Circular-polarization reconfigurable monopole antenna with enhanced boresight gain for GNSS applications

A circular-polarization (CP) reconfigurable monopole antenna with enhanced boresight-gain for GNSS applications is proposed. The antenna consists of two meandered monopoles placed perpendicular to each other, a feeding network using the Wilkinson power divider, two switchable 90°-phase-shifters, a defected ground structure (DGS) and a metallic reflector. The metallic reflector is placed at the back of the antenna to improve efficiency and boresight gain. Simulation results show that the metallic reflector can substantially increase the efficiency and boresight-gain of the antenna by about 20% and 5 dB, respectively, in the operating band, yet retaining the impedance bandwidth and axial-ratio bandwidth.postprin

Frequency-Reconfigurable MIMO Monopole Antenna with Wide-Continuous Tuning Range

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Compact frequency reconfigurable slot antenna with continuous tuning range for cognitive radios

The design of a compact frequency-reconfigurable slot antenna for cognitive radios is proposed in this paper. The antenna consists of a rectangular-ring slot, a T-shaped feed line, an inverted T-shaped stub and two varactors. The length of the rectangular-ring slot is designed to resonate at about 2.4 GHz. The inverted T-shaped stub is used to extend the current path, making the total size of the antenna smaller for low frequency operation. The two varactors are used to achieve continuous tuning. The proposed antenna is studied and designed using computer simulation. The simulated return loss, radiation pattern, realized peak gain and efficiency of the antenna are presented. Results show that the antenna has a wide tuning range from 2.14 to 3.33 GHz (43.51%) and is a potential candidate for use in cognitive radios.postprin

Dual-cap Mushroom-like Metasurface used in CP Reconfigurable Monopole Antenna for Performance Enhancement

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Circularly polarized monopole antenna using CRLH TL feed network

A circularly polarized (CP) monopole antenna with the feed network designed based on using composite right/left-handed transmission line (CRLH TL) is proposed. The CP antenna consists of two monopole elements, a 90°-phase shifter implemented using a CRLH TL unit cell and a Wilkinson power divider. The two monopole elements are designed to operate at a frequency of about 2.3 GHz and placed in perpendicular to each other to generate two orthogonal-electric fields. The power divider divides the input signal into two signals with equal amplitude and phase. One of the signals is fed to a monopole element via the phase shifter, while the other signal is fed directly to the other monopole element. The two signals at the corresponding monopole elements are therefore in phase quadrature, hence generating a CP signal. Simulation results show that the antenna has an impedance bandwidth (S11 < -10 dB) of 1.89-3.20 GHz and a wide axial-ratio bandwidth (AR < 3 dB) of 2.08-2.36 GHz.postprin

Dual-band MIMO antenna using double-T structure for WLAN applications

Session - Interactive 2.3: Multi-Band AntennasThe Conference program's website is located at http://www.iwat2014.org/index.php/program/detailed-programA dual-band multiple-input-multiple-output (MIMO) antenna is proposed for the wireless-local-area-network (WLAN) applications in the 2.4-GHz and 5.2-GHz bands. The antenna consists of two double-T monopole elements with microstrip-fed and symmetrically placed on a substrate. To enhance isolation between the two monopole elements, three slots are cut on the ground plane on the other side of the substrate. The longer slot is used for better isolation in the 2.4-GHz band, while the two shorter slots are used for the 5.2-GHz band. Simulation and measurement are used to study the antenna performance in terms of S parameters, radiation patterns, realized gain, efficiency, and envelope correlation coefficient. Results show that the MIMO antenna has the two operation bands of 2.20-2.75 GHz and 5.09-5.50 GHz with mutual coupling of less than -15 dB and envelope correlation coefficient of less than 0.1, making it a good candidate for WLAN applications.published_or_final_versio

The classification for 'equilibrium triad' sensory loss based on sEMG signals of calf muscles

© 2017 IEEE. Surface Electromyography (sEMG) has been commonly applied for analysing the electrical activities of skeletal muscles. The sensory system of maintaining posture balance includes vision, proprioception and vestibular senses. In this work, an attempt is made to classify whether the body is missing one of the sense during balance control by using sEMG signals. A trial of combination with different features and muscles is also developed. The results demonstrate that the classification accuracy between vision loss and the normal condition is higher than the one between vestibular sense loss and normal condition. When using different features and muscles, the impact on classification results is also different. The outcomes of this study could aid the development of sEMG based classification for the function of sensory systems during human balance movement

Inertial sensor based post fall analysis for false alarming reduction

One of the major public health problems among elderly people is falling injury. This study investigates fall detection and prevention by using inertial sensors for which the major existing challenging is how to significantly reduce false alarming in order to enhance the acceptance of elderly users during rehabilitation and daily exercises. Different from most existing approaches in the literature, the behavior after falling will be analyzed in details, which can not only greatly reduce false alarming, but also significantly improves the accuracy of the assessment of the severity of falling injuries

MnSb2O6: a polar magnet with a chiral crystal structure

Structural and magnetic chiralities are found to coexist in a small group of materials in which they produce intriguing phenomenologies such as the recently discovered Skyrmion phases. Here, we describe a previously unknown manifestation of this interplay in MnSb2O6, a trigonal oxide with a chiral crystal structure. Unlike all other known cases, the MnSb2O6 magnetic structure is based on corotating cycloids rather than helices. The coupling to the structural chirality is provided by a magnetic axial vector, related to the so-called vector chirality. We show that this unique arrangement is the magnetic ground state of the symmetric-exchange Hamiltonian, based on ab initio theoretical calculations of the Heisenberg exchange interactions, and is stabilized by out-of-plane anisotropy. MnSb2O6 is predicted to be multiferroic with a unique ferroelectric switching mechanism.open4