Accounting of the parasitic effects during measurement of the effective permittivity using the quarter-wavelength resonator method

The analysis, approximations and accounting of the influence of the main parasitic effects that affect the results of the measurement are provided in this paper. The method of dielectric constant measurement of coaxial connectors support beads is suggested. The comparison between the acquired results using the suggested method and the reference is made. The results suggest that the method can be used for dielectric constant measurement of the coaxial connector support beads with the accuracy comparable to the method of the volume resonator for rod samples H01p by GOST 8.623-2015.

Design of a High Sensitivity Microwave Sensor for Liquid Dielectric Constant Measurement

In order to improve the sensitivity of liquid dielectric constant measurements, a liquid dielectric constant sensor based on a cubic container structure is proposed for the first time. The cubic container, which consists of a dielectric substrate with a split resonant ring (SRR) and microstrip lines, can enhance the electric field intensity in the measuring area. High sensitivity can be obtained from measuring the dielectric constant with the characteristics of the structure resonate. The research results show that the resonant frequency of the sensor is shifted from 7.69 GHz to 5.70 GHz, with about a 2 GHz frequency offset, when the dielectric constant of the sample varied from 1 to 10. A resonance frequency offset of 200 MHz for the per unit dielectric constant is achieved, which is excellent regarding performance. The permittivity of oil with a different metal content is measured by using the relation between the fitted permittivity and the resonant frequency. The relative error is less than 1.5% and the sensitivity of measuring is up to 3.45%.

Moisture content investigation in the soil samples using microwave dielectric constant measurement method

The microwaves of typical frequency ranges of 3 GHz to 30 GHz have been in use for remote sensing applications which are progressing rapidly. The microwaves can sense existing moisture in any material that absorbs moisture such as soil or vegetation. In case of soils which may be comprised of variable mix proportionate of solids, liquids or gases and distinct textures subjected to the associated size and the arrangements of soil particles. Hence, the moisture absorption by a specific type of soil used to be different. The inherent physical and electrical properties such as color, texture, grains, dielectric constant, conductivity or permeability, etc. differentiate various soils. In this work, authors present soil moisture measurement by simple estimation of emissivity i.e. the ratio of energy radiated by an object to absorbing the body of same physical temperature. A strategic method of measuring dielectric constant using a microwave signal is used in this research work. The measurement of the dielectric constant of the soils collected from the specific regions and analysis of results has been reported. The proposed method is less complex and can further be used for the identification of soil moisture and agricultural applications.

Effect of Strontium Doping Into CaBi2Nb2O9 Aurivillius Oxide Nanoceramics: Structural and Electrical Properties

Herein, we report the synthesis and characterization of Ca1-xSrxBi2Nb2O9 (CSBNO) (0 ≤ x ≤ 1) nanoceramics prepared using sucrose-assisted sol–gel combustion methods. The synthesized nanoceramics were characterized by different tools like differential thermal and thermogravimetric analyzer (DTA-TG), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectrometer, X-ray powder diffraction (XRD), and impedance analyzer. DTA-TG reveals that the optimum temperature of calcination of CBN is higher than 1000 °C. The FTIR revealed the formation of CaBi2Nb2O9 (CBNO) at 614 cm-1. The XRD confirmed that all samples exhibited orthorhombic crystal structure. Increased orthorhombic distortion was spotted for doped CBNO and the structure acquires extra orthorhombicity through Sr doping. The TEM measurement inspected the increase of the grain size due to the inclusion of strontium into the orthorhombic crystal structure of CBNO from 56 nm to 76 nm. The dielectric constant measurement demonstrated that the increase in Sr content is associated with steady decrease in Curie temperature from 1207 K up to 720 K. The dielectric loss exhibited a minimum value at x = 0.5 and high stability along the temperature range of 300–850 K. Such property may enable this nanocomposite to be used for the application of FeRAM.

Frying Oil Evaluation by a Portable Sensor Based on Dielectric Constant Measurement

A portable capacitive sensor was designed to assess frying oil degradation by measuring the changes in electrical capacitance. An interdigital electrode (IDE) was designed to be implemented as the testing probe (as IDEs are resistive to parasitic capacitance), together with an adjacent capacitive chip Pcap01 and a further microprocessor STM32, which were used as the data-processing elements. Experimental results demonstrated that viscosity could be a useful frying oil quality indicator, and also proved a preliminary correlation between IDE capacitance and oils’ total polar materials. This implies that IDE capacitance could be a suitable metric for conveniently assessing frying oil degradation. The designed capacitance sensor is light in weight, cost effective, and has excellent potential for simple, inexpensive, on-the-spot testing of the current quality of frying oil.