We have designed, simulated and analyzed the performance of a single rectangular patch antenna for different feed techniques and substrate materials of given dielectric constants. The metric used for the performance measure were return loss, voltage standing wave ratio (VSWR) and total gain. We found that the patch antenna achieves better return loss, total gain and VSWR with Rogers RT Duroid 5880™ as the substrate material regardless of the feeding techniques utilized at 2.4GHz. Furthermore, among the three feeding techniques, inset-feed stand best when compared with other techniques. Based on the foregoing, we recommend that for WLAN applications at 2.4GHz employing a rectangular patch antenna, inset-feed technique and Rogers RT Duroid 5880™ should be given priority for optimum patch antenna.
In general, the design and construction of the star patch antenna consists of a star patch to be placed at the top of paper substrate material; partial ground plane with slit etched on the centre of ground plane beneath the paper substrate material. By introducing a star patch antenna and a partial ground plane, wide impedance bandwidth can be achieved which covers the frequency bands from 3.08 – 6 GHz. This antenna is denoted as a reference antenna. The L-stub on the patch and slit on the ground plane are introduced to cover the lower frequency bands and enhanced the bandwidth of the proposed antenna. In order to clarify the underlying mechanisms that influence the impedance bandwidth and to obtain an optimal design, the parametric studies of the antenna response to the L-stub and slit on the ground plane have been analysed.
Previous research using sustainable substrate material such as paper and textile for wearable antenna with various shapes of patch antenna have been reported. A jeans substrate material [Al-Ashwal, W.A.M. et. al., 2015, Sundarsingh, E. F. et. al., 2014], flannel and and jeans [Rahim, M. K. A. et. al., 2012], and polyster material [Ha, S. J. et. al., 2012] were proposed in the literature. Theoretically, the fabric substrate material that has low dielectric permittivity will minimize the surface wave loss and enhanced the impedance bandwidth of the antenna [Ahmad. S., et. al, 2012]. Wearable antenna using paper based substrate developed with inkjet printed EBG array and UWB antenna was discussed in details by [Kim, S., 2012 and Shaker, G., 2011]. The relative permittivity and the thickness of the substrate material are two significant factor of the antenna performances [ Shakhirul, M. S., et.al., 2014].
The preferred orientation can be determined semi- qualitatively by comparing the relative intensities of the diffractograms of the coatings with a random powder sample. A powder diamond diffractogram will give (111) : (220) planes integrated peaks at 100% : 25%. But significantly, our diffractograms read ratios up to 100% : 135% for (111) : (220) planes peaks. This can be seen clearly in Figures 1 to 3. To reason why powder diamond sample has a high (111) plane quantity is that the milling process of diamonds, being a very hard material, breaks down in smaller pieces at its (111) cleavage direction. Unlike grown thin film diamond, its orientation is determined by its nucleation orientation which is influenced by the substrate material and the deposition parameters.
In the coming years there is a great demand for high speed short range data transmission. With minimal interference there is a technology called UWB, which can be used anywhere, anybody at anytime in the communication applications. The present work involves the design of Ultra wideband antenna which can be operated at specific range of frequencies with light weight, inexpensive and compact portability. A substrate of K15 liquid crystal material is used in this present work with permittivity of 2.85 and loss tangent of 0.01. The proposed antenna has good performance over the entire UWB frequency (3.1 to 10.6GHz).
While designing Rectangular Microstrip Antenna (RMSA), Circular Microstrip Antenna (CMSA) and Non Linear Microstrip Antenna (NLMSA), the substrate thickness is 1.6 mm while dielectric materials used are FR4 Glass Epoxy, ROGERS and PAPER EPOXY with dielectric constant 4.4, 4.5 and 3.5 respectively. The process of measurement of performance parameters presented in this paper will be used for deciding the methodology to get best results at 2.4 GHz operating frequency with most widely used co-axial feeding technique as it gives proper impedance matching
In this paper, we constructed the halophyte Mesocosm experimental group which was used as a substrate ma- terial that consisted of tidal flat and dredged soil oil. Depending on whether the ingredients of vegetation and substrate material of Mesocosm, we constructed Mesocosm A (tidal flat soil + Salicornia herbecea), Mesocosm B (only dredged material), Mesocosm C (dredged soil + Salicornia herbecea). Monitoring was carried out of Warter quality factors (Chemical Oxygen Demand (COD), Total Nitrogen (T-N), Total Phosphorus (T-P), water temperature, salinity), Soil factors (Chemical Oxygen Demand (COD), Total (T-N), Total Phosphorus (T-P) and growth of Salricornia herbecea) in each Mesocosm. Habitat Stability Index of vegetation was calculated by us- ing the monitoring results.
Now days, this world is based on technology. The new research & development of wireless communication systems has the main region of this changed era. To fulfill the demand of these, invention of compact microstrip antennas with high gain and wideband operating frequencies has developed. Microstrip patch antenna has many salient features like small size, low profile, light weight, simple realization process and low manufacturing cost. With so many advantages, MSPA have some disadvantages also, such as narrow bandwidth etc. To improve the performance & Enhancement of the performance of such antennas &to meet the demand of bandwidth is necessary . There are many ways via them, we can improve the bandwidth of antennas, including of the substrate material, via different ways with low dielectric substrate, slotted patch antenna, the use of various impedance matching and feeding techniques, with the use of absorbers & resonators [2-8].
melting, the laser beam melts the powder line-by-line forming a consolidated layer from overlapping melt pools. The melt pool usually forms a circular or cylindrical segment. The stability of the melt pool is affected by the processing parameters such as laser power, scan speed, layer thickness, substrate material, and the properties of the powder  . The depth and width of a melt pool are controlled by the laser power and the scan speed  . Yadroitsev et al.  reported the presence of satellites on top of stainless steel 316L single tracks that promote the creation of pores and worsen the surface roughness. Tracing the causes and mechanisms of porosity formation is important in this area of research. Dai and Gu  proposed an hypothesis, based on modelling the process of selective laser melting of copper matrix composites, that pores form because of the entrapment of gaseous bubbles within each melt pool. However, this was not validated in their study.
After 28 days curing, two cylinders for each test material were sectioned using a masonry saw. The top and bottom 25 mm thick discs were removed from each cylinder and remainder was cut into discs of 100mm diameter x 50mm +/-5mm high. These disc specimens provided the test specimens for the permeameter. Specimens with large voids on the side surface, which might cause sealing problems in the permeameter, were discarded. Smaller surface voids were filled with Plaster of Paris prior to testing to ensure a good seal in the test cell. Following cutting and prior to testing all specimens were stored in a water tank at 20°C for a period of up to 2 weeks. . This procedure was repeated after 12 months for the second pair of cylinders of each material (repair and substrate). The total number of disc specimens of each material used for the permeability tests are given in table 4.2.
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The focus of this study was to immobilise zero valent bi-metals on a solid substrate for degradation of chlorine and chlorinated compounds in aqueous media. The protocol in preparation should use non toxic and environmentally friendly materials. It involved the synthesis of a solid material on which metal ions could be anchored on through a complexation reaction followed by reduction. Chlorine and chlorinated organic compounds can be removed from aqueous media by use of reducing materials containing zero valent bimetals (ZVB) in this case Fe/Zn couple. The ZVB were anchored on a solid phase ligands generated from polystyrene. The synthetic samples were made in the laboratory and real samples were fetched from Nairobi water and sewerage company, Kiamumbi water treatment plant and shallow well from Kiamumbi.
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As for any simulations, the boundary conditions are crucial and need to be defined. In this context, the loads applied and the kinematics of all the tooling involved in the SPR process need to be developed. The first step concerns the development of a CAD model able to reproduce the geometry and shape of the SPR tooling. Figure 13a shows the geometry of the real SPR C-frame while Figure 13b shows the virtual gun developed for the FE simulation. In the latter, the entire C-frame shape has been replaced by three main rigid bodies which are the punch, blank holder and die. Therefore, the only deformable bodies are the rivets and substrate materials. The second step concerns the identification of the loads and motions applied by the system. In general, depending on how the rivet is inserted, SPR systems are classified in two categories: “punching” or “pushing”. In a punching system, the punch is accelerated to a certain speed defined by the user and hits the rivet with an impact; while in a pushing system, a gradually increasing force is applied to push the rivet into the workpiece until it reaches a user defined displacement (Li et al., 2015).
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As stated earlier, covering the radiator and ground of the antenna by layers of a dielectric material improves impedance matching as also discussed in Section 3.1. For the proposed antenna, however, it is important to mention that the two layers of the dielectric (upper and lower) do not cover the entire length of the antenna. The upper and lower dielectrics start 2 mm from the feed point of the antenna to allow for soldering and radiation pattern symmetry. Using these layers adds gain on all frequency components in the band, and consequently increases the power delivered to the breast and reduces the power radiated in the free space around the antenna.
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Figure 3a shows an AFM image of an a-Si thin film prepared by PECVD on porous substrate. The image in Figure 3b was taken for the same structure after thermal annealing at 750°C for 2 h. These images show that after annealing, the sample is composed of large crystallites as compared with the untreated one. This behavior is due to the coalescence between grains during the crystallization process.
is similar to a patch antenna, the size of the metal should be large enough to prevent radiation on the back side. A reading range test using a 6 dBi circularly polarized antenna and 30 dBm reader power demonstrates the tag has 2.7 m reading range while placed on a 12 cm square aluminum plate. It decays to 2.1 m when the plate size is reduced to 9 cm. The calculated antenna efficiency is around 10%, while the efficiency is 45% for another metal tag design with more extensive reading range over 6 meters . The degraded antenna efficiency is primarily due to the lossy characteristics of the absorber, which dissipates a portion of the energy by its nonzero imaginary material constants.
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gain of 17 dBi and blanket up to 3.3 GHz to 3.8 GHz WiMAX band running frequency 4. Tommy Reynalda et al designed 4 x 4 array antenna using dielectric constant of 2.5. This structure is inspired by 3 having difference in number of array and dielectric substrate. Afterward it compare with one patch antenna having dielectric constant of 2.5. Researcher observed that modified structure has gain 16.02 dB and 150 MHz BW, when one patch antenna has gain 6.10 dB and 50 MHz BW 5. Researchers proved that array structure enhances the gain of the MSAs. Halim Boutayeb et al proposed new design of MSA introducing cylindrical EBG structure which enhanced the gain of 2.9 dB as compare to conventional MSAs 6. Shi – Wei Qu et al in the same year designed Y shaped stub proximity coupled V-slot MPA (Microstrip Patch Antenna)and observed 21% BW enhancement and 9 dBi gain feeding technique of this antenna is different than that of researchers 7. Jung-han Kim et al used very new structure for designing MSA known as SAP i.e. Short Annular Patch structure. Researcher succeeded to improve a gain by 3.12 dBi and 300 MHz BW compare to reference simple rectangular patch antenna 8. Bahadir Yildirim et al projected antenna in which a rectangular loop shaped parasitic radiator placed at different distance away from the patch antenna at 1.6 GHz operating frequency gain increases up to 3.3 dB 9. Kaushik Mandal and Partha Prtim Sarkar designed U-shaped patch antenna with two equal arms using PTFE (poly tetra fluro ethylene) substrate. Just below the U shaped patch inserted inverted U-shaped slot on circular shaped ground plane. They achieved 4.1 dBi gain and BW enhancement of 86.76%. Structural modification in MSAs effect the gain of the MSAs these proved by the researches 10. Modifications in shape of antenna tends to increase gain of MSAs was scrutinize by these researchers.
ABSTRACT: A major disadvantage of the micro strip-patch antenna is its inherently narrow impedance bandwidth of only a couple of per cent. Intensive research is going on to develop bandwidth-enhancement techniques by keeping its size as small as possible. In this paper a suspended rectangular microstrip antenna with rectangular slit (SRMSARS) is presented. Obtained bandwidth is 15.71% & 50.50% respectively with respect to center frequency. The substrate material of FR-4 with relative permittivity 4.4 and loss tangent of 0.0245 is used in this proposed antenna. The return loss and radiation pattern have been measured by using Vector Network Analyser.
Up to now, porous silicon is widely investigated for sens- ing, photonic, or MEMS applications as it is well sum- marized in , but its mesoporous or microporous electrical properties are not massively exploited. Two main topics have been discussed in the literature. First, the integration of inductances on the top of micro- or mesoporous layers improves their quality factor by low- ering Eddy currents in the substrate . Second, the iso- lation of silicon islands, where bipolar or MOS transistors may be integrated, has been studied in [3-5] for the development of a novel integrated circuit tech- nology. However, most of the time, porous silicon is oxi- dized in order to improve its dielectric performances.
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For a system of film - substrate spectrum transparency laws remain the same as for the free film, if < > ~ and = = ~ = 0. The film and the substrate are completely transparent. If < < ~ , when the substrate material is optically denser material film, the film material, the maxima and minima in the spectra of transparency shifted ,/2 with respect to the case, < > ~ , due to the difference of phase discontinuities at the interfaces media. Thus, on the basis of the interference fringes in the transparency and reflection spectra of the free film or a film on the substrate when the substrate and the film material does not absorb light, can be determined by one of the optical constants of the material at a blank principal refractive index, if the film thickness is known.
Cladding is similar with welding concept which is one of the thermal type techniques using a heat source to deposit a thin layer of a desired metal (by melting) on the substrate surface. Basically, the first thing that want to know is cladding is made from the laser cladding. Laser cladding using powder can be performed in two distinct ways. In the first process, powder is pasted on the surface by some adhesive and then the clad is formed by laser beam.
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