This paper presents a magnetic resonance wireless power transfer (WPT) system that uses three coils, a planar receiver and operates at 6.78 MHz,. Effective power transfer is ensured by establishing an impedance matching condition for this WPT system. A metamaterial (MTM) array having dimensions of 20 cm. 30 cm is also positioned near the load coil to concentrate the magnetic field and enhance the transfer efficiency. The result is a maximal improvement of 27% in the transfer efficiency at a transfer distance of 50 cm. The impact of a ground plane on the transfer efficiency is also examined. By utilizing the MTM array, making slits on the ground plane and increasing the gap between the ground plane and the load coil, it is possible to mitigate this impact. The highest transfer efficiency improvement is about 55% at a distance of 20 cm with the ground plane. A practical laptop model is fabricated to verify the impact of the load coil angle and position on the transfer efficiency. The result shows that the maximum transfer efficiency with the laptop model is 47.58% with the load coil angle of 90 degree(1)

A high efficiency and transparent seawater monopole antenna operating at 2.4 GHz for wireless local area network (WLAN) applications is proposed in this Letter. The antenna has high transparency (>85%) achieved by using seawater as its conductive medium contained within a clear acrylic tube. To improve the radiation efficiency of the antenna, a short metal tube with a metal disk at the base was loaded into a feeding probe to achieve greater excitation. The antenna is simulated and its properties are verified through this experiment. Measurement results show a −10 dB bandwidth of 1.1 GHz (2.1-3.2 GHz) and a high radiation efficiency (>71%) over the entire WLAN band (2.4-2.5 GHz). These results demonstrate the proposed antenna as an attractive alternative to conventional metal monopoles for WLAN applications.

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The present study examined the educational roles of games that were not designed for pedagogical purposes. With respect to the roles of gamers' communicationcommunication networks, network diversity, and heterogenous discussion-three specific sub-objectives of the present work include: (1) to examine the extent to which games can be social learning environments, (2) to examine how gamers' communication contributes to perceived learning, and (3) to evaluate the relationship between game genre's unique characteristics and learning effects. This work statistically tested a series of research hypotheses using empirical data obtained from a national survey of Korean gamers (N = 1392). The results from hierarchical multiple regression analysis indicate that game genres and gamers' communicative networks were significant predictors of perceived game learning. Importantly, game genres that are considered by policymakers to be violent and addictive were found to contribute to learning. Additionally, gamers' communication variables that are not closely related to education and politics significantly predicted their learning. Based on the results, this study suggests that game coplaying or gamers' social networks should be considered important for socio-cultural learning. Moreover, the current study provides empirical evidence that exposure to diverse perspectives during game playing contributes significantly to not only tolerance and deliberative democracy but also the sociopolitical learning of gamers. In this regard, the present study expands the literature on pedagogy (learning effects), political communication (benefits of heterogeneous/deliberative discussions), and game studies (game addiction/gaming disorder). Thus, this study provides new insights for current research on the educational roles of games.

This article introduces a performance investigation of textile patch antennas using double layer fabrics for wrist‐wearable applications. Two fabric substrates [top layer: conducting part (CP), bottom layer: fabric part (FP)] are used for an antenna design, and these are assembled using an adhesive. We chose polyester (PES) as the top fabric layer (CP) because the PES is a cloth of fine texture, which is useful for the steady screen printing of the antenna geometry. Four fabric samples (Fabric 1–4) were selected from actual clothes (i.e., pants and shirts), and these were used for the bottom fabric layer (FP). The textile antennas were simulated and measured to verify their performance and to compare this with that of the common microwave substrate. Moreover, a textile antenna was tested under various bent conditions as well as regarding its specific absorption rate for on‐body environments, such as the wrist and ankle. Based on the measurement results, it was confirmed that the textile antennas with double layer fabrics have good electrical performance, even in bent conditions, and can be used in wearable‐fabric applications, including body centric communications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2697–2702, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27200

Electromagnetic interference (EMI) shielding for visual observation applications, such as windows utilized in military or aerospace, is important but difficult to realize due to conventional materials having difficulty in achieving sufficient transparency and EMI shielding simultaneously. In this paper, we present multilayered structures based on salt water for simultaneous highly optical transparency (OT) and EM shielding effectiveness (SE) performance. In the proposed structures, planar acrylic and glass were used as two types of clear substrates to hold salt water. The measured OT of both acrylic/salt water/acrylic and glass/salt water/glass structures was higher than 90% with a nearly uniform light transmission, which introduced a negligible impact on optical observation. Furthermore, both simulations and experimental results demonstrated that the SE of the multilayer structure was higher than 20 dB in the X-band from 7.5 to 8.5 GHz. Moreover, the SE was significantly enhanced by increasing the thickness of the salt water layer. Especially, both OT and SE of the multilayered structures were improved simultaneously by increasing the salinity of the salt water. These proposed structures demonstrate great potential in EMI shielding observation applications.

This article presents a transparent microstrip line made of a transparent multilayer electrode (IZTO/Ag/IZTO) to investigate its feasibility in high frequency usage. The average transmittance of the transparent multilayer electrode is 81% in the range of visible wavelength and average conductivity is ∼2 × 106 S/m. The transparent microstrip lines, which are deposited on transparent acryl and glass substrates are fabricated and compared with the copper microstrip lines, which are printed on conventional microwave substrates, FR‐4. The transmission coefficient (S21) and reflection coefficient (S11) of the proposed microstrip line have been measured and reported. In addition, transparent microstrip lines on transparent ground planes have also been fabricated and measured with three IZTO/Ag/IZTO (IAI) electrodes (Thickness of Ag = 10, 12, 14 nm). © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1161–1164, 2017