Home About us Contact
|
Home About us Contact | ||
|
|
||
Impedance Bandwidth (impedance + bandwidth)
Selected AbstractsInvestigations on two-segment dielectric resonator antennasMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2005Atabak Rashidian Abstract Two segmented dielectric-resonator antennas have been investigated. A weighted average model is used to predict the resonant frequency. A simple method is then introduced to optimize the lower segment of the antenna. Finally, a fast and efficient design algorithm is presented. Three examples are used to implement the methods and the algorithm in three different frequency bands. Impedance bandwidths of up to 30% are achieved with the optimum design. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 533,537, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20871 [source] Probe-fed microstrip antennas loaded with very high-permittivity ceramicsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2006Y. Hwang Abstract This article reports the feasibility study of miniaturizing probe-fed microstrip patch antennas by dielectric loading. The loading materials are barium tetratitanate ceramics of very high dielectric constant (,r = 38, 80). It is shown that, simply through loading, the antenna sizes are greatly reduced; however, the antenna performances are deteriorated. For instance, the antenna gain becomes lower. Then enhancement of the antenna performances follows. A substrate,superstrate structure is used to recover the gain. Both the experiments and the finite-difference time-domain (FDTD) simulations demonstrate that the gain and impedance bandwidth can be retrieved such that they are comparable to those of conventional microstrip antennas loaded with low permittivity materials (,r < 3). © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. [source] Computer-aided design of a CPW-fed slot antenna for MM-wave applicationsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2004S. K. Padhi Abstract This article presents a comprehensive parametric study with experimental characterization of an inductively coupled CPW-fed slot antenna on a GaAs substrate for MMIC applications. The length, width, and feed inset of the antenna are varied and their influences on the input impedance, bandwidth, and gain are investigated. The parametric study reveals that the slot length is the prime factor for determining the resonant frequency, while the width is used for fine-tuning of resonant frequency and gain-bandwidth product. For the fixed slot dimensions, the feed inset tremendously affects both resonant frequency and input match. The manufactured antenna resonates at 22.4 GHz with a 6.1% impedance bandwidth, 2% gain bandwidth, 2.5-dBi boresight gain, and 5-dB front-to-back (F/B) radiation level. The antenna exhibits bidirectional radiation patterns with almost omnidirectional patterns in the E-plane and a wide beamwidth of 84° 3-dB beam width in the H-plane. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 4,14, 2004 [source] Very small aperture terminal broadband shared-aperture planar antennasINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2003N. C. Karmakar Abstract The design and development of a shared-aperture dual-band, dual-polarized, dual-aperture coupled rectangular microstrip patch antenna element is presented, which is suitable for portable very small aperture terminals. Detailed parametric studies of the locations of orthogonal coupling slots and their influences on the isolation and impedance bandwidth of the antenna element are performed. The experimental results are presented. The prototype dual-band dual-polarized antenna element achieves a 21% input impedance bandwidth at the S- and C-bands. The design and development of a four-element array with such an antenna element is also presented. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 180,193, 2003. [source] Numerical analysis of sleeve monopole in parallel-plate waveguideINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2001Zhi Ning Chen Abstract A monopole with double sleeves, which consists of a resonant loading and a conventional sleeve monopole, is experimentally investigated. The loaded monopole is put vertically in a parallel-plate waveguide and driven by a coaxial feeder. The new structure exhibits a remarkably broad impedance bandwidth. In this paper, a modal expansion technique is used to numerically evaluate the impedance characteristics of the monopole by modeling the fields between the plates using cylindrical harmonic functions. A Fourier least-square integration is applied to finding the expansion coefficients by the boundary and continuity conditions. Prior to modeling the proposed sleeve monopole, the developed analysis scheme is examined for its convergence and accuracy. Calculated results are validated by the measurements. For the optimum design at 5.8 Ghz, we investigate the effects of the structure parameters on the impedance characteristics. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 86,98, 2001. [source] Compact top-loaded ultra-wideband biconical antenna for indoor base-station applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2010W. J. Lu Abstract A biconical antenna employing the top-loaded technique is proposed for ultra-band (UWB) operation. The antenna is composed of a small cone mounted on a top-loaded disc and a conical ground plane, with both cones electrically connected together using four shorting pins to reduce the lower cutoff frequency. The antenna is investigated using computer simulation and measurement. Results show that the antenna has an impedance bandwidth from 0.8 GHz to over 11.2 GHz, dipole-like omnidirectional radiation pattern, average gain of about 4.2 dBi, and average radiation efficiency of over 88%. The antenna has the advantageous features of compact size, low profile, simple structure, and ultra-wideband characteristic and so is suitable for indoor base-station applications of many existing and future wireless and UWB systems. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2594,2598, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25540 [source] Bandwidth enhancement of a coplanar waveguide-fed asymmetrical slot antenna with a rectangular patchMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2010Shou-Tao Fan Abstract A coplanar waveguide-fed asymmetrical slot antenna with a rectangular patch for bandwidth enhancement is demonstrated. By attaching a rectangular patch to the monopole radiating element, a good performance of bandwidth enhancement for the antenna is achieved. From simulational and experimental results, the enhanced impedance bandwidth of the proposed antenna, defined by ,10 dB return loss, can reach 13.1 GHz, from 2.4 to 15.5 GHz, or about 146% with the center frequency 8.95 GHz, which makes it an excellent candidate for the ultra wideband (UWB, 3.1,10.6 GHz) applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2259,2261, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25476 [source] A compact pentagonal monopole antenna for portable UWB systemsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2010Paulbert Thomas Abstract Design of a compact microstrip-fed ultra-wideband antenna suitable for USB dongle and other such space constraint applications is presented. The structure consists of a pentagonal monopole element and a modified ground plane that gives an impedance bandwidth from 2.8 to 12 GHz. Radiation patterns are stable and omni-directional throughout the band with an average gain of 2.84 dBi. The antenna occupies only 11 × 30 mm2 on FR4 substrate with permittivity 4.4. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2390,2393, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25449 [source] Reconfigurable ultra-wideband slot antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2010James R. Kelly Abstract This article presents a reconfigurable uniplanar printed slot antenna with eight microwave switches, it is possible to reconfigure the impedance bandwidth, of the antenna between three discrete states (two ultra-wide band and one narrowband).© 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1988,1990, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25398 [source] Design of a planar ultra-wideband miniature monopole antenna for wireless USB dongle devicesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2010Yu-Chia Chang Abstract This article proposes a 3.1,5 GHz ultra-wideband antenna, defined by a ,10 dB return loss. The simplified planar antenna structures, compact size, and low profile make it profitable to the application of the embedded antenna in wireless universal serial bus dongle devices. The slit shape on the monopole radiator is tuned for miniature antenna size. A parasitic stub on the ground is adopted to increase antenna bandwidth for achieving 3.1,5 GHz impedance bandwidth. To reduce manufacturing cost and practical fabrication, we also propose a simplified rectangular antenna structure. It is found that wideband characteristics of the simplified rectangular structure antenna are similar to that of semicircular base structure. Finally, the antenna prototypes are fabricated and the antenna characteristics are measured. The radiation patterns are omnidirectional in azimuth cut. Moreover, the S -parameter of antenna characteristics has been measured. The consistency between the simulated results and the measurement results confirms the practicability of these techniques. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1013,1016, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25121 [source] Planar ultrawideband antenna array for short-range wireless communicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2010Osama M. H. Ahmed Abstract In this article, novel 2-element and 4-element planar ultrawideband (UWB) antenna arrays with bidirectional radiation patterns based on identical UWB antenna elements for UWB communications applications have been proposed, simulated and experimentally investigated. Each array is constructed by means of feeding omni-directional printed UWB monopole antennas with a UWB power divider. The proposed 2-element antenna array yields an impedance bandwidth of 110% (3.1,10.6 GHz) covering the whole UWB frequency bandwidth while the impedance bandwidth is multi-band in case of the 4-element antenna array because of the increasing effect of mutual coupling among antenna elements. The calculated gain of the 2-element and 4-element array is quite stable with about 3 and 6 dB higher than that of the single element, respectively. Both measured and calculated E-plane radiation patterns of the array and the single element are almost the same while the H-plane radiation patterns of the array are distinctively bidirectional compared to the omni-directional pattern of the single element. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1061,1066, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25140 [source] A novel key-shaped CPW-fed monopole UWB antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2010Rui-Jin Lin Abstract A novel key-shaped CPW-fed monopole UWB antenna is proposed in this article. A high frequency structure simulator is used to analyze the proposed antenna in the design process. The proposed antenna has an extremely wide frequency band range, the impedance bandwidth of which is measured as 2.87,40 GHz (1:13.9) for return loss <,10 dB. Simulated and measured results are presented for the proposed antenna. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:886,889, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25054 [source] A slot-coupling coplanar waveguide-fed fan-shaped antenna embedded in semicircle apertureMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2009Qin-Yi Li Abstract A novel design of a fan-shaped antenna embedded in semicircle aperture is proposed and experimentally studied in this article. The proposed antenna is fed by a tapered coplanar waveguide (CPW) and has an ultrawide band owing to the coupling between the fan-shaped radiation unit and the ground. From experimental results, the measured impedance bandwidth of the antenna, determined by ,10 dB return loss, can reach an operating bandwidth of 23.36 GHz (1.64,25 GHz), more than 175% with the center frequency operating at about 13.32 GHz. Good radiation patterns and gains covering the operating band have been observed. Details of the antenna design and experimental results are discussed in this article. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2385,2387, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24655 [source] A wideband circularly polarized microstrip antenna array with single feedingMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2009Ping Yao Abstract In this article, one wideband circularly polarized microstrip antenna array has been proposed and investigated. The technique of sequential rotation subarray has been employed to construct the whole antenna array, which enhances the impedance bandwidth and axial ratio (AR) bandwidth by 54.65 and 220.93%, respectively, when compared with the traditional way of CP array formation. One 8 × 4 antenna array has been fabricated and measured, agreement can be observed between the experimental and simulation results, the measured VSWR bandwidth is 7.33%, the AR bandwidth is 4.31%, and the gain is about 19 dB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1624,1627, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24438 [source] Wideband circularly polarized cavity-backed crossed loop antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2009Shi-Wei Qu Abstract A circularly polarized cavity-backed crossed loop antenna is proposed in this article. The optimized overall dimensions of the antenna are 1.13,o in diameter and 0.267,o in height (,o is the free-space wavelength at the center frequency), and the circumference of one loop is 1.1,o. Measurements show that the proposed antenna features an 81% impedance bandwidth for SWR ,2, a 40% bandwidth for axial ratio ,3 dB, an average gain of 10 dBi, and stable radiation patterns over the whole band from 1.42 to 2.13 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1714,1718, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24406 [source] Compact modified trapezoid-shaped ultra-wideband antenna with parasitic loopsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2009Jinwoo Jung Abstract A modified trapezoid-shaped monopole antenna for ultra-wideband operation having compact dimensions (12.7 × 22.5 × 1.6 mm3) is proposed. With a modified trapezoid radiator and parasitic loops, the proposed antenna has a very wide impedance bandwidth measured at 8.41 GHz (3.06,11.47 GHz, defined by 2:1 VSWR). The group delay, phase, and transmission loss are also measured and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1261,1263, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24313 [source] A compact dual-band modified T-shaped CPW-fed monopole antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2009R. Sujith Abstract A compact, dual band coplanar waveguide fed modified T-shaped uniplanar antenna is presented. The antenna has resonances at 1.77 and 5.54 GHz with a wide band from 1.47,1.97 GHz and from 5.13,6.48 GHz with an impedance bandwidth of 34% and 26%, respectively. Also the antenna has an average gain of 3 dBi in lower band and 3.5 dBi in higher band with an average efficiency of 90%. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 937,939, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24249 [source] A printed multiband antenna for cellphone applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2009Shih-Ying Sun Abstract A printed antenna is presented, which is working in bluetooth band of 2.4 GHz, worldwide interoperability for microwave access IEEE 802.16e band of 3.5 GHz and 5.8 GHz, wireless fidelity band of 2.4,2.5 GHz and 5.0,5.8 GHz, and wireless local area network band of 2.4,2.48 GHz, 5.15,5.35 GHz, and 5.72,5.83 GHz. The ratios of impedance bandwidth of the printed antenna to the central frequencies 3.5 GHz and 5.5 GHz are 54.5% and 15.5%, respectively. The total volume of the printed antenna is 20 (L) × 7.6 (W) × 0.4 (H) mm3, which is greatly reduced by 36% compared to generally internal printed antennas. The good characteristics of the printed antenna such as omnidirectional far-field patterns are attainable. The experimental results show agreement with the simulated data by high frequency structure simulator. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 742,744, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24177 [source] Compact multiband slotted antenna for wireless communication applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Yi-Chieh Lee Abstract New design of a compact antenna with slotted structure for multioperating bands of wireless communication systems is presented. By using compact configuration and slot designs on printed circuit board, the proposed antenna has the multiband measured operations for covering the 2.4-GHz WLAN (2.4,2.484 GHz), the WiMAX (IEEE 802.16e in the Taiwan: 2.5,2.69/3.5,3.65 GHz), and the 5-GHz WLAN (5.15,5.35/5.725,5.825 GHz) bands. Several properties of the proposed compact antenna for multiband operation such as impedance bandwidth, radiation pattern, and measured gain have been numerically and experimentally investigated. © 2008 Wiley Periodcals, Inc. Microwave Opt Technol Lett 51: 502,503, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24094 [source] Small antennas application in portable phonesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008Sheng-Yi Huang Abstract The compact antennas are introduced, which are working in universal mobile telecommunication system (UMTS) of 1920,2170 MHz and digital video broadcast-handheld (DVB-H+) of 1452,1492 MHz for portable phones applications. The resonant frequency of UMTS is presented by using a planar inverted-F antenna (PIFA) element. The other resonant frequency of DVB-H+ is presented by using meander-line configurations. The ratio of impedance bandwidth of the PIFA antenna to the center frequency 1500 MHz is 29% (DVB-H+). The ratio of impedance bandwidth of the meander radiator to the center frequency 2100 MHz is 20% (UMTS). The size of the two antennas is shortened to 65% compared to general internal radiators. The total volume of the two radiators is 40 (L) × 5 (W) × 0.2 (H) mm3 (PIFA) and 20 (L) × 5 (W) × 0.2 (H) mm3 (meander radiator), respectively. The experimental results are compared to the numerical simulation, high-frequency structure simulator, for agreement. The good performances of the antennas like wide bandwidth and omnidirectional far-field patterns can be obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3020,3023, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23872 [source] Ultra-wideband folded loop antenna fed by coplanar waveguideMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008W. J. Lui Abstract In this article, a novel and successful design of ultra-wideband folded loop antenna is proposed and investigated. The antenna is fed by coplanar waveguide directly and can be fabricated easily by employing printed circuit board technology. It is studied both numerically and experimentally. From calculated and measured results, it may be observed that impedance bandwidth of over 130% for return loss lower than ,9.54 dB and good omnidirectional radiation performance is obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3075,3077, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23890 [source] High gain cavity-backed slot antenna with a windowed metallic superstrateMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008M. A. Hanqing Abstract A novel technique for gain enhancement of cavity-backed slot antenna is developed and discussed. The high gain radiation of the proposed antenna is achieved by a windowed metallic superstrate above the slot. The parametric studies of the proposed structure are provided, the radiation mechanism of the proposed antenna is investigated, and then the design guidelines for this type of radiators are described. The prototype is fabricated and found to have an impedance bandwidth of 12% and a gain of 12.3 dBi at the center frequency of 2.4 GHz. The characteristics of the proposed antenna have been validated by CST simulation software and experiments. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3114,3118, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23880 [source] Planar 4-element UWB antenna array and time domain characterizationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008Ying-Ying Yang Abstract In this article, a novel planar ultra-wideband (UWB) antenna array based on four identical UWB antenna elements for UWB applications is presented. The proposed antenna array yields an impedance bandwidth of 3.1,10.6 GHz with VSWR <2. Over the entire bandwidths, it has constant high gain, which is about 6.5,10.5 dBi, and a 60° 3-dB beamwidth is obtained within the operational band. A planar 2-element UWB antenna array and a band-notched 4-element UWB antenna array are also provided for references. Time domain descriptors of the proposed antenna array have been used to estimate short-range UWB signal transmission, propagation, and reception. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3118,3123, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23874 [source] A wideband microstrip antenna with symmetric radiation patternsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2008Veeresh G. Kasabegoudar Abstract A wideband microstrip antenna using a coplanar capacitive feed with nearly 50% impedance bandwidth has been realized on a stacked air-dielectric substrate with only one metal layer above the ground plane. In this article an approach of modifying the patch shape is proposed to obtain symmetric radiation patterns in the entire frequency band of this antenna. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1991,1995, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23575 [source] An enhanced bandwidth design technique for Peano fractal loaded monopole antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2008Yu Yan-min Abstract A new technique for Peano fractal loaded monopole antenna to enhance impedance bandwidth by loading shorting pins is presented. Simulated and measured data show that relative impedance bandwidths of the proposed order 1 and order 2 antennas achieve 23 and 28% for VSWR less than 2 in L-band, which are enhanced 90 and 75% than those of conventional ones, respectively, while the profile and radiation patterns change little. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2045,2048, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23583 [source] Compact ultrawideband square slot antenna with an asymmetric protruding stubMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2008Jen-Yi Shiu Abstract A new compact ultra-wideband (UWB) square slot antenna fed by a coplanar waveguide (CPW) is proposed. A large impedance bandwidth of more than 13 GHz (2.8,16 GHz) was obtained by asymmetrically widening the tuning stub that is extended from the signal strip of the CPW into the square slot. The larger and smaller widened parts of the asymmetric tuning stub can be easily adjusted to achieve good impedance matching in the lower and upper regions, respectively, of the entire VSWR , 2 band. The simple design procedure along with reasonably agreed measured and simulated results is presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1776,1779, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23544 [source] Circular fractal monopole antenna based on descartes circle theorem for UWB applicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2008Salman Naeem Khan Abstract An apollonian shaped ultra-wideband circular monopole antenna based on descartes circle theorem is presented. Different self similar geometries from DCT are analyzed and optimized for UWB applications. The proposed design is slightly modified to ensure an overall smooth current distribution limited by the junction point nature of the fractal geometries. The experimental results are compared with conventional circular disk monopole and annular monopole antenna. The measured return loss of the proposed design below ,10 dB is from 2.4 to over 40 GHz and its radiation pattern is omni-directional compared with circular disk and annular antennas in most of its impedance bandwidth. Moreover due to the fractal shape, the proposed design has less weight and wind loading effect. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1605,1608, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23437 [source] Design of a diversity antenna with stubs for UWB applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2008Seokjin Hong Abstract A two-element diversity planar antenna for a multiple-input multiple-output application is proposed. By adopting two Y-shaped radiators, the antenna provides wideband impedance matching characteristics over the desired frequency band. To reduce the mutual coupling between two radiating elements, three stubs are inserted in the ground plane. Good impedance matching and improved isolation characteristics are observed. The measured impedance bandwidth of the proposed antenna ranges from 2.27 GHz to 10.2 GHz for a return loss of less than 10 dB. Parametric analysis has been conducted to investigate the effect of radiator length and the insertion of stubs on the impedance bandwidth and isolation characteristics. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1352,1356, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23389 [source] A circular CPW-FED slot antenna for broadband circularly polarized radiationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2007I-Chung Deng Abstract The design of a circular slot antenna for obtaining broadband circularly polarized (CP) radiation using a coplanar waveguide (CPW) feed is presented. The operation of the proposed antenna is achieved by protruding metallic mono-strip from the circular ground plane towards the slot center at , = 0° and feeding antenna using a 50-, CPW with a protruded single strip at , = 270°. In this design, the impedance bandwidth and 3 dB axial-ratio bandwidth can reach as large as 50 and 36%, respectively. The peak of antenna gain is about 3.9 dBi, with gain variations <1 dBi for the frequencies within CP bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2728,2733, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22881 [source] Spiral patch with wideband and circular polarization for millimeter-wave communicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007Wei He Abstract In this study, a spiral patch antenna operating millimeter-wave band is proposed. Using this spiral structure, the patch antenna is designed for circular polarization and wideband operation at about 30.8,36.9 GHz for millimeter-wave communication. Simulated and measured results for main parameters such as return loss, impedance bandwidth, radiation patterns, and gains are also discussed herein. The study shows that the modeling of such antennas, with simplicity in designing and feeding, can well meet millimeter-wave wireless communication. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2068,2071, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22648 [source] | ||||||||||