and cross-polarization reflection measurements in borehole radar. Most conventional borehole radars use axially-oriented electric dipole antennas for transmission and reception, resulting in a response only to the co-polarized signal component of the reflected wave. However, more information can be obtained if the cross-polarized component of the reflected wave is also measured. Cross-polarization borehole radar measurements are presented in which an axially-oriented slot antenna is used as the receiving antenna and an electric dipole is used as the transmitting antenna. The slot antenna was excited by a short DC pulse (< 10 ns in duration) to obtain broadband pulse-echo operation. The physical configuration of this antenna is quite suitable for borehole applications, because the slot antenna aperture can be made an integral part of a metallic cylinder. Field measurements using two prototype radar sonde arrangements containing co-polarized (vertical) and cross-polarized antennas were carried out in granite rock. The measured signals showed that detection of the short-range reflections can be significantly improved with cross-polarization measurements since direct coupling between the transmitting and receiving antennas is considerably reduced. Comparisons of the reflected signals produced by the co- and cross-polarization measurements exhibit responses which show that polarimetric radar measurements in a borehole can be practical and beneficial.
AB - In this paper we discuss co-polarization and cross-polarization reflection measurements in borehole radar. Most conventional borehole radars use axially-oriented electric dipole antennas for transmission and reception, resulting in a response only to the co-polarized signal component of the reflected wave. However, more information can be obtained if the cross-polarized component of the reflected wave is also measured. Cross-polarization borehole radar measurements are presented in which an axially-oriented slot antenna is used as the receiving antenna and an electric dipole is used as the transmitting antenna. The slot antenna was excited by a short DC pulse (< 10 ns in duration) to obtain broadband pulse-echo operation. The physical configuration of this antenna is quite suitable for borehole applications, because the slot antenna aperture can be made an integral part of a metallic cylinder. Field measurements using two prototype radar sonde arrangements containing co-polarized (vertical) and cross-polarized antennas were carried out in granite rock. The measured signals showed that detection of the short-range reflections can be significantly improved with cross-polarization measurements since direct coupling between the transmitting and receiving antennas is considerably reduced. Comparisons of the reflected signals produced by the co- and cross-polarization measurements exhibit responses which show that polarimetric radar measurements in a borehole can be practical and beneficial.
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U2 - 10.1016/0926-9851(95)90029-2
DO - 10.1016/0926-9851(95)90029-2
M3 - Article
AN - SCOPUS:0028974737
VL - 33
SP - 53
EP - 61
JO - Journal of Applied Geophysics
JF - Journal of Applied Geophysics
SN - 0926-9851
IS - 1-3
ER -