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Design of Stripline-Fed Dual Polarization Aperture-Coupled Stacked Microstrip Patch Phased Array Antenna for Wideband ApplicationKim, David G. 2010 August 1900 (has links)
Recent days, antennas play an important role in wireless communication system. Microstrip
patch antennas are well known to have positive features for cost-effective, low profile and
broadband. This type of antenna can be used in wide range of applications such as in wireless
communications, radar systems, and satellites. Inhibiting characteristics of single patch antenna
with low gain and narrow band leads to the research area to have array configuration. Beam
steering antennas are the ideal solution for various systems such as traffic control and collision
avoidance radar systems.
The goal of this work is to design and implement a dual-linear polarization stacked microstrip
patch phased array antenna. Single stacked microstrip patch antenna fed by microstrip line was
designed to have approximately 3 GHz bandwidth in X-band with another ground plane to form
a stripline-fed. Stripline-fed design protects feed lines from any outside effects. The array
configuration was adapted to design in order to accomplish beam scan angle of /- 30 degrees by /- 15 degrees.
Binomial power distribution of 3x2 array structure was used in order to reduce grating lobes, and
changing length of feed lines was implemented for phase shifting. Bowtie cross shape aperture
and dual-offset microstrip feedline was used to feed radiating patches. For the feed network, T-split power divider was implemented and optimized to achieve low loss. The length of microstrip
line was adjusted to meet desired phase shift that in wideband application, the length of the line
had to be long enough to have similar wavelength response over broad frequency range. The
antenna array was designed using standard equations and simulated by electromagnetic analysis
software called Zealand's IE3D which is method-of-moments based simulator. The resulting
measured impedance bandwidth and gain of both microstrip and stripline-fed single antenna are
43 percent and 5 to 10 dBi with low cross polarizations for all frequencies. The array antenna was
measured to have 29 to 60 percent impedance bandwidths depending on the different types of beam
scan angles. The gain of the array antenna is 8 to 13 dBi, and the beams are directed as required
with /- 3 degrees beam scan angle tolerance. The array antenna had a small offset as compared with
simulated results because of the fabrication process such as alignment, distorted feed lines while
etching, and etc, but the bandwidths and array patterns were acceptable.
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The response of lepidopteran pests to commercialised Bt maize in South Africa / Jakobus Gideon VenterVenter, Jakobus Gideon January 2015 (has links)
Bt maize expressing Cry1Ab was approved for release in South Africa for control of
Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe)
(Lepidoptera: Crambidae) in 1998. During 2012, a stacked Bt maize event,
expressing Cry2Ab2 + Cry1A.105, was also approved for control of these
abovementioned pests. The aim of this study was to determine the effects of two Bt
maize events expressing Cry1Ab (MON810 and Bt11) and a Bt maize event
expressing Cry2Ab2 + Cry1A.105 (MON89034) on selected lepidopteran non-target
pest species and certain lepidopteran stem borer species in South Africa. Results
from previous studies and this study will provide information regarding efficacy of Bt
maize against pests which have not been evaluated yet. Insects with significance in
maize agro-ecosystems in South Africa as well as the rest of Africa, were prioritised
and laboratory bioassays were conducted to evaluate the effect of Bt maize against
these selected target and non-target pest species. Studies were conducted on three
stem borers C. partellus, Eldana saccharina and Sesamia calamistis and three nontarget
lepidopteran pest species Agrotis segetum, Helicoverpa armigera and
Spodoptera exempta. Results showed that MON810 maize was not effective against
A. segetum larvae feeding on maize seedlings. Differential levels of survival were
observed between two A. segetum populations on MON89034 with a population from
Polokwane showing survival on the stacked maize event. No S. exempta 1st instar
larvae survived on MON810 and MON89034 but 3rd instar larvae survived on
MON810 maize. Helicoverpa armigera larvae survived on ears of MON810 maize
plants but not on events MON89034 or Bt 11. Results further indicated that C.
partellus larvae were highly susceptible to these three Bt maize events. Larval
survival of S. calamistis was recorded for larvae feeding on MON810 and Bt11 maize
ears but not on MON89034 maize ears. Bt maize during the vegetative growth
stages therefore effectively controlled C. partellus, S. calamistis and E. saccharina
but the latter two species was not effectively controlled when feeding on ear tissue.
This study provides important information on the effects of Bt maize on the most
important non-target pest species of maize in sub-Saharan Africa. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
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The response of lepidopteran pests to commercialised Bt maize in South Africa / Jakobus Gideon VenterVenter, Jakobus Gideon January 2015 (has links)
Bt maize expressing Cry1Ab was approved for release in South Africa for control of
Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe)
(Lepidoptera: Crambidae) in 1998. During 2012, a stacked Bt maize event,
expressing Cry2Ab2 + Cry1A.105, was also approved for control of these
abovementioned pests. The aim of this study was to determine the effects of two Bt
maize events expressing Cry1Ab (MON810 and Bt11) and a Bt maize event
expressing Cry2Ab2 + Cry1A.105 (MON89034) on selected lepidopteran non-target
pest species and certain lepidopteran stem borer species in South Africa. Results
from previous studies and this study will provide information regarding efficacy of Bt
maize against pests which have not been evaluated yet. Insects with significance in
maize agro-ecosystems in South Africa as well as the rest of Africa, were prioritised
and laboratory bioassays were conducted to evaluate the effect of Bt maize against
these selected target and non-target pest species. Studies were conducted on three
stem borers C. partellus, Eldana saccharina and Sesamia calamistis and three nontarget
lepidopteran pest species Agrotis segetum, Helicoverpa armigera and
Spodoptera exempta. Results showed that MON810 maize was not effective against
A. segetum larvae feeding on maize seedlings. Differential levels of survival were
observed between two A. segetum populations on MON89034 with a population from
Polokwane showing survival on the stacked maize event. No S. exempta 1st instar
larvae survived on MON810 and MON89034 but 3rd instar larvae survived on
MON810 maize. Helicoverpa armigera larvae survived on ears of MON810 maize
plants but not on events MON89034 or Bt 11. Results further indicated that C.
partellus larvae were highly susceptible to these three Bt maize events. Larval
survival of S. calamistis was recorded for larvae feeding on MON810 and Bt11 maize
ears but not on MON89034 maize ears. Bt maize during the vegetative growth
stages therefore effectively controlled C. partellus, S. calamistis and E. saccharina
but the latter two species was not effectively controlled when feeding on ear tissue.
This study provides important information on the effects of Bt maize on the most
important non-target pest species of maize in sub-Saharan Africa. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
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Modification in the noun phrase: the syntax, semantics, and pragmatics of adjectives and superlativesTeodorescu, Viorica Alexandra 05 February 2010 (has links)
The grammar of modification is highly complex and raises numerous questions about the relation between meaning and form. This dissertation provides a study of how modified noun phrases are interpreted and examines the consequences of these results for the syntax of the nominal domain. The discussion centers on two types of modification: superlatives and stacked modification. The data comes primarily from English, but other languages are also discussed. There is initial evidence that the main claims hold across a wide range of languages. The common view on superlatives is that they have two types of interpretations which are the result of a scope ambiguity and that the contrast between them needs to be captured by means of syntactic devices. Contra this standard approach I propose a saliency theory of superlatives which claims that there is no categorical difference between these two interpretations and where the variation in the meaning of superlatives is purely pragmatic in nature. Under this view the meaning of superlatives is a function of the properties of the surrounding discourse and the context-sensitivity of superlatives is subsumed to the more general phenomenon of context-dependency in the interpretation of natural language quantifiers. The saliency theory differs from other analyses that have adopted a discourse approach in that the so-called comparative reading does not depend on the presence or interpretation of focus. Previous approaches to multiple adjectives analyzed their order in terms of the semantics of individual adjectives. I present a new set of data which shows that this is insufficient and propose an explanation that takes into account the meaning of the whole nominal phrase. This result has consequences for how the architecture of grammar should be conceived. In particular, it shows that principles of syntactic well-formedness can sometimes be sensitive to compositional semantic interpretation, as well as pragmatic information. This is in contradiction to many contemporary approaches to grammar where the semantic component has no influence on the syntactic one. / text
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Stacked Package MIMO Antenna and Isolator Design of MIMO AntennaLee, Cheng-Han 30 July 2012 (has links)
This thesis is divided into two parts. In the first part, the antenna is integrated into the stacked package. The antenna and the semiconductor chip are co-designed together. We utilize the advantage of IPD manufacturing to develop strong capacitively coupled-fed miniaturization technology and fractal slots miniaturization technology. We design a miniaturized antenna operating at WLAN 2.4GHz band. The size of the antenna is only 4 mm¡Ñ8.625 mm (0.0327£f¡Ñ0.0707£f). The operating bandwidth is over 100 MHz. The radiation efficiency is over 60%.
In the second part, we design a stacked structure using FR4 substrate. The MIMO antenna is miniaturized by strong capacitively coupled-fed miniaturization technique, and we propose an S-shaped isolator which has wider isolation bandwidth to improve the isolation problem. The separation of both antennas is only 12 mm. The size of the isolator is only 10 mm¡Ñ10 mm. The measured operating bandwidth is 200 MHz, and the radiation efficiency is over 60%.
We also design a 10 mm¡Ñ10 mm size of MIMO antenna with 2 mm¡Ñ8 mm isolator on the stacked package structure. The antenna is operating at WLAN 2.45 GHz band, and the operating bandwidth is over 100 MHz. the radiation efficiency is over 40%.
Finally, we propose two different stacked package antenna applications. The first one is a dual-frequency design. The proposed antenna is operating at GPS (1.57 GHz) band and WLAN 2.4 GHz band. Another is a broadband design. The size of IPD is only 3 mm¡Ñ3 mm. The operating bandwidth is 40% (from 4.8 GHz to 7.2 GHz).
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The Study of Carrier Dynamics in Multi-Stacked InAs/GaAs Quantum DotsWang, Fu-Yun 08 August 2012 (has links)
This paper is using the Time-resolved Pump-Probe spectroscopy to study the quantum dots samples. The samples are InAs/GaAs multi-stacked quantum dots that with different spacer layer (10~30 nm). The stain between the InAs quantum dots and GaAs spacer layer that makes the valence band to split into heavy-hole and light-hole energy band. From the photoluminescence (PL), we see the heavy-hole and light-hole energy band are blue shift in InAs quantum dot, when the GaAs spacer layer decrease. We use the optic property of Pump-Probe spectroscopy of the change in the refraction index £Gn to investigate the shift of heavy-hole energy band, when the GaAs spacer layer decrease. We see the heavy-hole energy band of GaAs is blue shift when the GaAs spacer layer decrease. When we change the pump energy, the TRPP spectroscopy signal will change from positive to negative. This is the band-filling effect changes the refraction index £Gn , when the energy close to the GaAs heavy hole energy state. When the energy is above the GaAs heavy hole energy state, the TRPP signal is positive. When the excited carrier density decrease and the delay time increase, TRPP signal will change the positive value to negative value. These are band-gap renormalization and free-carrier absorption effect change the refraction index £Gn, when the carrier density decrease.
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Fabrication of Sb-doped CIGS by selenization of stacked elemental layer and thin solar cellJian, Chong-Yao 27 August 2012 (has links)
This study is using selenization of stacked elemental layers to form Cu(In,Ga)Se2(CIGS). In the process, use Cu/Sb/In/Ga/Se precursor to heat to 550 oC at Se vapor in vacuum chamber. From the result of XRD¡BRaman and EPMA, that show of the precursor do not form to CIGS. After that, The result of using different layers precursor to form CIGS show that only Cu/In/GaSe/Se reach to form CIGS, but it still has second phase. According to the literature¡Athe reason for the formation of CIGS selenide process due to interdiffusion caused the formation of ternary solid phase, the solid phase diffusion reaction could be hampered.And then change to use rapid thermal selenization to form CIGS with two step of heating (hold at 300 oC and 650 oC) at N2 atmosphere. The laminated follow the best results in the selenide process Cu/In/GaSe/Se precursors in Se atmosphere, the (112) preferred orientation is 26.8o-26.9o in the XRD results of the fixed process conditions. EPMA composition analysis and comparison of Ga actual amount will increase with the estimated value of the amount of increase(Estimated value 4atom% actual value 2atom%¡FEstimated value 9.2tom% actual value 10atom%¡AGa/¢»=0.32), but the composition has yet to amend. Then will join Sb on CIGS observed from the SEM results Sb does improve the CIGS thin film flatness as well as to help grain growth in rapid thermal selenization, grain size of about 1 to 3£gm.
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Investigation of miniaturized microstrip antenna efficiency enhancementRaju, Robin 31 July 2015 (has links)
Radiation Efficiency improvement of miniaturized microstrip antenna is studied in this thesis. It is shown that, the loss reduction in miniaturized Microstrip Antenna can be achieved through two possible ways. The first is by modifying the materials used for building the antenna, and the second method is by increasing the radiation conductance of the antenna. Material modification at nano/micro scale by replacing conductors with Metallo-Dielectric one dimensional medium for applications in loss reduction is investigated first. It is shown by the Transfer Matrix Method and using simulations that, for a one dimensional medium replacing very thin conductors (less than skin depth) by laminated multilayered conductors reduce losses. However, the improvement does not exceed the case of single conductor which is a few times thicker than skin depth. Secondly, the efficiency improvement of a small H-Shaped patch antenna by using closely coupled stacked parasitic resonators is studied. It is shown that significant improvement in efficiency can be achieved with minimal changes in the foot print, radiation pattern and cross polarization levels of the antenna. The effect of the overall thickness and superstrate dielectric constant on the efficiency improvement is studied parametrically. It is shown that by using 5 radiating resonators and appropriate choice of inter-conductor dielectric constant, for a small increase in thickness of 0.127mm (5mil), the radiation efficiency can be increased from 2.34% to 6.3%. This efficiency improvement can be made very significant from 2.4% to 33%, by increasing the height to 1.27mm (50mil). These translate to a gain improvement of 4dB and 13dB, respectively. This technique is also demonstrated experimentally in H-Shaped antennas with two different levels of miniaturizations. / October 2015
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On Optimizing Die-stacked DRAM CachesEl Nacouzi, Michel 22 November 2013 (has links)
Die-stacking is a new technology that allows multiple integrated circuits to be stacked on top of each other while connected with a high-bandwidth and high-speed interconnect. In particular, die-stacking can be useful in boosting the effective bandwidth and speed of DRAM systems. Die-stacked DRAM caches have recently emerged as one of the top applications of die-stacking. They provide higher capacity than their SRAM counterparts and are faster than offchip DRAMs. In addition, DRAM caches can provide almost eight times the bandwidth of off-chip DRAMs. They, however, come with their own challenges. Since they are only twice as fast as main memory, they considerably increase latency for misses and incur significant energy overhead for remote lookups in snoop-based multi-socket systems. In this thesis, we present a Dual-Grain Filter for avoiding unnecessary accesses to the DRAM cache at reduced hardware cost and we compare it to recent works on die-stacked DRAM caches.
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On Optimizing Die-stacked DRAM CachesEl Nacouzi, Michel 22 November 2013 (has links)
Die-stacking is a new technology that allows multiple integrated circuits to be stacked on top of each other while connected with a high-bandwidth and high-speed interconnect. In particular, die-stacking can be useful in boosting the effective bandwidth and speed of DRAM systems. Die-stacked DRAM caches have recently emerged as one of the top applications of die-stacking. They provide higher capacity than their SRAM counterparts and are faster than offchip DRAMs. In addition, DRAM caches can provide almost eight times the bandwidth of off-chip DRAMs. They, however, come with their own challenges. Since they are only twice as fast as main memory, they considerably increase latency for misses and incur significant energy overhead for remote lookups in snoop-based multi-socket systems. In this thesis, we present a Dual-Grain Filter for avoiding unnecessary accesses to the DRAM cache at reduced hardware cost and we compare it to recent works on die-stacked DRAM caches.
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