Development of pure and adulterated honey measurement system using multiple frequencies six-port reflectometer (SPR)

Abstract

This thesis presents a study on the development of multiple frequencies Six-Port Reflectometer (SPR) in characterizing pure and adulterated honey through reflection measurement. As honey adulteration is one of major health concern among consumer, thus it has paramount importance in inspecting the quality of honey. One of proposed methods is to characterize honey by using microwave reflection technique because this technique is simple, rapid and non-destructive. However, due to bulky and expensive PNA network analyzer, thus, SPR is introduced. In this work, reduction of cost and compactness are the main concern in designing Five-Port ring junction circuit. The microstrip Five-Port ring junction circuit was designed using AWR Microwave Office 2002. The fabricated circuit works with PICO analogue-digital converter (ADC), openended coaxial sensor, diode detectors and computing machine to form a complete SPR measurement system. The reflection measurements were conducted on Honey Gold and Trigona Honey for multiple frequencies of 0.60 GHz, 0.64 GHz, 0.80 GHz, 2.28 GHz, 2.42 GHz, 2.82 GHz, 3.47 GHz, 3.75 GHz and 4.21 GHz since most of the developed SPR implement at single frequency. The performance of SPR in reflection measurement was verified by Agilent E8362B PNA Network Analyzer. Besides, dielectric measurement was conducted to investigate its dielectric behavior due to water and sucrose content in honey. It can be noticed that dielectric constant, ε’ decreases when frequency increases. In the meantime, ε’ decreases with increases water and sucrose content for Honey Gold and Trigona Honey. Meanwhile, for water adulterated Honey Gold and Trigona Honey, loss factor, ε” decrease when frequencies increases. In addition, ε” decreases when water content < 36% and < 43% for Honey Gold and Trigona Honey, respectively. It can be found that at 1 GHz to 4 GHz, ε” increases when sucrose content increases which applicable for Honey Gold and Trigona Honey. In reflection measurement, magnitude of reflection coefficient, |Γ| decrease when frequency increases for all percentage of water and sucrose content for both honeys. Withal, phase, -φ increases as frequency increases for both water adulterated honeys. -φ varies insignificantly when sucrose content increases for both sucrose adulterated honeys. Furthermore, it was found that all fabricated circuits have good agreement in measurement for |Г| and φ. The measurement accuracy of water adulterated between PNA and SPR for both honeys exhibit absolute error less than 0.15 in |Г| and absolute error of 17° in φ. Meanwhile, sucrose adulterated honey measurement provides the high accuracy in measurement of sucrose content with absolute error for |Г| is less than 0.13 and in φ is 14°. On the other hand, all fabricated SPR circuits are able to provide an accurate prediction in terms of water content and sucrose content. This study shows that the SPR can be an alternative in replacing the bulky and expensive PNA. The SPR is a simple, fast, accurate and portable instrumentation system for characterize pure and adulterated honey.