A folded loop antenna with four resonant modes

A multimode loop antenna with compact volume for mobile applications is presented in this paper. The loop antenna consists of a loop strip with a length of about 0.5λ. The loop strip is meandered to save space and bent to generate three traditional resonant modes, the 0.5-λ, 1-λ and 1.5-λ modes, and an additional higher mode, the 2-λ mode. The additional 2-λ mode is generated by adjusting the distance between the feed point and shorting point of the loop strip. The 1-λ, 1.5-λ and 2-λ modes together form an upper band with a wide bandwidth of 1.71-2.69 GHz to cover the DCS1800, PCS1900, UMTS2100, LTE2300 and LTE2500 systems. By using a matching network at the loop input, the lower band generated by the 0.5-λ mode has a bandwidth of 0.76-1.09 GHz to cover the GSM850 and GSM900 systems.postprin

Isolation improvement using CMRC for MIMO antennas

In this paper, a compact microstrip resonant cell (CMRC) is proposed to improve isolation of antenna elements in the design of multiple-input multiple-output (MIMO) antennas. The MIMO antenna used for studies consists of two symmetrical L-shaped planar inverted-F antenna (PIFA) elements placed at a distance of 16.2 mm on a printed-circuit board (PCB). A single-layer CMRC is etched on the PCB between the PIFA elements to improve isolation between them. Computer simulation is used to study and design the MIMO antenna. Results show that the CMRC can increase isolation between the two PIFA elements by 10 dB in the 2.4-GHz WLAN band. The envelope correlation coefficient (ECC) is about 0.0005 to 0.0035 over the frequency band.postprin

A compact ultrawideband MIMO antenna

A multiple-input multiple-output (MIMO) antenna having a very compact size of 40×26 mm2 is proposed for portable ultrawideband (UWB) applications. Two planar monopole antennas with microstrip-fed are used as the elements of the MIMO antenna and are placed perpendicularly to each other to achieve pattern diversity. Two stubs are etched on the ground plane to enhance isolation between the two elements and increase the impedance bandwidth of the MIMO antenna. Results show the MIMO antenna can cover the entire UWB band from 3.1-10.6 GHz with an isolation of larger than 16 dB throughout the frequency band. © 2013 EurAAP.published_or_final_versio

A MIMO antenna for mobile applications

A multiband Multiple-Input Multiple-Output (MIMO) antenna for mobile phones applications in the next generation is proposed. The proposed MIMO antenna consists of two identical elements, each having three branches to generate two frequency bands, a wide higher and narrow lower frequency bands. Simulation results show that these two frequency bands can cover the lower band for Long-Term Evolution (LTE), the DCS1800, PCS1900 and UMTS-2100 bands, the Wibro Band, the 2.4-GHz band for the WLAN system and also the upper band for the WiMAX. By cutting a slit on the printed circuit board (PCB) serving the ground plane, a great enhancement of isolation between the two antenna elements can be achieved for the two frequency bands. © 2013 IEEE.published_or_final_versio

Design of a printed multiband MIMO antenna

A multiband MIMO antenna using planar technology is proposed for next generation mobile communication system. The antenna consists of two symmetrical monopole elements printed in parallel to each other at the upper and lower corners of a printed-circuit board (PCB) with a size 50×110 mm2 which is similar to the side of a mobile phone. The two monopoles have two branch strips to generate two frequency bands. By using a parasitic element in each monopole, a much enhanced bandwidth in the upper band can be obtained. A lumped-impedance network is designed to enhance matching at the input ports for the two antenna elements. Computer simulation is used to study, design and optimize the antenna. Results indicate that the proposed MIMO antenna has a very bandwidth enough to cover the LTE (lower band), DCS1800, PCS1900, UMTS-2100, Wibro Band, 2.4G-WLAN, and Wimax (upper band) systems. To enhance the isolation between the two monopole elements within the desirable frequency bands, a slit is cut in the middle on the PCB ground. The MIMO antenna a very low profile and low cost which makes the design very attractive for mobile phone applications. © 2013 EurAAP.published_or_final_versio

Restoration of optic neuropathy

Optic neuropathy refers to disorders involving the optic nerve (ON). Any damage to ON or ON-deriving neurons, the retinal ganglion cells (RGCs), may lead to the breakdown of the optical signal transmission from the eye to the brain, thus resulting in a partial or complete vision loss. The causes of optic neuropathy include trauma, ischemia, inflammation, compression, infiltration, and mitochondrial damages. ON injuries include primary and secondary injuries. During these injury phases, various factors orchestrate injured axons to die back and become unable to regenerate, and these factors could be divided into two categories: extrinsic and intrinsic. Extrinsic inhibitory factors refer to the environmental conditions that influence the regeneration of injured axons. The presence of myelin inhibitors and glial scar, lack of neurotrophic factors, and inflammation mediated by injury are regarded as these extrinsic factors. Extrinsic factors need to trigger the intracellular signals to exert inhibitory effect. Proper regulation of these intracellular signals has been shown to be beneficial to ON regeneration. Intrinsic factors of RGCs are the pivotal reasons that inhibit ON regeneration and are closely linked with extrinsic factors. Intracellular cyclic adenosine monophosphate (cAMP) and calcium levels affect axon guidance and growth cone response to guidance molecules. Many genes, such as Bcl-2, PTEN, and mTOR, are crucial in cell proliferation, axon guidance, and growth during development, and play important roles in the regeneration and extension of RGC axons. With transgenic mice and related gene regulations, robust regeneration of RGC axons has been observed after ON injury in laboratories. Although various means of experimental treatments such as cell transplantation and gene therapy have achieved significant progress in neuronal survival, axonal regeneration, and restoration of the visual function after ON injury, many unresolved scientific problems still exist for their clinical applications. Therefore, we still need to overcome hurdles before developing effective therapy to treat optic neuropathy diseases in patients.published_or_final_versio

Air quality monitoring for vulnerable groups in residential environments using a multiple hazard gas detector

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This paper presents a smart “e-nose” device to monitor indoor hazardous air. Indoor hazardous odor is a threat for seniors, infants, children, pregnant women, disabled residents, and patients. To overcome the limitations of using existing non-intelligent, slow-responding, deficient gas sensors, we propose a novel artificial-intelligent-based multiple hazard gas detector (MHGD) system that is mounted on a motor vehicle-based robot which can be remotely controlled. First, we optimized the sensor array for the classification of three hazardous gases, including cigarette smoke, inflammable ethanol, and off-flavor from spoiled food, using an e-nose with a mixing chamber. The mixing chamber can prevent the impact of environmental changes. We compared the classification results of all combinations of sensors, and selected the one with the highest accuracy (98.88%) as the optimal sensor array for the MHGD. The optimal sensor array was then mounted on the MHGD to detect and classify the target gases without a mixing chamber but in a controlled environment. Finally, we tested the MHGD under these conditions, and achieved an acceptable accuracy (70.00%)

Searching (the) FIRST radio arcs near ACO clusters

Gravitational lensing (GL) of distant radio sources by galaxy clusters should produce radio arc(let)s. We extracted radio sources from the FIRST survey near Abell cluster cores and found their radio position angles to be uniformly distributed with respect to the cluster centres. This result holds even when we restrict the sample to the richest or most centrally condensed clusters, and to sources with high S/N and large axial ratio. Our failure to detect GL with statistical methods may be due to poor cluster centre positions. We did not find convincing candidates for arcs either. Our result agrees with theoretical estimates predicting that surveys much deeper than FIRST are required to detect the effect. This is in apparent conflict with the detection of such an effect claimed by Bagchi & Kapahi (1995).Comment: 6 pages; 8 figures and 1 style file are included; to appear in Proc. "Observational Cosmology with the New Radio Surveys", eds. M. Bremer, N. Jackson & I. Perez-Fournon, Kluwer Acad. Pres

Correlating charge and thermoelectric transport to paracrystallinity in conducting polymers.

The conceptual understanding of charge transport in conducting polymers is still ambiguous due to a wide range of paracrystallinity (disorder). Here, we advance this understanding by presenting the relationship between transport, electronic density of states and scattering parameter in conducting polymers. We show that the tail of the density of states possesses a Gaussian form confirmed by two-dimensional tight-binding model supported by Density Functional Theory and Molecular Dynamics simulations. Furthermore, by using the Boltzmann Transport Equation, we find that transport can be understood by the scattering parameter and the effective density of states. Our model aligns well with the experimental transport properties of a variety of conducting polymers; the scattering parameter affects electrical conductivity, carrier mobility, and Seebeck coefficient, while the effective density of states only affects the electrical conductivity. We hope our results advance the fundamental understanding of charge transport in conducting polymers to further enhance their performance in electronic applications

Individually Frequency Tunable Dual- and Triple-band Filters in a Single Cavity

© 2013 IEEE. This paper presents a new class of second-order individually and continuously tunable dual- and triple-band bandpass filters in a single metal cavity. Each passband is realized by two identical metal posts. These dual- and triple-band tunable filters are achieved by putting two or three identical sets of metal-post pair in a single metal cavity. Metal screws are co-designed as a part of the metal posts to control their insertion depth inside the cavity. In this way, the resonant frequencies can be continuously controlled and designed at the desired frequency bands. Moreover, the distance between the two metal posts in a post pair can be freely tuned. Thus, the external quality factor (Qe) and coupling coefficient (k) between the adjacent modes can be easily adjusted to meet the specified requirement in synthesis design. At the bottom of the cavity, some grooves are used to extend the tunable frequency range and make the resonant frequency linearly varied with the height of the metal post. The center frequency of each passband can be independently tuned with a frequency range of 0.8-3.2 GHz and tunable ratio of 4. Finally, the continuously tunable dual- and triple-band bandpass filters prototypes with second order response are designed and fabricated, of which each passband can be individually tuned with a large tuning range