{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:01:53Z","timestamp":1760148113906,"version":"build-2065373602"},"reference-count":38,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,3,28]],"date-time":"2023-03-28T00:00:00Z","timestamp":1679961600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Reserve Talents Project of National High-level Personnel of Special Support Program","award":["Y9G0100BF0","61901445"],"award-info":[{"award-number":["Y9G0100BF0","61901445"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["Y9G0100BF0","61901445"],"award-info":[{"award-number":["Y9G0100BF0","61901445"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The calibration of channel imbalances is currently the main concern in polarimetric calibration (POLCAL) since the crosstalk of recent polarimetric synthetic aperture radar (Pol-SAR) systems is lower than \u221220 dB. The existing channel imbalance calibration method without corner reflectors utilizes both volume-dominated and Bragg-like targets. However, there are two limitations to using volume-dominated targets. One is that the inaccurate selection of volume-dominated areas in the uncalibrated Pol-SAR images has a negative influence on the estimation of cross-polarization (x-pol) channel imbalance, which subsequently impacts the estimation of copolarization (copol) channel imbalance. The other is that there are minimal volume-dominated areas in some special applications of Pol-SAR, such as planetary exploration. Thus, only selecting Bragg-like targets to estimate the values of both transmitting and receiving channel imbalances, which is proposed in this paper, can avoid the uncertainty brought about by selecting other distributed targets in an uncalibrated imaginary. In addition, the reciprocity assumption and characteristics corresponding to H\/\u03b1\u00af\u00a0decomposition are introduced to eliminate the phase ambiguity for the first time. Compared with previous methods, our method had an obvious advantage in terms of universality, since Bragg-like targets are common in the most illuminating areas. The novel method was applied to both the simulated data from the L-band Advanced Land Observing Satellite (ALOS) and C-band GaoFen-3 (GF-3), and to real data with corner reflectors on site. The results from the simulated data showed that the errors of the amplitude and phase estimation were less than 0.5 dB and 5.0\u00b0 in most topographical features. Meanwhile, the\u00a0VV\/HH\u00a0terms from all trihedral corner reflectors were less than 0.3 dB for amplitude, and 5.5\u00b0 for phase after calibration by using the estimated channel imbalances.<\/jats:p>","DOI":"10.3390\/rs15071810","type":"journal-article","created":{"date-parts":[[2023,3,29]],"date-time":"2023-03-29T01:33:00Z","timestamp":1680053580000},"page":"1810","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Channel Imbalance Calibration Based on the Zero Helix of Bragg-like Targets"],"prefix":"10.3390","volume":"15","author":[{"given":"Hanglan","family":"Guo","sequence":"first","affiliation":[{"name":"The Department of Space Microwave Remote Sensing System, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0149-1254","authenticated-orcid":false,"given":"Xingjie","family":"Zhao","sequence":"additional","affiliation":[{"name":"The Department of Space Microwave Remote Sensing System, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1885-0885","authenticated-orcid":false,"given":"Xiuqing","family":"Liu","sequence":"additional","affiliation":[{"name":"The Department of Space Microwave Remote Sensing System, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Weidong","family":"Yu","sequence":"additional","affiliation":[{"name":"The Department of Space Microwave Remote Sensing System, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1583","DOI":"10.1109\/5.118982","article-title":"Imaging radar polarimetry: A review","volume":"79","author":"Zebker","year":"1991","journal-title":"Proc. IEEE"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.isprsjprs.2015.02.004","article-title":"A three-component method for timely detection of land cover changes using polarimetric SAR images","volume":"107","author":"Qi","year":"2015","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"111699","DOI":"10.1016\/j.rse.2020.111699","article-title":"Modelling of early winter snow density using fully polarimetric C-band SAR data in the Indian Himalayas","volume":"240","author":"Varade","year":"2020","journal-title":"Remote Sens. Environ."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"111910","DOI":"10.1016\/j.rse.2020.111910","article-title":"Observations of SAR polarimetric parameters of lake and fast sea ice during the early growth phase","volume":"247","author":"Shokr","year":"2020","journal-title":"Remote Sens. Environ."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"112747","DOI":"10.1016\/j.rse.2021.112747","article-title":"Application of L-band SAR for mapping tundra shrub biomass, leaf area index, and rainfall interception","volume":"268","author":"Chang","year":"2022","journal-title":"Remote Sens. Environ."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"112485","DOI":"10.1016\/j.rse.2021.112485","article-title":"Soil moisture retrieval over agricultural fields from L-band multi-incidence and multitemporal PolSAR observations using polarimetric decomposition techniques","volume":"261","author":"Shi","year":"2021","journal-title":"Remote Sens. Environ."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"980","DOI":"10.1109\/TGRS.2013.2246171","article-title":"Ocean surface wind speed retrieval from C-band SAR images without wind direction input","volume":"52","author":"Komarov","year":"2013","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1107","DOI":"10.1109\/36.193786","article-title":"SAR calibration: An overview","volume":"30","author":"Freeman","year":"1992","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1109\/8.64436","article-title":"A general polarimetric radar calibration technique","volume":"39","author":"Whitt","year":"1991","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4513","DOI":"10.1109\/JSTARS.2018.2873218","article-title":"The polarimetric L-band imaging synthetic aperture radar (PLIS): Description, calibration, and cross-validation","volume":"11","author":"Zhu","year":"2018","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Li, L., Zhu, Y., Hong, J., Ming, F., and Wang, Y. (2018). Design and implementation of a novel polarimetric active radar calibrator for Gaofen-3 SAR. Sensors, 18.","DOI":"10.3390\/s18082620"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1109\/36.285192","article-title":"A unified algorithm for phase and cross-talk calibration of polarimetric data-theory and observations","volume":"32","author":"Quegan","year":"1994","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"994","DOI":"10.1109\/TGRS.2005.862508","article-title":"Orientation angle preserving a posteriori polarimetric SAR calibration","volume":"44","author":"Ainsworth","year":"2006","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1712","DOI":"10.1109\/TGRS.2010.2090046","article-title":"Model-based polarimetric SAR calibration method using forest and surface-scattering targets","volume":"49","author":"Shimada","year":"2011","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"963","DOI":"10.1109\/36.673687","article-title":"A three-component scattering model for polarimetric SAR data","volume":"36","author":"Freeman","year":"1998","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/j.isprsjprs.2014.06.007","article-title":"Co-polarization channel imbalance determination by the use of bare soil","volume":"95","author":"Shi","year":"2014","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4454","DOI":"10.1109\/TGRS.2020.2964732","article-title":"Polarimetric SAR calibration and residual error estimation when corner reflectors are unavailable","volume":"58","author":"Shi","year":"2020","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.isprsjprs.2019.12.003","article-title":"Polarimetric calibration for the distributed Gaofen-3 product by an improved unitary zero helix framework","volume":"160","author":"Shi","year":"2020","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"4282","DOI":"10.1109\/JSTARS.2020.3012151","article-title":"GF-3 Polarimetric Data Quality Assessment Based on Automatic Extraction of Distributed Targets","volume":"13","author":"Shangguan","year":"2020","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Azcueta, M., D\u2019Alessandro, M.M., Zajc, T., Grunfeld, N., and Thibeault, M. (2015, January 26\u201331). ALOS-2 preliminary calibration assessment. Proceedings of the IGARSS 2015\u20142015 IEEE International Geoscience and Remote Sensing Symposium, Milan, Italy.","DOI":"10.1109\/IGARSS.2015.7326731"},{"key":"ref_21","unstructured":"Touzi, R., Hawkins, R.K., and Cote, S. (2011, January 24\u201328). High Precision Assessment and Calibration of Polarimetric RADARSAT-2 Using Transponder Measurements. Proceedings of the PolinSAR 2011, Science and Applications of SAR Polarimetry and Polarimetric Interferometry, Frascati, Italy."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Zhao, X., Deng, Y., Zhang, H., and Liu, X. (2023). A Channel Imbalance Calibration Scheme with Distributed Targets for Circular Quad-Polarization SAR with Reciprocal Crosstalk. Remote Sens., 15.","DOI":"10.3390\/rs15051365"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1119","DOI":"10.1109\/IGARSS.2000.858041","article-title":"A novel approach in polarimetric covariance matrix eigendecomposition","volume":"Volume 3","author":"Praks","year":"2000","journal-title":"Proceedings of the IGARSS 2000, IEEE 2000 International Geoscience and Remote Sensing Symposium. Taking the Pulse of the Planet: The Role of Remote Sensing in Managing the Environment. Proceedings (Cat. No. 00CH37120)"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"498","DOI":"10.1109\/36.485127","article-title":"A review of target decomposition theorems in radar polarimetry","volume":"34","author":"Cloude","year":"1996","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1109\/36.551935","article-title":"An entropy based classification scheme for land applications of polarimetric SAR","volume":"35","author":"Cloude","year":"1997","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"476","DOI":"10.1109\/LGRS.2020.2981135","article-title":"Bright singularities: Polarimetric calibration of spaceborne PolSAR systems","volume":"18","author":"Cloude","year":"2020","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1109\/36.54360","article-title":"Calibration of polarimetric radar images using only image parameters and trihedral corner reflector responses","volume":"28","year":"1990","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1699","DOI":"10.1109\/TGRS.2005.852084","article-title":"Four-component scattering model for polarimetric SAR image decomposition","volume":"43","author":"Yamaguchi","year":"2005","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1029\/92RS01230","article-title":"Symmetry properties in polarimetric remote sensing","volume":"27","author":"Nghiem","year":"1992","journal-title":"Radio Sci."},{"key":"ref_30","first-page":"102559","article-title":"Polarimetric calibration of SAR images using reflection symmetric targets with low helix scattering","volume":"104","author":"Chang","year":"2021","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3481","DOI":"10.1109\/TGRS.2014.2377637","article-title":"UAVSAR polarimetric calibration","volume":"53","author":"Fore","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2262","DOI":"10.1109\/TGRS.2009.2013459","article-title":"Alternatives to target entropy and alpha angle in SAR polarimetry","volume":"47","author":"Praks","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1016\/S0924-2716(02)00124-7","article-title":"The shuttle radar topography mission\u2014A new class of digital elevation models acquired by spaceborne radar","volume":"57","author":"Rabus","year":"2003","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2153","DOI":"10.1109\/36.868874","article-title":"Polarimetric SAR data compensation for terrain azimuth slope variation","volume":"38","author":"Lee","year":"2000","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Borner, T., Papathanassiou, K.P., Marquart, N., Zink, M., Meadows, P., Rye, A., Wright, P., Meininger, M., Tell, B.R., and Traver, I.N. (2007, January 23\u201327). ALOS PALSAR products verification. Proceedings of the 2007 IEEE International Geoscience and Remote Sensing Symposium, Barcelona, Spain.","DOI":"10.1109\/IGARSS.2007.4424037"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Shimada, M., Isoguchi, O., Tadono, T., Higuchi, R., and Isono, K. (2007, January 23\u201327). PALSAR CALVAL summary and update 2007. Proceedings of the 2007 IEEE International Geoscience and Remote Sensing Symposium, Barcelona, Spain.","DOI":"10.1109\/IGARSS.2007.4423622"},{"key":"ref_37","first-page":"269","article-title":"System design and key technologies of the GF-3 satellite","volume":"46","author":"Zhang","year":"2017","journal-title":"Acta Geod. Cartogr. Sin."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"7517","DOI":"10.1109\/TGRS.2020.3033534","article-title":"NESZ Estimation and Calibration for Gaofen-3 Polarimetric Products by the Minimum Noise Envelope Estimator","volume":"59","author":"Shi","year":"2021","journal-title":"IEEE Trans. Geosci. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/7\/1810\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:05:24Z","timestamp":1760123124000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/7\/1810"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,3,28]]},"references-count":38,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2023,4]]}},"alternative-id":["rs15071810"],"URL":"https:\/\/doi.org\/10.3390\/rs15071810","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2023,3,28]]}}}