In this work, sensor abilities of the metamaterial absorber based on swastika shaped resonator are developed both theoretically and experimentally at X-band frequency range. The structure is ...consisted of a swastika shaped resonator on the top of dielectric layer and have an air gap to fill chemicals liquids between the copper plate and backside resonator. In this study, a full-wave EM solver CST Microwave Studio (Computer Simulation Technology) based on finite integrate technique has been used to simulate and investigate the absorption of the metamaterial structure with chemicals liquids depending on the electrical properties. A vector network analyzer 85070E probe kit has been used to measure the relative dielectric constants and loss tangent of some chemical liquids (ethanol content, methanol content, acetone, methanol, ethanol, Polyethylene Glycol 300, water) in the related frequency range. Absorption value of the sensor structure for selected chemicals placed in the air gaphas been investigated. It is obtained that there is a significant difference in absorption ratios between each chemicals and overall resonance frequency shifts have been observed which provides information to accurately estimate density rate of the sensed liquids. The absorption mechanisms of the metamaterial has been explained by using electric field, magnetic field and surface current distributions. Furthermore, the resonance absorption properties of the metamaterial based absorber sensor can be modified and adjusted easily by varying the dimensions of the resonator.
Experimental and simulated results demonstrate that the resonance frequency of the swastika metamaterial based sensor is linearly related to the permittivity of selected chemicals which creates an appropriate approach for multipurpose sensor devise and electrochemical sensor.
•Physical mechanism of absorption investigated by simulating surface current, electric and magnetic field distribution.•The dimensions effect of the resonator has been carried out.•Simulated and measured values for the absorption are in a good agreement.•The proposed metamaterial sensor is highly sensitive to the considered chemical liquids.
In this study, composites composed of glass fiber reinforced-epoxy laminates interleaved with electrospun polyvinylchloride (PVC) nano-fibres were designed for radar absorption investigations. The ...laminated composites which were produced in special molds were obtained by placing woven glass fibers between each of PVC nanofiber mats, and the composites were produced in three different forms as pure, multi-walled carbon nanotubes doped and graphene doped. The morphologies of the PVC nanofiber mats were analyzed by scanning electron microscope. The radar absorption efficiencies of the composites in the individual and different combinations were measured in the 3–8 GHz frequency band. Experimental results show that the produced graphene-added composite material has improvable microwave absorption effect at several points in 3–8 GHz band to provide excellent absorption in future studies. The graphene doped structure was found to have a certain absorption characteristic up to 33.82% at a constant frequency. Besides, various strong absorption frequency points have been obtained in the related frequency range. The cascaded graphene doped composite layers can provide broadband absorption for stealth technology.
In this study, Ni
x
Co
1−x
Fe
2
O
4
/Ni:ZnO (x:0.0, 0.5, and 1.0) epoxy-based composite structures were manufactured by sol–gel method. The structural, morphological and magnetic characteristics were ...investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Electromagnetic wave (EMW) absorption measurements were carried out using a vector network analyzer (VNA) between 8 and 12 GHz (X band). Ni substitution with Co decreases the crystallite size, average particle size, magnetic saturation (
M
s
)
and the coercive field (
H
c
) values of cobalt-ferrite spinel structure. EMW characterization results showed that minimum reflection loss (RL) − 30.91 dB (99.9% absorption) at 10.76 GHz, and the maximum bandwidth of 1.81 GHz were observed for the RAM1 composite. In addition, the substitution of Ni
2+
into the cobalt–ferrite structure resulted in the shifting absorption peaks to the higher frequency region (towards
K
u
band).
In this paper, a new metamaterials-based hypersensitized liquid sensor integrating omega-shaped resonator with microstrip transmission line is proposed. Microwave transmission responses to industrial ...energy-based liquids are investigated intensively from both numerical and experimental point of view. Simulation results concerning three-dimensional electromagnetic fields have shown that the transmission coefficient of the resonator could be monitored by the magnetic coupling between the transmission line and omega resonator. This sensor structure has been examined by methanol-water and ethanol-water mixtures. Moreover, the designed sensor is demonstrated to be very sensitive for identifying clean and waste transformer oils. A linear response characteristic of shifting the resonance frequency upon the increment of chemical contents/concentrations or changing the oil condition is observed. In addition to the high agreement of transmission coefficients (S21) between simulations and experiments, obvious resonant-frequency shift of transmission spectrum is recognized for typical pure chemical liquids (i.e., PEG 300, isopropyl alcohol, PEG1500, ammonia, and water), giving rise to identify the type and concentration of the chemical liquids. The novelty of the work is to utilize Q factor and minimum value of S21 as sensing agent in the proposed structure, which are seen to be well compatible at different frequencies ranging from 1-20 GHz. This metamaterial integrated transmission line-based sensor is considered to be promising candidate for precise detection of fluidics and for applications in the field of medicine and chemistry.
The detection of chemical samples having close dielectric response is a big challenge as the detection principle is driven by the variations in the dielectric parameters of the investigated samples. ...In the current work, a new metamaterial-based sensor is designed and fabricated in order to be used for the detection of liquid chemicals in the frequency range from 8 to 12 GHz. Several designs were tested using genetic algorithm, which is embedded in the CST microwave studio, in order to optimize the desired dimensions of the resonator. The simulation and experimental results showed that the proposed sensor is working well to detect various liquids, including (i) clean and waste transformer oils, (ii) corn, cotton and olive oils, (iii) branded and unbranded diesels and (iv) aniline doped ethyl-alcohol and benzene doped carbon tetrachloride. This was made possible through the occurrence of a shift in the resonant frequency of about 250 MHz, 200 MHz, 250 MHz, 150 MHz and 50 MHz for the aforementioned samples, respectively. The sensing mechanism was interpreted through the surface current and electric field distributions. We believe that the proposed sensor is viable to be used in various applications including liquid chemicals detection and industrial applications.
In this study, a triangular array of cylindrical holes was shown to function as a local resonator to seismic metamaterials against the vibration generator loading in the geophysics concept. The field ...test showed that the seismic waves applied to one side of the proposed array interacted with the triangularly arranged holes, resulting in a strong attenuation in two narrow frequency bands. The numerical analysis was carried out using simulations based on the finite element method, which provides optimal dimensions and arrangement at a sub-wavelength scale to achieve maximum attenuation against incoming seismic wave at a very low frequency range. Different band gaps were observed due to interaction of the longitudinal resonance between the cylindrical holes and vertical components of soil response under the applied wave. Experimental analysis was carried out using optimum dimensions and hole arrangements, and a strong attenuation due to impedance matching between soil and seismic metamaterials was shown. It was also observed that, at very low frequencies, the soil response was due to the inverse proportionality between the resonator length and the seismic energy wavelength applied for longitudinal resonance. Two band gaps have been observed around 25–36 Hz as shown in band diagram. The proposed structure exactly prevents the seismic wave propagation at 25 Hz and 36 Hz in accordance with band diagram. Therefore, the proposed system can prevent the seismic waves from attaining the backside of the seismic array. The attenuation was obtained at a level of 0.00125, observed at a 0.0001 source point, measured by a speed sensor located at the back of the seismic metamaterials, with an attenuation rate of 12.5 at 8 Hz.
In this study, the electromagnetic interference (EMI) and ultraviolet–infrared (UV–IR) shielding behavior of wool (WO) and cotton/elastane (CO/EL) nanocomposite fabrics have been investigated. The ...study aims to investigate the EMI and UV–IR shielding performance of the CO/EL and wool-based fabrics coated with carbon (C), graphite (Gr), and indium (In) nanocomposite layers. To produce nanocomposite fabric samples, these three materials were used in different compositions and the coating processes were carried out by electron cyclotron resonance (ECR) and thermal evaporation methods. Subsequently, the EMI and UV–IR measurements were performed for the coated fabric samples, and the results have been analyzed. In this study, it has been proven for the first time that the ECR coating method can be used for coating fabrics as a textile material. Finally, it is found that the C+Gr(grid filled)+In wool sample and the carbon-coated CO/EL sample have widely exhibited a significant positive effect on increasing the EMI shielding performance in the range of 18–43 and 12–18 GHz frequencies, respectively. In addition, the results show that the C+Gr(grid)+C-coated CO/EL fabric has significant potential to increase the UV–IR shielding performance.
In this study, the structural and magnetic properties of Ni
x
Co
1−x
Fe
2
O
4
(0.0
≤
x
≤
1.0) and ZnO nanoparticles synthesized by the sol-gel method were investigated. The microwave property of the ...composite structures produced from the combination of ZnO and Ni
x
Co
1−x
Fe
2
O
4
nanoparticles dispersed in the epoxy matrix property was studied in the X-band frequency range. The crystal structures of Ni
x
Co
1−x
Fe
2
O
4
have not been disrupted by Ni substitution, however, the lattice parameters of samples decrease due to the smaller ionic radii of Ni
+2
compared to Co
+2
ions. The magnetic saturation
(M
s
)
and remanence magnetization
(M
r
)
decreased with an increasing amount of Ni in Ni
x
Co
1−x
Fe
2
O
4
structure. According to the microwave absorption properties of samples, the maximum reflection loss (RL) value was found as −28.10 dB at 10.23 GHz frequency in RAC
4
sample. On the other hand, maximum bandwidth was found at 2.95 GHz around −10 dB for RAC
5
sample. All composites exhibit efficient RL in the X-band indicating that they can be used in potential applications in aviation, radar, and defense vehicles.
In this paper, a wideband antenna is proposed for ultra-wideband microwave imaging applications. The antenna is comprised of a tapered slot ground, a rectangular slotted patch and four star-shaped ...parasitic components. The added slotted patch is shown to be effective in improving the bandwidth and gain. The proposed antenna system provides a realized gain of 6 dBi, an efficiency of around 80% on the radiation bandwidth, and a wide impedance bandwidth (S11 < -10 dB) of 6.3 GHz (from 3.8 to 10.1 GHz). This supports a true wideband operation. Furthermore, the fidelity factor for face-to-face (FtF) direction is 91.6%, and for side by side (SbS) is 91.2%. This proves the excellent directionality and less signal distortion of the designed antenna. These high figures establish the potential use of the proposed antenna for imaging. A heterogeneous breast phantom with dielectric characteristics identical to actual breast tissue with the presence of tumors was constructed for experimental validation. An antenna array of the proposed antenna element was situated over an artificial breast to collect reflected and transmitted waves for tumor characterization. Finally, an imaging algorithm was used to process the retrieved data to recreate the image in order to detect the undesirable tumor object inside the breast phantom.
PDF
