Design and In-Orbit Validation of a Novel Compact Bidirectional Trapezoidal Reflector for X-Band Spaceborne SAR Absolute Radiometric Calibration.
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| Title: | Design and In-Orbit Validation of a Novel Compact Bidirectional Trapezoidal Reflector for X-Band Spaceborne SAR Absolute Radiometric Calibration. |
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| Authors: | Sun, Shiyu1 (AUTHOR), Wang, Yu1,2 (AUTHOR) wangyu@mail.ie.ac.cn, Li, Huijuan1,2 (AUTHOR), Zhang, Xin1,2 (AUTHOR) |
| Source: | Remote Sensing. Mar2026, Vol. 18 Issue 5, p770. 25p. |
| Subjects: | Synthetic aperture radar, Radar cross sections, Space-based radar, Model validation, Lighting reflectors |
| Abstract: | Highlights: What are the main findings? A novel compact bidirectional trapezoidal CR is proposed for spaceborne SAR radiometric calibration to eliminate the need for CR alignment reorientations in the field while minimizing RCS loss as much as possible. In-orbit validation demonstrates that the difference in calibration constants between the novel CR (non-aligned radiometric calibration method) and the TTCR (traditional aligned calibration method) meets the radiometric calibration accuracy requirement. What are the implications of the main findings? The novel CR significantly simplifies field operations and reduces labor dependency, making it suitable for the spaceborne SAR commissioning phase and long-term performance monitoring. Its bidirectional configuration supports both ascending and descending satellite passes, effectively increasing the frequency of radiometric calibration and enhancing the data acquisition efficiency. Spaceborne synthetic aperture radar (SAR) absolute radiometric calibration relies on point targets with a known radar cross-section (RCS), such as triangular trihedral corner reflectors (TTCRs). Traditionally, radiometric calibration using TTCRs requires precise alignment of the corner reflector (CR) boresight to the radar line-of-sight (LOS), leading to frequent field operations and high labor dependency. In this study, a novel compact bidirectional trapezoidal CR is proposed to eliminate such alignment reorientations. The novel CR adopts three design considerations: a scalene shape to optimize the boresight elevation angle and enhance the peak RCS; a bidirectional configuration with azimuth fine-tuning to align with the radar LOS for both ascending and descending passes; and trapezoidal plate trimming to reduce the volume and weight without sacrificing RCS performance. An in-orbit validation is conducted in Xi'an, China, using the SuperView Neo 2-03 satellite. The results demonstrate that the imaging quality of the bidirectional trapezoidal CRs is comparable to that of conventional TTCRs, with all the parameters meeting system specifications. The radiometric calibration constant of the bidirectional trapezoidal CR differs from that of the conventional TTCR by no more than 0.27 dB, with a total uncertainty of ~0.33 dB (1σ)—demonstrating that it achieves equivalent radiometric calibration accuracy to TTCRs. The experiment confirms the feasibility and engineering applicability of the bidirectional trapezoidal CR for X-band SAR radiometric calibration. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Highlights: What are the main findings? A novel compact bidirectional trapezoidal CR is proposed for spaceborne SAR radiometric calibration to eliminate the need for CR alignment reorientations in the field while minimizing RCS loss as much as possible. In-orbit validation demonstrates that the difference in calibration constants between the novel CR (non-aligned radiometric calibration method) and the TTCR (traditional aligned calibration method) meets the radiometric calibration accuracy requirement. What are the implications of the main findings? The novel CR significantly simplifies field operations and reduces labor dependency, making it suitable for the spaceborne SAR commissioning phase and long-term performance monitoring. Its bidirectional configuration supports both ascending and descending satellite passes, effectively increasing the frequency of radiometric calibration and enhancing the data acquisition efficiency. Spaceborne synthetic aperture radar (SAR) absolute radiometric calibration relies on point targets with a known radar cross-section (RCS), such as triangular trihedral corner reflectors (TTCRs). Traditionally, radiometric calibration using TTCRs requires precise alignment of the corner reflector (CR) boresight to the radar line-of-sight (LOS), leading to frequent field operations and high labor dependency. In this study, a novel compact bidirectional trapezoidal CR is proposed to eliminate such alignment reorientations. The novel CR adopts three design considerations: a scalene shape to optimize the boresight elevation angle and enhance the peak RCS; a bidirectional configuration with azimuth fine-tuning to align with the radar LOS for both ascending and descending passes; and trapezoidal plate trimming to reduce the volume and weight without sacrificing RCS performance. An in-orbit validation is conducted in Xi'an, China, using the SuperView Neo 2-03 satellite. The results demonstrate that the imaging quality of the bidirectional trapezoidal CRs is comparable to that of conventional TTCRs, with all the parameters meeting system specifications. The radiometric calibration constant of the bidirectional trapezoidal CR differs from that of the conventional TTCR by no more than 0.27 dB, with a total uncertainty of ~0.33 dB (1σ)—demonstrating that it achieves equivalent radiometric calibration accuracy to TTCRs. The experiment confirms the feasibility and engineering applicability of the bidirectional trapezoidal CR for X-band SAR radiometric calibration. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 20724292 |
| DOI: | 10.3390/rs18050770 |
