{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T02:56:37Z","timestamp":1762052197324,"version":"build-2065373602"},"reference-count":48,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,5,28]],"date-time":"2022-05-28T00:00:00Z","timestamp":1653696000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"ERDF\u2014European Regional Development Fund, through the Operational Programme for Competitiveness and Internationalisation\u2014COMPETE 2020 Programme","award":["POCI-01-0247-FEDER-046081"],"award-info":[{"award-number":["POCI-01-0247-FEDER-046081"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Applied Sciences"],"abstract":"<jats:p>Soil Moisture (SM) is one of the most critical factors for a crop\u2019s growth, yield, and quality. Although Ground-Penetrating RADAR (GPR) is commonly used in satelite observation to analyze soil moisture, it is not cost-effective for agricultural applications. Automotive RADAR uses the concept of Frequency-Modulated Continuous Wave (FMCW) and is more competitive in terms of price. This paper evaluates the viability of using a cost-effective RADAR as a substitute for GPR for soil moisture content estimation. The research consisted of four experiments, and the results show that the RADAR\u2019s output signal and the soil moisture sensor SEN0193 have a high correlation with values as high as 0.93 when the SM is below 15%. Such results show that the tested sensor (and its cost-effective working principle) are able to determine soil water content (with certain limitations) in a non-intrusive, proximal sensing manner.<\/jats:p>","DOI":"10.3390\/app12115471","type":"journal-article","created":{"date-parts":[[2022,5,29]],"date-time":"2022-05-29T08:50:51Z","timestamp":1653814251000},"page":"5471","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Contactless Soil Moisture Mapping Using Inexpensive Frequency-Modulated Continuous Wave RADAR for Agricultural Purposes"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8821-2224","authenticated-orcid":false,"given":"Rui M.","family":"Coutinho","sequence":"first","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, 4200-465 Porto, Portugal"},{"name":"FEUP\u2014Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0317-4714","authenticated-orcid":false,"given":"Armando","family":"Sousa","sequence":"additional","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, 4200-465 Porto, Portugal"},{"name":"FEUP\u2014Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8486-6113","authenticated-orcid":false,"given":"Filipe","family":"Santos","sequence":"additional","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8299-324X","authenticated-orcid":false,"given":"M\u00e1rio","family":"Cunha","sequence":"additional","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, 4200-465 Porto, Portugal"},{"name":"FCUP\u2014Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1175\/2007JCLI1822.1","article-title":"Global Trends and Variability in Soil Moisture and Drought Characteristics, 1950\u20132000, from Observation-Driven Simulations of the Terrestrial Hydrologic Cycle","volume":"21","author":"Sheffield","year":"2008","journal-title":"J. Clim."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1038\/s41558-018-0138-5","article-title":"Anthropogenic warming exacerbates European soil moisture droughts","volume":"8","author":"Samaniego","year":"2018","journal-title":"Nat. Clim. Chang."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.earscirev.2010.02.004","article-title":"Investigating soil moisture\u2013climate interactions in a changing climate: A review","volume":"99","author":"Seneviratne","year":"2010","journal-title":"Earth-Sci. Rev."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Dirmeyer, P.A. (2011). The terrestrial segment of soil moisture\u2013climate coupling. Geophys. Res. Lett., 38.","DOI":"10.1029\/2011GL048268"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1068","DOI":"10.1126\/science.1128845","article-title":"Global Hydrological Cycles and World Water Resources","volume":"313","author":"Oki","year":"2006","journal-title":"Science"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1016\/j.actao.2003.10.004","article-title":"Effects of soil moisture regimes on photosynthesis and growth in cattail (Typha latifolia)","volume":"25","author":"Li","year":"2004","journal-title":"Acta Oecol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3161","DOI":"10.1007\/s11269-017-1722-6","article-title":"Satellite Soil Moisture: Review of Theory and Applications in Water Resources","volume":"31","author":"Srivastava","year":"2017","journal-title":"Water Resour. Manag."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"102297","DOI":"10.1016\/j.ndteint.2020.102297","article-title":"Using GPR to analyze regeneration success of cork oaks in the Ma\u00e2mora forest (Morocco)","volume":"115","author":"Ponette","year":"2020","journal-title":"NDT E Int."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"180052","DOI":"10.2136\/vzj2018.03.0052","article-title":"Measuring Soil Water Content with Ground Penetrating Radar: A Decade of Progress","volume":"17","author":"Klotzsche","year":"2018","journal-title":"Vadose Zone J."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Viscarra Rossel, R., Mcbratney, A., and Minasny, B. (2010). Proximal Soil Sensing, Sringer.","DOI":"10.1007\/978-90-481-8859-8"},{"key":"ref_11","unstructured":"(2021, December 12). ESA\u2014Satellite Frequency Bands. Available online: https:\/\/www.esa.int\/Applications\/Telecommunications_Integrated_Applications\/Satellite_frequency_bands."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Hardie, M. (2020). Review of Novel and Emerging Proximal Soil Moisture Sensors for Use in Agriculture. Sensors, 20.","DOI":"10.3390\/s20236934"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1016\/j.agwat.2016.12.002","article-title":"Automatic fault detection in a low cost frequency domain (capacitance based) soil moisture sensor","volume":"183","author":"Oates","year":"2017","journal-title":"Agric. Water Manag."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"530","DOI":"10.1029\/2018RG000618","article-title":"Ground, Proximal, and Satellite Remote Sensing of Soil Moisture","volume":"57","author":"Babaeian","year":"2019","journal-title":"Rev. Geophys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1007\/s11104-018-03919-5","article-title":"Non-invasive estimation of root zone soil moisture from coarse root reflections in ground-penetrating radar images","volume":"436","author":"Liu","year":"2019","journal-title":"Plant Soil"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Toy, C.W., Steelman, C.M., and Endres, A.L. (2010, January 21\u201325). Comparing electromagnetic induction and ground penetrating radar techniques for estimating soil moisture content. Proceedings of the XIII Internarional Conference on Ground Penetrating Radar, Lecce, Italy.","DOI":"10.1109\/ICGPR.2010.5550068"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/j.measurement.2014.04.007","article-title":"A critical review of soil moisture measurement","volume":"54","author":"Singh","year":"2014","journal-title":"Measurement"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Chang, X., Jin, T., Yu, K., Li, Y., Li, J., and Zhang, Q. (2019). Soil Moisture Estimation by GNSS Multipath Signal. Remote Sens., 11.","DOI":"10.3390\/rs11212559"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Zhang, L., Lu, T., Yu, P., and Zhang, C. (2019, January 29\u201331). Parameter Measurement of Soil Moisture based on GNSS-R Signals. Proceedings of the 2019 IEEE International Conference on Artificial Intelligence and Computer Applications (ICAICA), Dalian, China.","DOI":"10.1109\/ICAICA.2019.8873523"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Larson, K.M., Small, E.E., Gutmann, E.D., Bilich, A.L., Braun, J.J., and Zavorotny, V.U. (2008). Use of GPS receivers as a soil moisture network for water cycle studies. Geophys. Res. Lett., 35.","DOI":"10.1029\/2008GL036013"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1002\/wat2.1097","article-title":"Emerging methods for noninvasive sensing of soil moisture dynamics from field to catchment scale: A review","volume":"2","author":"Bogena","year":"2015","journal-title":"WIREs Water"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1109\/JSTARS.2009.2033612","article-title":"GPS Multipath and Its Relation to Near-Surface Soil Moisture Content","volume":"3","author":"Larson","year":"2010","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Koch, F., Schlenz, F., Prasch, M., Appel, F., Ruf, T., and Mauser, W. (2016). Soil Moisture Retrieval Based on GPS Signal Strength Attenuation. Water, 8.","DOI":"10.3390\/w8070276"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Han, M., Zhu, Y., Yang, D., Hong, X., and Song, S. (2018). A Semi-Empirical SNR Model for Soil Moisture Retrieval Using GNSS SNR Data. Remote Sens., 10.","DOI":"10.3390\/rs10020280"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1931","DOI":"10.5194\/hess-22-1931-2018","article-title":"Deriving surface soil moisture from reflected GNSS signal observations from a grassland site in southwestern France","volume":"22","author":"Zhang","year":"2018","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Badewa, E., Unc, A., Cheema, M., Kavanagh, V., and Galagedara, L. (2018). Soil Moisture Mapping Using Multi-Frequency and Multi-Coil Electromagnetic Induction Sensors on Managed Podzols. Agronomy, 8.","DOI":"10.3390\/agronomy8100224"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"459","DOI":"10.2136\/sssaj2014.09.0360","article-title":"The Use of Electromagnetic Induction to Monitor Changes in Soil Moisture Profiles beneath Different Wheat Genotypes","volume":"79","author":"Shanahan","year":"2015","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1016\/j.catena.2016.09.018","article-title":"Using residual analysis in electromagnetic induction data interpretation to improve the prediction of soil properties","volume":"149","author":"Lu","year":"2017","journal-title":"CATENA"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1524","DOI":"10.1029\/2019JG005046","article-title":"Pattern Extraction of Topsoil and Subsoil Heterogeneity and Soil-Crop Interaction Using Unsupervised Bayesian Machine Learning: An Application to Satellite-Derived NDVI Time Series and Electromagnetic Induction Measurements","volume":"124","author":"Wang","year":"2019","journal-title":"J. Geophys. Res. Biogeosci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1267","DOI":"10.1111\/j.1365-246X.2010.04706.x","article-title":"Joint full-waveform analysis of off-ground zero-offset ground penetrating radar and electromagnetic induction synthetic data for estimating soil electrical properties","volume":"182","author":"Moghadas","year":"2010","journal-title":"Geophys. J. Int."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.jappgeo.2011.08.002","article-title":"High-resolution imaging of a vineyard in south of France using ground-penetrating radar, electromagnetic induction and electrical resistivity tomography","volume":"78","author":"Saussez","year":"2012","journal-title":"J. Appl. Geophys."},{"key":"ref_32","unstructured":"(2022, April 28). Radar Systems Tutorial. Available online: https:\/\/www.tutorialspoint.com\/radar_systems\/index.htm."},{"key":"ref_33","unstructured":"Wolff, C. (2021, December 12). Doppler Filter. Available online: https:\/\/www.radartutorial.eu\/11.coherent\/Doppler-Filter.en.html."},{"key":"ref_34","unstructured":"Khan, R., and Power, D. (1995, January 8\u201311). Aircraft detection and tracking with high frequency radar. Proceedings of the International Radar Conference, Alexandria, VA, USA."},{"key":"ref_35","unstructured":"Cook, C.E., and Bernfeld, M. (1993). Radar Signals: An Introduction to Theory and Application, Artech House."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Maaref, N., Millot, P., Pichot, C., and Picon, O. (October, January 30). Ultra-wideband Frequency Modulated Continuous Wave synthetic aperture radar for Through-The-Wall localization. Proceedings of the 2009 European Radar Conference (EuRAD), Rome, Italy.","DOI":"10.23919\/EUMC.2009.5296253"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"McGregor, J.D., Silva, R.S., and Almeida, E.S. (2018). Architectures of Transportation Cyber-Physical Systems, Elsevier. Chapter 2.","DOI":"10.1016\/B978-0-12-814295-0.00002-2"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Grasmueck, M., and Viggiano, D. (2018, January 18\u201321). PondView: Intuitive and Efficient Visualization of 3D GPR Data. Proceedings of the 17th International Conference on Ground Penetrating Radar (GPR), Rapperswil, Switzerland.","DOI":"10.1109\/ICGPR.2018.8441634"},{"key":"ref_39","unstructured":"(2021, December 12). IWR1843BOOST Evaluation Board|TI.com. Available online: https:\/\/www.ti.com\/tool\/IWR1843BOOST."},{"key":"ref_40","unstructured":"(2021, December 12). Capacitive Soil Moisture Sensor SKU SEN0193 DFRobot. Available online: https:\/\/wiki.dfrobot.com\/Capacitive_Soil_Moisture_Sensor_SKU_SEN0193."},{"key":"ref_41","unstructured":"Adafruit (2021, December 12). AM2302 (Wired DHT22) Temperature-Humidity Sensor. Available online: https:\/\/www.adafruit.com\/product\/393."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Nagahage, E.A.A.D., Nagahage, I.S.P., and Fujino, T. (2019). Calibration and Validation of a Low-Cost Capacitive Moisture Sensor to Integrate the Automated Soil Moisture Monitoring System. Agriculture, 9.","DOI":"10.3390\/agriculture9070141"},{"key":"ref_43","unstructured":"Muzdrikah, F.S., Nuha, M.S., and Rizqi, F.A. (2018, January 7\u20138). Calibration of Capacitive Soil Moisture Sensor (SKU:SEN0193). Proceedings of the 4th International Conference on Science and Technology (ICST), Yogyakarta, Indonesia."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Sofwan, A., Sumardi, S., Ahmada, A.I., Ibrahim, I., Budiraharjo, K., and Karno, K. (2020, January 20). Smart Greetthings: Smart Greenhouse Based on Internet of Things for Environmental Engineering. Proceedings of the International Conference on Smart Technology and Applications (ICoSTA), Surabaya, Indonesia.","DOI":"10.1109\/ICoSTA48221.2020.1570614124"},{"key":"ref_45","unstructured":"Li, M. (2021, December 12). Humidity Sensors\u2014Resistive or Capacitive?. Available online: https:\/\/www.zhinst.com\/europe\/en\/blogs\/humidity-sensors-resistive-or-capacitive-mfia-can-tell-answer."},{"key":"ref_46","unstructured":"Hayes, A. (2021, April 29). Cross-Correlation. Available online: https:\/\/www.investopedia.com\/terms\/c\/crosscorrelation.asp."},{"key":"ref_47","unstructured":"(2021, December 12). AxiDraw Writing and Drawing Machines. Available online: https:\/\/www.axidraw.com\/."},{"key":"ref_48","unstructured":"(2021, December 12). Drawing Robot\u2014Arduino Uno + CNC Shield + GRBL by henryarnold\u2014Thingiverse. Available online: https:\/\/www.thingiverse.com\/thing:2349232."}],"container-title":["Applied Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-3417\/12\/11\/5471\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:20:23Z","timestamp":1760138423000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-3417\/12\/11\/5471"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,28]]},"references-count":48,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2022,6]]}},"alternative-id":["app12115471"],"URL":"https:\/\/doi.org\/10.3390\/app12115471","relation":{},"ISSN":["2076-3417"],"issn-type":[{"type":"electronic","value":"2076-3417"}],"subject":[],"published":{"date-parts":[[2022,5,28]]}}}