Comparison of Calibration Methods in Free-Space Monostatic Reflection Coefficient Measurement

YANG Ruonan; LIANG Weijun; XU Hao

doi:10.12338/j.issn.2096-9015.2024.0080

Volume 68 Issue 8

Aug. 2024

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Article Navigation > Metrology Science and Technology > 2024 > 68(8): 25-31

YANG Ruonan, LIANG Weijun, XU Hao. Comparison of Calibration Methods in Free-Space Monostatic Reflection Coefficient Measurement[J]. Metrology Science and Technology, 2024, 68(8): 25-31. doi: 10.12338/j.issn.2096-9015.2024.0080

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YANG Ruonan, LIANG Weijun, XU Hao. Comparison of Calibration Methods in Free-Space Monostatic Reflection Coefficient Measurement[J]. Metrology Science and Technology, 2024, 68(8): 25-31. doi: 10.12338/j.issn.2096-9015.2024.0080

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Comparison of Calibration Methods in Free-Space Monostatic Reflection Coefficient Measurement

doi: 10.12338/j.issn.2096-9015.2024.0080

National Institute of Metrology, Beijing 100029, China

Received Date: 2024-03-13
Accepted Date: 2024-03-13
Rev Recd Date: 2024-03-18

Available Online: 2024-05-30

Publish Date: 2024-08-30

Abstract

Abstract

Microwave blackbodies provide high-precision brightness temperature signals for microwave radiometers to accurately calibrate observed target radiation signals. The emissivity of a microwave blackbody is a crucial parameter affecting its radiative characteristics. Therefore, accurately measuring blackbody emissivity is significant for enhancing radiometer calibration precision and ensuring measurement value traceability and effective transfer. Currently, blackbody emissivity is mainly obtained indirectly by measuring reflectivity. This study implements two calibration methods in free-space monostatic reflection coefficient measurement: the offset-short calibration method and the sliding-load calibration method. Time-domain gating techniques are utilized to address multipath reflection signals during small reflection measurements. A reflectivity measurement system was established, and the reflectivity of the same blackbody target was measured within the 75-110 GHz frequency band, with results analyzed and compared. The error terms solved by the two calibration methods exhibit high consistency, with measured emissivity reaching levels of 0.999-0.9999. When the measurement target satisfies approximation conditions, the sliding-load calibration method proves more efficient. Finally, using the offset-short method as an example, the Monte Carlo method was employed to evaluate the uncertainty of the solved blackbody target reflection coefficient.
- metrology,
- microwave blackbody,
- emissivity,
- reflectivity measurement,
- one-port calibration,
- offset-short method,
- sliding-load method

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References(30)

References

[1]	Cho K, Naoki K, Nakayama M, et al. The Relationship Between Microwave Brightness Temperature, Salinity, and Thickness of Sea Ice Acquired With a Tank Experiment[J]. ITGRS, 2024, 62: 1-9.
[2]	Ulaby FT, Long DG. Microwave Radar and Radiometric Remote Sensing[M]. Michigan: The University of Michigan Press, 2014.
[3]	关越, 高福生. 黑体辐射源发射率对测量误差的影响[J]. 轻工标准与质量, 2018(1): 82-83,7.
[4]	年丰, 于杰, 陈云梅, 等. 中国星载微波辐射计地面定标技术的研究进展[J]. 宇航计测技术, 2007(S1): 27-33.
[5]	李彬. 一种新型全极化微波辐射计定标源研制及定标方法研究[D]. 北京: 中国科学院大学(中国科学院国家空间科学中心), 2017.
[6]	Khatib O, Gu D, Smith J, et al. Planar Metamaterial Absorbers for Calibration of Microwave Radiometers for Atmospheric Remote Sensing[C]. IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium, 2022.
[7]	ISO. Space systems-- Calibration requirements for satellite-based passive microwave sensors: ISO 20930: 2018[S]. Geneva: ISO, 2018.
[8]	A. Murk AD. ALMA Calibration Device Prototype Calibration Load Test Report. [R]. Institute of Applied Physics, University of Bern, 2007.
[9]	A. Murk, A. Duric, Patt F. Characterization of ALMA Calibration Targets[C]. 19th International Symposium on Space Terahertz Technology.
[10]	Hein WHCBASM. Challenges of RF Absorber Characterization: Comparison Between RCS- and NRL-Arch-Methods[C]. 2019 International Symposium on Electromagnetic Compatibility (EMC Europe ), 2019.
[11]	Hofmann W, Schwind A, Bornkessel C, et al. Bi-static reflectivity measurements of microwave absorbers between 2 and 18 GHz[C]. 2021 Antenna Measurement Techniques Association Symposium (AMTA), 2021.
[12]	李彬, 金铭, 白明, 等. 微波黑体发射率计量标准装置的准光照射天线设计[J]. 宇航计测技术, 2018, 38(6): 7. doi: 10.12060/j.issn.1000-7202.2018.06.02
[13]	Jin M, Li B, Bai M. On the Reflectivity Measurements of Microwave Blackbody in Bistatic Near-Field Configuration[J]. IEEE Transactions on Antennas and Propagation, 2021, 69(11): 8027-8032. doi: 10.1109/TAP.2021.3083762
[14]	Jin M, Li B, Bai M. Development of the Standard Facility for the Microwave Blackbody Emissivity Determination in China[C]. 2021 International Conference on Microwave and Millimeter Wave Technology (ICMMT), 2021.
[15]	Dazhen G, Houtz D, Randa J, et al. Reflectivity Study of Microwave Blackbody Target[J]. ITGRS, 2011, 49(9): 3443-3451.
[16]	Houtz DA, Gu D. A Measurement Technique for Infrared Emissivity of Epoxy-Based Microwave Absorbing Materials[J]. IEEE Geoscience and Remote Sensing Letters, 2018, 15(1): 48-52. doi: 10.1109/LGRS.2017.2772783
[17]	Cheng CY, Li F, Yang YJ, et al. Emissivity measurement study on wide aperture microwave radiator[C]. 2008 International Conference on Microwave and Millimeter Wave Technology, 2008.
[18]	Cheng J, Cao Y, Zhai H, et al. Development of New Calibration Targets for FY-3 Satellites Microwave Radiometer[C]. 2021 International Conference on Microwave and Millimeter Wave Technology (ICMMT), 2021.
[19]	Wang T, Zeng J, Chen K-S, et al. Comparison of Different Intercalibration Methods of Brightness Temperatures From FY-3D and AMSR2[J]. ITGRS, 2022, 60: 12-17.
[20]	程春悦, 何巍. 140GHz~220GHz微波黑体发射率测量研究[C]. 2011年全国微波毫米波会议, 2011.
[21]	Wang J, Miao J, Yang Y, et al. Scattering Property and Emissivity of a Periodic Pyramid Array Covered With Absorbing Material[J]. IEEE Transactions on Antennas and Propagation, 2008, 56(8): 2656-2663. doi: 10.1109/TAP.2008.927570
[22]	金铭. 锥形阵列微波辐射计定标源的电磁波散射和发射率研究 [D]. 北京: 北京航空航天大学, 2012.
[23]	Junhong W, Yujie Y, Jungang M, et al. Emissivity Calculation for a Finite Circular Array of Pyramidal Absorbers Based on Kirchhoff's Law of Thermal Radiation[J]. IEEE Transactions on Antennas and Propagation, 2010, 58(4): 1173-1180. doi: 10.1109/TAP.2010.2041148
[24]	Jin M, Fan B, Li X, et al. On the Total Reflectivity Estimation of Microwave Calibration Targets by Backscattering Measurements[J]. ITGRS, 2022, 60: 1-11.
[25]	Houtz DA. NIST MICROWAVE BLACKBODY: The design, testing, and verification of a conical brightness temperature source [D]. Boulder : University of Colorado Boulder, 2017.
[26]	andersteen GV. It is possible to improve the Sliding Load Calibration Procedure using a Semi-Parametric Circle Fitting Algorithm [D]. Brussel : Vrije Universiteit Brussel, 1997.
[27]	Yang R, Liang W, Xu H. Design and Fabrication of WR-28 Blackbody Target[C]. 2023 16th UK-Europe-China Workshop on Millimetre Waves and Terahertz Technologies (UCMMT), 2023.
[28]	倪育才. 实用测量不确定度评定[M]. 北京: 中国质量标准出版传媒有限公司, 2020.
[29]	Dirix M, Enayati A. On the Uncertainty Evaluation of Absorber Reflectivity Measurements[C]. 2023 Antenna Measurement Techniques Association Symposium (AMTA), 2023.
[30]	Doug Rytting. Network analyzer error models and calibration methods [R]. 1998.