Designs of Compact, Planar, Wideband, Monopole Filtennas with Near-Field Resonant Parasitic Elements

© 2018 IEEE. Two planar efficient wideband, electrically small monopole filtennas are presented. The first one directly evolves from a common planar capacitively loaded loop (CLL)-based filter possessing a flat realized gain response within the operational band and good band-edge selectivity. The second filtenna consists of a driven element augmented with a CLL structure and with slots etched into its ground plane. It expands the fractional impedance bandwidth of the first case from 6.28 percent up to 7.9 percent. It also has a gain response that remains flat over its operational bandwidth and even higher band-edge selectivity. Both filtennas are electrically small with ka less than 1. The experimental results, which are in good agreement with their simulated values, demonstrate that both filtennas exhibit excellent impedance matching, high radiation efficiency, flat gain response, and steep skirts at both band edges. Moreover, they produce monopole radiation patterns that are uniform and nearly omnidirectional in their H-planes

Experimentally Validated, Planar, Wideband, Electrically Small, Monopole Filtennas Based on Capacitively Loaded Loop Resonators

© 2016 IEEE. Two planar efficient wideband electrically small monopole filtennas are presented. The first one directly evolved from a common planar capacitively loaded loop (CLL)-based filter. This filtenna possesses a flat realized gain response within the operational band and good band-edge selectivity. The second filtenna consists of a driven element augmented with a CLL structure and with slots etched into its ground plane. It expands the fractional impedance bandwidth of the first case from 6.28% up to 7.9%. It too has a gain response that remains flat over its operational bandwidth and even higher band-edge selectivity. Both filtennas are electrically small: ka < 1. The experimental results, which are in good agreement with their simulated values, demonstrate that both filtennas exhibit excellent impedance matching, high radiation efficiency, flat gain response, and steep skirts at both band edges, as well as producing monopole radiation patterns that are uniform and nearly omnidirectional in their H-planes

Bandwidth-enhanced, compact, near-field resonant parasitic filtennas with sharp out-of-band suppression

© 2002-2011 IEEE. The designs, simulations, and measurements of a class of compact, bandwidth-enhanced filtennas are reported. Our design strategy is illustrated by separately designing a monopole and a bandpass filter to operate primarily in their respective fundamental modes. By combining these elements and manipulating the mutual coupling between them, an enhanced impedance bandwidth filtenna is realized. This strategy is applied to augment metamaterial-inspired near-field resonant parasitic antennas with filters. Simulations of these filtenna systems demonstrate that one can maintain stable radiation performance characteristics no matter how one arranges their component configurations, i.e., their relative positions and orientations. A selected filtenna design prototype was fabricated and tested. The good agreement between the simulated and measured results validates these design principles

Pattern-Reconfigurable, Flexible, Wideband, Directive, Electrically Small Near-Field Resonant Parasitic Antenna

© 1963-2012 IEEE. A pattern-reconfigurable, flexible, wideband, directive, electrically small near-field resonant parasitic (NFRP) antenna is presented. The antenna consists of a pair of Egyptian axe dipole NFRP elements, together with a pair of shaped metallic strips that act as the driven element and are fed by a coaxial cable. These NFRP and driven elements are designed to achieve compactness. Two pairs of p-i-n diodes are integrated into the driven element to enable the pattern reconfigurability. The antenna has two switchable directive endfire states, each pointed in direct opposition to the other. Examples of the evolution of the antenna are used to illustrate its operating principles. A prototype of the optimized design operating in a frequency range centered at 1.8 GHz was fabricated and measured. The simulation and experimental results are in good agreement. The antenna exhibits a wide 13.1% impedance bandwidth and a 4.42 dBi peak realized gain in both pattern-reconfigurable states while maintaining its electrically small size: ka ∼ 0.94. The flexibility of this antenna is demonstrated under different bending conditions by mounting it on cylinders with several different radii, and the results confirm that its performance characteristics are maintained under all of them

Pattern reconfigurable, vertically polarized, low-profile, compact, near-field resonant parasitic antenna

© 1963-2012 IEEE. A vertically polarized, low-profile, compact, near-field resonant parasitic antenna with pattern reconfigurability is demonstrated. The antenna has three dynamic end-fire states facilitated with only three p-i-n diodes. The radiation pattern in each state covers more than 120° in its azimuth plane and, hence, it achieves beam scanning that covers the entire azimuth plane. The antenna height and transverse size are, respectively, only 0.048λ 0 and 0.1λ 02 . Measured results, in good agreement with their simulated values, demonstrate that the antenna exhibits a 11% fractional impedance bandwidth, and a 6.6 dBi peak realized gain in all three of its pattern-reconfigurable states. Stable and high peak realized gain values are realized over its entire operational band surrounding 2.22 GHz

Designs of Compact, Flexible, Directive, Near-Field Resonant Parasitic (NFRP) Antennas

© 2018 IEEE. The designs of compact, low-profile, planar, flexible, directive, quasi-Yagi antennas are presented. By placing near-field resonant parasitic (NFRP) elements around the basic driven dipoles, these NFRP antennas achieve compactness, high efficiency and high directivity. The NFRP elements act either as director or reflector elements, empowering the antenna with desirable quasi-Yagi performance characteristics. These NFRP antennas are fabricated using thin substrates which can be bent without enduring any structure damage. The flexibility of these antennas is investigated under two bending conditions by mounting them on different radii cylinders. These antennas can be used in many advanced applications such as intelligent transportation system (ITS) and wearable devices

Natural frequency assignment for mass-chain systems with inerters

This paper studies the problem of natural frequency assignment for mass-chain systems with inerters. This is the problem to determine whether an arbitrary set of positive numbers may be assigned as the natural frequencies of a chain of n masses in which each element has fixed mass and is connected to its neighbour by a parallel combination of a spring and inerter. It is proved that mass-chain systems with inerters may have multiple natural frequencies, which is different from conventional mass-chain systems (without inerters) whose natural frequencies are always simple. It is shown that arbitrary assignment of natural frequencies including multiplicities is not possible with the choice of n inerters and n springs. In particular, it is shown that an eigenvalue of multiplicity m may occur only if n is greater than or equal to 2m -1. However, it is proved that n-1 inerters and n springs are necessary and sufficient to freely assign an arbitrary set of distinct positive numbers as the natural frequencies of an n-degree-of-freedom mass-chain system

Rapid quantification of semen hepatitis B virus DNA by real-time polymerase chain reaction

Aim: To examine the sensitivity and accuracy of real-time polymerase chain reaction (PCR) for the quantification of hepatitis B virus (HBV) DNA in semen. Methods: Hepatitis B viral DNA was isolated from HBV carriers' semen and sera using phenol extraction method and QIAamp DNA blood mini kit (Qiagen, Germany). HBV DNA was detected by conventional PCR and quantified by TaqMan technology-based real-time PCR (quantitative polymerase chain reaction (qPCR)). The detection threshold was 200 copies of HBV DNA for conventional PCR and 10 copies of HBV DNA for real time PCR per reaction. Results: Both methods of phenol extraction and QIAamp DNA blood mini kit were suitable for isolating HBV DNA from semen. The value of the detection thresholds was 500 copies of HBV DNA per mL in the semen. The viral loads were 7.5×10 7 and 1.67×10 7 copies of HBV DNA per mL in two HBV infected patients' sera, while 2.14×10 5 and 3.02×10 5 copies of HBV DNA per mL in the semen. Conclusion: Real-time PCR is a more sensitive and accurate method to detect and quantify HBV DNA in the semen. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Long-Term Physical Exercise and Mindfulness Practice in an Aging Population

Previous studies have shown that physical exercise and mindfulness meditation can both lead to improvement in physical and mental health. However, it is unclear whether these two forms of training share the same underlying mechanisms. We compared two groups of older adults with 10 years of mindfulness meditation (integrative body-mind training, IBMT) or physical exercise (PE) experience to demonstrate their effects on brain, physiology and behavior. Healthy older adults were randomly selected from a large community health project and the groups were compared on measures of quality of life, autonomic activity (heart rate, heart rate variability, skin conductance response, respiratory amplitude/rate), immune function (secretory Immunoglobulin A, sIgA), stress hormone (cortisol) and brain imaging (resting state functional connectivity, structural differences). In comparison with PE, we found significantly higher ratings for the IBMT group on dimensions of life quality. Parasympathetic activity indexed by skin conductance response and high-frequency heart rate variability also showed more favorable outcomes in the IBMT group. However, the PE group showed lower basal heart rate and greater chest respiratory amplitude. Basal sIgA level was significantly higher and cortisol concentration was lower in the IBMT group. Lastly, the IBMT group had stronger brain connectivity between the dorsal anterior cingulate cortex (dACC) and the striatum at resting state, as well as greater volume of gray matter in the striatum. Our results indicate that mindfulness meditation and physical exercise function in part by different mechanisms, with PE increasing physical fitness and IBMT inducing plasticity in the central nervous systems. These findings suggest combining physical and mental training may achieve better health and quality of life results for an aging population

Development of interfering RNA agents to inhibit SARS-associated coronavirus infection and replication.

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