Substrate Width Research Articles

Generation of Radiation Null for the HMSIW Leaky-Wave Antenna

A new design of half-mode substrate integrated waveguide leaky-wave antenna with radiation null in the radiation pattern is proposed in this letter. The radiation null is realized by controlling the leakage constant of the effective radiation sections (ERSs). By changing the vias position and extending width of substrate at the locations of the ERSs for the prescribed angle, the null region can occur in any desired direction. In this way a null region with depth 36.2 dB around θ = -96° at 9 GHz is achieved, and at the same time the main beam is almost not affected. A tapered microstrip line with shaped single-stub tuning is used for good impedance matching with the antenna. The advantage of this design is that only simple modification of structure is needed to achieve good result of radiation null.

Evaluation of the holographic parameters by electrosynthesized CdXZn1−XS (X=0.3) thin films using double exposure digital holographic interferometry technique

In this paper, we have reported the optical non destructive technique, which uses double exposure digital holographic interferometry (DEDHI) together with simple mathematical interpretation, which instantly situates to the thickness of thin films, deposited mass, stress to substrate and fringe width for different deposition times. Here, the stainless steel substrate was exposed for different intervals of time. It is observed that the fringe width, stress to substrate changes with changing the time of deposition. This effect is due to the increase in thickness of CdXZn1−XS (X=0.3) thin films. Thus, holographic studies show sensitivity to deposition time and concentrations of solution.

Determination of size-independent effective permittivity of an overlay material using microstrip ring resonator

This letter describes a size-independent effective permittivity of biological tissues, using microstrip ring resonator (MRR), to evaluate the moisture content more effectively. As permittivity is depends on material density, the optimum sample size where further size variations will not change the effective permittivity are identified. Using simulation and experimental results it is found that, a sample having thickness more than 9% of substrate height (tsub) and width greater than 18.3% of guided wavelength (λg) shows size-independent effective permittivity. Both simulation and experimental results are in good agreement (within 3%). These findings allow more effective characterization of muscles according to their moisture content. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:4–9, 2016

Re-meandering of lowland streams: will disobeying the laws of geomorphology have ecological consequences?

We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats and macroinvertebrate communities of restored streams would resemble those of natural streams, while those of the channelized streams would differ from both restored and near-natural streams. Physical habitats were surveyed for substrate composition, depth, width and current velocity. Macroinvertebrates were sampled along 100 m reaches in each stream, in edge habitats and in riffle/run habitats located in the center of the stream. Restoration significantly altered the physical conditions and affected the interactions between stream habitat heterogeneity and macroinvertebrate diversity. The substrate in the restored streams was dominated by pebble, whereas the substrate in the channelized and natural streams was dominated by sand. In the natural streams a relationship was identified between slope and pebble/gravel coverage, indicating a coupling of energy and substrate characteristics. Such a relationship did not occur in the channelized or in the restored streams where placement of large amounts of pebble/gravel distorted the natural relationship. The analyses revealed, a direct link between substrate heterogeneity and macroinvertebrate diversity in the natural streams. A similar relationship was not found in either the channelized or the restored streams, which we attribute to a de-coupling of the natural relationship between benthic community diversity and physical habitat diversity. Our study results suggest that restoration schemes should aim at restoring the natural physical structural complexity in the streams and at the same time enhance the possibility of re-generating the natural geomorphological processes sustaining the habitats in streams and rivers. Documentation of restoration efforts should be intensified with continuous monitoring of geomorphological and ecological changes including surveys of reference river systems.

Adsorption of multiple spherical particles onto sinusoidally corrugated substrates.

We utilize a Monte Carlo simulation scheme based on the bond fluctuation model to simulate settlement of adhesive particles onto sinusoidally corrugated substrates. The particles are composed of a hard inner core with either an effective potential shell or a "soft" adhesive shell made of flexible arms attached to the particle surface. These chains adhere via either the effective potential shell or the sticky chain ends to the surface via pairwise nonspecific interactions. This simulation model allows for multiple particles to settle onto each tested substrate to elucidate the behavior of the collective adhesive layer featuring multiparticle assembly. Particles move within a 3D lattice space and settle on the substrate due to attractive particle/substrate interactions. Once a single particle adheres to the substrate, a new particle is introduced into the lattice to begin a new settlement. Through this multiparticle settlement mode, we explore the interplay among the characteristics of the particles (i.e., size, interaction shell) and the substrates (i.e., wavelength and periodicity) as well as interparticle interactions. We report that the adhesion of particles with an effective interaction shell to the substrates is reduced dramatically when the particle size is smaller than the feature width of the periodic substrate. The settlement of particles with flexible hair on the sinusoidally corrugated substrates is more complex. Specifically, the presence of flexible polymeric hairs makes the particle settlement more likely to occur on nearly all substrates studied irrespective of the characteristics of the substrate.

Magnetism and transport properties of zigzag graphene nanoribbons/hexagonal boron nitride heterostructures

Results of ab initio study of magnetism and transport properties of charge carriers in zigzag graphene nanoribbons (ZGNR) on hexagonal boron nitride (h-BN(0001)) substrate are presented within the density functional theory framework. Peculiarities of the interface band structure and its role in the formation of magnetism and transport properties of the ZGNR/h-BN(0001) heterostructure have been studied using two different density functional approximations. The effect of the substrate and graphene nanoribbons width on the low-energy spectrum of π-electrons, local magnetic moments on atoms of interface, and charge carriers mobility in the ZGNR/h-BN(0001) heterostructures have been established for the first time. The regularity consisting in the charge carrier mobility growth with decrease of dimers number in nanoribbon was also established. It is found that the charge carriers mobility in the N-ZGNR/h-BN(0001) (N—number of carbon (C) dimers) heterostructures is 5% higher than in freestanding ZGNR.

DESIGN OF MULTIPLE BEAM FORMING ANTENNA SYSTEM USING SUBSTRATE INTEGRATED FOLDED WAVEGUIDE (SIFW) TECHNOLOGY

This paper introduces a novel structure of 4£4 multiple beam forming antenna system using substrate integrated folded waveguide technology. For high speed wireless communication it is necessary to minimize the interferences and multipath fading. Multiple beam forming antenna system is a good solution to these problems. The substrate integrated folded waveguide (SIFW) technology reduces the width of substrate integrated waveguide (SIW) by half. All the basic building blocks required for the antenna array system are designed and simulated individually. They are then combined to form the butler matrix fed antenna array system. The SIFW technology reduces the total width of butler matrix. The radiation performance of the multiple beam forming antenna system is realized by integrating the H-plane SIFW horn antennas with the output ports of the butler matrix. The system is practically realized and good directive multiple beams with symmetric gain (5.8dB, 5.63dB, 5.31dB and 5.9dB for the beams 1R, 2L, 2R and 1L) have been achieved.

Designing the Width of Substrate Integrated Waveguide Structures

A new formula for the effective width design of substrate integrated waveguide (SIW) structures is presented. Contrary to another formulation of similar accuracy, which requires an iterative process or solution of a fifth-order polynomial, the new equation allows the direct design of the SIW's width for a given cutoff frequency. The presented formula is obtained by minimizing the reflections from the junction between the SIW and an all-dielectric waveguide of equivalent width. A mode-matching approach is used to derive the equation which is verified by comparison with μWaveWizard for three SIW examples. Further optimizations in CST Microwave Studio and μWaveWizard demonstrate the robustness of the new formula.

Thermal crosstalk in arrays of III-N-based Lasers

Abstract This paper presents a 3D comprehensive thermal-electrical self-consistent model of the continuous-wave (CW) operation of one-dimensional arrays of III-N-based laser diodes at room-temperature (RT). Their performance is mostly limited by thermal processes, in particular by thermal crosstalk between array emitters. Based on data collected from a range of secondary sources, the temperature dependence of the thermal and electrical conductivities of III-N materials used to manufacture nitride-based devices is shown to be a function of the thickness, aluminum mole fractions and Si- and Mg-doping levels of the nitride layers. The impact of substrate width and thickness on increasing the efficiency of heat-flux transport and reducing thermal crosstalk is investigated. As expected, the application of a top-mounted diamond heat spreader was found to have considerable influence on the thermal crosstalk between array emitters, enabling the RT CW operation of laser diode arrays with additional emitters.

이동통신 기지국용 광대역 직렬 급전 보우타이 다이폴 쌍 안테나 설계

본 논문에서는 1.7-2.7 GHz 대역에서 동작하는 이동통신 기지국용 광대역 직렬 급전 보우타이 다이폴 쌍(series-fed bow-tie dipole pair; SBDP) 안테나를 제안하였다. 기존의 직렬 급전 다이폴 쌍(series-fed dipole pair; SDP) 안테나에서 사용하는 직선 스트립 다이폴 소자 대신에, 제안된 안테나는 보우타이 모양의 다이폴 소자를 사용하였다. 시뮬레이션 분석 결과, 양 끝으로 벌어진 각도가 증가할수록 안테나의 가장 낮은 동작 주파수가 저주파수 대역으로 이동하였으며, 이를 이용하여 저주파수 대역으로 이동한 만큼 다이폴 소자의 길이를 줄일 수 있다. 양 끝으로 벌어진 각도가 10도인 SBDP 안테나를 FR4 기판(비유전율 4.4, 두께 1.6 mm) 상에 제작하였고, SDP 안테나와 비교하여 폭이 10% 줄어들었다. 제작된 SBDP 안테나를 측정한 결과, 전압 정재파비(voltage standing wave ratio; VSWR)가 2 이하인 임피던스 대역폭은 48.8% (1.69-2.78 GHz), 이득은 5.8-6.3 dBi, 전후방비는 14-17 dB이다. In this paper, a broadband series-fed bow-tie dipole pair (SBDP) antenna operating in the band of 1.7-2.7 GHz for mobile communication base station applications is proposed. The proposed antenna uses bow-tie-shaped dipole elements instead of straight strip dipole ones used in a conventional series-fed dipole pair (SDP) antenna. The simulation results show that the lowest operating frequency is shifted toward lower frequency as the flare angle increases, and so the lengths of the bow-tie dipole elements can be reduced in proportion to the frequency shift toward lower frequency. An SBDP antenna with a flare angle of 10 degrees is fabricated on an FR4 substrate (dielectric constant = 4.4 and thickness = 1.6 mm) and total width of the fabricated antenna is reduced by 10% compared to that of the conventional SDP antenna. The measured impedance bandwidth for voltage standing wave ratio (VSWR) < 2 is 48.8% (1.69-2.78 GHz), gain is 5.8-6.3 dBi, and the front-to-back ratio (FBR) is 14-17 dB.

Folded Substrate Integrated Waveguide Based Composite Right/Left-Handed Transmission Line and Its Application to Partial $H$-Plane Filters

Composite right/left-handed (CRLH) transmission line structures based on the folded substrate integrated waveguide (FSIW) are presented and discussed in this paper. This FSIW-based CRLH (FSIW-CRLH) transmission line exhibits much lower cut-off frequencies as compared to the ordinary FSIW of the same footprint, and furthermore, it requires only one-half width of the conventional substrate integrated waveguide (SIW) based CRLH (SIW-CRLH) transmission lines while possessing the same dispersion characteristics. In addition, the proposed structure offers the advantage of a high quality factor for preventing the guided-wave circuits from radiation as suffered in the previous open CRLH transmission line structures when operated in the fast-wave region. All of the aforementioned properties lend the proposed FSIW-based CRLH transmission lines best suited to miniaturized and guided-wave microwave applications. In this paper, a comprehensive study on the FSIW-CRLH transmission structures is conducted by means of its dispersion relation and Bloch impedance. In addition, two partial <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane filters are implemented here to demonstrate the capabilities of miniaturization and high quality factor based on the proposed FSIW-CRLH structures. The resultant filters are shown to have about 80% size reduction as compared to the conventional FSIW filters, and 59% size reduction as compared to the SIW-CRLH filters. To the best of our knowledge, it is the first time that the partial <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane filters are implemented utilizing both the dispersion behavior of the CRLH transmission structures and the structural benefits of the FSIW configuration.

Optimization of Angular Alignment in Self-Assembly of Thin Parts at an Air–Water Interface

This letter presents an analysis of self-assembly of thin disk-shaped parts (diameter: 2 mm; thickness: 100 μm) with the objective of optimizing their angular alignment. The assembly proceeds continuously on a substrate that is pulled up through an air-water interface where thin parts with magnetic markers are floating. Angular deviations from the assembly site are significantly reduced by repositioning magnets that guide the self-assembly process. Temporary Faraday waves aid one-to-one part-to-site registration. Ninety parts are assembled, row by row, in 1 min. The assembly rate scales with the width of the assembly substrate. Compared with that of our previous work, the assembly rate is increased threefold due to reduced part-to-part interactions.

Reference Aquatic Macrophyte Communities at Rivers in Southwestern Bulgaria

Aquatic macrophytes were studied at nine near-natural river sites together with water chemistry (pH, electrical conductivity, nitrate nitrogen, orthophosphates, total N and P) and physical characteristics (substrate type, shading, flow velocity, mean depth and width). Reference Index reflecting general degradation was applied to assess the ecological quality. As the reference conditions are represented by minimally-disturbed sites, the study presented innovative approach to assess potentially-impaired sites based on the reference community approach.

Comment on ‘Analytical equivalence between substrate‐integrated waveguide and rectangular waveguide’

The authors discuss a recently proposed analytical method for calculation of equivalent width of substrate integrated waveguide. Modifications are made to calculate the final analytical formula more accurately.

Flux-pinning-induced interfacial shearing and transverse normal stress in a superconducting coated conductor long strip

In this paper, a theoretical model is proposed to analyze the transverse normal stress and interfacial shearing stress induced by the electromagnetic force in the superconducting coated conductor. The plane strain approach is used and a singular integral equation is derived. By assuming that the critical current density is magnetic field independent and the superconducting film is infinitely thin, the interfacial shearing stress and normal stress in the film are evaluated for the coated conductor during the increasing and decreasing in the transport current, respectively. The calculation results are discussed and compared for the conductor with different substrate and geometry. The results indicate that the coated conductor with stiffer substrate and larger width experiences larger interfacial shearing stress and less normal stress in the film.

The influence of substrate morphology on thickness uniformity and unintentional doping of epitaxial graphene on SiC

A pivotal issue for the fabrication of electronic devices on epitaxial graphene on SiC is controlling the number of layers and reducing localized thickness inhomogeneities. Of equal importance is to understand what governs the unintentional doping of the graphene from the substrate. The influence of substrate surface topography on these two issues was studied by work function measurements and local surface potential mapping. The carrier concentration and the uniformity of epitaxial graphene samples grown under identical conditions and on substrates of nominally identical orientation were both found to depend strongly on the terrace width of the SiC substrate after growth.

Transmission of Dirac Electrons Through Graphene Multilayers with Gaussian Profile

ABSTRACTIn this work, we use the T-matrix method to study the tunneling of Dirac electrons through graphene multilayers. A graphene sheet is deposited on top of slabs of SiO2-SiC substrates, of which we applied a Gaussian distribution in the size width of the SiC substrate. We calculate the transmittance as a function of energy for different incident angles and different number of layers of the Gaussian distribution. We obtain different stop-band regions. These regions are wider when the width of the barrier is increased. Furthermore, it is possible to tune the width and the position of stop-band with the angle of incidence, the σ value of the Gaussian distribution, and the difference between the maximum-minimum sizes of the barrier.

Wide stopband compact microstrip lowpass filter using circular ring resonator and split ring resonators

In this contribution, a microstrip low-pass filter with a wide stop-band using split ring resonators and a circular ring resonator is introduced. The passband ripple of proposed filter was measured 0.6 dB and minimum insertion loss of passband is about 0.75 dB at 0.5 GHz frequency. Moreover, the 1.0 dB cut off frequency of proposed filter is 1.45 GHz in measurement. Designing this type of low-pass filter requires a high impedance transmission-line. However, the microstrip line width cannot be taken less than 0.2 mm in practical implementation. This causes to a small mismatch in passband. Furthermore, these results show wide stop-band up to 9.0 GHz with more than 30 dB rejection. The dimensions of proposed compact filter are about 12.5×30 mm2 (excluding extra substrate width). The proposed filter is a microstrip filter and can compete with defected ground structure (DGS) or defected microstrip structures lowpass filters in miniaturizing and wide stopband. However, the DGS or DGS filters have some problems in manufacturing applications such as radiation fields from defected structures and requiring a specific box. In addition, a distributed equivalent circuit model based on geometrical filer parameters is introduced, and good agreement can be seen between EM simulation and distributed equivalent circuit model up to 6.0 GHz frequency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26203

Evaluation of the gauge factor for single-walled carbon nanonets on the flexible plastic substrates by nano-transfer-printing

Nano-transfer-printing (nTP) is increasingly used for the micro-fabrication of nanoscale materials onto flexible plastic substrates. This paper reports a nTP process for single-walled carbon nanonets (SWCNNs) for use in strain sensors. Traditional SWCNNs grown on a silicon substrate by alcohol catalytic chemical vapor deposition (ACCVD) can serve as strain-sensing elements in strain sensors and nano-electromechanical system (NEMS) sensors, but ACCVD is not well suited to the task. To improve SWCNN fabrication, this work deposits a parylene-C thin film on SWCNNs for transfer-printing onto flexible plastic substrates with polyimide tape. Quantification of the fabricated SWCNN strain-sensing ability (gauge factor) is performed by comparing two specimens with different pattern features and substrates. The gauge factor is measured by tensile testing. SWCNN density variations relative to the observed gauge factors are discussed. Results show that SWCNN gauge factors range from 1.46 to 8.22, depending on the substrate and pattern width. It is further observed that the gauge factor of the presented SWCNN thin film increases when the width of the SWCNN decreases to the low micro-dimensions, i.e. below 40 µm, indicating a significant scaling factor.

Prototype testing of a composite-type active grating bender with Si substrate for surface profile high-order term elimination

The previous monolithic active grating bender design met some basic design requirements. However, after a real grating (BM-AGM) had been fabricated and installed for testing, the results showed that the usable length is a mere 60 mm because of the higher-order term error in the surface profile. A method was thus derived to eliminate the higher-order term error by modifying the width of the bender substrate through finite-element method simulation, reducing the residual error from about 100 nm to 6 nm. Owing to the closure of the grating department of Zeiss, ruling the monolithic bender is no longer available and the design has to be modified to a composite-type bender with Si substrate. A prototype was fabricated and assembled to examine all the design situations. The surface roughness of the width-modified Si substrate is around 30 nm before assembly. The residual error after assembly and bending is less than 10 nm. It proves that the design is feasible. However, due to the manufacturing capacity of the vendor, a short-length substrate is required and the design has to be modified. The detailed design modification and testing results are presented in this paper.