X-band Microwave Research Articles

Role of Cx43 in iPSC-CM Damage Induced by Microwave Radiation.

The heart is one of the major organs affected by microwave radiation, and these effects have been extensively studied. Previous studies have shown that microwave-radiation-induced heart injury might be related to the abnormal expression and distribution of Cx43. In order to make the research model closer to humans, we used iPSC-CMs as the cell injury model to investigate the biological effect and mechanism of iPSC-CM injury after microwave radiation. To model the damage, iPSC-CMs were separated into four groups and exposed to single or composite S-band (2.856 GHz) and X-band (9.375 GHz) microwave radiation sources with an average power density of 30 mW/cm2. After that, FCM was used to detect cell activity, and ELISA was used to detect the contents of myocardial enzymes and injury markers in the culture medium, and it was discovered that cell activity decreased and the contents increased after radiation. TEM and SEM showed that the ultrastructure of the cell membrane, mitochondria, and ID was damaged. Mitochondrial function was aberrant, and glycolytic capacity decreased after exposure. The electrical conduction function of iPSC-CM was abnormal; the conduction velocity was decreased, and the pulsation amplitude was reduced. Wb, qRT-PCR, and IF detections showed that the expression of Cx43 was decreased and the distribution of Cx43 at the gap junction was disordered. Single or composite exposure to S- and X-band microwave radiation caused damage to the structure and function of iPSC-CMs, primarily affecting the cell membrane, mitochondria, and ID. The composite exposure group was more severely harmed than the single exposure group. These abnormalities in structure and function were related to the decreased expression and disordered distribution of Cx43.

Ba1−xSrxTiO3 thin-film-based X-band selective coplanar waveguide microwave resonator using SiO2 as buffer layer

Ba1−xSrxTiO3 thin-film-based X-band selective coplanar waveguide microwave resonator using SiO2 as buffer layer

Trident-shaped monopole antenna withp-methoxy-benzylidene-p-n-butyl aniline (MBBA) nematic liquid crystal (NLC) for C- and X-band applications

AbstractIn this research article, a novel MBBA nematic liquid crystal (NLC) based circular trident-shaped antenna is proposed for both C-band and X-band microwave applications. The proposed antenna contains a trident-shaped radiating patch, which is made of copper material, and glass material is utilized as a dielectric substrate for the proposed novel MBBA-based trident shaped antenna. The dielectric substrate contains two glass plates with a thickness of 1 mm each and is separated by an air gap of 0.003 mm to fill MBBA nematic liquid crystal. So, the overall size of the proposed antenna will become 15 × 20 × 2.003 mm3. The dielectric constant of each glass plate is chosen as 5.438. However, the antenna operates at a single frequency band, when MBBA material is not present between the glass plates and produces two distinct resonant frequencies when the air gap between the glass plates is filled with MBBA NLC. Antenna radiation parameters such as gain, radiation efficiency, reflection coefficient, and radiation patterns are compared for both simulation and measurement.

Crystal structure refinement, optical, magnetic, and X-band microwave shielding properties of Dy3+ doped Ni2Y-type strontium hexagonal ferrites

Ni2Y-type strontium hexaferrites having chemical dddof Sr1·8Ba0·2Ni2Fe12-xDyxO22 (x = 0.0, 0.1, 0.2) were made utilizing the sol-gel combustion technique. All samples' XRD patterns demonstrate the production of NiFe2O4 and Fe3O4 which are a phase that is intermediate in the synthesis of the required Ni2Y-type strontium hexaferrites. The FTIR indicates the presence of absorption peaks at about 557 and 432 cm−1, this shows the possibility of the formation of Y-type hexaferrites. UV-vis NIR spectroscopy analysis indicates that the energy band-gap of Y-type hexaferrites is affected by the increase in Dy3+ concentration. The values of the band-gap were found to be between 1.66 and 1.78 eV. According to the FESEM analysis, platelet-structure is formed with particles that range in size from 3.665 to 3.927 μm. The observed coercivity, saturation, and remnant magnetization first decreased with an increase in the concentration of Dy3+ for the sample having x = 0.1 and then increases for the sample with x = 0.2. The sample with the greatest amount of Dy3+ (i.e.x = 0.2) has a value of total shielding effectiveness of 27.5 dB. The prepared Ni2Y-type hexaferrites sample could be use for efficient shielding of microwaves in X-band.

Electron spin resonance and induction heating studies of zinc substituted (Mn, Co) ferrite nanoparticles for potential magnetic hyperthermia applications

This study presents an investigation on the various spin relaxation processes taking place at X-Band microwave energy in Zn substituted MnFe2O4 and CoFe2O4 and their induction heating studies. The material properties of these citric acid assisted sol-gel synthesized nanoparticles have been explored using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscope, Vibrating sample magnetometer (VSM) and Electron spin resonance spectroscopy. XRD and Rietveld refinement confirm the face centered cubic spinel structure of the synthesized samples, which is further supported by the observation of absorption bands characteristic of the spinel ferrites in the FTIR spectra. The remanence, coercivity and effective magnetocrystalline anisotropy values from VSM studies show lower value with zinc substitution which is desirable for biomedical application. Various spin resonance parameters like gyromagnetic ratio, peak to peak linewidth, resonance field, spin-lattice and spin-spin relaxation times have been calculated. The induction heating studies of the samples in an alternating magnetic field have been carried out using a field strength of 4.58 × 109 Am-1s-1. All the investigated MNPs are able to raise the temperature to the therapeutic limit of 42–45 °C. The specific absorption rate (SAR) which describe the heating potential of the MNPs is calculated using four different concentrations of each sample - 5 mg mL-1, 10 mg mL-1, 15 mg mL-1 and 20 mg mL-1. SAR values are found to decrease with increase in concentration and achieve the highest value of 303 W/g for Co0.5Zn0.5Fe2O4 nanoparticles with 5 mg mL-1 concentration. The ability of the MNPs to give rise to the therapeutic temperature points toward their suitability as an effective heat mediator in magnetic hyperthermia treatment of cancer.

Dielectric Characterization of Heterogeneous Composites Using Time Domain Spectroscopy and Microwave Test Benches in Microwave Frequency

Dielectric composite materials made of polymers and ferroelectric ceramics have recently emerged as one of the important components for applications involving the generation, transformation, and storage of sustainable energy. Because there is a trade-off between dielectric permittivity, dielectric loss, and dissipation factor, the end use is the energy storage capacity. In the present study, epoxy resin (RE)/barium titanate (BaTiO3) composite samples are prepared using the mixture cast method with new molds. The dielectric properties, such as dielectric permittivity, dielectric loss, electrical modulus, static conductivity and dissipation factors due to the concentration of barium titanate and frequency effect on the composites, are examined using two characterization methods. The objective of this study is to determine the dielectric permittivity of the material using two microwave methods, the first is time domain spectroscopy (TDS) and the second is on the X-band microwave test bench (MTB). Additionally, different empirical mixture laws are used to estimate the dielectric permittivity of our composites. It is found that an increase in filler concentration (BaTiO3) increases the effective dielectric permittivity, which is confirmed with different empirical mixture models. The findings of this research can be used for electrical devices, including sensors, wave absorbers, resonators, and antennas.

Optical, magnetic and spin resonance studies of MFe2O4 (M = Mn, Co, Zn) ferrites

MFe2O4 (M = Mn, Co, Zn) ferrites have been prepared using citric acid assisted sol–gel autocombustion technique. Structural, microstructural, optical, magnetic and spin resonance studies have been carried out using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscope (FESEM), UV–Visible spectroscopy, Vibrating sample magnetometer (VSM) and Electron spin resonance spectroscopy (ESR) respectively. The crystallite size determined using Scherrer method lies between 12 nm and 21 nm. From the UV–Visible absorption spectra the optical band gap energy, refractive index and optical dielectric constant have been estimated. The magnetic parameters have been obtained from the room temperature M−H loop of the ferrite samples. ESR spectra obtained at X-band microwave energy have been fitted using Lorentzian function to determine the spin resonance parameters like gyromagnetic ratio, peak to peak linewidth and resonance field. CoFe2O4 has the largest linewidth of 4874 Oe. The observed broad ESR linewidth of the investigated samples may find suitability as radar absorbing materials for microwave applications.

A low-noise X-band microwave source with digital automatic frequency control for electron paramagnetic resonance spectroscopy

We report a new design of microwave source for X-band electron paramagnetic resonance spectrometer. The microwave source is equipped with a digital automatic frequency control circuit. The parameters of the digital automatic frequency control circuit can be flexibly configured for different experimental conditions, such as the input powers or the quality factors of the resonator. The configurability makes the microwave source universally compatible and greatly extends its application. To demonstrate the ability of adapting to various experimental conditions, the microwave source is tested by varying the input powers and the quality factors of the resonator. A satisfactory phase noise as low as −135 dBc/Hz at 100-kHz offset from the center frequency is achieved, due to the use of a phase-locked dielectric resonator oscillator and a direct digital synthesizer. Continuous-wave electron paramagnetic resonance experiments are conducted to examine the performance of the microwave source. The outstanding performance shows a prospect of wide applications of the microwave source in numerous fields of science.

Heterointerfaces via decoration of walnut iron tungstate with bismuth vanadate as high efficiency X-band microwave absorbing materials

The fabrication of FeWO4/BiVO4 composites is a key initial step in the development of effective microwave absorber fillers. Tweaking the loading ratio of composites, complex permittivity and complex permeability of walnut-shaped FeWO4/BiVO4 microspheres is significantly improved. In addition, best sample displays a reasonable minimal reflection loss (RLmini) value, and its effective absorption bandwidth (EAB, with RL -10 dB) value is 3.6 GHz. Moreover, the best samples were evaluated via free-space testing technique too, and comparison is made between the waveguide and free-space measurements. Evidence suggests that the free-space approach can be a valuable additional testing strategy due to its touch-free and non-destructive characteristics. The ability to fabricate high-quality FeWO4/BiVO4 samples with adjustable characteristics and an alternate measurement procedure opens the door to promising novel microwave absorbers. As a result, FeWO4/BiVO4 is predicted to be an exceptionally efficient microwave absorbent material.

Aerodynamic slotted SIW-to-MS line transition using mitered end taper for satellite and RADAR communications

PurposeThis paper aims to present the design development and measurement of two aerodynamic slotted X-bands back-to-back planer substrate-integrated rectangular waveguide (SIRWG/SIW) to Microstrip (MS) line transition for satellite and RADAR applications. It facilitates the realization of nonplanar (waveguide-based) circuits into planar form for easy integration with other planar (microstrip) devices, circuits and systems. This paper describes the design of a SIW to microstrip transition. The transition is broadband covering the frequency range of 8–12 GHz. The design and interconnection of microwave components like filters, power dividers, resonators, satellite dishes, sensors, transmitters and transponders are further aided by these transitions. A common planar interconnect is designed with better reflection coefficient/return loss (RL) (S11/S22 ≤ 10 dB), transmission coefficient/insertion loss (IL) (S12/S21: 0–3.0 dB) and ultra-wideband bandwidth on low profile FR-4 substrate for X-band and Ku-band functioning to interconnect modern era MIC/MMIC circuits, components and devices.Design/methodology/approachTwo series of metal via (6 via/row) have been used so that all surface current and electric field vectors are confined within the metallic via-wall in SIW length. Introduced aerodynamic slots in tapered portions achieve excellent impedance matching and tapered junctions with SIW are mitered for fine tuning to achieve minimum reflections and improved transmissions at X-band center frequency.FindingsUsing this method, the measured IL and RLs are found in concord with simulated results in full X-band (8.22–12.4 GHz). RLC T-equivalent and p-equivalent electrical circuits of the proposed design are presented at the end.Practical implicationsThe measurement of the prototype has been carried out by an available low-cost X-band microwave bench and with a Keysight E4416A power meter in the microwave laboratory.Originality/valueThe transition is fabricated on FR-4 substrate with compact size 14 mm × 21.35 mm × 1.6 mm and hence economical with IL lie within limits 0.6–1 dB and RL is lower than −10 dB in bandwidth 7.05–17.10 GHz. Because of such outstanding fractional bandwidth (FBW: 100.5%), the transition could also be useful for Ku-band with IL close to 1.6 dB.

Broadband absorber with dispersive metamaterials

Abstract A broadband absorber that utilizes a dispersive metamaterial and covers the entire microwave X-band (8–12 GHz) is proposed in the present study. An ideal absorber attached to the surface of a perfect electric conductor requires the permittivity of the absorbing layer to be anomalously dispersive in the targeted broad frequency band. We show that anomalous dispersion of the permittivity for the X-band can be fitted to a two-pole Lorentz oscillator model and realized with the use of a double-layered, square-loop metamaterial. We explain the connection between the two-pole oscillator model and the double-layered, square-loop metamaterial using an equivalent circuit model and present explicit design rules for the metamaterial. We fabricate a 4-mm-thick metamaterial absorber with flexible silicon rubber, a resistor element, and conductive wire using carbon and silver conductive ink. Our metamaterial absorber achieves a reflectance of less than −20 dB over the entire X-band region.

Cr-substituted nanocrystalline Ni–Co ferrites: tuning dielectric, magnetic, structural, X-band microwave absorption, and characteristic properties

Cr-substituted nanocrystalline Ni–Co ferrites: tuning dielectric, magnetic, structural, X-band microwave absorption, and characteristic properties

Ultra-light-weight microwave X-band EMI shielding or RAM material made from sustainable pyrolysed cork templates.

Cork is a renewable and sustainable material, highly porous and lightweight. We valorised waste cork and recycled wine stoppers to make pyrolysed/carbonised solid cork, for use as economic and sustainable microwave (MW) absorbers at the microwave X-band (8-12 GHz), without binder or additives. Although cork is already a very lightweight material (0.16 g cm-3), the pyrolysed cork is five-times less dense at 0.031 g cm-3, was amorphous graphitic carbon, and had an excellent shielding effectiveness (SET) of -18 to -38 dB, depending on thickness, with attenuation of the electromagnetic energy through internal reflection within the cellular cork structure. Furthermore, this ultra-light-weight material has an extremely high MW specific shielding effectiveness or efficiency (SSE), between -640 to -1235 dB g-1 cm3 over the entire X-band range, depending on thickness (3.0-8.6 mm), one of the highest reported for any pure carbon material, this upper value being more than twice that of any previously reported graphite-based foams.

DESIGN OF X-BAND MMIC LOW-NOISE AMPLIFIER IN GAAS-BASED 0.5 UM PHEMT TECHNOLOGY

One of the most important functional units of the receiving tract as part of the transceivers is a Low-Noise Amplifier (LNA). This paper presents the design process of a X-band (8…12 GHz) Microwave Monolithic Integrated Circuit (MMIC) LNA. The design was carried out using the Process Design Kit of the GaAs-based pHEMT05D technological process of JSC «Svetlana-Rost». The active nonlinear elements in this technological process are depletion mode pseudomorphic high electron mobility transistors with a 0,5-microns gate length.

A magnetic X-band frequency microwave nanoabsorbent made of iron oxide/halloysite nanostructures combined with polystyrene.

A novel nanocomposite has been designed and fabricated through an in situ polymerization process, based on iron oxide nanoparticles (Fe3O4 NPs), halloysite nanotubes (HNTs), and polystyrene (PS). The prepared nanocomposite (formulated as Fe3O4/HNT-PS) has been fully characterized through various methods, and its applicability in microwave absorption was investigated by using some single-layer and bilayer pellets containing nanocomposite and resin. The efficiency of the Fe3O4/HNT-PS composite with different weight ratios and pellets with the thickness of 3.0 and 4.0 mm were examined. Vector network analysis (VNA) revealed that the microwave (12 GHz) can be noticeably absorbed by Fe3O4/HNT-60% PS particles in a bilayer structure with 4.0 mm thickness and 85% resin of the pellets, resulting in a microwave absorption value of ca. -26.9 dB. The observed bandwidth (RL < -10 dB) was about 1.27 GHz, where ca. 95% of the radiated wave is absorbed. Ultimately, due to low-cost raw materials and high performance of the presented absorbent system, the Fe3O4/HNT-PS nanocomposite and the construction of the presented bilayer system can be subjected to further investigations to test and compare with other compounds for industrialization.

Nonlinear Properties of an Inhomogeneous Diode Structure in a Strong Microwave Field

Results of experimental investigation of detection (rectification) of high power X-band microwave signal in diodes of various design (semiconductor p-n-junction, point-contact, Schottky, Metal-Isolator-Metal—MIM) are reported. The maximum of the detected direct voltage V vs. power P of microwave signal and subsequent polarity reversal, previously found in MIM diodes in the optical and microwave bands, have found to be characteristic of all investigated diodes as well. After the reversal of polarity, this dependence comes linear, and the sign of the voltage corresponds to thermoEMF. In some diodes, the hysteresis on V(P) was observed. All 5 types of V(P) of MIM diodes (have made from different pairs of metals), reported earlier, were reproduced on same p-n-junction diode by variable external DC bias. These results joined with abnormal frequency cutoff forced to suggest that there is an unknown mechanism for direct flow of charge carriers (and for generate direct current) in the high-frequency electrical field, which differs from the conventional rectification.

Electromagnetic Interference Shielding and Characterization of Ni2+ Substituted Cobalt Nanoferrites Prepared by Sol-Gel Auto Combustion Method

The structural, magnetic, and dielectric properties of a series of Ni2+ substituted cobalt nanoferrite particle samples with the composition Co1−xNixFe2O4 (where x = 0.0 ≤ x ≤ 1.0) synthesized by using the sol-gel auto combustion route are presented in this report. The electromagnetic interference shielding of Co1−xNixFe2O4/PVA nanocomposite films has been determined in the microwave X-band (8.2–12.4 GHz) frequencies. X-ray analysis revealed the single-phase formation of nickel-substituted cobalt nanoferrite samples. The decreasing trend of lattice parameters with Ni2+ substitution indicates the incorporation of Ni2+ into the crystal structure, obeying Vegard’s law. FTIR showed the absorption bands at 560–590 cm−1 ( v 1 ) and 390–400 cm−1 ( v 2 ) were attributed to (A-site) tetrahedral and (B-site) octahedral groups complex, respectively which confirm the spinel structure of the samples. Field emission scanning electron microscopy showed agglomerated grains of different sizes and shapes in the morphological observation. EDS reveals the chemical composition of the prepared samples. TEM analysis revealed that the synthesized particles were nearly monodisperse, show to be roughly spherical in shape, and have a polycrystalline nature. The dielectric constant and loss tangent (tanδ) is found to decrease with increasing frequency which shows normal behavior for ferrimagnetic materials. The magnetic properties determined using VSM have substantially changed with the substitution of Ni2+ ions. The saturation magnetization and the experimentally magnetic moment are observed to decrease with an increase in Ni2+ content x. A series of Co1−xNixFe2O4/PVA nanocomposite films are prepared by applying simple, rapid, and inexpensive methods for EMI shielding materials. The vector network analyzer data were used to evaluate the electromagnetic interference (EMI) shielding properties of the Co1−xNixFe2O4/PVA samples. At 9.2 GHz, a study of reflection loss showed a minimum reflection loss (RL) of −32.08 dB. Also, the synthesized Co1−xNixFe2O4/PVA nanocomposite samples show improved performance for EMI efficiency which proves the utility of this doping. With this low RL value, the results and techniques also promise a simple, effective approach to achieve light-weight Co1−xNixFe2O4/PVA nanocomposite films and make it excellent microwave absorbers, capable of working at gigahertz frequencies for application potentials in EMI shielding material, communication, radar stealth technology, and electronic warfare.

Study of the Structural and Magnetic Properties of a Novel Cola/Lah Nanocomposite Material

A novel nanocomposite consisting of 0.3 cobalt lanthanum nanoferrite/0.7 lanthanum perovskite–hematite nanoparticles (CoLa/LaH) and lanthanum perovskite–hematite nanoparticles (LaH) was synthesized using a simple method. The crystallite size was determined by the X-ray diffraction (XRD) pattern, and the particle size was determined using atomic force microscopy (AFM) to demonstrate that the nano-samples had sizes within the nanoscale range. Fourier transform infrared analysis was utilized to ensure that the nano-samples were formed. By adding CoLa nanoferrite to the LaH nanoparticles, an improvement in magnetic measurements was observed. The saturation magnetization of the CoLa/LaH nanocomposite was 1.1-fold larger than that of LaH. Also, the CoLa/LaH coercivity was 1.7-fold higher than in LaH. Furthermore, the CoLa/LaH nanocomposite displayed a higher operating high frequency of 8.9 GHz, which could be used in an X-band super-high microwave frequency, than the LaH nanoparticles. The LaH nanoparticles, on the other hand, demonstrated a high operating frequency of 8.2 GHz, which could be used in the C-band super-high microwave frequency. No activity was observed for the investigated samples against the tested microorganisms, which was unexpected behavior. Therefore, the investigated nano-samples are interesting for being applied in magnetic targeting and separators, in particular the CoLa/LaH nanocomposite.

X-Band Dielectric Characterization and Microwave Absorption Characteristics of Polyaniline Loaded Poly Vinyl Butyral (PVB)

X-Band Dielectric Characterization and Microwave Absorption Characteristics of Polyaniline Loaded Poly Vinyl Butyral (PVB)

Heterogeneous Interfaces of Magnetic CIP and Binary Dielectric Carbon-Based Material Toward High-Efficiency Microwave Attenuation

Carbon-based materials, as lightweight absorbers, have been widely applied in varied fields to counteract the adverse effects of electromagnetic waves. Nevertheless, there remain challenges in coping with the impairment of microwave absorption performance caused by the excessively high permittivity of carbon materials. Herein, carbonyl iron powder (CIP) was added to graphene oxide/carbon black (RGO-CB) composites to adjust the permittivity improving impedance matching and electromagnetic absorption properties. In this work, the RGO provides a three-dimensional structure net, which introduces circularly and variously electromagnetic loss interfaces within the RGO-CB/CIP composites. Owing to the unique architecture and synergy of the three components, the as-prepared absorber exhibits good impedance matching and gratifying microwave absorption properties. It was found that the 1:1 mixture of RGO-CB and CIP in the composite had superb impedance matching at the thicknesses of 2.6 and 2.7 mm to achieve complete X-band microwave absorption. Such excellent performance benefits from the multiple polarization provided by the heterogeneous interfaces and the ideal impedance match attributed to the tunable permeability and permittivity of this work.