3D intrawall imaging using backprojection for synthetic aperture radar (SAR)
| dc.contributor.advisor | Paine, Stephen | |
| dc.contributor.author | Dass, Reevelen | |
| dc.date.accessioned | 2025-01-31T09:17:38Z | |
| dc.date.available | 2025-01-31T09:17:38Z | |
| dc.date.issued | 2024 | |
| dc.date.updated | 2025-01-31T08:10:14Z | |
| dc.description.abstract | The Council of Scientific and Industrial Research (CSIR) has evolving synthetic aperture radar (SAR) capabilities in the C-band and the L-band. Currently, these capabilities are used to generate aerial landscape images; however, to explore the feasibility of using this technology in different environments, an experimental SAR system has been developed. This is referred to as the wall scanner. The purpose of the wall scanner is to image the interior of a wall, revealing details of the substructures inside the wall such as conduits and piping. This is done by moving the antenna system across the wall surface to create SAR images using backprojection. The radar used two different types of antennas, a log periodic dipole array (LPDA) antenna and horn antenna. The horn antenna performed well in the experiments, producing images with minimal artefacts. On the contrary, the LPDA antenna did not perform as well in the experiments and as such the characteristics of the antenna were investigated. The investigation revealed that the antenna did not function throughout the frequency range specified by its manufacturer. This produced artefacts in the image; however, some of the effects of these artefacts were minimised by a series of preprocessing techniques. A variety of preprocessing techniques were used to improve image quality. In addition to compensating for the properties of the LPDA antenna, windowing and different methods of background subtraction were used. It was difficult to compensate for the antenna issues in preprocessing; however, windowing and background subtraction had a significant effect on the images that were produced. Two postprocessing techniques were used, gradient descent optimisation based on image contrast and polarimetry. The developed gradient descent optimiser was able to automatically adjust for the system group delay based on the contrast of the image. Polarimetry post-processing revealed that the horizontally transmitted horizontally received polarisation (HH) and vertically transmitted vertically received polarisation (VV) were effective in creating images in this environment; however, cross-polarisation in the form of horizontally transmitted vertically received polarisation (HV) was not effective. The wall scanning environment that was measured consisted of scanning both drywall and brick wall. This was split into three experiments. The experiments used different materials that were placed in front of a wall, behind the wall at a distance, and directly behind the wall. The wall scanner was able to successfully create images of the three different experiments for the drywall; however, the desired results for the brick wall were not achieved. For drywall, the substructures placed directly behind the wall were more difficult to see because they were masked by the wall and its sidelobes. The materials scanned were a copper pipe, a PVC pipe, a wooden beam, and a highly reflective calibration target. The calibration target and the copper target performed well in the three experiments. The wooden beam did not perform as well; especially when placed directly behind the wall; however, it was still visible in all experiments. The PVC performed the worst and was only faintly visible in the experiments and was not visible when placed directly behind the wall. | |
| dc.identifier.apacitation | Dass, R. (2024). <i>3D intrawall imaging using backprojection for synthetic aperture radar (SAR)</i>. (). University of Cape Town ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering. Retrieved from http://hdl.handle.net/11427/40858 | en_ZA |
| dc.identifier.chicagocitation | Dass, Reevelen. <i>"3D intrawall imaging using backprojection for synthetic aperture radar (SAR)."</i> ., University of Cape Town ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering, 2024. http://hdl.handle.net/11427/40858 | en_ZA |
| dc.identifier.citation | Dass, R. 2024. 3D intrawall imaging using backprojection for synthetic aperture radar (SAR). . University of Cape Town ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering. http://hdl.handle.net/11427/40858 | en_ZA |
| dc.identifier.ris | TY - Thesis / Dissertation AU - Dass, Reevelen AB - The Council of Scientific and Industrial Research (CSIR) has evolving synthetic aperture radar (SAR) capabilities in the C-band and the L-band. Currently, these capabilities are used to generate aerial landscape images; however, to explore the feasibility of using this technology in different environments, an experimental SAR system has been developed. This is referred to as the wall scanner. The purpose of the wall scanner is to image the interior of a wall, revealing details of the substructures inside the wall such as conduits and piping. This is done by moving the antenna system across the wall surface to create SAR images using backprojection. The radar used two different types of antennas, a log periodic dipole array (LPDA) antenna and horn antenna. The horn antenna performed well in the experiments, producing images with minimal artefacts. On the contrary, the LPDA antenna did not perform as well in the experiments and as such the characteristics of the antenna were investigated. The investigation revealed that the antenna did not function throughout the frequency range specified by its manufacturer. This produced artefacts in the image; however, some of the effects of these artefacts were minimised by a series of preprocessing techniques. A variety of preprocessing techniques were used to improve image quality. In addition to compensating for the properties of the LPDA antenna, windowing and different methods of background subtraction were used. It was difficult to compensate for the antenna issues in preprocessing; however, windowing and background subtraction had a significant effect on the images that were produced. Two postprocessing techniques were used, gradient descent optimisation based on image contrast and polarimetry. The developed gradient descent optimiser was able to automatically adjust for the system group delay based on the contrast of the image. Polarimetry post-processing revealed that the horizontally transmitted horizontally received polarisation (HH) and vertically transmitted vertically received polarisation (VV) were effective in creating images in this environment; however, cross-polarisation in the form of horizontally transmitted vertically received polarisation (HV) was not effective. The wall scanning environment that was measured consisted of scanning both drywall and brick wall. This was split into three experiments. The experiments used different materials that were placed in front of a wall, behind the wall at a distance, and directly behind the wall. The wall scanner was able to successfully create images of the three different experiments for the drywall; however, the desired results for the brick wall were not achieved. For drywall, the substructures placed directly behind the wall were more difficult to see because they were masked by the wall and its sidelobes. The materials scanned were a copper pipe, a PVC pipe, a wooden beam, and a highly reflective calibration target. The calibration target and the copper target performed well in the three experiments. The wooden beam did not perform as well; especially when placed directly behind the wall; however, it was still visible in all experiments. The PVC performed the worst and was only faintly visible in the experiments and was not visible when placed directly behind the wall. DA - 2024 DB - OpenUCT DP - University of Cape Town KW - Electrical Engineering LK - https://open.uct.ac.za PB - University of Cape Town PY - 2024 T1 - 3D intrawall imaging using backprojection for synthetic aperture radar (SAR) TI - 3D intrawall imaging using backprojection for synthetic aperture radar (SAR) UR - http://hdl.handle.net/11427/40858 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/40858 | |
| dc.identifier.vancouvercitation | Dass R. 3D intrawall imaging using backprojection for synthetic aperture radar (SAR). []. University of Cape Town ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering, 2024 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/40858 | en_ZA |
| dc.language.rfc3066 | eng | |
| dc.publisher.department | Department of Electrical Engineering | |
| dc.publisher.faculty | Faculty of Engineering and the Built Environment | |
| dc.publisher.institution | University of Cape Town | |
| dc.subject | Electrical Engineering | |
| dc.title | 3D intrawall imaging using backprojection for synthetic aperture radar (SAR) | |
| dc.type | Thesis / Dissertation | |
| dc.type.qualificationlevel | Masters | |
| dc.type.qualificationlevel | MSc (Eng) |