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Antenna Configuration (antenna + configuration)

Distribution by Scientific Domains
Engineering57%
Earth and Environmental Science42%

Selected Abstracts

Fixed relaying with adaptive antenna arrays for the downlink of multihop cellular networks

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 2 2010
Zaher Dawy
Multihop cellular networks are expected to play an important role in the evolution towards 4G. In this work, we propose the use of advanced antenna techniques (adaptive antenna arrays and directional antennas) at fixed relay stations in order to enhance the downlink performance of multihop cellular networks. The performance gains of various adaptive antenna configurations are analytically studied by introducing a new system-level parameter called the interference reduction factor. Moreover, Monte-Carlo simulation results as a function of various design parameters are presented and analysed in order to further highlight the gains of advanced antenna techniques. Based on the presented analysis, we propose the use of a hybrid antenna configuration at relay stations in order to obtain high gains with limited increase in complexity and cost. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Finding the strike direction of fractures using GPR

GEOPHYSICAL PROSPECTING, Issue 3 2001
Soon Jee Seol
GPR reflection energy varies with antenna orientation relative to the strike and dip of the reflector. This directional dependence of GPR responses was investigated through numerical experiments and was used to estimate the azimuth of fractures and joints. Three antenna configurations were considered in this study: perpendicular-broadside (YY mode), parallel-broadside (XX mode) and cross-polarization (YX mode). The reflection energy in the cross-polarization mode shows a shape characteristic similar to the strike, regardless of the dip angle. Those in the other two modes show quite different amplitudes from the strike, depending on the dip angle. We have developed a strike-direction-finding scheme using data obtained from the three different modes for the same survey line. The azimuth angle of each reflector was displayed in colour on the GPR profile. This scheme was applied to a field survey at a granite quarry in southern Korea. The GPR profiles showed different images of the reflectors depending on the antenna configuration. The estimated azimuths of reflectors obtained using our scheme matched fairly well with those of known fractures and joints. [source]

Compact design of T-type monopole antenna with asymmetrical ground plane for WLAN/WiMAX applications

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2008
Wen-Shan Chen
Abstract The article proposed and studied a compact coplanar waveguide-feed antenna for WiMAX applications. In this design, using notches on the ground plane and trapezoid-feed line is to generate broadband operation of 10-dB return loss from 1.95 to 6.55 GHz. Furthermore, embedded a narrow slit etching on the radiation patch accounts for triple-band operation of 1.68,2.71 GHz, 3.26,4.06 GHz, and 5.03,6.24 GHz. It plays a role as a filter to eliminate the undesired band. The proposed antenna with a band-reject characteristic is calibrated for WLAN/WiMAX applications which covers the band from 2.4 to 2.7, 3.3 to 3.8, and 5.15 to 5.85 GHz. And, this antenna has advantages of good radiation characteristics, compact size, and omni-directional patterns. Details of the proposed antenna configuration and experimental results are discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 515,519, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23120 [source]

Stepped frequency ground-penetrating radar survey with a multi-element array antenna: Results from field application on archaeological sites,

ARCHAEOLOGICAL PROSPECTION, Issue 3 2010
Neil Linford
Abstract A series of trial geophysical surveys were conducted with a 3d-Radar GeoScope ground-penetrating radar (GPR) utilizing a multi-element array antenna. This system offers the potential for rapid data acquisition at very high sample densities over a wide frequency bandwidth. Field tests, conducted over the Roman town at Silchester, Hampshire, UK, suggested that a revised antenna configuration was necessary to obtain optimum results from the system, which was then successfully deployed in the collection of over 5,ha of survey data at a sample density of 0.075,m,×,0.075,m. The wide area survey produced a wealth of archaeological detail to complement and expand upon the extensive record of excavation, aerial photography and other geophysical results. Initial trial surveys were conducted with a range of antenna arrays (B2431, B1831 and B1823) incorporating different sized elements to fully exploit the wide potential bandwidth of the system. However, the differing response of elements proved difficult to combine within a single data set and a marked increase in quality was obtained with the use of a prototype V1821 antenna array of identical sized elements. Some concerns remain regarding both the suitability of air-launched antenna arrays to certain site conditions, as one early survey visit to Silchester produced very poor results that remain unexplained, and the maximum penetration depth compared with an impulse GPR using ground-coupled antenna. © 2010 Crown copyright. [source]

Fixed relaying with adaptive antenna arrays for the downlink of multihop cellular networks

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 2 2010
Zaher Dawy
Multihop cellular networks are expected to play an important role in the evolution towards 4G. In this work, we propose the use of advanced antenna techniques (adaptive antenna arrays and directional antennas) at fixed relay stations in order to enhance the downlink performance of multihop cellular networks. The performance gains of various adaptive antenna configurations are analytically studied by introducing a new system-level parameter called the interference reduction factor. Moreover, Monte-Carlo simulation results as a function of various design parameters are presented and analysed in order to further highlight the gains of advanced antenna techniques. Based on the presented analysis, we propose the use of a hybrid antenna configuration at relay stations in order to obtain high gains with limited increase in complexity and cost. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Finding the strike direction of fractures using GPR

GEOPHYSICAL PROSPECTING, Issue 3 2001
Soon Jee Seol
GPR reflection energy varies with antenna orientation relative to the strike and dip of the reflector. This directional dependence of GPR responses was investigated through numerical experiments and was used to estimate the azimuth of fractures and joints. Three antenna configurations were considered in this study: perpendicular-broadside (YY mode), parallel-broadside (XX mode) and cross-polarization (YX mode). The reflection energy in the cross-polarization mode shows a shape characteristic similar to the strike, regardless of the dip angle. Those in the other two modes show quite different amplitudes from the strike, depending on the dip angle. We have developed a strike-direction-finding scheme using data obtained from the three different modes for the same survey line. The azimuth angle of each reflector was displayed in colour on the GPR profile. This scheme was applied to a field survey at a granite quarry in southern Korea. The GPR profiles showed different images of the reflectors depending on the antenna configuration. The estimated azimuths of reflectors obtained using our scheme matched fairly well with those of known fractures and joints. [source]

Performance of multi level-turbo coding with neural network-based channel estimation over WSSUS MIMO channels

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2009
Ersin Gose
Abstract This paper presents the performance of the transmit diversity-multi level turbo codes (TD-MLTC) over the multiple-input,multiple-output (MIMO) channels based on the wide sense stationary uncorrelated scattering (WSSUS). The multi level-turbo code (ML-TC) system contains more than one turbo encoder/decoder block in its structure. At the transmitter side, the ML-TC uses the group partitioning technique that partitions a signal set into several levels and encodes each level separately by a proper component of the encoder to improve error performance. The binary input sequence is passed through the MLTC encoder and mapped to 4-PSK and then fed into the transmit diversity scheme for high data transmission over wireless fading channels. At the receiver side, distorted multi-path signals are received by multiple receiver antennae. WSSUS MIMO channel parameters are estimated by using an artificial neural network and an iterative combiner. Input sequence of the first level of the MLTC encoder is estimated at the first level of MLTC decoder. Subsequently, the other input sequences are computed by using the estimated input bit streams of the previous levels. 4-PSK two-level turbo codes are simulated for 2Tx,1Rx and 2Tx,2Rx antenna configurations over WSSUS MIMO channels. Here, TD-MLTC and its efficient implementations are discussed and simulation results are given. Copyright © 2008 John Wiley & Sons, Ltd. [source]