Analysis of the Borehole Effect in Borehole Radar Detection
The directional borehole radar can accurately locate and image the geological target around the borehole, which overcomes the shortcomings that the conventional borehole radar can only detect the depth of the target and the distance from the borehole. The directional borehole radar under considerati...
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| Format: | Article |
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MDPI AG
2020-10-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/20/20/5812 |
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| author | Wentian Wang Sixin Liu Xuzhang Shen Wenjun Zheng |
| author_facet | Wentian Wang Sixin Liu Xuzhang Shen Wenjun Zheng |
| author_sort | Wentian Wang |
| collection | DOAJ |
| description | The directional borehole radar can accurately locate and image the geological target around the borehole, which overcomes the shortcomings that the conventional borehole radar can only detect the depth of the target and the distance from the borehole. The directional borehole radar under consideration consists of a transmitting antenna and four receiving antennas equally distributed on the ring in the borehole. The nonuniformity caused by the borehole and sonde, as well as the mutual coupling among the four receiving antennas, will have a serious impact on the received signal and then cause interference to the azimuth recognition for the targets. In this paper, Finite difference time domain (FDTD), including the subgrid, is applied to study these effects and interferences, and the influence of borehole, sonde, and mutual coupling among the receiving antennas is found. The results show that, without considering the sonde and the fluid in the borehole, the one transmitting and one receiving borehole radar system does not have resonance, but the wave pattern of the reflected wave will have obvious distortion. For the four receiving antennas of the borehole radar system, there is obvious resonance, which is caused by the multiple reflections between the receiving antennas. However, when the fluid in the borehole is water and the relative permittivity of the sonde is low to a certain extent, the resonance disappears; that is, the generation of resonance requires a large relative permittivity material between the receiving antennas. When the influence of the sonde is considered, the resonance disappears because the relative permittivity of the sonde is low, which makes the propagation speed of the electromagnetic wave between the antennas accelerate and lose the conditions for resonance. In addition, the diameters of the sonde and the circular array of the receiving antennas can affect the received signal: the higher the diameter of the sonde and the higher the diameter of the circular array are, the better the differentiation of the received signal. The development of the research provides scientific guidance for the design and application of borehole radar in the future. |
| first_indexed | 2024-03-10T15:37:57Z |
| format | Article |
| id | doaj.art-de45b9ccc5a64e6298a61e862fddd5e5 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-10T15:37:57Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-de45b9ccc5a64e6298a61e862fddd5e52023-11-20T17:07:04ZengMDPI AGSensors1424-82202020-10-012020581210.3390/s20205812Analysis of the Borehole Effect in Borehole Radar DetectionWentian Wang0Sixin Liu1Xuzhang Shen2Wenjun Zheng3School of Earth Science and Engineering, Sun Yat-Sen University, Zhuhai 519082, ChinaCollege of Geo-Exploration Science and Technology, Jilin University, Changchun 130026, ChinaSchool of Earth Science and Engineering, Sun Yat-Sen University, Zhuhai 519082, ChinaSchool of Earth Science and Engineering, Sun Yat-Sen University, Zhuhai 519082, ChinaThe directional borehole radar can accurately locate and image the geological target around the borehole, which overcomes the shortcomings that the conventional borehole radar can only detect the depth of the target and the distance from the borehole. The directional borehole radar under consideration consists of a transmitting antenna and four receiving antennas equally distributed on the ring in the borehole. The nonuniformity caused by the borehole and sonde, as well as the mutual coupling among the four receiving antennas, will have a serious impact on the received signal and then cause interference to the azimuth recognition for the targets. In this paper, Finite difference time domain (FDTD), including the subgrid, is applied to study these effects and interferences, and the influence of borehole, sonde, and mutual coupling among the receiving antennas is found. The results show that, without considering the sonde and the fluid in the borehole, the one transmitting and one receiving borehole radar system does not have resonance, but the wave pattern of the reflected wave will have obvious distortion. For the four receiving antennas of the borehole radar system, there is obvious resonance, which is caused by the multiple reflections between the receiving antennas. However, when the fluid in the borehole is water and the relative permittivity of the sonde is low to a certain extent, the resonance disappears; that is, the generation of resonance requires a large relative permittivity material between the receiving antennas. When the influence of the sonde is considered, the resonance disappears because the relative permittivity of the sonde is low, which makes the propagation speed of the electromagnetic wave between the antennas accelerate and lose the conditions for resonance. In addition, the diameters of the sonde and the circular array of the receiving antennas can affect the received signal: the higher the diameter of the sonde and the higher the diameter of the circular array are, the better the differentiation of the received signal. The development of the research provides scientific guidance for the design and application of borehole radar in the future.https://www.mdpi.com/1424-8220/20/20/5812directional borehole radarinfluence of nonuniformity around boreholeantenna mutual couplingFDTDresonance |
| spellingShingle | Wentian Wang Sixin Liu Xuzhang Shen Wenjun Zheng Analysis of the Borehole Effect in Borehole Radar Detection Sensors directional borehole radar influence of nonuniformity around borehole antenna mutual coupling FDTD resonance |
| title | Analysis of the Borehole Effect in Borehole Radar Detection |
| title_full | Analysis of the Borehole Effect in Borehole Radar Detection |
| title_fullStr | Analysis of the Borehole Effect in Borehole Radar Detection |
| title_full_unstemmed | Analysis of the Borehole Effect in Borehole Radar Detection |
| title_short | Analysis of the Borehole Effect in Borehole Radar Detection |
| title_sort | analysis of the borehole effect in borehole radar detection |
| topic | directional borehole radar influence of nonuniformity around borehole antenna mutual coupling FDTD resonance |
| url | https://www.mdpi.com/1424-8220/20/20/5812 |
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