Estimation of dielectric constant for various standard materials using microstrip ring resonator

Microstrip ring resonator (MRR) is known for dielectric constant determination and many studies used Teflon as a standard sample. However, there are many other materials available which able to perform better or equivalence as the Teflon in calibrating certain dielectric constant measurement. This paper presents simulation of the MRR to investigate frequency shift of materials for dielectric constant estimation using the CST STUDIO SUITE 2016 software. The MRR was designed on RT/Duroid®5880 substrate (εr = 2.2, tanδ = 0.0004) with 50 Ω matching impedance where microstrip width, substrate thickness and ring mean radius were 4.893, 1.575 and 14 mm, respectively to resonate at 2.65340 GHz. Teflon, Polyimide, Isola FR408, Arlon AD250, Arlon AD270 and Gil GML1032 were alternately selected to be placed on top of the MRR as a standard sample to obtain the frequency shift. The frequency shifts for the above materials were 2.56932, 2.46149, 2.44680, 2.53748, 2.52007 and 2.48608 GHz, correspondingly. The differences in frequency shift were used in NetBeans IDE 8.1 algorithm of Java for dielectric constant calculation. The results indicated that Polyimide and Arlon AD250 had the lowest and highest mean percentage error of 0.83536 and 1.76505 %, respectively. Hence, Polyimide might as well be the most suitable candidate as a standard sample in MRR technique for dielectric constant measurement

Multiband metamaterial microwave absorbers using split ring and multiwidth slot structure

This article proposes a multiband metamaterial microwave absorber based on a split ring-slot structure. Both simulation and experimental measurements are carried out to obtain the scattering parameters which are used to retrieve the absorption coefficient, relative permittivity, and relative permeability. The influences on the absorption produced by geometrical dimensions, incidence angles and polarisation angles are investigated from 1.5 to 18.0 GHz. The results show that the absorber possesses three resonance peaks with absorption greater than 70% measured experimentally at 3.0, 5.8, and 11.0 GHz. The absorption performance is insensitive to the angle of incidence, θ up to 60�.The absorption mechanisms are studied based on the surface current distribution, electric field distribution, and constitutive parameters (μr and εr). Furthermore, a mechanical mean using dielectric material to tune the absorption frequencies (up to 1.0 GHz of tuning range) and enhance the absorption bandwidth (up to 50%) is demonstrated

Controlling the properties of OPEFBPLA polymer composite by using fe2o3 for microwave applications

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe2O3) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S11 and coefficient of transmission S21 of the composites for various Fe2O3 filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe2O3) reduces the crystallinity of the composites. SEM data indicated that Fe2O3 filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8-12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe2O3 embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe2O3 filler content. Theoretical simulation studied the relation between ε' and ε" of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe2O3/OPEFB/PLA, the unique dielectric characteristics of Fe2O3 cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe2O3 filler in the composite

Complex permittivity of materials at broadband frequency using transmission phase shift method

This paper reports determination of complex relative permittivity of non-magnetic samples Teflon, Nylon and Epoxy via transmission phase shift method. The transmission phase shift method offers calibration independent and invariant position features. In this work, a Coaxial Cavity Test Fixture (CCTF) with dimension of 1.8 and 4.1 mm for inner and outer conductor, respectively was customized based on impedance matching theory to study broadband scattering in the range of frequency 1-18 GHz. Impedance matching and cable calibration were performed to reduce the measurement error of scattering parameters; reflection and transmission . Magnitude and phase of and were measured by vector network analyzer (VNA). The measured phase of ( ) for all samples under test were linearized using the MATLAB “unwrap” command for further calculation of . The phase shift in between with and without sample inside the cavity was detected and it was used to determine for each material under test. The average value of dielectric constants for Teflon, Nylon and Epoxy were 2.11, 2.42 and 3.05, correspondingly for the selected frequency 2, 4, 6, 8, 10, 12 and 14 GHz. While, the average of dielectric losses for Teflon and Epoxy were almost overlapped which the values were 0.001 and 0.002, respectively that were higher than that of Nylon at 0.0006. The calculated values are comparable with the theoretical values with small absolute errors. These results suggested that this transmission phase shift method using CCTF was equally consistent when compared to the other techniques used for the determination of and

Finite Element Analysis (FEA) in Electronics Devices and Photonics through Process Oriented Guided Inquiry Learning (POGIL)

Advance and complex mathematical skill such as finite element analysis are traditionally required to the understanding of electronics devices and photonics applications. Unless the students want to further their studies in theoretical field using complex calculations, students are offered an alternate learning skill such as POGIL by using software simulation packages with embedded FEA to help them visualize the abstract of photonics theories. Students were allowed to modify the original template given in the package, but in the learning process, they have to answer several guided questions in the activity specified. We presented two studies: Thermo Photovoltaic (TPV) cell and Acoustic Levitator (AL), prepared by two groups of third year physics students using COMSOL software and POGIL. As a result, students were able to complete their activities with a new skill of a standard researche

Synthesis and Properties of Zinc Iron Phosphate Glasses Prepared by Microwave and Conventional Processing Methods

The synthesis and properties of zinc iron phosphate glasses, xZnO-(40-x)Fe2O3-60P2O5 where x = 0, 2.5, 5.0, 7.5, 10.0 (mol %) formed using domestic microwave oven and electric furnace are reported. In microwave glass melting, microwave absorber namely high purity magnetite powder has successfully coupled with microwave radiation at 2.45 GHz and completed the glass melting process at about 10 minutes radiation time. The properties of microwave samples are compared with equivalent samples prepared conventionally by melting the batches at 1300 ËšC for 2 hours in electric furnace. Although the mass loss trend is in agreement with the theoretical data, it is found that the microwave melted samples have slight increase in mass loss than conventionally melted ones and the mass loss is increased gradually with the increasing of ZnO contents. The powder density values of zinc iron phosphate glasses prepared using microwave method is found to be higher than the corresponding glasses prepared using conventional processing method. Identical trend of Fourier transform infrared spectra are recorded despite using different processing methods; it is clear that the addition of ZnO increased the cross-linking in the glass structure as well as improving the strength of the samples. Overall, the use of microwave radiation for the production of zinc iron phosphate glasses are promising and viable method as it gives comparable properties, faster glass melting and low energy consumption compared to conventional melting method

Physical characterization and electrical conductivity of Li1.2Ti1.8Al0.2(PO4)3 and Li1.2Ta0.9Al1.1(PO4)3 NASICON material

Sodium superionic conducting materials (NASICON) are promising solid electrolytes for Li-ion batteries and suitable to be used in the area that requires high energy density as well as rechargeable power sources. Fabrication of all-solid-state Li battery with non-flammable ceramics electrolyte has been strongly required to solve safety issues of present Li batteries. In this study, lithium titanium aluminium phosphate Li1+xTi2-xAlx(PO4)3, LTAP (x = 0.2) and lithium tantalum aluminium phosphate Li1+2xTa1-xAlx+1(PO4)3, LTaAP (x = 0.1) were prepared via conventional solid state reaction techniques at various sintering temperature ranging from 700 to 1000 °C. LTAP and LTaAP compositions attain their optimum sintering temperature at 800 °C. Physical properties of LTAP and LTaAP show the bulk density of 2.83 and 3.63 g/cm3 which resulted into high densification of the material. The XRD analysis revealed NASICON crystalline phase dominated by LiTi2(PO4)3 and minor impurity phases for LTaAP composition. Bulk conductivity values for LTAP and LTaAP were found to be 1.06 x 10-4 and 9.854 x 10-6 S/cm at room temperature. LTAP had better conductivity behavior compare to LTaAP composition which could be due to differences in their ionic radius (titanium, 0.605 nm tantalum, 0.64 nm and the aluminium, 0.53 nm) in sizes, though the conductivity obtained for both compositions has the capacity to serve as solid electrolyte material could be used in lithium ion rechargeable battery

Effect in positioning gold nanoparticle inside Plasmonic Solar Cell on absorption, reflection and transmission

Gold nanoparticle has been explored in different ways to enhance the absorption of light and improve the efficiency of plasmonic solar cell. In this study, various positions of a gold nanoparticle which are at 115 nm, 230 nm and 305 nm measured vertically from the bottom of the solar cell to the centre of gold nanoparticle embedded into silicon layer of plasmonic solar cell is demonstrated using numerical simulation. The aim is to investigate the absorption, reflection and transmission percentage with different wavelength in different position of gold nanoparticle in plasmonic solar cell. The numerical results showed that the highest absorption and lowest reflection and transmission occurred at position 305 nm in the range 100 nm to 1000 nm compared to the simulation without nanoparticle and other position. The overall simulation results proved that at position 305 nm of gold nanoparticle which is near to the top layer is more efficient because this position has high electric field intensity in visible range

Controlling the properties of OPEFB/PLA polymer composite by using Fe2O3 for microwave applications

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe2O3) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S11 and coefficient of transmission S21 of the composites for various Fe2O3 filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe2O3) reduces the crystallinity of the composites. SEM data indicated that Fe2O3 filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8–12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe2O3 embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe2O3 filler content. Theoretical simulation studied the relation between ε′ and ε″ of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe2O3/OPEFB/PLA, the unique dielectric characteristics of Fe2O3 cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe2O3 filler in the composites

Effect of processing parameters on the morphology, particulate, and superconducting properties of electrospun YBCO nanostructures

Superconductivity in nanostructured ceramics offers significant advantages over the conventional coarse-grained materials in view of miniaturization of superconducting electronic devices. In this paper, we report the formation of four morphologies of superconducting YBa2Cu3O7-δ (YBCO) nanostructures by electrospinning technique using polymeric polyvinyl pyrrolidone (PVP) solutions of different molecular weight and altering the total content of the metallic precursors. The morphologies prepared using this strategy are nanorods (NRs), nanogarlands (NGs), nanohierarchical (NH), and nanoparticles (NPs). Alternating current susceptibility measurements showed high critical temperatures (TC ~90 K) for the NH YBCO synthesized using PVP of the lowest molecular weight; whereas the YBCO NRs synthesized using a higher molecular weight polymer showed the lowest TC (82 K). A relationship between the particulate properties and TC was also observed – the lower is the pore size the higher is the TC. The YBCO NGs showed the highest specific surface area (7.06 m2/g) with intermediate TC (88 K). Electrospinning process appears an effective and controllable technique to produce different nanomorphologies with intrinsic properties suitable for practical applications