{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,27]],"date-time":"2025-10-27T04:57:41Z","timestamp":1761541061582,"version":"build-2065373602"},"reference-count":8,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2011,4,6]],"date-time":"2011-04-06T00:00:00Z","timestamp":1302048000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents the development of a PC-based microwave five-port reflectometer for the determination of moisture content in oil palm fruits. The reflectometer was designed to measure both the magnitude and phase of the reflection coefficient of any passive microwave device. The stand-alone reflectometer consists of a PC, a microwave source, diode detectors and an analog to digital converter. All the measurement and data acquisition were done using Agilent VEE graphical programming software. The relectometer can be used with any reflection based microwave sensor. In this work, the application of the reflectometer as a useful instrument to determine the moisture content in oil palm fruits using monopole and coaxial sensors was demonstrated. Calibration equations between reflection coefficients and moisture content have been established for both sensors. The equation based on phase measurement of monopole sensor was found to be accurate within 5% in predicting moisture content in the fruits when compared to the conventional oven drying method.<\/jats:p>","DOI":"10.3390\/s110404073","type":"journal-article","created":{"date-parts":[[2011,9,27]],"date-time":"2011-09-27T20:09:10Z","timestamp":1317154150000},"page":"4073-4085","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":30,"title":["Determination of Moisture Content in Oil Palm Fruits Using a Five-Port Reflectometer"],"prefix":"10.3390","volume":"11","author":[{"given":"Lee Kim","family":"Yee","sequence":"first","affiliation":[{"name":"Department of Electrical and Electronic Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Setapak, Kuala Lumpur, Malaysia"}]},{"given":"Zulkifly","family":"Abbas","sequence":"additional","affiliation":[{"name":"Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia"}]},{"given":"Mohamad Ashry","family":"Jusoh","sequence":"additional","affiliation":[{"name":"Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5214-7571","authenticated-orcid":false,"given":"You Kok","family":"Yeow","sequence":"additional","affiliation":[{"name":"Radio Communication Engineering Department (RaCED), Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia"}]},{"given":"Cheng Ee","family":"Meng","sequence":"additional","affiliation":[{"name":"School of Mechatronic Engineering, University Malaysia Perlis, Ulu Pauh Campus, 02600 Arau, Perlis, Malaysia"}]}],"member":"1968","published-online":{"date-parts":[[2011,4,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1075","DOI":"10.1109\/TMTT.1977.1129277","article-title":"The Six-Port Reflectometer: An Alternative Network Analyzer","volume":"25","author":"Engen","year":"1977","journal-title":"IEEE Trans. Microwave Theory Tech"},{"key":"ref_2","unstructured":"Ball, JAR, Horsfield, B, Holdem, JR, Keam, RB, Holmes, WS, and Green, A (1997, January 2\u20135). Cheese Curd Permittivity and Moisture Measurement Using a 6-Port Reflectometer. Hong Kong."},{"key":"ref_3","first-page":"22","article-title":"Software Support for Six-Port Measurement System","volume":"4","author":"Urbanec","year":"2004","journal-title":"Meas. Sci. Rev"},{"key":"ref_4","first-page":"285","article-title":"The Six Port Reflectometer and its Complete Calibration by Four Standard Terminations","volume":"135","author":"Ganouchi","year":"1988","journal-title":"IEEE Proc"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1109\/TMTT.1983.1131477","article-title":"An Ideal Six-Port Network Consisting of a Matched Reciprocal Lossless Five-Port and a Perfect Directional Coupler","volume":"31","author":"Hansson","year":"1983","journal-title":"IEEE Trans. Micro. Theory Techn"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Chahine, SA, Huyart, B, and Osman, Z (2003, January 18\u201320). Performance Comparison Between Six Port and Five-Port Reflectometer. Cairo, Egypt.","DOI":"10.1109\/NRSC.2003.157316"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1281","DOI":"10.1109\/JSEN.2005.859249","article-title":"Complex Permittivity and Moisture Measurements of Oil Palm Fruits Using an Open-Ended Coaxial Sensor","volume":"5","author":"Abbas","year":"2005","journal-title":"IEEE Sens. J"},{"key":"ref_8","unstructured":"Durney, CH, and Iskander, MF (1993). Antenna Handbook, Van Nostrand Reinhold. Chapter 24."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/4\/4073\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:55:45Z","timestamp":1760219745000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/4\/4073"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011,4,6]]},"references-count":8,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2011,4]]}},"alternative-id":["s110404073"],"URL":"https:\/\/doi.org\/10.3390\/s110404073","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2011,4,6]]}}}