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Radiation Properties (radiation + property)
Selected AbstractsRadiation properties of an omnidirectional planar microstrip antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2008Randy Bancroft Abstract The pattern and directivity of an ideal omnidirectional antenna, collinear coaxial, and omnidirectiontal microstrip antenna (OMA) are compared. The radiation of an OMA originates from the arraying of two radiating edges along each element. The width of the (OMA) elements determines omni-plane pattern variation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 55,58, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22995 [source] Numerical study on flame structure and NO formation in CH4,O2,N2 counterflow diffusion flame diluted with H2OINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2004Dong-Jin Hwang Abstract Numerical study on flame structure and NO emission behaviour has been conducted to grasp chemical effects of added H2O on either fuel- or oxidizer-side in CH4,O2,N2 counterflow diffusion flames. An artificial species, which has the same thermodynamic, transport, and radiation properties of added H2O, is introduced to feasibly isolate the chemical effects. Special concern is focused on the important role of remarkably produced OH radicals due to chemical effects of added H2O on flame structure and NO emission. The reason why the difference of behaviours between the principal chain branching reaction rate and flame temperature appear is attributed to the drastic change of reaction step (R120) from the production to the consumption of OH. It is also, however, seen that the most important contribution of produced OH due to chemical effects of added H2O is through reaction step (R127). The importantly contributing reaction steps to NO production are also examined. The production rates of thermal NO and prompt NO are suppressed by chemical effects of added H2O. The contribution of the reaction steps related to HNO intermediate species to the production of prompt NO is also stressed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Chemical effects of CO2 addition to oxidizer and fuel streams on flame structure in H2,O2 counterflow diffusion flamesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2003Jeong Park Abstract Numerical simulation of CO2 addition effects to fuel and oxidizer streams on flame structure has been conducted with detailed chemistry in H2,O2 diffusion flames of a counterflow configuration. An artificial species, which displaces added CO2 in the fuel- and oxidizer-sides and has the same thermochemical, transport, and radiation properties to that of added CO2, is introduced to extract pure chemical effects in flame structure. Chemical effects due to thermal dissociation of added CO2 causes the reduction flame temperature in addition to some thermal effects. The reason why flame temperature due to chemical effects is larger in cases of CO2 addition to oxidizer stream is well explained though a defined characteristic strain rate. The produced CO is responsible for the reaction, CO2+H=CO+OH and takes its origin from chemical effects due to thermal dissociation. It is also found that the behavior of produced CO mole fraction is closely related to added CO2 mole fraction, maximum H mole fraction and its position, and maximum flame temperature and its position. Copyright © 2003 John Wiley & Sons, Ltd. [source] Analysis of the radiation properties of a planar antenna on a photonic crystal substrateMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 13 2001Habib Ammari Abstract This paper is concerned with the rigorous investigation of the radiation properties of a planar patch antenna on a photonic crystal substrate. Under the assumptions that the driving frequency of the antenna lies within the band gap of the photonic crystal substrate and that the crystal satisfies a symmetry condition, we prove that the power radiated into the substrate decays exponentially. To do this, we reduce the radiation problem to the study of the well-posedness of a weakly singular integral equation on the patch antenna, and to the study of the asymptotic behaviour of the corresponding Green's function. We also provide a mathematical justification of the use of a photonic crystal substrate as a perfect mirror at any incidence angle. Copyright © 2001 John Wiley & Sons, Ltd. [source] Compact high-gain printed loop-antenna array integrated into a 5-GHz WLAN access pointMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2010Tzi-Chieh Hong Abstract A printed, planar loop-antenna array having a compact structure and high-gain, directional radiation properties for WLAN operation in the 5 GHz band is presented. The antenna-array design is composed of four-folded loops arranged to be of 2 × 2 configuration, printed on both sides of a 1.6-mm thick FR4 substrate, and one system printed circuit board (PCB) serving as an efficient reflector for the loops. The antenna array is set within the boundary of the PCB (size of 50 mm ×65 mm) and stacked there above by a separation distance of 5.4 mm only. That's, the design integrates the system PCB of an access point (AP) into an internal antenna solution for compact outdoor AP applications. The results show that good input matching with voltage standing wave ratio (VSWR) below 1.5 over the 5150,5825 MHz band can be achieved. Directional radiation patterns with peak gain at about 10 dBi were also obtained. Details of the antenna design are described and discussed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2261,2267, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25487 [source] A novel P-shaped printed monopole antenna for RFID applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Hanhua Yang Abstract In this article, a novel p-shaped printed monopole antenna is first proposed to operate simultaneously at the 2.45 and 5.8 GHz bands for radio frequency identification tag. Printed on a standard 1.6 mm FR4 substrate material, the printed monopole antenna has been demonstrated to provide an ultra wide 10 dB return loss bandwidth with satisfactory gains and radiation properties. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated. A good agreement is achieved between the simulation and the experiment. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 554,556, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24083 [source] Analysis on a novel ultra-wide bandwidth antenna of double-printed circular discMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2007Yi-Min Lu Abstract A novel ultra-wide bandwidth antenna of double-printed circular disc is presented in this article. Some reasonable theoretical analyses are proposed. Printed on the dielectric substrate and fed by a microstrip line, the antenna has been demonstrated to provide an UWB with return loss less than ,10 dB from 3.1 to 10.6 GHz and the satisfactory radiation properties. In addition, an even better impedance matching can be got by improved the feed point, which is quite valuable for broadband antennas design. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 311,313, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22115 [source] Experimental investigation of radiation properties of an antenna embedded in low permittivity thin-wire-based metamaterialMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2006Davor Bonefa Abstract Experimental results regarding the increase in directivity and gain of an antenna embedded in low-permittivity two-dimensional anisotropic thin-wire-based metamaterial are presented. As expected, increase in directivity and gain has been observed. The effect of main beam splitting with frequency increase, predicted by theoretical analysis, has been confirmed. The influence of the number of layers forming the metamaterial on the radiation pattern and gain has been investigated. Input impedance was measured both as a function of frequency and of the number of wire layers forming the metamaterial. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2581,2586, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21994 [source] Pentaband internal antenna for handset communication devicesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2006P. Ciais Abstract A compact pentaband planar inverted-F antenna (PIFA) suitable for handheld terminals is presented. This antenna is made of capacitively loaded shorted patches, a slot, and an efficient antenna-chassis combination to achieve multiband and wideband performances to operate in the 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and UMTS bands. Matching, radiation properties, and efficiency show that this antenna is suitable for these mobile communication standards. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1509,1512, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21717 [source] Electromagnetically-coupled microstrip-fed planar monopoleMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2006M. Beer Abstract A printed rectangular planar monopole that is electromagnetically coupled to a microstrip feedline is investigated. In contrast to directly feeding the plate by a microstrip line, this technique offers the advantage of isolating the radiator from the feed system and provides an extra parameter to control the tuning. The electromagnetic coupling is examined in relation to the impedance-bandwidth and radiation properties, and compared to the direct microstrip-feed method. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 108,110, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21278 [source] A compact dual-element antenna array for adaptive MIMO systemMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Xuan Wang Abstract A novel compact dual-element antenna array is proposed for adaptive MIMO system. By four embedded PIN diodes in the feeding network, the antenna array has three different working states. It can operate as a dual-element antenna array or work as a single antenna while the unselected antenna is terminated to a lumped matched resistor. As a dual-element antenna array, it has a ,10 dB impedance bandwidth of 595 MHz covering UMTS band with mutual coupling lower than ,15 dB in the whole band. The measured radiation patterns show that the radiation property of the selected antenna keeps steady no matter the other antenna is selected or not. The proposed antenna array can achieve antenna selection scheme to adapt to the time-varying channel conditions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 348,351, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24044 [source] | ||||||||||