{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T15:02:48Z","timestamp":1781794968930,"version":"3.54.5"},"reference-count":21,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2024,7,16]],"date-time":"2024-07-16T00:00:00Z","timestamp":1721088000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key Laboratory of Atmospheric Sounding of China Meteorological Administration","award":["2023KLAS11M"],"award-info":[{"award-number":["2023KLAS11M"]}]},{"name":"Key Laboratory of Atmospheric Sounding of China Meteorological Administration","award":["CXFZ2024-FZZX32"],"award-info":[{"award-number":["CXFZ2024-FZZX32"]}]},{"name":"Special Project for Innovative Development of Hunan Provincial Meteorological Bureau","award":["2023KLAS11M"],"award-info":[{"award-number":["2023KLAS11M"]}]},{"name":"Special Project for Innovative Development of Hunan Provincial Meteorological Bureau","award":["CXFZ2024-FZZX32"],"award-info":[{"award-number":["CXFZ2024-FZZX32"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Weather radar is an active remote sensing device used to monitor the full lifecycle changes in severe convective weather with high spatial and temporal resolution. Effective radar calibration is a crucial foundation for ensuring the high-quality application of observational data. This paper utilizes a UAV platform equipped with a high-precision RTK system and standard metal spheres to study the principles and methods of metal sphere calibration, constructing a complete calibration process and calibration accuracy evaluation metrics. Additionally, a collocated radar comparison observation experiment was conducted for cross-validation, and metal sphere calibration tests were performed on problematic radars. The experimental results indicate the following: (1) The combined application of a high-precision RTK system and a laser range camera can provide real-time position information on the metal sphere, improving the efficiency of radar target acquisition. (2) The calibration method based on UAV-suspended metal spheres can periodically conduct the quantitative calibration of Z and ZDR, achieving calibration accuracies within 0.5 dB and 0.2 dB, respectively, and supports the qualitative inspection of key parameters such as beamwidth and pulse width. (3) During field tests, a high success rate \u201ccoarse adjustment + fine adjustment + staring\u201d sphere-finding technique was established, based on automatic switching between RHI, PPI, and FIX scanning modes. This method directs the UAV to adjust the metal sphere to the center of the radar distance bin, reducing the impact of uneven beam filling and bin crossing, ensuring the accuracy of scattering characteristic measurements.<\/jats:p>","DOI":"10.3390\/s24144611","type":"journal-article","created":{"date-parts":[[2024,7,17]],"date-time":"2024-07-17T15:15:19Z","timestamp":1721229319000},"page":"4611","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Weather Radar Calibration Method Based on UAV-Suspended Metal Sphere"],"prefix":"10.3390","volume":"24","author":[{"given":"Fei","family":"Ye","sequence":"first","affiliation":[{"name":"Changsha Meteorological Radar Calibration Center, Changsha 410207, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaopeng","family":"Wang","sequence":"additional","affiliation":[{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lu","family":"Li","sequence":"additional","affiliation":[{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yubao","family":"Chen","sequence":"additional","affiliation":[{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yongheng","family":"Lei","sequence":"additional","affiliation":[{"name":"Changsha Meteorological Radar Calibration Center, Changsha 410207, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Haifeng","family":"Yu","sequence":"additional","affiliation":[{"name":"HuaYun METSTAR Radar (Beijing) Company, Ltd., Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiazhi","family":"Yin","sequence":"additional","affiliation":[{"name":"Changsha Meteorological Radar Calibration Center, Changsha 410207, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lixia","family":"Shi","sequence":"additional","affiliation":[{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qian","family":"Yang","sequence":"additional","affiliation":[{"name":"Changsha Meteorological Radar Calibration Center, Changsha 410207, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zehao","family":"Huang","sequence":"additional","affiliation":[{"name":"Changsha Meteorological Radar Calibration Center, Changsha 410207, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"616","DOI":"10.1175\/1520-0426(2001)018<0616:TUOTPR>2.0.CO;2","article-title":"The use of TRMM precipitation radar observations in determining ground radar calibration biases","volume":"18","author":"Anagnostou","year":"2001","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_2","first-page":"41","article-title":"Weather radar data calibration and monitoring","volume":"2","author":"Schneebeli","year":"2024","journal-title":"Adv. Weather. Radar"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"10362","DOI":"10.1109\/TGRS.2019.2933912","article-title":"UAV-aided weather radar calibration","volume":"57","author":"Yin","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Gabella, M., Sartori, M., Progin, O., and Germann, U. (2013, January 9\u201313). Acceptance tests and monitoring of the next generation polarimetric weather radar network in Switzerland. Proceedings of the 2013 International Conference on Electromagnetics in Advanced Applications (ICEAA), Torino, Italy.","DOI":"10.1109\/ICEAA.2013.6632311"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Kumar, M., and Kelly, P.K. (2023). Non-Linear Signal Processing methods for UAV detections from a Multi-function X-band Radar. Drones, 7.","DOI":"10.3390\/drones7040251"},{"key":"ref_6","unstructured":"Schneebeli, M., Leuenberger, A., Gehring, J., Lee, G., Ahn, K.D., Tapiador, F., and Berne, A. (2024, May 19). Absolute Calibration and Propagation Effect Assessment with a Target Simulator. Available online: https:\/\/palindrome-rs.ch\/wp-content\/uploads\/2023\/07\/2018_ERAD_poster_schneebeli_V0.4.pdf."},{"key":"ref_7","unstructured":"Williams, E., Hood, K., Cho, J., Smalley, D., Sandifer, J., Zrnic, D., Melnikov, V., Burgess, D., Forsyth, D., and Webster, T. (2013, January 6\u201320). End-to-end calibration of NEXRAD differential reflectivity with metal spheres. Proceedings of the 36th Conference on Radar Meteorology, Breckenridge, CO, USA."},{"key":"ref_8","first-page":"33","article-title":"Calibration of Weather Radar Using UAV Platform","volume":"43","author":"Sun","year":"2021","journal-title":"Mod. Radar"},{"key":"ref_9","first-page":"517","article-title":"Metal Sphere Calibration for ZDR Parameters of CINRA\/SA-D Radar","volume":"49","author":"Zhu","year":"2021","journal-title":"Meteorol. Sci. Technol."},{"key":"ref_10","first-page":"259","article-title":"Calibration For X-Band Solid-State Weather Radar with Metal Sphere","volume":"33","author":"Li","year":"2018","journal-title":"Remote Sens. Technol. Appl."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Duthoit, S., Salazar, J.L., Doyle, W., Segales, A., Wolf, B., Fulton, C., and Chilson, P. (2017, January 8\u201312). A new approach for in-situ antenna characterization, radome inspection and radar calibration, using an unmanned aircraft system (UAS). Proceedings of the 2017 IEEE Radar Conference (RadarConf), Seattle DC, USA.","DOI":"10.1109\/RADAR.2017.7944287"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1220","DOI":"10.1109\/TAES.2007.4383614","article-title":"Weather radar equation correction for frequency agile and phased array radars","volume":"43","author":"Knorr","year":"2007","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Joshil, S.S., and Chandrasekar, C.V. (2022). Calibration of d3r weather radar using uav-hosted target. Remote Sens., 14.","DOI":"10.3390\/rs14153534"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2189","DOI":"10.1109\/TIM.2017.2687518","article-title":"Drone-based external calibration of a fully synchronized ku-band heterodyne FMCW radar","volume":"66","author":"Suh","year":"2017","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Paonessa, F., Virone, G., Sarri, A., Dell\u2019Omodarme, K., Fiori, L., Addamo, G., Matteoli, S., and Peverini, O.A. (2018, January 3\u20136). UAV-mounted corner reflector for in-situ radar verification and calibration. Proceedings of the 2018 IEEE Conference on Antenna Measurements & Applications (CAMA), Vasteras, Sweden.","DOI":"10.1109\/CAMA.2018.8530616"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1002\/qj.49708837810","article-title":"The radar equation in meteorology","volume":"88","year":"1962","journal-title":"Q. J. R. Meteorol. Soc."},{"key":"ref_17","unstructured":"Zhang, P., Du, B., and Dai, T. (2001). Radar Meteorology, Meteorological Press."},{"key":"ref_18","unstructured":"Han, X. (2016). Related Algorithms and Technologies of Near-Field to Far-Field Transformation on Antennas. [Master\u2019s Thesis, University of Science and Technology of China]."},{"key":"ref_19","unstructured":"Huang, P., Yin, H., Xu, X., and Bai, Y. (2005). Radar Target Characteristics, Publishing House of Electronics Industry."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1109\/MAP.2013.6781745","article-title":"Radar cross section (RCS) measurements [Testing ourselves]","volume":"55","author":"Sevgi","year":"2013","journal-title":"IEEE Antennas Propag. Mag."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Chen, Y., Li, L., Ye, F., Kang, B., Wang, X., Bu, Z., Zhu, M., Yang, Q., Shao, N., and Zhang, J. (2024). An RTK UAV-Based Method for Radial Velocity Validation of Weather Radar. Remote Sens., 16.","DOI":"10.3390\/rs16071153"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/14\/4611\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T15:17:51Z","timestamp":1760109471000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/14\/4611"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,7,16]]},"references-count":21,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2024,7]]}},"alternative-id":["s24144611"],"URL":"https:\/\/doi.org\/10.3390\/s24144611","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,7,16]]}}}