{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T13:18:35Z","timestamp":1785417515961,"version":"3.56.0"},"reference-count":33,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T00:00:00Z","timestamp":1783641600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100009757","name":"National Institute of Advanced Industrial Science and Technology","doi-asserted-by":"crossref","award":["NMIJ\/AIST"],"award-info":[{"award-number":["NMIJ\/AIST"]}],"id":[{"id":"10.13039\/100009757","id-type":"DOI","asserted-by":"crossref"}]},{"award":["NMIJ\/AIST"],"award-info":[{"award-number":["NMIJ\/AIST"]}],"id":[{"id":"https:\/\/ror.org\/01703db54","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Accurate and traceable attenuation measurements are essential for RF instrumentation, communication equipment, electromagnetic compatibility (EMC) testing, and wide dynamic-range signal characterization. This paper presents a practical, accurate, and robust working-standard attenuation measurement system covering the frequency range from 9 kHz to 10 MHz for traceable RF attenuation calibration and wide dynamic-range characterization. The system is based on a direct RF substitution technique and employs two cascaded resistive step attenuators with 10 dB and 1 dB step sizes as the reference standard, providing a total attenuation range of 60 dB with 1 dB resolution. A general-purpose receiver is used as a precision level detector, enabling a simple and fully automated measurement configuration. Traceability is established through calibration against an inductive voltage divider (IVD)-based primary attenuation standard. Owing to the excellent frequency flatness of the reference standard, a single-frequency calibration at 1 MHz is sufficient to characterize the entire operating range from 9 kHz to 10 MHz. The direct measurement capability extends to 60 dB and is further expanded beyond 100 dB through a double-step measurement technique. A comprehensive uncertainty evaluation in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) yields expanded uncertainties of 3.6 \u00d7 10\u22123 dB at 20 dB, 5.6 \u00d7 10\u22123 dB at 60 dB, and 8.4 \u00d7 10\u22123 dB at 100 dB. Measurements up to 60 dB show excellent agreement with the primary attenuation standard, while alternative validation demonstrates consistency at 80 dB and 100 dB. The obtained uncertainty levels are comparable to or lower than those reported for similar systems in the literature. The proposed system provides a practical and traceable solution for routine RF attenuation calibration, supporting EMC testing, communication-system characterization, RF sensing and measurement applications, and the dissemination of RF metrological traceability.<\/jats:p>","DOI":"10.3390\/s26144379","type":"journal-article","created":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T11:43:34Z","timestamp":1783683814000},"page":"4379","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Wide Dynamic Range RF Attenuation Calibration System for 9 kHz to 10 MHz"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7550-3337","authenticated-orcid":false,"given":"Anton","family":"Widarta","sequence":"first","affiliation":[{"name":"Research Institute for Physical Measurement, National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8563, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Collin, R.E. (2001). Foundations for Microwave Engineering, Wiley-IEEE Press. [2nd ed.].","DOI":"10.1109\/9780470544662"},{"key":"ref_2","unstructured":"Pozar, D.M. (2011). Microwave Engineering, Wiley. [4th ed.]."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Beatty, R.W. (1967). Microwave Attenuation Measurements and Standards, National Bureau of Standards.","DOI":"10.6028\/NBS.MONO.97"},{"key":"ref_4","unstructured":"Warner, F.L. (1977). Microwave Attenuation Measurement, Peter Peregrinus."},{"key":"ref_5","unstructured":"Tse, D., and Viswanath, P. (2012). Fundamentals of Wireless Communication, Cambridge University Press."},{"key":"ref_6","unstructured":"(2013). IEEE Standard for Calibration of Electromagnetic Field Sensors and Probes (Excluding Antennas) from 9 kHz to 40 GHz (Standard No. IEEE Std 1309-2013)."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Ott, H.W. (2009). Electromagnetic Compatibility Engineering, Wiley.","DOI":"10.1002\/9780470508510"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1109\/MSP.2016.2628914","article-title":"Automotive Radars: A Review of Signal Processing Techniques","volume":"34","author":"Patole","year":"2017","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"845","DOI":"10.1109\/TMTT.2011.2178427","article-title":"Millimeter-Wave Technology for Automotive Radar Sensors in the 77 GHz Frequency Band","volume":"60","author":"Hasch","year":"2012","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Lee, J.-E., Kwon, S., and Jung, S.-H. (2021). Real-Time Calibration and Monitoring of Radar Reflectivity on Nationwide Dual-Polarization Weather Radar Network. Remote Sens., 13.","DOI":"10.3390\/rs13152936"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1109\/TIM.1969.4313806","article-title":"Superheterodyne measurement of microwave attenuation at a 10 kHz intermediate frequency","volume":"18","author":"Clark","year":"1969","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1109\/TIM.1978.4314623","article-title":"A voltage doubling circuit for absolute calibration of 30-MHz attenuation measurement systems","volume":"27","author":"Solmo","year":"1978","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1109\/19.192324","article-title":"30-MHz attenuation standard using binary phase modulation method","volume":"38","author":"Kawakami","year":"1989","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1014","DOI":"10.1109\/19.245655","article-title":"RF attenuation measurement system with 1-kHz voltage ratio standard","volume":"42","author":"Kawakami","year":"1993","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_15","first-page":"2408","article-title":"The waveguide below-cutoff attenuation standard","volume":"45","author":"Russell","year":"1997","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"705","DOI":"10.1109\/TIM.2004.843336","article-title":"Uncertainty evaluation of a broadband attenuation standard","volume":"54","author":"Lee","year":"2005","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_17","unstructured":"Gao, Q.L., Liang, W., Huang, H., and Chen, H. (2006, January 9\u201314). Design of attenuation calibrator. Proceedings of the 2006 Conference on Precision Electromagnetic Measurements Digest, Torino, Italy."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1109\/TIM.2007.891133","article-title":"Attenuation-Measurement System in the Frequency Range of 18\u201340 GHz","volume":"56","author":"Widarta","year":"2007","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Wu, T.Y., and Chua, S.W. (2009, January 5\u20137). Broadband microwave attenuation measurement standard in the frequency range from 10 MHz to 26.5 GHz. Proceedings of the IEEE Instrumentation and Measurement Technology Conference, Singapore.","DOI":"10.1109\/IMTC.2009.5168714"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2921","DOI":"10.1109\/TIM.2010.2045944","article-title":"Attenuation Standard in the Frequency Range of 50\u201375 GHz","volume":"59","author":"Iida","year":"2010","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1016\/j.measurement.2012.01.030","article-title":"Accurate measurement of millimeter-wave attenuation from 75 GHz to 110 GHz using a dual-channel heterodyne receiver","volume":"45","author":"Wu","year":"2012","journal-title":"Measurement"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1865","DOI":"10.1109\/TIM.2016.2549718","article-title":"A novel hybrid-channel attenuation measurement system at 50\u2013110 GHz","volume":"65","author":"Gao","year":"2016","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_23","unstructured":"(2014). Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods\u2014Part 2-1: Methods of Measurement of Disturbances and Immunity\u2014Conducted Disturbance Measurements (Standard No. CISPR 16-2-1:2014)."},{"key":"ref_24","unstructured":"(2017). American National Standard for Electroma gnetic Compatibility\u2014Radiated Emission Measurements in Electromagnetic Interference (EMI) Control\u2014Calibration and Qualification of Antennas (9 kHz to 40 GHz) (Standard No. ANSI C63.5-2017). Available online: https:\/\/ebooks.mpdl.mpg.de\/ebooks\/Record\/EB001577861."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1109\/19.377838","article-title":"The accurate measurement of high attenuation at radio frequencies","volume":"44","author":"Kilby","year":"1995","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"370","DOI":"10.26866\/jees.2024.4.r.236","article-title":"Attenuation measurement using the IF substitution method in the frequency range of 9 kHz to 10 MHz","volume":"4","author":"Lee","year":"2024","journal-title":"J. Electromagn. Eng. Sci."},{"key":"ref_27","unstructured":"International Bureau of Weights and Measures (2026, April 25). Key and Supplementary Comparisons. Available online: https:\/\/www.bipm.org\/kcdb."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Widarta, A. (2025). A Traceable Low-Frequency Attenuation Standard from 1 kHz to 10 MHz for Next Generation Wireless and EMC Calibration. Sensors, 25.","DOI":"10.3390\/s25196227"},{"key":"ref_29","first-page":"91","article-title":"RF attenuation calibration system in the frequency range of 9 kHz to 10 MHz","volume":"78","author":"Widarta","year":"2016","journal-title":"J. Teknol. (Sci. Eng.)"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1587\/transele.2024MMP0003","article-title":"Double step technique for accurate microwave high attenuation measurements","volume":"E107-C","author":"Widarta","year":"2024","journal-title":"IEICE Trans. Electron."},{"key":"ref_31","unstructured":"ISO (1993). Guide to the Expression of Uncertainty in Measurement, International Organization for Standardization (ISO). [1st ed.]."},{"key":"ref_32","unstructured":"(2017). General Requirements for the Competence of Testing and Calibration Laboratories, 3rd ed. (Standard No. ISO\/IEC 17025:2017(E))."},{"key":"ref_33","first-page":"35","article-title":"Re-examination of mismatch uncertainty when measuring microwave power and attenuation","volume":"128","author":"Harris","year":"1981","journal-title":"Proc. Inst. Electr. Eng."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/14\/4379\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,12]],"date-time":"2026-07-12T04:21:28Z","timestamp":1783830088000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/14\/4379"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,10]]},"references-count":33,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["s26144379"],"URL":"https:\/\/doi.org\/10.3390\/s26144379","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,10]]}}}