coupled with a square patch where a single-layersubstrate is suspended 2.5 mm above another double- layersubstrate. A square patch is etched on the top side of the singlelayer. Two bent microstriplines are fed separately from two ports on the bottom side of the double-layersubstrate, where the ground- plane includes four apertures etched on the top side. The directional antenna operates over a narrow bandwidth of 163 MHz centered at 2.4 GHz and has isolation better than 30 dB between its ports. The dimensions of this antenna are 80 × 80 × 6 . 8 mm 3 . The antenna structure in  resembles an elongated chevron which is etched on the top side of the substrate. It is excited by two orthogonal 50 ohm microstrip feedlines from the bottom side of the substrate. The antenna operates at 1.2 GHz and 1.7 GHz with bandwidth of − 31 MHz, and radiates directionally. The isolation between the ports is better than 25 dB. It has dimensions of 60 × 40 × 3 . 2 mm 3 . In  the antenna is composed of two layers of dielectric substrate and three layers of copper patches. Radiators consisting of two regular Sierpinski fractal triangles are onstructed on the top layer. The antenna contains two main ports and one auxiliary port. The two main ports are directly connected to the radiator. The auxiliary port is under the ground and feeds the radiator with an inverted-L feeding line. Ports 1 and 3 operate over the same frequency band of 1–4 GHz. The auxiliary port is multiband and operates at 2.4, 3.4, and 5.2 GHz to provide an additional WLAN/WiMAX port. Isolation between the two main ports is better than 10 dB. The isolation between the auxiliary port and the two main ports is better than 7.5 dB. The antenna has dimensions of 57 × 40 × 2 . 7 mm 3 . The radiation eﬃciency of the above antennas is unspeciﬁed.
To enhance the bandwidth of patch antenna aperture coupling feed and proximity coupling feed. Aperture feed and proximity feed both are difficult to fabricate. These techniques requires multi-layer substrates. However they are quite difficult and results in high cost. The same is done in single-layersubstrate as depicted in Fig.1, which reduces the cost effectiveness and simple to fabricate. Hence microstrip-fed is used because the substrate thickness can be reduced so that the bandwidth is enhanced. In addition harmonics can be fully suppressed.
Abstract—Evanescent mode substrate integrated waveguide (SIW) is one of the promising technologies for design of light-weight low-cost microwave components. Traditional realization methods used in the standard evanescent waveguide technology are often not directly applicable to SIW due to dielectric ﬁlling and small height of the waveguide. In this work, one of the realization methods of evanescent mode waveguides using a singlelayersubstrate is considered. The method is based on the use of coaxial stubs as capacitive susceptances externally connected to a SIW. A microwave ﬁlter based on these principles is designed, fabricated, and tested. The ﬁlter exhibits a transmission zero due to the implemented stubs. The problem of evanescent mode ﬁlter analysis is formulated in terms of conventional network concepts. This formulation is then used for modelling of the ﬁlters. Strategies to further miniaturization of the microwave ﬁlter are discussed. The approach is useful in applications where a sharp roll-oﬀ at the upper stop-band is required.
Circularly polarized (CP) antennas are extensively applied in satellite and wireless communication systems because of their ability to mitigate polarization mismatch and reduce multipath eﬀects. Single- fed CP antennas are especially desired due to their simple conﬁguration and ease of connection. On the other hand, the substrate integrated waveguide (SIW) has attracted great attention since it can beneﬁt from the advantages oﬀered by the waveguide and microstrip technologies, such as light weight, low proﬁle, reduced losses, and ease of integration with planar circuits [1–6]. Aiming at the miniaturization of the SIW, three types of structures derived from the traditional SIW have been proposed: the half- mode substrate integrated waveguide (HMSIW) [6–11], which is achieved by cutting the SIW along its ﬁctitious magnetic wall; the quarter-mode substrate integrated waveguide (QMSIW) [12–14], which is obtained by bisecting the HMSIW on its ﬁctitious magnetic wall; and the eighth-mode substrate integrated waveguide (EMSIW) [15, 16], which is realized by splitting the QMSIW along its ﬁctitious magnetic wall. An SIW antenna using a cross-shaped slot for obtaining CP radiation is presented in . In this antenna, the cross-shaped slot, whose arms have diﬀerent lengths, allows the excitation of two degenerate resonant modes that are orthogonal and 90 ◦ out of phase. The 3-dB axial-ratio (AR) bandwidth exhibited by this antenna is 0.8%. In , two single-fed cavity-backed slot CP antennas are investigated. The ﬁrst one is based on the SIW using a spoon-shaped slot, and the second one is based on the HMSIW employing a semicircle slot. The 3-dB AR bandwidths of these antennas are 1.8% and 2.3%, respectively. By exciting two quarter-wavelength patch modes that are orthogonal to each other, a single-layer slot antenna using HMSIW is designed in  to produce CP radiation with a 3-dB AR bandwidth of 1.74%. A CP QMSIW antenna operating in a higher-order resonant mode that exhibits
The electromagnetic theory of the fields in stratified me- dia can be derived from the plane wave assumption and the boundary conditions of electromagnetic waves (time- harmonic convention e j ωt ). In Kurt Altenburg (1953) this theory is derived. It can be found today in many books for op- tics, electromagnetics or microwave theory (Hecht, 2005). In the case of perpendicular incidence of a TE-wave (derivation for TM-waves accordingly) forward- and backward waves are defined, which summarize all waves in the same direc- tion (important difference to other approaches). The com- plete derivation can be found in Hecht (2005) and a sum- mary of it in Fitzek and Rasshofer (2009). For each layer i with the material parameters n i as the index of refraction
Love proposed that a superficial layer of relatively slow material over a faster half space might act as a wave guide for horizontally polarized transverse waves (SH waves). Love demonstrated that such a system would be dispersive: Low frequency waves would travel more quickly than high frequency waves. Accordingly, the inter- action between Earth’s crust and the mantle could sort a relatively short burst of seismic energy, such as is produced by an earthquake, into a long train of periodic, large amplitude, lateral waves similar to those observed in the seismic record. In his essay, Love also developed a theory of Rayleigh wave propagation in layered me- dia, but he did not extend the method to the propagation of Love waves in layered media. In Chapter 3, our development of Love wave relationships will begin in a manner reminiscent of Love’s own work; however, our treatment will diverge so that we can extend it to layered media with viscoelastic properties. We will also derive relationships that will allow us to account for the effects of geometric spreading.
A phenol-degrading microorganism, Rhodococcus sp.RSP8, was used to study the substrate interactions during cell growth on phenol and p-chlorophenol dual substrates. Both phenol and p-chlorophenol could be utilized by the bacteria as the sole carbon and energy sources. When cells grew on the mixture of phenol and p-chlorophenol, strong substrate interactions were observed. The p-chlorophenol inhibited the degradation of phenol, on the other hand, phenol also inhibited the utilization of p-chlorophenol. The overall cell growth rate depends on the co-actions of phenol and p-chlorophenol. In addition, the cell growth and substrate deg- radation kinetics of phenol, p-chlorophenol as single and mixed substrates for Rhodococcus sp.RSP8 in batch cultures were also investigated over a wide range of initial phenol concentrations (5 - 1600 mg·L –1 ) and ini- tial p-chlorophenol concentrations (5 - 250 mg·L –1 ). The single-substrate kinetics was described well using the Haldane-type kinetic models, with model constants of µ m1 = 0.15 h –1 , K S1 = 2.22 mg·L –1 and K i1 = 245.37
Lateral, power MOSFETs, exhibiting blocking voltages up to 600 V and beyond, have been implemented in thick-film silicon-on-insulator (SOI) having a thick, buried oxide (i.e. silicon dioxide). This type of device has an advantage that it is possible to support power and logic circuits on the same substrate, but isolate different parts of the circuits using the buried oxide. This arrangement, however, has not been widely adopted due, 35
is, as stated in previous chapters, that the SXW technique determines layer spacings with respect to the underlying bulk periodicity of the substrate and therefore these values will be susceptible to any relaxations o f the topmost sub strate layers which occur in a direction perpendicular to the surface, [ie if the top layer relaxes outward to produce an enlarged value of the distance between the first and second atomic layers of the substrate, then the SXW technique will overestimate the true local value of the layer spacing by an amount corre sponding to this relaxation and the opposite effect occurs for substratelayer contractions.) The fact that these relaxations are generally never observed to be more than a few percent of the bulk interlayer spacing and noting that an outer layer expansion of greater than 20% is required to reconcile the result of this study with four fold site occupation, seems to suggest that this effect alone cannot be giving rise to a false site determination. It is interesting to note, however , that an adsorbate induced surface layer relaxation of this size has been reported for the adsorption of oxygen on C’u( 110) .
In some cases, alterations and modifications of the adhesive and surface can be found in the vicinity of the interface, signifying the formation of an interfacial zone. This interfacial zone may demonstrate properties (or property gradients) that vary from those seen in bulk materials. The first proponent of this theory was Bikerman, who stated that the cohesive strength of a weak boundary layer (wbl) was the main factor in assessing adhesion, even when the failure appeared to be interfacial. 75-77 According to this theory, the measured adhesion energy (G) is every time equal to the cohesive energy (Gc(wbl)) of the weaker interfacial layer. This theory is based on statistics and probability, which suggest that the fracture should never propagate only along the adhesive-substrate interface and that the cohesive failure within the weaker material near the interface is more likely. Therefore, Bikerman suggested several types of wbl’s, including those resulting from impurities, molecules, or polymer chains.
Concerted efforts on the piezoresistive microcantilever biosensor development generally focus on integrating different sensor elements and electronic functions on a single chip, and combining microelectronics with biologically related molecules such as deoxyribonucleic acid (DNA), or any other biological entities (Wee et al. 2005, Villanueva et al. 2007) . To achieve these long-term goals, current researches are now focusing on achieving smaller size device, simpler fabrication process, reduced cost and high performance of the fabricated biosensor (Bais et al. 2009, Bais et al. 2011, Park et al. 2010, Firdaus et al. 2010).Various microfabrication techniques, from bulk to surface micromachining, or a combination of both are considered. Still, not many of the fabrication approaches available today satisfy all the desired requirements. Very few commercial products of the piezoresistive microcantilever sensor are currently available in the market today, indicating that the device’s fabrication processes have not matured yet. Fabrication of the device utilizing high-cost process of dry etching in microcantilever release have been widely used (Fang et al. 2006, Zhou et al. 2009). Using wet etching, the fabrication cost is significantly reduced but common issues in the fabrication of the suspended microcantilever structure, particularly in the
ABSTRACT: In recent years, the demand for broadband antennas has increased for use in lower frequency and high- speed data communication systems. Printed antennas are economical and easily hidden inside packages, making them well suited for consumer applications. In this study a design has been developed to improve the antenna parameters in terms of impedance bandwidth, gain and radiation properties. The proximity-coupled rectangular microstrip antenna (PRMSA) is proposed. The fabricated antenna uses two-layersubstrate with the microstrip-line on the lower layer and the patch antenna on upper layer such as the feed line finishes in an open end underneath the patch. The study is made by comparing thickness of substrate of two layers. By increasing the substrate thickness it is found to be increase in impedance bandwidth and gain. The antenna parameters such as Radiation pattern, reflection coefficient, VSWR and HPBW is calculated and discussed.
From the several cross sectional observations of zinc coating using samples quenched in water during galvanneal- ing process, it has been understood that the Fe-Zn interme- tallic compound grows from the vicinity of the interface between zinc coating and steel substrate as shown in Fig. 2(a). Therefore, the eﬀect of absorption of X-ray should be taken into account in the estimation of thickness of the Fe-Zn intermetallic compound. Although the Fe-Zn layer has rough- ness in a microscopic viewpoint, the layer can be considered to be a uniform layer in macroscopic viewpoint such as X-ray diﬀraction method. Therefore, the layered structure model shown in Fig. 2(b) was used in the estimation.
Figure 15 shows that there is an optimum n value providing maximum performance, and for a device of this composition and base dimension, it is approximately 70 mW when n = 12. As n is increased the volume of piezoelectric material increases and so one would expect superior performance. However, a balance between number of layers and maximum power is clear and this results from: (i) reductions in the core substrate thickness whilst increasing n, causing decreased distance between the neutral axis and the piezoelectric material; and, (ii) the decrease in maximum displacement, both of which reduce strain in the piezoelectric layers. Further inspection of Figure 15 indicates that one can be mislead by the optimum n value from such parameter studies; comparing a 12-layer device to one with 2-layers, an approximate tripling in performance is observed, although six times more piezoelectric material is required. If space restriction is not a factor, in this example it is better to use several 2-layer devices. However, if space is limited then the 12-layer device is recommended as it has a similar overall volume to the 2-layer device but performs substantially better.
The nonlinear four-wave mixing (FWM) technique is becoming a versatile tool for the characterization of bulk crystals, as well as semiconductor micro- and nanostructures because it allows the fast and reliable evaluation of novel optoelectronic materials and related technologies. The technique opens a possibility to measure a number of electrical parameters of semiconductors in an “all-optical” way by using well-established correlations between electrical and optical processes. The unique advantage of this technique is the possibility of direct analysis of carrier transport by varying a spacing of light interference pattern. Previous studies on InGaN materials by FWM technique were carried out in heterostructures and single-quantum well samples [20-22]. Okamoto et al.  demonstrated that the main reason for the reduction of η ext for a large amount of In is not the
and 1.0 3 10 17 cm 2 3 for n-substrate; these are the same con- centrations used for the calculations in Fig. 4 ~ b ! and 5 ~ b ! , and will be used throughout the remainder of this article. The calculations in these two figures demonstrate that physically thicker oxide/nitride dual layer films, having the same capacitance-voltage ~ or equivalently oxide-equivalent thick- ness ! as the physically thinner singlelayer oxides, may re- duce the tunneling current up to several orders of magnitude for both substrate injection and gate injection for a range of applied bias voltages up to at least 1.5 V. These currents were calculated using the same effective mass for the oxide and nitride regions with the other parameters the same as used in Fig. 4 ~ a ! . The effective mass for the nitride layer may be smaller than that of the oxide due to the increased dielec- tric constant and decreased band gap, and the implications of this difference in effective mass between the two layers of the dual gate dielectric structure will be addressed immedi- ately below in this section of the article. However, it is still anticipated that the dual layer structures will have lower di- rect tunneling currents with respect to singlelayer oxides with the same oxide equivalent thicknesses. This means from the perspective of direct tunneling currents, these types of oxide/nitride dual layer dielectrics should be useful for future generations of ULSI devices.
5 microstructure. The microstructure contains primary Co-rich dendrites (light grey areas) which are surrounded by Cr-rich eutectic carbides (dark grey areas) in a solid solution cobalt- rich matrix. It is noticeable that both weld claddings had smaller and finer dispersed carbides compared to the lost wax cast Stellite 6. A small percentage of tungsten-rich phases (white regions) are also present in both microstructures. A commercial vendor conducted the chemical analysis of the single and double layer Stellite 6 weld claddings as well as the lost wax cast Stellite 6 using standard chemical analysis techniques. The chemical analysis of the tested materials, the nominal composition of the feedstock used for HWTIG process as well as the low alloy steel substrate and stainless steel alloys are given in Table 3. The depths of the single and double layer weld deposits were measured using Image J software on cross sections and were found to be 1.4mm and 3.1mm respectively.
• SINGLE-LAYER NET (FEED-FORWARD NETWORKS): A singleLayer nets has one layer of connection weights , the unit can be distinguished as input units which receives signals from outside world and output units from which the response of the net can be read . In a singlelayer net, the weight for one output unit do not influence the weights for other output units.
All the above mentioned antennas are microstrip patch antenna with the patch and feed line with stub matching edge feed in between the two. The substrate material used is FR4 Epoxy with a dielectric constant of 4.4. Rectangular patch is the most commonly used microstrip patch antenna which looks like a truncated microstrip transmission line. It is approximately of one-half wavelength long. As the antenna is loaded with a dielectric as its substrate, the length of the antenna decreases as the relative dielectric constant of the substrate increases. The resonant length of the antenna is slightly shorter because of the extended electric "fringing fields" which increase the electrical length of the antenna slightly. An early model of the microstrip antenna section of microstrip transmission line with equivalent loads on either end to represent the radiation loss.