Substrate Height Research Articles

Modified e-slotted patch antenna for WLAN/Wi-Max satellite applications

A low profile modified e-slotted microstrip antenna is proposed for multiple wireless communication applications. The performance of antenna is measured in terms of return loss, current distribution. The effect of variation of height of substrate on antenna impedance bandwidth is also studied. The antenna with overall size 30×50×.8m.m. 3 resonates at eight frequencies which covers some important applications like GPS, wireless local area network (WLAN), worldwide interoperability for microwave access (WiMax), Satellite communication etc. The proposed antenna structure offers great advantages due to compact size, simple structure and multiple applications. The multi band antenna was designed and optimized using ansoft HFSS v13 simulator. The simulated result is good agreement with measured result.

Height patterning of nanostructured surfaces with a focused helium ion beam: a precise and gentle non-sputtering method

This work presents a new technique for surface patterning with focused ion beams. The technique is based on chemical decomposition in the bulk of a polymer substrate with negligible surface sputtering effects. By using a focused helium ion beam, generated in a helium ion microscope, we show that the surface height of polymethyl methacrylate substrates can be patterned with nanometer depth precision, while preserving the essential features of the nanostructures prefabricated on this surface. The key factors that control this patterning process are discussed.

Facile and rigorous route to distinguish the boundary structure of monolayer MoS2 domains by oxygen etching

The boundary structure of 2D materials exhibits an important influence on their physical and chemical properties. We report the controllable growth of molybdenum disulfide with different boundary structures via chemical vapor deposition (CVD). A facile and rigorous route to distinguish the boundary structure via oxygen etching was proposed. The boundary control was realized by changing the substrate height to adjust the Mo:S ratios. Based on the stability differences of the boundary structures in oxygen, the microscopic boundary structures were characterized by oxygen etching. Our work combined growth and etching to develop a general route to identify the boundary structure of MoS2. Results of this study provide a mean to determine the controllable growth of MoS2 domains with different boundaries and to design the domains with special boundary structure efficiently.

Species composition and diversity of morphotypes in epilithic biotopes of Zhytomyr region, Ukraine

16 species of naked amoebae are recorded in the eplithic biotopes of Zhytomyr region, Ukraine: Saccamoeba sp. (1), Saccamoeba sp. (2), Saccamoeba sp. (3), Cashia limacoides Page, 1974, Thecamoeba striata (Penard, 1890) Schaeffer, 1926, Thecamoeba sp., Stenamoeba stenopodia (Page, 1969) Smirnov et al., 2007, Mayorella cantabrigiensis Page, 1983, Mayorella sp., Korotnevella sp., Vexillifera sp., Vannella sp., Ripella platypodia Smirnov, Nassonova, Chao et Cavalier-Smith, 2007, Acanthamoeba sp. (1), Cochliopodium sp., Vahlkampfia sp. (1). The frequency of occurrence in samples is highest for Thecamoeba sp., Mayorella sp., Vahlkampfia sp. (1), Korotnevella sp., Vannella sp., and is lowest for Saccamoeba sp. (1), C. limacoides, M. cantabrigiensis, Cochliopodium sp., S. stenopodia, R. platypodia, T. striata, Saccamoeba sp. (2). The species and morphotype diversity of naked amoebae of the epilithic mosses and lichens is influenced by the humidity and the height above soil of the substrate. The species and morphotype diversity of naked amoebae decreases with the increase in height above soil and the decrease of humidity of substrate. We recorded naked amoebae of 9 morphotypes: monotactic, dactylopodial, fan-shaped, lens-like, lingulate, mayorellian, striate, acanthopodial, and eruptive. Amoebae of the lens-like and fan-shaped morphotypes disappear with the increase of height of substrate above soil.

Effects of Substrate Parameters on the Residual Stress and Deflection of Ti-6Al-4V Walls in Additive Manufacturing Process

Given substrate parameters affect the heat transfer during additive manufacturing (AM) deposition process, the precision and residual stress of the component will also be affected. Such effect is an important aspect that should be considered but has not been reported. Thus, this paper presents a three-dimensional thermo-mechanical finite element model to study the effects of substrate parameters on the residual stress of Ti-6Al-4V walls during the AM process. The thermal and deflection histories and residual stress profile with different substrate parameters were investigated. Results show that the influence of the substrate height on the deflection, heat transfer and residual stress is most obvious, the length change has little influence on the deflection and stress distribution. The maximum deflection difference between the heights of 2.4 and 10.4 mm is 92.12%, the maximum deflection is reduced by 39.65% with the width increased from 15.4mm to 35.4mm. And the increased height is beneficial to the uniform of Z component residual stress but decrease uniformity of Y component residual stress.

Numerical and Analytical Analysis of Stochastic Electromagnetic Fields Coupling to a Printed Circuit Board Trace

Stochastic electromagnetic fields coupling to printed circuit board (PCB) traces are important to the understanding of electromagnetic compatibility at high frequencies when the circuits or systems are electrically large. In this article, it is studied both numerically and analytically, and the factors affecting the absorbed power are investigated. We present new methods to determine the level of coupling on PCB traces or other transmission lines on a dielectric substrate. A Monte Carlo method is applied to generate random uniform fields, and the quasi-TEM transmission line model is employed to compute the response of the trace for each plane wave numerically. In the analytical method, the closed-form expressions of the zero-order and the first-order approximations are established for the PCB trace. Based on the first-order approximation method and the numerical results, a computationally efficient empirical method is developed to estimate the power received. The absorbed power increases with frequency in the electrically short case after which multiple resonances can be seen. The absorbed power in the matched case is neither the largest nor the smallest among all the cases. It increases with the square of the substrate height but decreases with the permittivity of the substrate.

Measuring nanoscale friction at graphene step edges

Although graphene is well known for super-lubricity on its basal plane, friction at its step edge is not well understood and contradictory friction behaviors have been reported. In this study, friction of mono-layer thick graphene step edges was studied using atomic force microscopy (AFM) with a Si tip in dry nitrogen atmosphere. It is found that, when the tip slides over a ‘buried’ graphene step edge, there is a resistive force during the step-up motion and an assistive force during the step-down motion due to the topographic height change. The magnitude of these two forces is small and the same in both step-up and step-down motions. As for the ‘exposed’ graphene step edge, friction increases in magnitude and exhibits more complicated behaviors. During the step-down motion of the tip over the exposed step edge, both resistive and assistive components can be detected in the lateral force signal of AFM if the scan resolution is sufficiently high. The resistive component is attributed to chemical interactions between the functional groups at the tip and step-edge surfaces, and the assistive component is due to the topographic effect, same as the case of buried step edge. If a blunt tip is used, the distinct effects of these two components become more prominent. In the step-up scan direction, the blunt tip appears to have two separate topographic effects elastic deformation of the contact region at the bottom of the tip due to the substrate height change at the step edge and tilting of the tip while the vertical position of the cantilever (the end of the tip) ascends from the lower terrace to the upper terrace. The high-resolution measurement of friction behaviors at graphene step edges will further enrich understanding of interfacial friction behaviors on graphene-covered surfaces.

Finger-Worn UHF Far-Field RFID Tag Antenna

This letter presents the design and measurement of an experimental passive UHF radio frequency identification (RFID) tag worn as a ring with applications particularly in healthcare or secure environments. Three sizes of rings were designed for the European UHF RFID band over two different substrates at varying heights off the skin. Designing effective body-mounted antennas for passive RFID is very challenging, particularly when mounted directly upon the skin. The rings were simulated with a commercial electromagnetic simulation software and then constructed and tested on an adult male ring finger over several angles of RF illumination so that read ranges and directivity could be determined. Main beam read distances between 2 and 5 m were achieved dependent on the ring substrate height.

A new model of Holocene reef initiation and growth in response to sea-level rise on the Southern Great Barrier Reef

The fossil record provides valuable data for improving our understanding of both past and future reef resilience and vulnerability to environmental change. The spatial and temporal pattern of the initiation of the Holocene Great Barrier Reef presents a case study of reef response to rapid sea-level rise. Past studies have been limited by the lack of well-dated and closely spaced reef core transects and have not closely examined the composition of the reef-building communities through time. This study presents 80 new high precision UTh and 5 radiocarbon ages from twelve new cores located along three transects across different geomorphic and hydrodynamic settings of One Tree Reef, southern Great Barrier Reef, to document three distinct stages of Holocene reef development in unprecedented detail. Temporal constraints on changing paleoecological assemblages of coral, coralline algae and associated biota revealed three distinct phases of reef development, consisting of: 1)a fast, shallow and clear-water reef initiation from 8.2 until 8 ka; 2)a shift to slower, deeper and more turbid-water reef growth from 8 to 7 ka; and 3)a return to shallow and rapid branching coral growth in clear-water conditions as the reef “catches up” to sea-level. A minimum lag prior to reef initiation of 700 years was identified, which differs in length depending on reef environment and Pleistocene substrate height. In this new model, reef growth initiated on the topographically lower leeward margin and patch reef, prior to the start of windward margin development, contrary to the traditional reef growth model. While there was a shift to conditions less favorable for reef growth at 8 ka, this did not prevent the slow accretion of more sediment-tolerant coral communities. The majority of the reef reached sea level by ~6 ka. This new conceptual model of Holocene reef growth provides new constraints on changes in paleoenvironment that controlled reef community composition and growth trajectories through sea-level rise following inundation.

Novel analysis of the size and orientation dependent resonance phenomenon of the microstrip line coupled complementary split‐ring resonator

The purpose of this article is to provide a comprehensive investigation on the resonance phenomenon of microstrip line coupled complementary split-ring resonator (CSRR) with different orientation and relative size. It is shown that when the relative size of the CSRR is smaller than the host line, the CSRR with its slit oriented orthogonal to the line axis will not excite effectively and show weak resonance behavior. However, when the slit is positioned along the line axis, the cross-polarization effect comes into play, which excites the CSRR through the mixed coupling. To ensure the correctness, several numerical simulations are carried out for different substrate height and relative permittivity. Finally, a prototype is fabricated and measured for the experimental validation.

A Microstrip Patch Antenna with Defected Ground Structure(DGS) for WiMAX and WLAN Applications

A rectangular microstrip patch antenna with defected ground structure with E-shaped and square shaped slot on the patch is proposed here. The proposed antenna design consists of H-shaped defect on the ground plane. The complete antenna system is constructed on 45.4mm X 45.4mm X 1.6mm, FR-4 substrate with dielectric constant of 4.4 and substrate height of 1.6mm. The antenna mainly works in 4-6 GHz band. The various characteristics parameters of the antenna like return loss, voltage standing wave ratio, impedance, gain, bandwidth and radiation pattern are studied. The antenna is simulated using high frequency structured simulator software , simulated < -10dB, in the entire operating range of 4-6 GHz.The proposed antenna design is mainly focused for the wireless applications and is suitable for IEEE 802.11 WLAN standards in the bands 5.2/5.8 GHz and WiMAX standards in the bands at 5.5 GHz. In this design microstrip line feeding is used.

Simulation of Rectangular Microstrip Patch Antenna u sing ANSYS

This paper presents the design and simulation of a rectangular microstrip patch antenna with enhanced results. Antennas are playing the most important key role in wireless communication systems and especially microstrip patch antenna is the simplest and best form for mobile communication systems. Therefore, the design of antenna for mobile satellite communication and space to earth communication is described in this proposed work. The working of rectangular micro strip patch antenna is studied and the effect of height of the substrate on antenna performance is analyzed and the results are plotted. It has been noticed that the height of substrate should be neither small nor large. The effect of inserting a slot in the patch is also observed in this paper. Return Loss results are plotted for the designed structure and it is noticed that return loss is almost doubled by inserting a slot. Further two symmetrical slots are inserted in the patch and the respective results are plotted. Insertion of two slots gave multiple operating frequencies to the antenna with a compromise of s11. The simulation of proposed structures of antennas is done using ANSYS HFSS (high-frequency structure simulator) which is commercially used as a finite element method solver for electromagnetic structures. A sphere with human brain characteristics is created and average SAR (specific absorption ratio) is plotted on the head model. The proposed antenna has enhanced return loss of -52dB and VSWR of 1.005 at 2.24GHz. This work also introduces multiple operating frequencies using two slots of same size.

Tunable Resonator as the Load of a Microstrip Line

A microstrip resonator is studied in which frequency tuning is carried out by micromechanical movements of the signal electrode above the substrate. The investigated resonator can be used as a component of a tunable antenna element, turned on as the load of the line. It is shown that the effective dielectric permittivity, which determines the resonant frequency, significantly decreases as a result of the movement of the signal electrode at a distance of several percents from the thickness of the substrate. Absolute values of the displacement usually stand tens or hundreds of micrometers depending on substrate thickness. Such displacements are available for modern piezoelectric or electrostrictive actuators. It opens an opportunity to implement the electrical type of tuning. For resonator performed on the substrate with dielectric permittivity about 10, resonant frequency tuning achieves more than 30 percent while the displacement of the signal electrode above the substrate does not exceed 10 percent. It is established that the variation range and sensitivity of the resonant frequency tuning can be increased by increasing the dielectric permittivity and decreasing the height of the microstrip line's substrate. Although the ratio between the width and the length of the resonator affects the tuning characteristics, the choice of these parameters is conditioned by the requirement for the formation of the required radiation pattern of the antenna element, the component of which is the viewed resonator. An equivalent circuit of a microstrip resonator as an element of a tunable antenna is proposed. The equivalent circuit model gives results that are satisfactorily consistent with those obtained based on a rigorous electromagnetic field model and a three-dimensional finite element method. At the same time, the schematic model simplifies the analysis of the influence of the geometric and electrophysical parameters of the resonant element on its characteristics and allows simplifying the design process of the antenna element and optimize its characteristics. The need to find the optimal parameters at the stage of designing the antenna element, in particular, arises during the matching of the feeder's and the radiator's characteristics and to provide the necessary range of the center frequency tuning.

An Extensive Judgment of Rectangular Microstrip Patch Antenna with Flexible Substrates

In this paper, the performance of U-slot Rectangular Microstrip Patch Antennas (RMSA) is analyzed by using different flexible substrates. The RMSA is designed to operate for a resonant frequency of 2.45 GHz with flexible substrate materials like Polydimethylsiloxane (PDMS), GML-1032 and Polyethylene. The antenna parameters like reflection coefficient, voltage standing wave ratio (VSWR), radiation pattern, bandwidth and cost are analyzed by keeping all the substrate height same and the value is 2.5mm. U-slot cutting is used in the patch to overcome the narrow bandwidth limitation in RMSA because U-slot tunes the higher order orthogonal mode resonance frequency of the patch with respect to fundamental mode to realize the wider bandwidth. The maximum bandwidth of 80MHz is achieved with the use of PDMS. The antenna is simulated using HFSS software.

Optimization of Micro strip Patch Antenna with Zig-Zag Slot in Broadband Communication

In this paper designed and analysis of the rectangular Microstrip patch antenna for GSM band with frequency band 5.1 GHz. Primarily the designed a conventional unslotted rectangular microstrip patch antenna and measure its different parameters using simulation tools .again introduced a Zig –Zag slotted antenna with dielectric substrate 2.2 and used the centre resonance frequency of 5.1 GHz. The substrate height of the FR4 was 0.787 mm.The comparison results of slotted and unslotted antenna are achieved large bandwidth and gain.The bandwidth of 35.2 % and achieved gain is 7.18 dBi in this poposed designed antenna. To model the probe feed for the microstrip patch we used a lumped port with port impedance equal to 50 ohm. The Zig-Zag antenna developed and its performance are utilized by Zealand IE3D tools. This antenna is used in GSM application and many other communication systems.

Amplifier type active antenna at 2.45 GHz for wireless applications

In this paper, an active antenna is proposed, where microwave amplifier is directly integrated on passive antenna. The amplifier provides required RF power to the antenna, hence improves the system efficiency. This paper presents a slotted patch antenna, resonating at 2.45 GHz for Industrial Scientific Medical band, having excellent return loss of − 30 dB and radiation efficiency of 100%. The microwave amplifier was designed and optimized on AWR Microwave Office software for 11 dB gain and noise figure less than 2 at the frequency of 2.45 GHz. The proposed amplifier type active antenna was designed using FR4 substrate with substrate height, 1.6 mm and dielectric constant of er = 4.4. In active antenna, amplifier provides extra power to the antenna while electric parameters of active antenna are same, such as return loss is − 21.95 dB at 2.11 GHz and the improved bandwidth of 125 MHz. The passive antenna is designed, analyzed and optimized on IE3D Zeland software version 15.30.

Direct simulation Monte Carlo study of metal evaporation with collimator in e-beam physical vapor deposition

The flow properties and substrate deposition rate profile, which are the important parameters in electron beam physical vapor deposition, are investigated computationally in this article. Collimators are used to achieve the desired vapor beam and deposition rate profile in some applications. This increases the difficulty measuring boundary conditions and the size of the liquid metal pool inside the collimators. It is accordingly hard to obtain accurate results from numerical calculations. In this article, two-dimensional direct simulation Monte Carlo (DSMC) codes are executed to quantify the influence of uncertainties of boundary conditions and pool sizes. Then, three-dimensional DSMC simulations are established to simulate cerium and neodymium evaporation with the collimator. Experimental and computational results of substrate deposition rate profile are in excellent agreement at various evaporation rates and substrate heights. The results show that the DSMC method can assist in metal evaporation with a collimator.

Computationally Optimized MIMO Antenna with Improved Isolation and Extended Bandwidth for UWB Applications

Isolation and bandwidth are the two important performance parameters of the multiple-input-multiple-output (MIMO) antenna. A small footprint of an antenna with enhanced isolation and extended bandwidth is highly desirable for space-limited UWB applications. In this paper, we present a compact and computationally optimized MIMO antenna for UWB applications. The proposed antenna consists of two micro-strip-fed semicircular radiating elements. The inverted prism-shaped ground stub is used to enhance isolation. A truncated-shaped partial ground plane with two ground slots is used for impedance matching over the extended UWB. The circular monopole radiating elements of the reference antenna (RA) are converted into semicircular radiating elements for efficient utilization of the available space. The initial design parameters are obtained from the RA. In the next step, the initial design parameters are optimized by a fast and accurate surrogate-assisted optimization model. Using the optimized design parameters, the final design of the antenna is simulated using a computer simulation tool. The prototype of the antenna is fabricated on a Roger substrate (substrate height ‘h’ = 0.8 mm) with a dielectric constant of 3. The manufactured prototype with the size of 31 × 18 mm2 is experimentally evaluated and validated using vector network analyser and anechoic chamber. The proposed MIMO antenna provides extended ultra-wide impedance bandwidth of 3–25 GHz (fractional bandwidth 157%), enhanced isolation S21 ≤ − 27 dB envelope correlation coefficient (ECC = 0.002), good pattern diversity, and constant group delay. Finally, the obtained results are compared with the existing literature.

Nighttime roosting substrate type and height among 4 strains of laying hens in an aviary system

ABSTRACTMulti-tiered aviaries for laying hens are designed to provide resources, such as perches, that allow birds to perform natural behaviors, thus improving their welfare. This research examined nighttime roosting heights and substrates used by laying hens of 4 genetic strains (Dekalb White: W1, Hy-Line W36: W2, Hy-Line Brown: B1, Bovans Brown: B2), in multitier aviaries (144 hens/unit, 4 units/strain) at 25 to 28 wk of age (peak lay). Influence of litter provision on roosting patterns of the strains was also tested. Direct observations of hens’ nighttime roosting patterns on wire floors, ledges and perches across tiers were conducted before (PRE), immediately after (IMM), and 3 wk after (ACC) hens gained access to litter. During all periods, more W1 and W2 hens roosted on middle and upper ledges than B1 and B2 hens (all P≤0.05), while more B1 and B2 hens used perches throughout the aviary than W1 and W2 hens (all P≤0.05). W1 (15±1.9, 14±3.36) and W2 (19±2.1, 18±2.6) hens occupied perches in the upper tier in greater numbers than B1 (7±3.2, 3±4.6) and B2 (11±2.1, 5±3.36) hens during PRE (P = 0.01) and ACC (P = 0.02) periods, respectively. B1 and B2 hens occupied wire floors in larger numbers than W1 and W2 hens during PRE (P = 0.02) and IMM (P = 0.03) periods, though this difference disappeared in the ACC period. During the IMM period, more W1 and W2 roosted in the lower tier, while more B1 and B2 hens were observed in the middle and upper tiers (all P ≤ 0.05). These findings demonstrate the importance of perches for B1 and B2 hens and space to roost higher in aviary units for W1 and W2 hens during the night, and underscore the need to consider aviary design, management practices, and preferences of different hen strains to ensure good hen welfare in aviaries.

Thermal ratchetting effect of AMB-AlN ceramic substrate: Experiments and calculations

Abstract Active-metal-brazing aluminium nitride (AMB-AlN) ceramic substrate with high thermal conductivity can provide a good alternative to conventional substrates in the high-temperature applications. However, the reliability of ceramic substrate when exposed to thermal cycling is still an issue. The aim of this study is to address the cyclic growth of warpage and stress of AMB-AlN ceramic substrate subjected to cyclic thermal loading (20-200-20 °C), which is of great significance for exploring the failure mechanism of ceramic substrate. The experimental results show that there is a hysteresis between the curves of bending height in the heating and cooling process, which can be explained by the Bauschinger effect. In addition, after five thermal cycles, the bending height of the ceramic substrate accumulates, showing a thermal ratcheting effect. By performing finite element analysis, it is also demonstrated that the warpage and stress of the ceramic substrate accumulates during the cyclic process. Furthermore, the stress on the ceramic layer is caused by the sum of the equivalent plastic strain of the copper layer and the filler metal, which is related to the thickness of the copper layer and the filler metal.