Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
In this letter, a novel 3D multi-beam reconfigurable THz loop antenna capable of steering\nits main beam in the semi-sphere space................................
Ultrawideband (UWB) antennas are widely used as core devices in high-speed wireless\ncommunication. A novel compact UWB monopole antenna with an additional narrow band for\nWi-Fi applications comprising a metamaterial (MTM) is proposed in this paper. The antenna has\na compact size of 27 * 33 mm2 and consists of a V-shaped slot with two rectangular slots in the\nradiation patch. The inductance and capacitance develop due to the V-shaped slot in the radiation\npatch. The proposed antenna has -10 dB bandwidths of 3.2 GHz to 14 GHz for UWB and 2.38 GHz\nto 2.57 GHz for narrowband, corresponding to 144% and 7.66% fractional bandwidths, respectively.\nThe measured gain and efficiency meet the desired values for UWB and Wi-Fi applications. To verify\nthe performance of the antenna, the proposed antenna is fabricated and tested. The simulated and\nmeasured results agree well at UWB frequencies and Wi-Fi frequencies, and the antenna can be used\nas a smart device for portable IoT applications....
Snowpack is an important fresh water storage; the retrieval of snow water equivalents\nfrom satellite data permits to estimate potentially available water amounts which is an essential\nparameter in water management plans running in several application fields (e.g., basic needs,\nhydroelectric, agriculture, hazard and risk monitoring, climate change studies). The possibility to\nassess snowpack height from Global Navigation Satellite Systems (GNSS) observations by means of\nthe GNSS reflectometry technique (GNSS-R) has been shown by several studies. However, in general,\nstudies are being conducted using observations collected by continuously operating reference stations\n(CORS) built for geodetic purposes and equipped with geodetic-grade instruments. Moreover, CORS\nare located on sites selected according to criteria different from those more suitable for snowpack\nstudies. In this work, beside an overview of key elements of GNSS reflectometry, single-frequency\nGNSS observations collected by u-blox M8T GNSS receivers and patch antennas from u-blox and\nTallysman have been considered for the determination of antenna height from the snowpack surface\non a selected test site. Results demonstrate the feasibility of GNSS-R even with non-geodetic-grade\ninstruments, opening the way towards diffuse GNSS-R targeted applications....
This paper presents a passive cavity type Ultra High Frequency (UHF) Radio Frequency\nIdentification (RFID) tag antenna having the longest read-range, and compares it with existing\nlong-range UHF RFID tag antenna. The study also demonstrates mathematically and experimentally\nthat our proposed longest-range UHF RFID cavity type tag antenna has a longer read-range than\nexisting passive tag antennas. Our tag antenna was designed with 140 * 60 * 10mm3 size, and reached\n26 m measured read-range and 36.3 m mathematically calculated read-range. This UHF tag antenna\ncan be applied to metal and non-metal objects. By adding a further sensing capability, it can have a\ngreat benefit for the Internet of Things (IoT) and wireless sensor networks (WSN)....
Owing to the widespread use of smartphones and various cloud services, user traffic\nin cellular networks is rapidly increasing. Especially, the traffic congestion is severe in urban\nareas, and effective service-cell planning is required in the area for efficient radio resource usage.\nBecause many users are also inside high buildings in the urban area, the knowledge of propagation\nloss characteristics in the outdoor-to-indoor (O2I) scenario is indispensable for the purpose. The\nray-tracing simulation has been widely used for service-cell planning, but it has a problem that\nthe propagation loss tends to be underestimated in a typical O2I scenario in which the incident\nradio waves penetrate indoors through building windows. In this paper, we proposed the extension\nmethod of the ray-tracing simulation to solve the problem. In the proposed method, the additional\nloss factors such as the Fresnel zone shielding loss and the transmission loss by the equivalent\ndielectric plate were calculated for respective rays to eliminate the penetration loss prediction error.\nTo evaluate the effectiveness of the proposed method, we conducted radio propagation measurements\nin a high-building environment by using the developed unmanned aerial vehicle (UAV)-based\nmeasurement system. The results showed that the penetration loss of direct and reflection rays was\nsignificantly underestimated in the ray-tracing simulation and the proposed method could correct\nthe problem. The mean prediction error was improved from 7.0 dB to -0.5 dB, and the standard\ndeviation was also improved from 8.2 dB to 5.3 dB. The results are expected to be utilized for actual\nservice-cell planning in the urban environment....
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