Realizing the High Q-Factor of a CSIW Microwave Resonator Based on an MDGS for Semisolid Material Characterization

Abstract

In this work, the high-quality factor (Q-factor) and high sensitivity of a circular substrate-integrated waveguide (CSIW) are proposed for the characterization of semisolid materials. The modeled sensor was designed based on the CSIW structure with a mill-shaped defective ground structure (MDGS) to improve measurement sensitivity. The designed sensor oscillates at a single frequency of 2.45 GHz, which was simulated using an Ansys HFSS simulator. Electromagnetic simulation explains the basis of the mode resonance of all two-port resonators. Six variations of the materials under test (SUTs) were simulated and measured, including air (without an SUT), Javanese turmeric, mango ginger, black turmeric, turmeric, and distilled water (DI). A detailed sensitivity calculation was performed for the resonance band at 2.45 GHz. The SUT test mechanism was performed using a polypropylene tube (PP). The samples of dielectric material were filled into the channels of the PP tube and loaded into the center hole of the MDGS. The E-fields around the sensor affect the relationship with the SUTs, resulting in a high Q-factor value. The final sensor had a Q-factor of 700 and a sensitivity of 2.864 at 2.45 GHz. Due to the high sensitivity of the presented sensor for characterization of various semisolid penetrations, the sensor is also of interest for accurate estimation of solute concentration in liquid media. Finally, the relationship between the loss tangent, permittivity, and Q-factor at the resonant frequency were derived and investigated. These results make the presented resonator ideal for the characterization of semisolid materials.

A Miniaturized and Highly Sensitive Microwave Sensor Based on CSRR for Characterization of Liquid Materials

“…Two different methods have been presented to characterize the permittivity of the sensor: dumbbell-shaped microwave sensors [40] and slow-wavelength microfluidic integrated waveguides [41]. In particular, numerous approaches have been used to determine the properties of the samples under study, such as complementary split-ring resonators (CSRRs), which are considered to be the most typical resonators in the structure of microwave sensors for fluids [42][43][44][45]. In [42], a sensor was designed to maintain the media under tests (MUTs) in a liquid state during experiments, which caused an RF loss in the liquid and affected the measurement accuracy.…”

“…In particular, numerous approaches have been used to determine the properties of the samples under study, such as complementary split-ring resonators (CSRRs), which are considered to be the most typical resonators in the structure of microwave sensors for fluids [42][43][44][45]. In [42], a sensor was designed to maintain the media under tests (MUTs) in a liquid state during experiments, which caused an RF loss in the liquid and affected the measurement accuracy. While the microwave sensors proposed by Kiani et al [43] can accurately measure the dielectric constant of liquids, they are unable to measure the loss tangent of the liquid material.…”

Ultrasensitive miniaturized planar microwave sensor for characterization of water–alcohol mixtures

“…Substrate-integrated waveguides 29 – 31 and microstrip resonators 32 are also among other structures utilized for dielectric characterization. Furthermore, some designs rely on strong electrical fields generated in structures such as interdigital capacitors (IDC) to increase the sensitivity for the characterization of dielectric 33 , 34 and magnetodielectric materials 35 .…”