{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T16:23:38Z","timestamp":1772555018568,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,1,25]],"date-time":"2022-01-25T00:00:00Z","timestamp":1643068800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"University of Rijeka","award":["1435"],"award-info":[{"award-number":["1435"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, we present a simple yet efficient method for determination of the relative permittivity of thin dielectric materials. An analysis that led to definition of the proper size and placement of a sample under test (SUT) on the surface of a microstrip ring resonator (MRR) was presented based on the full-wave simulations and measurements on benchmark materials. For completeness, the paper includes short descriptions of the design of an MRR and the variational method-based algorithm that processes the measured values. The efficiency of the proposed method is demonstrated on 12 SUT materials of different thicknesses and permittivity values, and the accuracy between 0% and 10% of the relative error was achieved for all SUTs thinner than 2 mm.<\/jats:p>","DOI":"10.3390\/s22030928","type":"journal-article","created":{"date-parts":[[2022,1,25]],"date-time":"2022-01-25T21:07:11Z","timestamp":1643144831000},"page":"928","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["A Simplified Measurement Configuration for Evaluation of Relative Permittivity Using a Microstrip Ring Resonator with a Variational Method-Based Algorithm"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8080-2342","authenticated-orcid":false,"given":"Miroslav","family":"Joler","sequence":"first","affiliation":[{"name":"Department of Computer Engineering, Faculty of Engineering, University of Rijeka, 51000 Rijeka, Croatia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1505-3159","authenticated-orcid":false,"given":"Alex Noel Joseph","family":"Raj","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, College of Engineering, Shantou University, Shantou 515063, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9003-0198","authenticated-orcid":false,"given":"Juraj","family":"Bartoli\u0107","sequence":"additional","affiliation":[{"name":"Department of Wireless Communications, Faculty of Electrical Engineering and Computing, University of Zagreb, 10000 Zagreb, Croatia"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,25]]},"reference":[{"key":"ref_1","unstructured":"Phommakesone, S. 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