A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits

The thesis describes an investigation into the use of rectangular dielectric waveguide (RDWG) as a new technique for the determination of both complex permittivity and moisture content of oil palm fruits. The technique is analysed from the viewpoint of assessing its suitability as a simple, quick a...

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Main Author:	Mokhtar, Roslina
Format:	Thesis
Language:	English English
Published:	2004
Subjects:	Oil palm - Moisture - Measurement - Case studies
Online Access:	http://psasir.upm.edu.my/id/eprint/579/1/549670_FS_2004_15.pdf
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spelling	my-upm-ir.5792013-05-27T06:49:27Z A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits 2004-10 Mokhtar, Roslina The thesis describes an investigation into the use of rectangular dielectric waveguide (RDWG) as a new technique for the determination of both complex permittivity and moisture content of oil palm fruits. The technique is analysed from the viewpoint of assessing its suitability as a simple, quick and flexible approach to permittivity and moisture measurements. An effective permittivity model is proposed where the rectangular dielectric waveguide/sample/rectangular dielectric waveguide interfaces are represented by a homogeneous medium with an effective permittivity obtained from the solution to the wave equation in the rectangular dielectric waveguide whilst the effective permittivity of the sample was found using a dielectric mixture model. The transmission and reflection coefficients are considered to be the effective values due to various interactions at the rectangular dielectric waveguide/sample/rectangular dielectric waveguide interfaces, which include both the radiation and guided modes. The measurement system consists of a HP8720B Vector Network Analyzer (VNA), rectangular dielectric waveguide, WR-90 standard waveguides and horn antennas. All microwave measurements were carried out using the VNA in the frequency range between 8 GHz and 12 GHz. A dielectric measurement software has been developed to control and retrieve data from the VNA using Agilent Visual Engineering Environment Software. The actual moisture content was found by applying standard oven drying method. A calibration equation relating the measured return loss and actual moisture content was established. The sensitivity of the rectangular dielectric waveguide sensor at 10 GHz is dB/% moisture content. The complex permittivity of the fruit samples was calculated using two methods. In the first method, the permittivity was calculated by inserting predicted moisture content values from an empirical relationship between the return loss and moisture content in the oil palm fruits into a dielectric mixture model. The second method directly calculates both the moisture content and permittivity using an optimization routine. The accuracy of the technique for the determination of moisture content was tested on 500 different fruit samples and was found to be within ±5% of the mean moisture content value from the standard oven drying method. The rectangular dielectric waveguide technique can be used to monitor fruit ripeness based on the measurement of the magnitude of the reflection coefficient alone. Fruit bunch with return loss values between 4.4 and 4.7 dB are considered ripe. Oil palm - Moisture - Measurement - Case studies 2004-10 Thesis http://psasir.upm.edu.my/id/eprint/579/ http://psasir.upm.edu.my/id/eprint/579/1/549670_FS_2004_15.pdf application/pdf en public masters Universiti Putra Malaysia Oil palm - Moisture - Measurement - Case studies Faculty of Science English
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English English
topic	Oil palm - Moisture - Measurement - Case studies
spellingShingle	Oil palm - Moisture - Measurement - Case studies Mokhtar, Roslina A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits
description	The thesis describes an investigation into the use of rectangular dielectric waveguide (RDWG) as a new technique for the determination of both complex permittivity and moisture content of oil palm fruits. The technique is analysed from the viewpoint of assessing its suitability as a simple, quick and flexible approach to permittivity and moisture measurements. An effective permittivity model is proposed where the rectangular dielectric waveguide/sample/rectangular dielectric waveguide interfaces are represented by a homogeneous medium with an effective permittivity obtained from the solution to the wave equation in the rectangular dielectric waveguide whilst the effective permittivity of the sample was found using a dielectric mixture model. The transmission and reflection coefficients are considered to be the effective values due to various interactions at the rectangular dielectric waveguide/sample/rectangular dielectric waveguide interfaces, which include both the radiation and guided modes. The measurement system consists of a HP8720B Vector Network Analyzer (VNA), rectangular dielectric waveguide, WR-90 standard waveguides and horn antennas. All microwave measurements were carried out using the VNA in the frequency range between 8 GHz and 12 GHz. A dielectric measurement software has been developed to control and retrieve data from the VNA using Agilent Visual Engineering Environment Software. The actual moisture content was found by applying standard oven drying method. A calibration equation relating the measured return loss and actual moisture content was established. The sensitivity of the rectangular dielectric waveguide sensor at 10 GHz is dB/% moisture content. The complex permittivity of the fruit samples was calculated using two methods. In the first method, the permittivity was calculated by inserting predicted moisture content values from an empirical relationship between the return loss and moisture content in the oil palm fruits into a dielectric mixture model. The second method directly calculates both the moisture content and permittivity using an optimization routine. The accuracy of the technique for the determination of moisture content was tested on 500 different fruit samples and was found to be within ±5% of the mean moisture content value from the standard oven drying method. The rectangular dielectric waveguide technique can be used to monitor fruit ripeness based on the measurement of the magnitude of the reflection coefficient alone. Fruit bunch with return loss values between 4.4 and 4.7 dB are considered ripe.
format	Thesis
qualification_level	Master's degree
author	Mokhtar, Roslina
author_facet	Mokhtar, Roslina
author_sort	Mokhtar, Roslina
title	A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits
title_short	A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits
title_full	A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits
title_fullStr	A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits
title_full_unstemmed	A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits
title_sort	new rectangular dielectric waveguide technique for ripeness determination of palm fruits
granting_institution	Universiti Putra Malaysia
granting_department	Faculty of Science
publishDate	2004
url	http://psasir.upm.edu.my/id/eprint/579/1/549670_FS_2004_15.pdf
_version_	1747810253568737280

A New Rectangular Dielectric Waveguide Technique for Ripeness Determination of Palm Fruits

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