{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:24:46Z","timestamp":1760243086321,"version":"build-2065373602"},"reference-count":14,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2015,9,15]],"date-time":"2015-09-15T00:00:00Z","timestamp":1442275200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Foundation of China","award":["61403160"],"award-info":[{"award-number":["61403160"]}]},{"DOI":"10.13039\/501100002858","name":"China Postdoctoral Science Foundation","doi-asserted-by":"publisher","award":["2014M551194"],"award-info":[{"award-number":["2014M551194"]}],"id":[{"id":"10.13039\/501100002858","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Science and Technology Office, Jilin Province of China","award":["20140520118JH","20150414052GH"],"award-info":[{"award-number":["20140520118JH","20150414052GH"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>An air-coil sensor (ACS) is a type of induction magnetometer used as a transducer to measure the variations of a magnetic field. This device is widely applied in helicopter transient electromagnetic method (TEM) exploration. Most helicopter TEM explorations generate common-mode noise and require extreme ACS specifications, both of which inevitably challenge geophysical explorations. This study proposes a differential air-core coil combined with a differential pre-amplifier to reduce the common-mode noise induced in exploration surveys. To satisfy the stringent performance requirements, including the geometric parameters and electrical specifications, the physical calculations in theory and the equivalent schematic of an ACS with noise location are investigated, respectively. The theory calculation and experimental result for the optimized ACS are then compared on the basis of a differential structure. Correspondingly, an ACS is constructed with a mass, resultant effective area, 3 dB bandwidth, signal-to-noise ratio, and normalized equivalent input noise of 2.5 kg, 5.5 m2 (diameter is 0.5 m), 71 kHz, 20 (the varying magnetic field strength is 1 nT\/s), and 5.43 nV\/m2, respectively. These data are superior to those of the traditional induction sensor 3D-3. Finally, a field experiment is performed with a fabricated sensor to show a valid measurement of the time-varying magnetic field of a helicopter TEM system based on the designed ACS.<\/jats:p>","DOI":"10.3390\/s150923325","type":"journal-article","created":{"date-parts":[[2015,9,16]],"date-time":"2015-09-16T10:33:36Z","timestamp":1442399616000},"page":"23325-23340","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Investigation and Optimization of the Performance of  an Air-Coil Sensor with a Differential Structure Suited to Helicopter TEM Exploration"],"prefix":"10.3390","volume":"15","author":[{"given":"Chen","family":"Chen","sequence":"first","affiliation":[{"name":"College of Instrumentation & Electrical Engineering, Jilin University, Changchun 130061, China"},{"name":"Key Laboratory of Geo-exploration Instruments, Ministry of Education of China,  Changchun 130061, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fei","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Instrumentation & Electrical Engineering, Jilin University, Changchun 130061, China"},{"name":"Key Laboratory of Geo-exploration Instruments, Ministry of Education of China,  Changchun 130061, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun","family":"Lin","sequence":"additional","affiliation":[{"name":"College of Instrumentation & Electrical Engineering, Jilin University, Changchun 130061, China"},{"name":"Key Laboratory of Geo-exploration Instruments, Ministry of Education of China,  Changchun 130061, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanzhang","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Instrumentation & Electrical Engineering, Jilin University, Changchun 130061, China"},{"name":"Key Laboratory of Geo-exploration Instruments, Ministry of Education of China,  Changchun 130061, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,9,15]]},"reference":[{"key":"ref_1","unstructured":"Allard, M. (2007, January 9\u201312). On the origin of the HTEM species. Proceedings of the Exploration 07: Fifth Decennial International Conference on Mineral Exploration, Toronto, ON, Canada."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"631","DOI":"10.1109\/JSEN.2006.874493","article-title":"Magnetic sensors and their applications","volume":"6","author":"Lenz","year":"2006","journal-title":"IEEE Sens. J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"R31","DOI":"10.1088\/0957-0233\/18\/3\/R01","article-title":"Induction coil sensors\u2014A review","volume":"18","author":"Tumanski","year":"2007","journal-title":"Meas. Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"11539","DOI":"10.3390\/s130911539","article-title":"Research on the dynamic hysteresis loop model of the residence times difference (RTD)-fluxgate","volume":"13","author":"Wang","year":"2013","journal-title":"Sensors"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1007\/s11214-008-9371-y","article-title":"First results of the THEMIS search coil magnetometers","volume":"141","author":"Contel","year":"2008","journal-title":"Space Sci. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/S0263-2241(00)00034-8","article-title":"Advanced field magnetometers comparative study","volume":"29","author":"Korepanov","year":"2001","journal-title":"Measurement"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1109\/TGE.1979.294613","article-title":"Optimization theory for induction-coil magnetometers at higher frequencies","volume":"17","author":"Lukoschus","year":"1979","journal-title":"IEEE Trans. Geosci. Electron."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2719","DOI":"10.1109\/JSEN.2012.2202179","article-title":"Analytical optimization of low-frequency search coil magnetometers","volume":"12","author":"Grosz","year":"2012","journal-title":"IEEE Sens. J."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4442","DOI":"10.1109\/JSEN.2014.2336971","article-title":"Equivalent input magnetic noise analysis for the induction magnetometer of 0.1 mHz to 1 Hz","volume":"14","author":"Yan","year":"2014","journal-title":"IEEE Sens. J."},{"key":"ref_10","unstructured":"Geonics Limited, Geophysical Instrumentation for Exploration & the Environment. Available online: http:\/\/www.geonics.com\/."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Zhao, J., Zhang, Y., Lee, Y.H., and Krause, H.J. (2014). Investigation and optimization of low-frequency noise performance in readout electronics of dc superconducting quantum interference device. Rev. Sci. Instrum.","DOI":"10.1063\/1.4878342"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Lin, T., Zhang, Y., Lee, Y.H., Krause, H.J., Lin, J., and Zhao, J. (2014). High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range. Rev. Sci. Instrum.","DOI":"10.1063\/1.4901964"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"712","DOI":"10.3390\/s6070712","article-title":"A miniaturized magnetic induction sensor using geomagnetism for turn count of small-caliber ammunition","volume":"6","author":"Yoon","year":"2006","journal-title":"Sensors"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2468","DOI":"10.3390\/s140202468","article-title":"Magnetic sensor for building structural vibrations","volume":"14","author":"Tremps","year":"2014","journal-title":"Sensors"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/9\/23325\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T20:48:33Z","timestamp":1760215713000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/9\/23325"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,9,15]]},"references-count":14,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2015,9]]}},"alternative-id":["s150923325"],"URL":"https:\/\/doi.org\/10.3390\/s150923325","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2015,9,15]]}}}