Current Issue : July - September Volume : 2019 Issue Number : 3 Articles : 6 Articles
This paper proposes a segmented parabolic curved antenna, which can be used in the base\nstation of a 60 GHz millimeter wave communication system, with an oblique Yagi antenna as a feed.\nBy analyzing the reflection and multi-path interference cancellation phenomenon when the main\nlobe of the Yagi antenna is reflected, the problem of main lobe splitting is solved. 3D printing\ntechnology relying on PLA (polylactic acid) granule raw materials was used to make the coaxial\nconnector bracket and segmented parabolic surface. The reflective surface was vacuum coated (via\naluminum evaporation) with low-loss aluminum. The manufacturing method is environmentally\nfriendly and the structure was printed with 0.1 mm accuracy based on large-scale commercial\napplications at a low cost. The experimental results show that the reflector antenna proposed in this\npaper achieves a high gain of nearly 20 dBi in 57â??64 GHz frequency band and ensures that the main\nlobe does not split....
A horizontal azimuth pattern-reconfigurable antenna with configurable parasitic element arrays for WLAN applications is\nproposed in this paper. It consists of a control board, a central series-fed omnidirectional microstrip array, four configurable\nparasitic elements, a bottom conducting plate, and a top supporting plate. The omnidirectional microstrip array is adopted as an\nexciter, around which the four same parasitic element arrays are arranged at four corners. The p-i-n diodes as switches are\nplaced between the parasitic element arrays and the conducting plate to control the fifteen radiation patterns of the proposed\nantenna. The parasitic element arrays are configured as reflectors or directors by switching the p-i-n diodes on or off. The\nbandwidth achieved ranges from 5.00 GHz to 5.27 GHz. A gain of 8.52 dBi is obtained when the antenna reaches the maximum\ngain in the H-plane at 5.2 GHz. Good agreements between the simulated and measured results were observed. The proposed\nparasitic structure which has the same structure with the driven element can enhance the horizontal azimuth gain of the\nantenna. Only 4 p-i-n diodes are used to produce up to 15 useful beam configurations with a gain range of 4.56-8.52 dBi at the\nhorizontal azimuth....
The characterization of slow and fast fading in wireless body area networks with space diversity scheme has been presented. The\nanalysis, based on the measurements at 2.45 GHz in an indoor environment, has shown that for all investigated configurations\nof receiving wearable antennas, the correlation coefficient values of the received signalsâ?? parameters are below the assumed value\nof 0.5, being close to zero for the vast majority of cases. It has been shown that the slow fading component may be modelled by\na lognormal distribution with zero average and the standard deviation from the range of [1.43, 1.98] dB. The fast fading\ncomponent is the best modelled by a Rice distribution with the noncentrality parameter and the scale parameter being in the\nrange [0.8125, 0.9624] and [0.5269, 0.6954], respectively....
This work addresses the design and implementation of a broadband differential rectifier\n(DR) combined with an Archimedean spiral dipole antenna (ASDA) for wireless power harvesting\nat low incident power densities below 200 micro W/cm2. The proposed design exhibits an improved\nRF-DC conversion efficiency over a wide frequency range from 1.2 to 5 GHz. This frequency band is\nassociated with several wireless communication services, for instance, ISM, WLAN, 5G, LTE, and\nGPS applications. The receiving planar ASDA exhibits circular polarization and has an average\nmeasured gain of 4.5 dBi from 1.2 to 5 GHz. To enable a wide operating bandwidth, the rectifier\ncircuit is constituted by two architectures, designated A and B. Each scheme is designed to harvest\npower efficiently across a specific bandwidth. The optimal performance of both rectifiers are obtained\nusing the nonlinear harmonic-balance simulations. The antennaâ??rectifier integration yields a compact\nrectenna with a high-efficiency performance over the intended bandwidth from 1.2 to 5 GHz for an\ninput power of 9 dBm and terminal load resistance of 1 kilo Ohms. The total measured RF-DC conversion\nefficiency is maintained above 30% across the entire frequency range with a peak value of 61%\nachieved at 1.2 GHz. In comparison with similar architectures, the proposed rectenna maintains a\nstable output efficiency despite the wide fluctuations in the input frequency and also has a minimum\nfootprint size (58 * 55 mm2)....
A single-layer miniaturized reflectarray element with low sensitivity to mutual coupling effects of surrounding elements is\npresented in this paper. The configuration is proposed to preserve the effectiveness of the infinite array approach in those\napplications requiring reflectarrays with very small interelement spacing. The inherent ability of the proposed geometry to be\nadopted in highly miniaturized cells is demonstrated through an extensive analysis of mutual coupling effects on reflectarray\nphase design curves. In order to prove the independence of the proposed cell to mutual coupling effect, the phase curve\nvariations due to the presence of different surrounding elements with respect to the case of identical cells are evaluated using the\nwell-known extended local periodicity method. Small and negligible mutual coupling errors are retrieved for the proposed\nminiaturized unit cell, thus demonstrating lower sensitivity to mutual coupling adverse effects....
A new wideband dual-polarized (DP) quasi-omnidirectional antenna is proposed. The DP antenna consists of a vertical slot for\nhorizontal polarization (HP) and a folded horizontal slot for vertical polarization (VP). A tapered strip is employed to coupling\nfeed the vertical slot while a straight strip is used to excite the horizontal slot. Due to the coupling feed and the orthogonality\nbetween the vertical and horizontal slots, the DP antenna features a wide bandwidth and a very high isolation. The simulated\nisolation is higher than 70 dB, although the measured isolation is about 50 dB. As experimental results indicate, the DP antenna\nrealizes an impedance bandwidth (BW) of 45% (1.7â??2.73 GHz) with quasi-omnidirectional radiation patterns for both HP and\nVP. The DP quasi-omnidirectional antenna may be packaged into a radome with a shape of a blade for mobile applications in\nhigh-speed vehicles....
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