Conduction Plane Research Articles

Skin Effect of Alternating Current on a Planar Conductor

Skin Effect of Alternating Current on a Planar Conductor

Simplified Calculation Method of Impedance of a Planar Coil in Consideration of the Influence Depending on Eddy Current

An eddy current sensors have various uses, for example metal detection and determination, nondestructive inspection, and position detection. However, there are few studies which show the influence of a conductor on the impedance of a detector coil using a theoretical formula. This paper shows the simplified calculation method on impedance of a planar coil that can be found from an equivalent circuit by considering that a conductor plate is one turn of coil which form changes according to displacement. The impedance corresponding to the overlap length of a conductor plate was calculated about the planar rectangular coil and the planar triangular coil. The calculated value was compared with the measured value and the calculated value of finite element method. The calculated value of impedance of rectangular coil and triangular coil agreed with the measured value within an error of ± 5.98%. Mutual inductance between the planar coil and conductor plate was calculated from the area ratio of planar coil and overlap.

A Computational Algorithm for Corona Power Loss in Grid

In this paper a new efficient algorithm for computation of corona power loss in grid is described. The algorithm is based on a new finite element method (FEM) which allows computing corona power loss in high-voltage lines transmission. The new algorithm method is intended for considering the effects of various parameters on corona current such as: the height of conductor, the radius of conductor, the surface factor, distribution of electric potentials in space of between conductor and ground plane with applying space charges, and ambient temperature. The algorithm results were compared with the existing methods and the result accuracy was confirmed. Also, the results show that the new algorithm has positional to reduce the number of iteration for calculation of the corona current. The knowledge of the corona phenomena discharge will assist in monitoring and controlling the reliability of high voltage systems. This information can be monitored for measuring, detecting and taking appropriate control actions.

TEXTILE ARTIFICIAL MAGNETIC CONDUCTOR WAVEGUIDE JACKET FOR ON-BODY TRANSMISSION ENHANCEMENT

Diamond dipole antennas with textile Artiflcial Magnetic Conductor (AMC) sheet-like waveguide were designed to investigate the possibility of improving transmission between antennas. Fleece fabric is used as the substrate of the textile AMC while SHIELDIT fabric is used as the conductive patches and ground plane. The AMC surface is designed to resonate at 2.45GHz with the goal to enhance the transmission between antennas. A small textile AMC waveguide sheet as well as an AMC waveguide jacket were fabricated. The S-parameters performance of the two antennas with textile AMC sheet was investigated in a free space environment and near to human body setting. The efiect of difierent antennas' orientations was also considered. Measurements were conducted thoroughly to validate the simulated flndings. Compared to free space environment, S21 transmission between two dipoles is improved up to maximum i10dB when having textile AMC waveguide sheet beneath them. For both ofi-body and on-body placements, signiflcant transmission enhancement has been observed with the introduction of the AMC sheet-like waveguide. Directive radiation patterns with high gain have also been achieved with the proposed AMC waveguide jacket.

Design and Implementation of Electro-Textile Ground Planes for Wearable UHF RFID Patch Tag Antennas

Localization, wireless monitoring, and emerging body-centric wireless systems demand low-cost and low-power devices that are efficient, maintenance-free, and comfortable to wear. Patch-type UHF radio frequency identification (RFID) tag antennas realized using electro-textiles are promising candidates for this purpose. In this letter, we design a patch-type tag antenna operating at 900 MHz and investigate how different types of ground planes using electro-textiles affect the antenna performance. Various conductive fabrics and embroidery structures are considered. We demonstrate that depending on the ground plane structure and density, it is possible to influence the tag impedance behavior and radiation characteristics. Furthermore, wireless reflectometry measurements are conducted to characterize the sheet resistance for the investigated electro-textiles. We then use the sheet resistance in modeling the conductive fabric ground planes in a full-wave electromagnetic solver. Our results contribute to deeper understanding of the complex electro-textiles structures and guidelines for future practical wearable antenna designs.

A BROADBAND OUT-OF-PHASE POWER DIVIDER FOR HIGH POWER APPLICATIONS USING THROUGH GROUND VIA (TGV)

In this paper, we present a broadband out-of-phase power divider with high power-handling capability. The proposed device consists of several sections of double-sided parallel-strip lines (DSPSLs), a mid-inserted conductor plane, and two external isolation resistors, which are directly grounded for heat sinking. A through ground via (TGV), connecting the top and bottom sides of DSPSLs, is employed. The special metal via is realized to short the isolation resistors at full-frequency band when the odd-mode is excited. Meanwhile, it can be ignored as the excitation is even-mode. This property is e-ciently utilized to improve the bandwidth. To examine the proposed power divider in detail, a set of closed-form equations are derived. Meanwhile, the power operation analysis illustrates that the proposed power divider is a good candidate for high power applications. The design charts show that the proposed device can support a wide frequency ratio range (1{1.7). Furthermore, broadband responses can be obtained when proper frequency ratios are adopted. For veriflcation, an experimental power divider operating at 1.25/1.75GHz is implemented. The measured results exhibit a bandwidth of 44.3% with better than 15dB return loss and 18dB port isolation is achieved.

REALIZATION OF MICROSTRIP BANDPASS FILTER BALUN USING DOUBLE-SIDED PARALLEL-STRIP LINE WITH NOVEL COUPLING SCHEME

In this paper, we propose a microstrip fllter balun adopting double-sided parallel-strip line (DSPSL) with a conductor plane inserted in the middle of the substrate. Fed by the DSPSL at input port, two microstrip fllters on top and bottom layers are excited simultaneously, with the frequency-independent out-of-phase feature obtained between two output ports. The proposed fllter balun exhibits excellent performance with good frequency selectivity because of multiple transmission zeros generated by a new coupling scheme. Finally, a fllter balun sample is designed and fabricated, and good agreement is obtained between its measured and simulated S- parameters.

Electromagnetic Power Transmission through Two Circular Apertures in Parallel Conducting Planes Penetrated by a Long Cylinder

Electromagnetic power transmission through two cyl-inder-penetrated circular apertures in parallel conducting planes is studied. The Weber transform and superposition principle are used to represent the scattered field. A set of simultaneous equations for the modal coefficients are constituted based on the mode-matching and boundary conditions. The whole integration path is slightly deformed into a new one below the positive real axis not to pass through the pole singularities encountered on the original path so that it is easily calculated by direct numerical quadrature. Computation shows the behaviors of power transmission in terms of aperture geometry and wavelength. The presented scheme is very amenable to numerical evaluations and useful for various electromagnetic scattering and antenna radiation analysis involved with singularity problems.

Analytical Wideband Model for Strip/Slit Gratings Loaded With Dielectric Slabs

This paper presents a fully analytical model to determine the transmission and reflection properties of planar 1-D distributions of metal strips or slits made in thin metal screens. In contrast with other analytical or quasi-analytical approaches, the formulation incorporates the presence of dielectric slabs and is valid over a wide frequency band, from the long wavelength limit to the grating lobes operation. The model has been adapted to the case where two 1-D planar grids are stacked or a single grid is printed on a grounded substrate. In these cases, the model rigorously takes into account higher order mode interaction between the two stacked arrays of strips/slits or with the ground plane. Oblique incidence and both TE and TM polarizations have been considered. The analytical results show a good agreement with those computed by high-performance numerical methods, accounting for very fine details of extremely complicated transmission/reflection spectra. These results are of straightforward application to a variety of practical situations from microwaves to the terahertz regime. The present methodology can still be useful at higher frequencies provided that adequate models of the planar conductors are incorporated. In general, the model provides physical insight on the nature of the expected spectra and facilitates the design of devices based on planar metallic gratings.

Reflection of Conductive Plane Covered by Double Inhomogeneous Plasma Slab

This paper presents numerical results in the form of graphs of the power reflection coefficients for electromagnetic signals normally incident upon a conductive plane covered with two layers of inhomogeneous plasma slabs. The plasma electron density varies only in the direction perpendicular to the plane. Parameters considered in the computation cover a relatively wide range and the functional dependence of the power reflection coefficients on these parameters is studied. The results indicate that in a rather broad frequency range, the electromagnetic attenuations by the double slabs obviously excel the sum of attenuations resulted from two plasma layers when each layer exits respectively. The structure presented is easy to set up, which is instructive for plasma stealth.

Vertically Oriented Iron Oxide Films Produced by Hydrothermal Process: Effect of Thermal Treatment on the Physical Chemical Properties

Our study describes the influence of the thermal treatment on the fundamental properties of the vertical oriented iron oxide nanorods synthesized under hydrothermal condition onto a conductor substrate. X-ray diffraction and X-ray absorption near edge structure spectra were used to investigate the phase evolution from iron oxyhydroxide (β-FeOOH) to pure hematite phase. The formation of nanorods distributed along of substrate was observed by top-view SEM images and the rod growth preferentially oriented at the highly conductive (001) basal plane of hematite, perpendicular to the substrate. Light absorption capacity increases with the temperature of treatment and the electronic transitions (direct and indirect electronic transition) were estimated from this result. From the electrochemical measurement, the hematite/electrolyte interface was evaluated. These findings demonstrated that the temperature plays an important role on the hematite (structural, morphological, and catalytic) properties and that many influences must work in great harmony in order to produce a promising hematite photoanode.

Near Field Radiated From Carbon Nanotube Bundles

The near field radiated in the common-mode excitation from single-walled carbon nanotube (SWCNT) bundles with rectangular or hexagonal cross section above a perfect conductive plane is predicted in the gigahertz frequency range using the equivalent single conductor (ESC) method. The risk of electromagnetic interference against nearby components and devices can be estimated. The computed frequency spectra and spatial distributions of the electric and magnetic fields are validated by comparison with the ones radiated from all the conductive SWCNTs in the bundle represented by the multiconductor transmission line (MTL) model. The obtained results highlight the noticeable accuracy and simplicity of the ESC approach with respect to the very time consuming MTL formulation.

Electromagnetic detection of plate hydration due to bending faults at the Middle America Trench

Water plays an important role in the processes occurring at subduction zones since the release of water from the downgoing slab impacts seismicity and enhances arc volcanism. Geochemical indicators suggest that the Nicaraguan slab is anomalously wet, yet the mechanism of slab hydration remains poorly constrained. Extensional bending faults on the incoming oceanic plate of the Middle America Trench offshore Nicaragua have been observed to penetrate to mantle depths, suggesting a permeable pathway for hydration of the crust and serpentinization of the upper mantle. Low seismic velocities observed in the uppermost mantle of the incoming plate have been explained as serpentinization due to deep fluid penetration but could also be explained by intrinsic anisotropy and fractures in the absence of fluid circulation. Here we use controlled-source electromagnetic imaging to map the electrical resistivity of the crust and uppermost mantle along a 220km profile crossing the trench offshore Nicaragua. Along the incoming plate our data reveal that crustal resistivity decreases by up to a factor of five directly with the onset of the bending faults. Furthermore, a strong azimuthal anisotropy compatible with conductive vertical fault planes is observed only on the faulted trench seafloor. The observed resistivity decrease and anisotropy can be explained by a porosity increase along vertical fault planes, which we interpret as evidence that the lithospheric bending faults provide the necessary permeable fluid pathways required for serpentinization of the uppermost mantle. This implies that most serpentinisation happens at the trench, with the width of the faulting region and the density of fractures controlling the extent of upper mantle alteration. This observation explains why the heavily faulted trench offshore Nicaragua is associated with an anomalously wet slab, whereas other sections of the Middle America Trench containing fewer bending faults have less fluid flux from the subducting slab.

Photoelectrochemical water splitting at nanostructured α-Fe2O3 electrodes

In this study, nanostructured α-Fe2O3 thin films were deposited by simple electrodeposition for photoelectrochemical water splitting. Post-annealing temperature was found to have drastic effect on photoactivity of these films. SEM analysis illustrated that size of nanoparticles increases with annealing temperature. The current–potential characteristics showed that the water-splitting photocurrent strongly depends on post-annealing temperature. A maximum photocurrent density of 0.67 mA/cm2 was observed at 1.23 V versus reversible hydrogen electrode (RHE) under standard illumination conditions (AM 1.5 G 100 mW/cm2), and the water-splitting current was over 1.0 mA/cm2 before the dark current flow starts (at 1.55 V versus RHE). The electrode shows an onset potential as low as 0.8 V (versus RHE) for water photooxidation, which is one of the best results reported for hematite photoanodes. This high photoactivity of electrodes is attributed to the preferential growth of hematite nanostructures along the most conductive plane (001) and incorporation of Sn in film from the substrate at high annealing temperature. The best-performing electrode shows an incident photon conversion efficiency (IPCE) of 12% at 400 nm (in 1 M NaOH at 1.23 V versus RHE), which indicate the improved light-harvesting properties of these nanostructures.

Novel Dual-Band Out-of-Phase Power Divider With High Power-Handling Capability

In this paper, we present a novel dual-band out-of- phase power divider with high power-handling capability. The proposed device consists of five ports including one input port, two output ports, and two extra ones, which are connected by the external isolation resistors. To obtain the out-of-phase feature between the two output ports, double-sided parallel-strip lines are employed, and a conductor plane is inserted in the middle of the substrate as a common ground. A set of closed-form design equations is developed for analysis of the novel design structure by using the rigorous even- and odd-mode analysis method. The analysis shows that the proposed power divider can operate at two frequencies of f1 and mf1 with a wide frequency ratio range at 1.62 <; m <; 3. Furthermore, the power operation analysis also illustrates that the new circuit is superior in high power-handling capability over the conventional dividers with internal isolation resistors. For verification, an example power divider with frequency ratios of 2.4:1 is implemented. Simulation and experimental results agree well, validating the proposed design methodology.

Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

Radiation induced current in the RF coils of integrated linac‐MR systems: The effect of buildup and magnetic field

In integrated linac-MRI systems, a measurable radiation induced current (RIC) is caused in RF coils by pulsed irradiation. This work (1) tests a buildup method of RIC removal in planar conductors; (2) validates a Monte Carlo method of RIC calculation in metal conductors; and (3) uses the Monte Carlo method to examine the effects of magnetic fields on both planar conductor and practical cylindrical coil geometries. The RIC was measured in copper and aluminum plates, taken as the RF coil conductor surrogates, as a function of increasing thickness of buildup materials (teflon and copper). Based on the Penelope Monte Carlo code, a method of RIC calculation was implemented and validated against measurements. This method was then used to calculate the RIC in cylindrical coil geometries with various air gaps between the coil conductor and the enclosed water phantom. Magnetic fields, both parallel and perpendicular to the radiation beam direction, were then included in the simulation program. The effect of magnetic fields on the effectiveness of RIC removal with the application of buildup material was examined in both the planar and the cylindrical geometries. Buildup reduced RIC in metal plate conductors. For copper detector∕copper buildup case, the RIC amplitude was reduced to zero value with 0.15 cm copper buildup. However, when the copper is replaced with teflon as buildup atop the copper conductor, the RIC was only reduced to 80% of its value at zero buildup since the true electronic equilibrium cannot be obtained in this case. For the aluminum detector∕teflon buildup case, the initial amplitude of the RIC was reduced by 90% and 92% in planar aluminum conductor and a surface coil, respectively. In case of cylindrical coils made of aluminum, teflon buildup around the coil's outer surface was generally effective but failed to remove RIC when there was an air gap between the coil and the phantom. Stronger magnetic fields (>0.5 T) perpendicular to the beam direction showed a modest decrease in the RIC for planar conductors with buildup. In the cylindrical geometries, the effect of magnetic fields was very small compared to the effect of introducing air gaps. Loss in signal-to-noise ratio (SNR) due to RIC was reduced from 11% to 5% when a simple buildup was applied to the solenoid in a preliminary experiment. The RIC in RF coils results from the lack of electronic equilibrium in the coil conductor as the RIC in planar conductor was completely removed by identical buildup of adequate thickness to create electronic equilibrium. The buildup method of RIC removal is effective in cylindrical coil geometry when the coil conductor is in direct contact with the patient. The presence of air makes this method of RIC removal less effective although placing buildup still reduces the RIC by up to 60%. The RIC Monte Carlo simulation is a useful tool for practical coil design where radiation effects must be considered. The SNR is improved in the images obtained concurrently withradiation if buildup is applied to the coil.

Spatial distribution of transition radiation of relativistic particles in the dihedral angle formed by perfectly conductive planes

Spatial distributions of transition radiation intensity of particles entering the dihedral angle and escaping from it are calculated. It was shown that radiation of escaping charge at any opening of the dihedral angle α is concentrated near the motion direction. If the particle enters the angle, the radiation distribution is defined by the opening angle. At opening angles α = π/n, radiation is concentrated near the direction of actual charge motion when n is an even number and near the direction of image charge motion when n is an odd number. At other opening angles, the spatial distribution of entering particle radiation has two maxima whose positions are defined by the injection angle.

The magneto-kinematic effect for the case of rectilinear motion

The magneto-kinematic effect has been previously observed for the case of a rotating permanent magnet. Using this effect, this paper presents a novel method for calculation of the induced electromotive force (EMF) in a conductor for the case of rectilinear motion of a 25.4 mm diameter permanently magnetized sphere (magnetic dipole) past the conductor. Three scenarios are considered: a magnetic dipole moving through a circular conducting loop, a magnetic dipole moving underneath a long conductor with magnetic moment perpendicular to the conductor plane and a moving magnetic dipole with magnetic moment parallel to the conductor plane. In all cases the theoretical time-dependent EMF calculated using the method was in excellent quantitative agreement with the induced EMF measured on an oscilloscope. The new method of calculation is applicable in a range of generic problems dealing with moving sources of magnetic flux. Using this approach a novel neutrino detector is proposed.

New approach for sustaining energetic, efficient and scalable non-equilibrium plasma in water vapours at atmospheric pressure

Energetic and scalable non-equilibrium plasma was formed in pure water vapour at atmospheric pressure between wire-to-strip electrodes on a dielectric surface with one of the electrodes extended forming a conductive plane on the back side of the dielectric surface. The energy deposition increased by an order of magnitude compared with the conventional pulsed corona discharges under the same conditions. The scalability was demonstrated by operating two electrode assemblies with a common conductive plane between two dielectric layers. The energy yields for hydrogen and hydrogen peroxide generation were measured as ∼1.2 g H2/kWh and ∼4 g H2O2/kWh.