Distribution by Scientific Domains
Distribution within Engineering

Kinds of Slot

  • narrow slot
  • time slot

  • Terms modified by Slot

  • slot antenna
  • slot antennas
  • slot die coating
  • slot width

  • Selected Abstracts

    Analysis of Particle Pumping Using SOLDOR/NEUT2D Code in the JT-60U Tokamak

    H. Kawashima
    Abstract In order to understand the particle pumping on JT-60U, we analyze the roles of atomic and molecular processes using SOLDOR/NEUT2D code. A case of short strike point distance shows that most of neutrals produced on the targets go toward the exhaust slot directly. Whereas, neutrals are scattered in the spherically at random for the long distance case by collision processes and a few of them go toward the slot. It is clarified that the incident neutrals to the slot at low ne/high Te divertor plasma condition are dominated by atoms. Those at high ne/low Te condition are dominated by molecules due to elastic collision. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    How do crystal lattice contacts reveal protein crystallization mechanism?

    Christo N. Nanev
    Abstract The nature of crystal lattice contacts is discussed because they reflect the selection of the most appropriate (for the given set of conditions) contact patches on the surface of protein molecules. The conclusion is that, along with chemical composition, the protein structure at the crystal lattice contacts is the key to crystallization behavior. The reason is that most stable are conformations, which do not only maximize the number of the bonds but simultaneously minimize van der Waals repulsions. A plausible explanation of the crystallization slot that exists for proteins is given on this basis. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    The long-term average capacity region per unit cost with application to protocols for sensor networks

    Daniela Tuninetti
    We consider a wireless sensor network where K sensors must deliver their messages within a frame of N time slots by spending a given finite energy. If the messages are not transmitted within the required delay they become useless and the residual energy is wasted. The channel is block-fading, with independent fades for each sensor and each slot. Sensors know the fading levels up to the current slot, but do not know the future fading levels. The receiver collects the signal on all the slots of the frame and performs joint decoding of all the messages. We characterize the region of long-term average achievable rates and we show that the optimal policy tends to waterfilling in time (optimal policy without delay constraints) as N increases. In this setting, we also characterize the long-term average capacity region per unit energy by showing that the optimal policy is ,one-shot', totally decentralized and extremely simple, i.e., every user spends all its available energy on the first slot of the frame, the fading gain of which is larger than a pre-computed time-varying threshold. Furthermore, the ,one-shot' policy not only makes the most efficient use of the energy, but also reduces to the minimum the interference to other users as it makes all the users transmit with the minimum energy per bit required for reliable communications. These characteristics make the ,one-shot' policy appealing for systems with severe energy limitation as wireless sensor networks. Copyright © 2003 AEI [source]

    Effect of depth and width of cultivation and sowing date on establishment of red clover (Trifolium pratense L.) by rotary slot-seeding into grassland

    GRASS & FORAGE SCIENCE, Issue 2 2010
    P. Komárek
    Abstract The effect of different combinations of time of sowing and depth and width of soil cultivation using a rotary slot-seeding machine to introduce red clover (Trifolium pratense) was determined for some characteristics of newly established red clover plants in a lowland Dactylis glomerata -dominated grassland in the Czech Republic. Sowing was carried out on four sowing dates in one growing season: 11 May; 21 June (after the first cut); 9 August (after the second cut); and 19 September. The experimental treatments consisted of all combinations of four depths (5, 10, 15 and 20 cm) and four widths (5, 10, 15 and 20 cm) of soil cultivation. Measurements were made of number of plants, weight and height of plants, weight and height of roots. Measurements at 2 months after sowing showed fewer seedlings for the 11 May sowing than for later sowing dates. The number of red clover plants increased as the row width was increased up to 15 cm, regardless of the depth of slot. Positive effects of slot width on weight and height of plants and weight and length of roots were recorded. A highly positive correlation was found between weight of plants and weight of roots. Width of row was the key factor for the successful establishment of seedlings into the existing sward by slot-seeding. A row width of 10 cm and depth of slot of 5 cm was considered a satisfactory combination. [source]

    Adaptive protocols for optical LANs with bursty and correlated traffic

    G. I. Papadimitriou
    Abstract Traffic in gigabit LANs is highly bursty. Furthermore, the destinations of packets transmitted by the same station are highly correlated. An adaptive protocol for WDM passive star networks, which is capable of operating efficiently under bursty and correlated traffic, is introduced. According to the proposed protocol, the stations which are granted permission to transmit at each time slot are selected by taking into account the network feedback information. Although the traffic parameters are unknown and time-variable, the bandwidth of each wavelength is allocated to the stations according to their needs. In this way, the number of idle slots is reduced, resulting in a significant improvement in the network throughput. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Study of a longitudinal flux permanent magnet linear generator for wave energy converters

    O. Danielsson
    Abstract A directly coupled linear permanent magnet generator of longitudinal flux-type is investigated. The generator will be used for power take-off in a wave energy converter. A combined field- and circuit model, solved by a time stepping finite element technique, is used to model and analyse the electromagnetic behaviour of the machine. A large number of simulations form the basis of a design study where the influence of armature current level, number of cables per slot, and pole width is investigated with respect to efficiency, generator size, and the load angle. A case study is performed for a chosen generator design. The electromagnetic behaviour is examined both for nominal load and for overloads. The generator has a nominal output power of 10 kW for a constant piston speed of 0.7 ms,1. The electromagnetic efficiency at nominal load is 86.0%, the load angle 6.6°, and the power fluctuation 1.3%. At 300% overload the load angle barely exceeds 12° and the cable temperature is below 25°C provided that the stator back is thermally connected to the sea water. The numerical calculations have been verified for small speeds by experiments. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    A novel virtually centered broad wall longitudinal slot for antenna application

    A. Anand
    Abstract A virtually centered broad-wall longitudinal slot antenna have been designed and studied using commercial Electromagnetic Simulation Software (CST Microwave Studio). The result obtained for the S21 of such an antenna has been compared with the measured data to find the accuracy of the software. Also the results obtained for the slot have been compared with the more common offset broad-wall longitudinal slot. Different slot characteristics also have been studied by varying different slot parameters. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source]

    Microstrip-fed cusp antenna for ultra-wide band communication systems

    Ezzeldin A. Soliman
    Abstract A novel antenna for ultra-wideband (UWB) applications is presented in this article. The proposed antenna consists of one circular patch placed on one side of a substrate and one circular slot placed on the other side. The antenna is fed with a microstrip line connected to the circular patch. The radii of the circular patch and slot and the separation between their edges represent the three design parameters which are optimized such that the antenna satisfies the design specifications. The proposed antenna has been fabricated using printed circuit board (PCB) technology. It has been characterized both theoretically and experimentally. The measured and calculated results are presented, compared, and discussed. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]

    Wideband slot antenna using a new feeding technique for wireless applications

    Mourad Nedil
    Abstract This article presents a new wideband slot antenna for wireless applications at 5.8 GHz. To improve the antenna bandwidth, a new feeding mechanism based on a capacitively- and inductively-coupled slot is proposed. To demonstrate this approach, an experimental antenna prototype operating at the 5.8-GHz band was designed, fabricated, and measured. The obtained results indicate very good agreement between the numerical and experimental results. The proposed antenna achieves a 28.5% bandwidth, a 5.7-dBi gain, and a ,15-dB front-to-back ratio, which are very sufficient for broadband wireless applications. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. [source]

    From lumped-element circuits to monolithic integrated circuits: A contribution to RF and microwave mixer design

    Peter Waldow
    Abstract This article deals with the mixer design for UHF-, microwave- and millimeter-wave applications. Thereby, several aspects such as the chosen technology (lumped elements, hybrid- or monolithic integration) and the applied transmission line (printed circuits, strip-, slot- or coplanar line) are considered. During the course of this contribution, the authors point out the developments in mixer design from lumped-element circuits to monolithic integrated circuits on the example of research activities in Duisburg and Kamp-Lintfort, Germany. The results of these scientific investigations, regarding both the theoretical and experimental aspects, show the feasibility of the proposed techniques. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

    Study of the design of waveguide filters with improved suppression of modal interference through the cross-shaped slot

    Sungtek Kahng
    Abstract In this article, a new method is suggested to improve the frequency responses of dual-mode waveguide filters employing cross-shaped slots. According to this method, regarding one cross-shaped slot between two cavities, the horizontal (vertical) mode in one cavity influences the vertical (horizontal) mode in the other cavity to a much lesser extent. It enhances the overall performances. A 4th -order dual-mode filter is used as an example and it validates the method. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 285,292, 2003. [source]

    Recipe determination and scheduling of gasoline blending operations

    AICHE JOURNAL, Issue 2 2010
    Jie Li
    Abstract Gasoline is a major contributor to the profit of a refinery. Scheduling gasoline-blending operations is a critical and complex routine task involving tank allocation, component mixing, blending, product storage, and order delivery. Optimized schedules can maximize profit by avoiding ship demurrage, improving order delivery, minimizing quality give-aways, avoiding costly transitions and slop generation, and reducing inventory costs. However, the blending recipe and scheduling decisions make this problem a nonconvex mixed-integer nonlinear program (MINLP). In this article, we develop a slot-based MILP formulation for an integrated treatment of recipe, specifications, blending, and storage and incorporate many real-life features such as multipurpose product tanks, parallel nonidentical blenders, minimum run lengths, changeovers, piecewise constant profiles for blend component qualities and feed rates, etc. To ensure constant blending rates during a run, we develop a novel and efficient procedure that solves successive MILPs instead of a nonconvex MINLP. We use 14 examples with varying sizes and features to illustrate the superiority and effectiveness of our formulation and solution approach. The results show that our solution approach is superior to commercial solvers (BARON and DICOPT). © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

    Content analysis of food advertising in Turkish television

    Tulay Guran
    Aim: Television (TV) viewing has been implicated in children's weight gain. We aimed to conduct a comprehensive content analysis of TV food advertising in Turkey. Methods: TV advertisements (ads) in the four most popular national free to air Turkish TV channels, were assessed on two weekdays and two weekend days at four time periods of the day; 0800,1200,1200,1600,1600,2000 and 2000,2400 h for each TV channel (64 h assessed for each TV channel), making a total of 256 h. Each ad was analysed for food and drink content, duration and audiovisual properties. Results: There were 8853 TV ads and 2848 of these were related to food (32.1%). A majority of food ads included high-calorie, high-fat, high-sugar food and drink rather than core/healthy foods (81%). Chocolate and chocolate bars were the most frequently advertised food/drink product, followed by cakes, coffee, tea, candies, gum, fast food, chips, juices/carbonated beverages, margarine and ice-cream formed the highest rate of food products advertised in decreasing order. Thirty per cent of all obesogenic/unhealthy ads targeted childhood by using audiovisual techniques. The proportion of total advertisements which were for food or drink, and the proportion of food advertisements that were for unhealthy foods were both much higher at the weekend (33% vs. 30% and 84% vs. 78%, respectively). The time period between 1600 and 2000 h was the most concentrated time slot (33%) for food advertising. Conclusions: This study provides data for the first time on the high levels of obesogenic food advertising on Turkish TV. This should alarm policy-makers to set limits on food advertising targeted towards children especially in countries like Turkey in which childhood obesity is emerging as an important public health issue. [source]

    Preservation potential for Late Quaternary river alluvium

    John Lewin
    Abstract Valley sequences of Late Quaternary alluvial units reflect alluvial preservation as well as alluvial production factors. Effects of lateral channel migration, incision, aggradation and channel stability on preservation potential are explored and then considered in the light of 14 available data sets: cartographically dated and model data based on lateral channel migration; well-mapped and dated Late Quaternary valley unit surveys; and composite age,frequency plots for dated alluvial units and flood sediments. Despite much expectable variation between sites, and the complex effects of river-activity combinations, a common characteristic of the data sets examined is the significance of preservation factors. Lateral migration tends to eliminate older units as it creates new alluvial deposits, whereas incision may lead to the preferential preservation of older units beyond the incision slot. Aggradational environments are likely to preserve more complete records, although simultaneous lateral migration may eliminate, possibly repeatedly, the upper parts of alluvial units. The common pattern of inset and incised streams within Pleistocene and early Holocene fills or bedrock gives finite extent to later units within narrowing valleys so that development of new valley-floor units is necessarily at the expense of reprocessing earlier ones. Floods associated with both slack water deposits and berms are also responsible for the removal of accessible earlier materials, thus limiting the preserved record of earlier events. In light of these censoring effects of river activities, the sequence of preserved Late Quaternary units within UK sequences is reconsidered. It is concluded that preservation potential factors have led to spatial and temporal bias in the alluvial record, and that both here and elsewhere preservation potential needs to be considered systematically alongside variable sedimentation resulting from allogenic environmental factors when interpreting the alluvial archive. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Cavity backed dual slot antenna for gain improvement

    Jin Xin Li
    Abstract A simple method of gain improvement for the cavity backed slot antenna based on the substrate integrated waveguide technique has been presented in this article. By using dual slot at the cavity edges to substitute a single slot at the cavity center as the radiating element, gain of the cavity backed slot antenna has been improved about 1.7 dB whereas its total size is little reduced. The proposed antenna has high radiation performance and keeps the advantages low profile, easy integration, and low cost fabrication. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2767,2769, 2010; View this article online at DOI 10.1002/mop.25582 [source]

    Dual band-notched ultra-wideband printed antenna with two different types of slots

    Jun-Bo Jiang
    Abstract A compact wideband printed antenna with dual band-notched characteristics for wireless local area network (WLAN) (2.4 GHz/5.8 GHz) is introduced. It is demonstrated that dual band rejection characteristics at 2.4 and 5.8 GHz with desired bandwidths can be obtained by using two different types of slots, one is a folded stripline slot on the radiation patch, and the other is a pair of inverted-L-shaped slot on the ground. The proposed antenna operates over 2.2,11 GHz for VSWR <2, while providing a band-stop function in the frequency bands of 2.3,2.9 GHz and 5.5,6.3 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1930,1933, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25411 [source]

    A band-notched CPW fed antenna with ring ground for ultra-wideband applications

    Qingxin Guo
    Abstract A new CPW-fed antenna with band-notched is proposed for ultra-wideband antenna applications. It consists of a ring strip connecting with two triangle patches as the ground and a rectangular patch connecting with a strip as the radiator and feeding line. A narrow slot is embedded in the radiator to obtain notched-band characteristics within bandwidth of 5,6 GHz. Simulated results gotten by FDTD method are given and compared with the experimental results. Measured results show that the antenna can cover a bandwidth from 2.5 to 10.7 GHz for VSWR < 2 except the notched-band. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1691,1694, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25333 [source]

    A reconfigurable design for bandwidth enhancement of circularly polarized slot antennas

    Tsung-Hsun Hsieh
    Abstract A reconfigurable design is proposed to improve the circular polarization (CP) operating bandwidth of an annular-ring slot antenna fed with an L-shaped coupling strip. The design involves four voltage-controlled varactor diodes, which are placed below the slot and symmetrically distributed along the circumference of the slot. When all antenna dimensions remain constant, the CP operating frequency of the slot antenna can be decreased by varying dc voltage values. In addition, theses CP operating frequencies, which are corresponding to different dc voltage values can form a successive frequency band, and the available CP bandwidth is thus improved. Experimental results indicate that with the reconfigurable design, the 3-dB axial-ratio CP bandwidth can be increased by a factor of 4 for the annular-ring slot antenna with a reflector. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1377,1380, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25192 [source]

    C-shaped ultra-wideband bandpass filter with WLAN notch band

    Pai-Yi Hsiao
    Abstract A compact bandpass filter (BPF) embedded with 5.8 GHz wireless-LAN notch is presented for 3.1,10.6 GHz ultra-wideband (UWB) systems. The proposed UWB-BPF based on a defect-grounded structure is implemented with an FR4 board. Two open-loop resonators on the top layer provide a narrow notch band whose center frequency can be easily adjusted by varying the sizes of the open-loop. A simple C-shaped slot on the bottom ground layer is adopted to improve the bandwidth performance. The characteristics of UWB-BPF are analyzed and simulated using a circuit model of LC lump elements. The size of the filter is at least 34% less than those filters with the same specification. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1215,1218, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25153 [source]

    Double-printed rectangular patch dipole antenna with band-notched function for UWB communications

    Jin-Xiang Xiao
    Abstract A novel double-printed rectangular patch dipole antenna with a band-notched function suitable for UWB application is presented and investigated in this article. The band-notched characteristic is achieved by connecting L-shaped strips to the antenna rather than inserting slot to the antenna. The measured results show that the frequency band of VSWR < 2 covers 3.1 to 10.6 GHz UWB band, whereas the notched-frequency range is 5.05,6.1 GHz which covers 5GHz WLAN band of 5.15,5.825 GHz. Transfer function and time domain characteristics are also studied in this article. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 269,272, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.24921 [source]

    Bandwidth enhancement of slot-fed dielectric resonator antenna

    R. G. Madhuri
    Abstract Novel slot-fed dielectric resonator antenna is studied experimentally. The antenna is comprised of a rectangular dielectric resonator and a mictrostrip fed coupling slot. The multiband resonances of the two radiators i.e., slot and dielectric resonator are combined to extend the antenna bandwidth. Dielectric resonator of three different thicknesses is studied, providing a bandwidth of 49.25%. The radiation patterns are measured and are presented. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 316,318, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.24937 [source]

    Design of compact coplanar bandstop filter composed on open-loop-ring resonator and defected ground structure (DGS)

    Anatoliy Batmanov
    Abstract Design of a novel compact bandstop filter composed on an open-loop-ring resonator and a defected ground structure (DGS) for coplanar waveguide is proposed and investigated. A simple coplanar open-loop-ring resonator has been designed and tested for the stop-band from 3.9 to 4.3 GHz with tree transmission zeroes inside the stop-band. Two almost symmetrical poles are obtained on both sides of the stop-band. Then the proposed broad band bandstop filter based on the one open-loop-ring resonator has been transformed to the bandstop filter with a narrower stop-band but with improved pass- and stop-band characteristics. It is realized by adding a conventional rectangular DGS slot inside the open-loop-ring. The equivalent circuit model has been proposed to describe the behaviour of the bandstop filters. The improved bandstop filter introduces the stop-band from 3.75 to 5.3 GHz with two transmission zeroes within and more than ,20 dB rejection. The total size of the proposed structure is 13.8 × 13.4 mm2. Both bandstop filters have been fabricated and measured. Measurements are in good agreement with simulation results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 478,483, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.24905 [source]

    Novel UWB planar monopole antenna with dual band-notched characteristics

    Wentao Li
    Abstract A novel spade-shaped microstrip-fed ultrawideband planar monopole antenna with dual band-notched characteristics is presented. Dual narrow band-notched characteristics are achieved by employing an ,-shaped slot on the radiating patch and a split-ring resonator on the backed side. Experimental results demonstrate that the proposed antenna satisfies the voltage standing wave ratio requirement of less than 2.0 in the frequency band of 3,12 GHz, except two frequency stop-bands of 3.3,3.9 GHz and 5.70,6.05 GHz. Moreover, measured group delay and transmission characteristics indicate that the proposed antenna has good transient response. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 48,51, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.24827 [source]

    A novel ultrawideband planar antenna with dual band-notched performance

    Meng Zhang
    Abstract In this article, a novel and compact ultrawideband (UWB) planar antenna is presented. This antenna consists of an annular patch and a 50 , microstrip feed line. The 3.5/5.5 GHz dual band-notched characteristic gets achieved by etching a C-shaped slot in the patch and complimentary split ring resonator (CSRR) structure in the ground. The measured results show that the proposed antenna can achieve the voltage standing wave ratio (VSWR) requirement of less than 2.0 in very UWB frequency range from 3.05 to 23.8 GHz with dual band-rejection performance of 3.4 to 4.0 GHz and 4.92 to 6.0 GHz. Measured VSWR of the proposed antenna is in good agreement with the simulated result. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 90,92, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.24856 [source]

    A novel monopole antenna with a self-similar slot for wideband applications

    Kun Song
    Abstract In this article, a printed flame-shaped monopole antenna with a self-similar slot for wideband application has been presented and investigated. The wideband characteristic is easily achieved by inserting a self-similar slot in the flame-shaped radiator. The effect of the slot is investigated. We discover that the slot can be effectively used for bandwidth enhancement, while the position of the slot has a negligible effect on the performance of the proposed antenna. Experimental results show that the proposed antenna obtains a bandwidth from 2.65 to over 12 GHz with VSWR < 2. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 95,97, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.24873 [source]

    Design of multilayer triangular substrate integrated waveguide filter in LTCC

    Wei Shen
    Abstract This article proposes a four-pole quasi-elliptic function triangular substrate integrated waveguide bandpass filter, which was fabricated using multilayer low-temperature cofired ceramic technology. In our design, neural network inverse model is adopted to fast capture the sizes of TSIW cavities, with the coupling matrix transformation implemented to achieve cross coupling on the basis of multilayer TSIW. A slot on the top metal layer is introduced so as to suppress the two higher spurious modes. The filter has 65% size reduction in comparison with its planar counterpart, with good agreement obtained between the simulated and measured S-parameters. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2582,2585, 2009; Published online in Wiley InterScience ( DOI 10.1002/mop.24680 [source]

    Composite right/left-handed transmission line based on Koch fractal shape slot in the ground and UWB filter application

    Jian An
    Abstract A novel composite right/left-handed transmission line is presented which is synthesized by etching Koch fractal shape slot in the ground plane and series capacitive gap in the conductor strip. Unlike the structures loaded with complementary split ring resonators, the proposed structure can operate at very wideband and is used to design an ultra-wideband (UWB) filter. The UWB filter is fabricated and tested. The relative bandwidth of the ,10 dB return loss is 128% and the insertion loss is larger than ,1.5 dB except at high frequencies. The equivalent circuit model of the proposed structure is presented and the electrical parameters are also extracted. The circuit model results are compared with the simulation and measurement results which verify that not only the extracted parameters are exact but also the equivalent circuit model is reasonable. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2160,2163, 2009; Published online in Wiley InterScience ( DOI 10.1002/mop.24553 [source]

    Ultra-wideband slot antenna with band-notch characteristics for wireless USB dongle applications

    Deepti Das Krishna
    Abstract A compact ultra-wideband (UWB) printed slot antenna is described, suitable for integration with the printed circuit board (PCB) of a wireless, universal, serial-bus dongle. The design comprises of a near-rectangular slot fed by a coplanar waveguide (CPW) printed on a PCB of size 20 × 30 mm2. It has a large bandwidth covering the 3.1,10.6 GHz UWB band, with omnidirectional radiation patterns. Further, a notched band centered at 5.45 GHz wireless local area network bands is obtained within the wide bandwidth by inserting a narrow slot inside the tuning stub. Details of the antenna design are described, and the experimental results of the constructed prototype are presented. The time domain studies on the antenna shows a linear phase response throughout the band except at the notched frequency. The transient analysis of the antenna indicates very little pulse distortion confirming its suitability for high speed wireless connectivity. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1500,1504, 2009; Published online in Wiley InterScience ( DOI 10.1002/mop.24385 [source]

    Design of dual-band antenna with U-shaped open stub for WLAN/UWB applications

    Jung N. Lee
    Abstract In this article, we have proposed a dual-band antenna with U-shaped open stub for wideband local area network (WLAN)/ultra wideband (UWB) applications. The designed dual-band antenna consists of two semicircle radiating patches, a rectangular slot separating the two semicircles, one step for impedance matching, and coplanar waveguide (CPW) feeding. Two kinds of prototypes (CPW-fed UWB antenna and the dual-band antenna with U-shaped open stub) are fabricated and measured. Parametric studies and radiation characteristics for the two antennas are presented. The designed antenna has the figure-of-eight radiation pattern, wide bandwidth, and negligible dispersion over the operating frequency band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 284,289, 2009; Published online in Wiley InterScience ( DOI 10.1002/mop.24033 [source]

    A shorted square-ring slot antenna with a branched slot for the 1575 MHz and 2.4 GHz dual-band operations

    Chin-Long Tsai
    Abstract A shorted square-ring slot antenna with a branched slot is presented for the 1575 MHz and 2.4 GHz dual-band operations. This proposed antenna can be designed by two steps. First, the shorted square-ring slot antenna is designed for circular polarization in the GPS band. Then, a branched slot is added to the original structure to result linear polarization in the 2.4 GHz band. Because the added branched slot almost has no influence in the GPS band's characteristics, the design rule is very simple. The impedance and axial ratio bandwidths for the GPS band is 23.3% and 4.2%, respectively. Besides, the AR and antenna gain is 1.23 dB and 2.3 dBic at the frequency of 1575 MHz. The impedance bandwidth for the 2.4 GHz band is 4.5% and antenna gain at the center frequency of 2.445 GHz is 2.8 dBi. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 402,405, 2009; Published online in Wiley InterScience ( DOI 10.1002/mop.24073 [source]