A compact CPW fed slot antenna for ultra wide band applications

A printed compact coplanar waveguide fed triangular slot antenna for ultra wide band (UWB) communication systems is presented. The antenna comprises of a triangular slot loaded ground plane with a T shaped strip radiator to enhance the bandwidth and radiation. This compact antenna has a dimension of 26mm×26mm when printed on a substrate of dielectric constant 4.4 and thickness 1.6mm. Design equations are implemented and validated for different substrates. The pulse distortion is insignificant and is verified by the measured antenna performance with high signal fidelity and virtually steady group delay. The simulation and experiment reveal that the proposed antenna exhibits good impedance match, stable radiation patterns and constant gain and group delay over the entire operating band

Compact Coplanar Waveguide Fed Ground Meandered Antenna for Wireless Application

A compact Co-Planar Waveguide (CPW) fed antenna operating at 2.4GHz with 300MHz 2:1 VSWR bandwidth is presented. Compared to a conventional quarter wavelength CPW fed monopole antenna, the aperture area reduction of the present antenna is 85%. The prototype antenna fabricated on a substrate of εr = 4.4 and thickness 1.6mm is only 22x10x1.6mm3. This much size reduction and impedance matching is achieved by adjusting the signal to ground plane separation and meandering the ground plane of a 50Ω CPW transmission line

A Novel Planar Fractal Antenna with CPW-Feed for Multiband Applications

In this paper, a multiband antenna using a novel fractal design is presented. The antenna structure is formed by inscribing a hexagonal slot within a circle. This base structure is then scaled and arranged within the hexagon along its sides without touching the outer structure. The proposed CPW fed, low profile antenna offers good performance in the 1.65 – 2.59 GHz, 4.16 – 4.52 GHz and 5.54 – 6.42 GHz bands and is suitable for GSM 1800/1900, Bluetooth, IMT advanced systems and upper WLAN applications. The antenna has been fabricated on a substrate of height 1.6 mm and εr = 4.4 and simulation and experimental results are found to be in good agreement

Compact CPW-Fed Slot Antenna with Harmonic Suppression

A compact coplanar waveguide (CPW)-fed uniplanar antenna with harmonic suppression characteristics is presented. The above characteristics are achieved by properly modifying the ground plane and adjusting the signal strip of an open-ended CPW-fed transmission line. The simulated and experimental characteristics of the antenna are presented, compared, and discussed.

A Compact Modified Ground CPW Fed Antenna for UWB Applications

A Coplanar waveguide fed compact planar monopole antenna with a modified ground plane is presented. Measured and simulated results reveal that the antenna operates in the Ultra Wide Band with almost constant group delay throughout the band. Developed design equations of the antenna are validated for different substrates. Time domain performance of the antenna is also discussed in order to assess its suitability for impulse radio applications

A Planar Compact Metamaterialinspired Broadband Antenna

An electrically small, broadband-modified, truncated ground metamaterial EZ antenna is presented. This, a modified EZ antenna system, achieves a larger bandwidth of the order of 650 MHz by adjusting the metamaterial-inspired meandered ground element fed by a top loaded monopole. The design is devoid of the large ground planes and the external parasitic elements used in conventional designs for achieving proper impedance matching characteristics. The antenna requires a small foot print of kg/5 3 kg/10, where kg is the guided wavelength corresponding to the lowest frequency of operation, when printed on a substrate of dielectric constant 4.4 and thickness 1.6 mm. The antenna offers a 2:1 VSWR bandwidth from 750 MHz to 1.4 GHz, which covers CDMA, GSM, and ISM bands

Compact CPW-fed uniplanar antenna for multiband wireless applications

A compact coplanar waveguide (CPW) fed uniplanar antenna for Quad-band applications is presented. The Quad-band operation is realized by imposing various current paths in a modified T-shaped radiating element. The antenna covers GSM 900, DCS 1800, IEEE802.11.a, IEEE802.11.b and HiperLAN-2 bands and exhibits good radiation characteristics. This low profile antenna has a dimension of 32mm×31mmwhen printed on a substrate of dielectric constant 4.4 and height 1.6mm. Details of design with experimental and simulated results are presented

Design Of Compact Microstrip Antennas Using A Modified Ground Plane

A method for simultaneously enhancing the bandwidth and reducing the size of microstrip antennas (MSAs) using a modified ground plane (GP) has been proposed with design formulas. A combshaped truncated GP is used for this purpose. This method provides an overall compactness up to 85% for proximity-coupled MSAs in the frequency range of 900 MHz–5.5 GHz with an improvement inbandwidth up to seven times when compared with the conventional ones

CPW-Fed Quad-Band Antenna for Compact Wireless Application

This paper presents the design and development of a compact CPW fed quad band antenna. This low profile antenna has a dimension of 32mmx31mm when printed on a substrate of dielectric constant 4.4 and height 1.6mm. The antenna covers GSM 900, DCS 1800, IEEE802.11.a, IEEE802.11.b and HiperLAN2 bands. The antenna exhibits good radiation characteristics with moderate gain

A Multi-Objective Antenna Placement Genetic Algorithm for Matched Array Synthesis on Complex Platforms

A Multi-Objective Antenna Placement Genetic Algorithm (MO-APGA) has been proposed for the synthesis of matched antenna arrays on complex platforms. The total number of antennas required, their position on the platform, location of loads, loading circuit parameters, decoupling and matching network topology, matching network parameters and feed network parameters are optimized simultaneously. The optimization goal was to provide a given minimum gain, specific gain discrimination between the main and back lobes and broadband performance. This algorithm is developed based on the non-dominated sorting genetic algorithm (NSGA-II) and Minimum Spanning Tree (MST) technique for producing diverse solutions when the number of objectives is increased beyond two. The proposed method is validated through the design of a wideband airborne SAR

Dual retrieval in conceptual information systems

Conceptual Information Systems provide a multi-dimensional conceptually structured view on data stored in relational databases. On restricting the expressiveness of the retrieval language, they allow the visualization of sets of realted queries in conceptual hierarchies, hence supporting the search of something one does not have a precise description, but only a vague idea of. Information Retrieval is considered as the process of finding specific objects (documents etc.) out of a large set of objects which fit to some description. In some data analysis and knowledge discovery applications, the dual task is of interest: The analyst needs to determine, for a subset of objects, a description for this subset. In this paper we discuss how Conceptual Information Systems can be extended to support also the second task.

Heat stress response for physiological traits in dairy and dual purpose cattle populations on phenotypic and genetic scales

The main objective of this thesis was to determine the potential impact of heat stress (HS) on physiological traits of lactating cows and semen quality of bulls kept in a temperate climate. The thesis is comprised of three studies. An innovative statistical modeling aspect common to all three studies was the application of random regression methodology (RRM) to study the phenotypic and genetic trajectory of traits in dependency of a continuous temperature humidity index (THI). In the first study, semen quality and quantity traits of 562 Holstein sires kept on an AI station in northwestern Germany were analyzed in the course of THI calculated from data obtained from the nearest weather station. Heat stress was identified based on a decline in semen quality and quantity parameters. The identified general HS threshold (THI = 60) and the thermoneutal zone (THI in the range from 50 to 60) for semen production were lower than detected in studies conducted in tropical and subtropical climates. Even though adult bulls were characterized by higher semen productivity compared to younger bulls, they responded with a stronger semen production loss during harsh environments. Heritabilities (low to moderate range) and additive genetic variances of semen characteristics varied with different levels of THI. Also, based on genetic correlations genotype, by environment interactions were detected. Taken together, these findings suggest the application of specific selection strategies for specific climate conditions. In the second study, the effect of the continuous environmental descriptor THI as measured inside the barns on rectal temperatures (RT), skin temperatures (ST), vaginal temperatures (VT), respiration rates (RR), and pulse rate (PR) of lactating Holstein Friesian (HF) and dual-purpose German black pied cattle (DSN) was analyzed. Increasing HS from THI 65 (threshold) to THI 86 (maximal THI) resulted in an increase of RT by 0.6 °C (DSN) and 1 °C (HF), ST by 3.5 °C (HF) and 8 °C (DSN), VT by 0.3 °C (DSN), and RR by 47 breaths / minute (DSN), and decreased PR by 7 beats / minute (DSN). The undesired effects of rising THI on physiological traits were most pronounced for cows with high levels of milk yield and milk constituents, cows in early days in milk and later parities, and during summer seasons in the year 2014. In the third study of this dissertation, the genetic components of the cow’s physiological responses to HS were investigated. Heat stress was deduced from indoor THI measurements, and physiological traits were recorded on native DSN cows and their genetically upgraded crosses with Holstein Friesian sires in two experimental herds from pasture-based production systems reflecting a harsh environment of the northern part of Germany. Although heritabilities were in a low range (from 0.018 to 0.072), alterations of heritabilities, repeatabilities, and genetic components in the course of THI justify the implementation of genetic evaluations including heat stress components. However, low repeatabilities indicate the necessity of using repeated records for measuring physiological traits in German cattle. Moderate EBV correlations between different trait combinations indicate the potential of selection for one trait to simultaneously improve the other physiological attributes. In conclusion, bulls of AI centers and lactating cows suffer from HS during more extreme weather conditions also in the temperate climate of Northern Germany. Monitoring physiological traits during warm and humid conditions could provide precious information for detection of appropriate times for implementation of cooling systems and changes in feeding and management strategies. Subsequently, the inclusion of these physiological traits with THI specific breeding values into overall breeding goals could contribute to improving cattle adaptability by selecting the optimal animal for extreme hot and humid conditions. Furthermore, the recording of meteorological data in close distance to the cow and visualizing the surface body temperature by infrared thermography techniques might be helpful for recognizing heat tolerance and adaptability in cattle.

Apatite-Polymer Composites for the Controlled Dual Delivery of BMP-2 and BMP-6 for Bone Tissue Engineering

The release of growth factors from tissue engineering scaffolds provides signals that influence the migration, differentiation, and proliferation of cells. The incorporation of a drug delivery platform that is capable of tunable release will give tissue engineers greater versatility in the direction of tissue regeneration. We have prepared a novel composite of two biomaterials with proven track records - apatite and poly(lactic-co-glycolic acid) (PLGA) – as a drug delivery platform with promising controlled release properties. These composites have been tested in the delivery of a model protein, bovine serum albumin (BSA), as well as therapeutic proteins, recombinant human bone morphogenetic protein-2 (rhBMP-2) and rhBMP-6. The controlled release strategy is based on the use of a polymer with acidic degradation products to control the dissolution of the basic apatitic component, resulting in protein release. Therefore, any parameter that affects either polymer degradation or apatite dissolution can be used to control protein release. We have modified the protein release profile systematically by varying the polymer molecular weight, polymer hydrophobicity, apatite loading, apatite particle size, and other material and processing parameters. Biologically active rhBMP-2 was released from these composite microparticles over 100 days, in contrast to conventional collagen sponge carriers, which were depleted in approximately 2 weeks. The released rhBMP-2 was able to induce elevated alkaline phosphatase and osteocalcin expression in pluripotent murine embryonic fibroblasts. To augment tissue engineering scaffolds with tunable and sustained protein release capabilities, these composite microparticles can be dispersed in the scaffolds in different combinations to obtain a superposition of the release profiles. We have loaded rhBMP-2 into composite microparticles with a fast release profile, and rhBMP-6 into slow-releasing composite microparticles. An equi-mixture of these two sets of composite particles was then injected into a collagen sponge, allowing for dual release of the proteins from the collagenous scaffold. The ability of these BMP-loaded scaffolds to induce osteoblastic differentiation in vitro and ectopic bone formation in a rat model is being investigated. We anticipate that these apatite-polymer composite microparticles can be extended to the delivery of other signalling molecules, and can be incorporated into other types of tissue engineering scaffolds.

The Influence of Adjacent Segment on the Reliability of Cu Dual Damascene Interconnects

Three terminal ‘dotted-I’ interconnect structures, with vias at both ends and an additional via in the middle, were tested under various test conditions. Mortalities (failures) were found in right segments with jL value as low as 1250 A/cm, and the mortality of a dotted-I segment is dependent on the direction and magnitude of the current in the adjacent segment. Some mortalities were also found in the right segments under a test condition where no failure was expected. Cu extrusion along the delaminated Cu/Si₃N₄ interface near the central via region was believed to cause the unexpected failures. From the time-to-failure (TTF), it is possible to quantify the Cu/Si₃N₄ interfacial strength and bonding energy. Hence, the demonstrated test methodology can be used to investigate the integrity of the Cu dual damascene processes. As conventionally determined critical jL values in two-terminal via-terminated lines cannot be directly applied to interconnects with branched segments, this also serves as a good methodology to identify the critical effective jL values for immortality.