bluuebunny/crossref_metadata_2025_split huggingface dataset:
Randomness test of signal generated by microwave chaotic Colpitts oscillator
Authors: Shi Zhiguo , Zhang Ye , Liu Haiwen , Ran Lixin 
Published: May 2007

AbstractRandomness test was conducted on signal sampled from the output of a microwave chaotic Colpitts oscillator operating with fundamental frequency of 960 MHz. Experimental data analysis shows the signal has an irregular distribution and a low degree of autocorrelation. Binary sequences converted from the signal can pass the four but one randomness tests in FIPS standard. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1981–1984, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22565
Efficiency ehancement of W‐CDMA base‐station envelope tracking power amplifiers via load modulation
Authors: Jeong Jinho , Asbeck Peter 
Published: May 2007

AbstractLoad impedance modulation and gate bias control were investigated to improve the performance of W‐CDMA base‐station envelope tracking amplifiers by means of simulations based on the measured data of a 10‐W GaAs FET power amplifier. It is shown that adapting the load impedance along with the drain bias voltage can effectively improve the average efficiency of envelope tracking amplifier. The improvement becomes more apparent in the operating regime of power back‐off. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1954–1957, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22566
Bidirectional artificial magnetic reflectors at microwave frequencies
Authors: Ferrer P. J. , González‐Arbesú J. M. , Romeu J. , Cardama A. 
Published: May 2007

AbstractMetamaterial slabs made of magnetic resonators (artificial magnetic conductor, AMC surfaces) can provide unusual electromagnetic properties, such as the dual PMC/PEC behavior, when used as reflectors. This property has been assessed and tested with the design and fabrication of a one‐layer spiral AMC slab. Moreover, two bidirectional AMC surfaces have also been designed and measured. These structures, composed of spiral (SR) or capacitive loaded loop (CLL) resonators printed on dielectric strips, can provide 0° reflection coefficient phase when the incident electric field wave impinges on any side. A very low electrical thickness is achieved. Compact antenna systems with two (or more) close isolated antennas can be designed with such structures. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1949–1953, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22567
A band‐pass filter consisting of two substrate integrated waveguide cavities coupled by an aperture on their common side wall
Authors: Hwang R. B. , Chang C. W. 
Published: May 2007

AbstractIn this article, we present a substrate‐integrated waveguide‐based band‐pass filter with wide stop‐band rejection property. This band‐pass filter is made up of two substrate‐integrated waveguide cavities, which couple to each other by an aperture on their common waveguide side wall. By using the empirical formula [19] for obtaining the equivalent rectangular waveguide dimensions, the substrate integrated waveguide structure could then be properly approximated by a closed rectangular waveguide. We employed the rigorous mode‐matching method to analyze the electromagnetic boundary‐value problem of the structure containing multiple discontinuities. In comparison with the conventional end‐to‐end coupled cavity filters, we found that our new side‐wall‐coupled cavity filter can suppress the second resonance frequency and therefore, provide a considerably wide rejection band. It is interesting to note that the suppression of the second resonance frequency can be achieved by properly shifting the second cavity in lateral direction. To explore its physical insight, the resonant modes in the substrate integrated waveguide cavities are carefully inspected for realizing the physical picture of wave process taking place in the two cavities system. In addition to the theoretical analysis, we have fabricated the filters and measured their scattering parameters. The good agreement between the theoretical and measured results validates the accuracy of numerical computation, and also shows the promising performance of the proposed filters. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1884–1887, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22570
Characteristics of compact‐size D lens collimator for micro‐optics devices applications
Authors: Lin Yu‐Cheng 
Published: May 2007

AbstractA compact‐size D lens collimator was fabricated and characterized. High circular rate 98%, small divergence angle 0.186°, and low return loss 59.8 dB were achieved in experiment to present the excellent performance of D lens collimator. Insertion loss sensitivity due to variation in working distance, operating wavelength, and misalignment tolerance were demonstrated in experiment and verified with theoretical simulation by OSLO. It is worth to note that the compact‐size D lens collimator exhibits low insertion loss, less than 0.3 dB, not only for large working distance range 10–30 mm but also for wide operating wavelength band 1560 ± 50 nm. When compared with gradient index lens collimators, the D lens collimator is potentially suitable for the application in the design of micro‐optics devices. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1946–1949, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22581
Multiband meander antenna with a backed microstrip line
Authors: Kim Jae H. , Lee Jung N. , Kim Hyun H. , Lee Jae C. , Park Jong K. , Kim Hak S. 
Published: May 2007

AbstractA novel multiband meander antenna with a backed microstrip line is proposed for GSM/DCS/ISM and WiMAX triple‐band operations. We have used meandering technique and U‐shaped line to produce the GSM and DCS bands, respectively, and a backed microstrip line technique to produce the ISM and WiMAX band. Prototypes of the multiband antennas have been successfully implemented and good radiation characteristics in the operating frequency bands have been achieved. The effect of the backed microstrip line geometry on the return loss was also studied. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1942–1946, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22582
Increasing the efficiency of microstrip interconnects using additional coupling capacitors
Authors: Khalaj‐Amirhosseini M. , Moeeni‐Fard M. 
Published: May 2007

AbstractA way to increase the efficiency of previously designed microstrip interconnects is adding discrete capacitors between their strips. A closed form relation is obtained for optimum value of additional capacitors for previously designed microstrip interconnects, in this article. The effect of adding discrete capacitors is verified using an experimental example. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2035–2037, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22591
A wideband microstrip bandpass filter for ultra‐wideband wireless communication application
Authors: Gao Shanshan , Xiao Shaoqiu , Wang Jianpeng , Yang Xuesong , Wang Bing‐Zhong 
Published: May 2007

AbstractA novel wideband bandpass filter for ultra‐wideband system application is proposed, designed, and implemented on the basis of a modified stepped impedance resonator structure. The modified stepped impedance resonator can not only generate multiple‐resonant peaks within the ultra‐wideband passband but also easily realize a tight coupling with the feed‐lines. Both simulation and measurement results are presented and they are in good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1975–1976, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22594
Spiral antenna with helix loaded for dual circularly polarized bands radiation
Authors: Chen Can‐Hui , Yung E. K. N. , Hu Bin‐Jie 
Published: May 2007

AbstractA spiral antenna with a helix loaded is investigated in this paper. Through combining the spiral with a helix together, circular polarization can be achieved in dual bands. Since the helix is loaded in the lower part of the spiral, this technique doesn't increase the antenna's volume but at the same time introduces another CP band. The experimental result shows that the lower band and upper band are 4.0% and 62.07% respectively. The characteristics of impedance, current distribution and radiation pattern will also be presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1939–1942, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22596
A new compact balance‐fed T‐monopole antenna for UMTS mobile applications
Authors: Chiu Cheng‐Nan , Chen Hung‐Ruei 
Published: May 2007

AbstractA balance‐fed T‐monopole printed antenna is newly proposed in this letter for modern mobile applications. This T‐monopole antenna is for stripline‐feeding with balanced signals. The antenna is compact and has the particular merit of immunity to the influence of size variation in feed ground. A prototype of the antenna for operating at the universal mobile telecommunication system (UMTS) band has been constructed and is shown as an example. Its return loss and radiation patterns have been simulated and measured. The experimental results demonstrate the broad bandwidth and omnidirectional radiation characteristics of the newly developed antenna, as well as the merits summarized here. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1904–1907, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22598
Internal multiband printed folded slot antenna for mobile phone application
Authors: Wong Kin‐Lu , Chi Yun‐Wen , Tu Shu‐Yang 
Published: May 2007

AbstractA novel printed folded slot antenna suitable for GSM/DCS/PCS/UMTS multiband operation in the mobile phone is presented. The proposed slot antenna has a planar configuration and is easy to fabricate by printing on the system circuit board of the mobile phone. The slot antenna has a length of 106 mm and is folded into a compact structure with its two slot ends facing toward each other. This configuration allows the antenna to occupy a small area of 21 × 45 mm2 centered on the top portion of the system ground plane. By feeding the slot antenna using a 50 Ω microstrip line printed along the centerline of the system ground plane, two wide bands (the half‐ and one‐wavelength modes) of the antenna can be generated, with the lower band covering GSM operation and the upper band covering DSC/PCS/UMTS operation. In addition, small excited surface currents in the system ground plane are observed, and the antenna's two operating bands are in general not sensitive to the ground‐plane length variations. These features are attractive for practical applications and different from those of the conventional internal mobile phone antennas. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1833–1837, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22602
Dielectric wedge antenna with stepped phase correction in a nonradiative mode
Authors: Malherbe J. A. G. , Malekela P. M. 
Published: May 2007

AbstractThe performance of a dielectric wedge antenna with stepped phase correction in a nonradiative dielectric structure is described. The stepped wave numbers are achieved by perforating the dielectric with a series of holes designed to modify the dielectric constant in a predetermined fashion. The aperture of the wedge is then divided into a number of zones, each with its own dielectric constant. The step correction of the aperture phase error results in a substantial improvement in radiation pattern. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2030–2032, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22607
Application of the FDTD method to determine complex permittivity of dielectric materials at microwave frequencies using a rectangular waveguide
Authors: Terhzaz Jaouad , Ammor Hassan , Assir Abdelhadi , Mamouni Ahmed 
Published: May 2007

AbstractA new measurement technique is presented to determine the complex permittivity of a dielectric material. The dielectric sample is loaded in a short‐circuited rectangular waveguide. The reflection coefficient of the waveguide is measured by Network analyzer and calculated as a function of the complex permittivity using finite difference time domain method (FDTD). The Newton–Raphson method is then used to determine complex permittivity by matching the calculated value with the measured value. A comparison of determined values of the dielectric constant obtained from the Nicholson–Ross technique and the FDTD method is presented. Numerical resultants for complex permittivity of Teflon and Plexiglass measured at the microwave frequencies are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1964–1968, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22611
Radiation characteristics of a monopole‐type antenna and an inverted‐F antenna for mobile handset applications
Authors: Kim Jeong I. , Yoon Dongweon , Cho Kyongkuk 
Published: May 2007

AbstractTwo types of wire antennas, a monopole‐type antenna (MTA) and an inverted‐F antenna (IFA), to be internally mounted in a mobile handset, differing only in the presence of a shorting point for the IFA, are proposed, analyzed numerically and experimentally, and compared. Agreement is remarkable between the numerical and experimental analyses for the electromagnetic radiation patterns. Radiation pattern characteristics of the MTA are close to those of the IFA over the frequency range from 3.0 to 3.6 GHz. On the other hand, the resonance frequency and bandwidth are changed by a fraction of 10 and 3%, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1931–1935, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22612
Unconditionally stable Laguerre‐based BOR‐FDTD scheme for scattering from bodies of revolution
Authors: Chen Hai‐Lin , Chen Bin , Duan Yan‐Tao , Yi Yun , Fang Da‐Gang 
Published: May 2007

AbstractThis work presents a new unconditionally stable BOR‐FDTD method based on weighted Laguerre polynomials. To validate the accuracy and efficiency of the proposed method, we apply it to analyze the scattering from a PEC cylinder with a slot. Comparing the results from the proposed method and those from the conventional BOR‐FDTD method, they show good agreement. And a substantial savings in computational time is achieved. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1897–1900, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22614
Harmonic‐suppressed slot‐coupled microstrip patch antenna with enhanced bandwidth
Authors: Ooi S. F. , Lee S. K. , Sambell A. , Korolkiewicz E. , Gao S. , Butterworth P. 
Published: May 2007

AbstractThis letter presents a slot‐coupled microstrip patch antenna with harmonics suppression capability within an enhanced bandwidth. Measured return loss result at the operating frequency, second harmonic frequency, and third harmonic frequency were 22.2 dB, 1.77 dB, and 1.93 dB, respectively, with a 9% impedance bandwidth around 2.45 GHz. The antenna is a good candidate for further integration with class‐F amplifiers. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1827–1829, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22618
Fabrication and measurement of triangular‐slot antenna for triple‐band (2.4/5.2/5.8 GHz) antenna with rectangular tuning stub
Authors: Yoon JoongHan , Jeong Gyey Teak , Kwak Kyung Sup 
Published: May 2007

AbstractIn this paper, a novel design of a triangular‐slot antenna with rectangular tuning stub for 2.4/5.2/5.8 GHz triple‐band applications is presented. The prototype consists of a triangular slot and rectangular tuning stub. Results show that the impedance matching of the proposed antenna is greatly affected by the feed gap width. Experimental results indicate that the impedance bandwidth (VSWR 1:2) of the proposed antenna is about 423 MHz for the 2.4‐GHz band and 1.92 GHz for the 5‐GHz band. The simulated and experimental results for the return loss, radiation patterns, and gains are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1793–1797, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22621
Design and performance of ultra low phase noise reflection whispering gallery resonator oscillator
Authors: Shtin Nicolás A. , Romero J. M. López , Prokhorov Eugen 
Published: May 2007

AbstractThis article deals with the design and experimental testing of the ultra low phase noise reflection oscillator incorporating a sapphire whispering gallery resonator (WGR). On a contrast with the conventional loop configuration oscillators with transmission WGR the presented oscillator is based on a reflection WGR excited by a single probe. It is shown that a phase noise of C‐band oscillator of the proposed configuration can be as low as −136 dBc/Hz at 1‐kHz Fourier frequency. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2026–2030, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22623
Design of wideband high and low impedance metatransmission lines
Authors: Perruisseau‐Carrier J. , Skrivervik A. K. 
Published: May 2007

AbstractThe modeling and design of “metamaterial ” composite right/left handed transmission lines (CRLH‐TL) is usually based on the assumption that its unit cell is small in terms of the host TL wavelength (d ≪≪λ0). However, it was also shown that this assumption is not required for most CRLH‐TL applications and difficult to meet for balanced CRLH‐TLs in particular cases. Thus, a more general design strategy, free of this assumption, has been implemented. In this letter, we further develop this second approach to show that it allows designing CRLH‐TLs whose impedance is much beyond the range achievable in the case where d ≪λ0, for a given technology and fabrication tolerances. The use of the presented concept is illustrated by means of a quartz‐integrated CRLH‐TL exhibiting a low‐impedance (20 Ω). Measured results are in good agreement with the theory and satisfactory performances are observed on a bandwidth covering almost the entire Ku band. Potential applications of the presented results are also discussed in a dedicated section. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1926–1929, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22628
Switchless bidirectional amplifier for wireless communication systems
Authors: Bechteler A. Sevinc Aydinlik , Bechteler Thomas F. 
Published: May 2007

AbstractA bidirectional amplifier working at 2.4 GHz is presented in this article. The presented amplifier is able to amplify two signals simultaneously. This, since commonly used radio frequency switches are replaced by circulators. The amplifier is designed on a single small‐sized printed circuit board. First, the new amplifier circuit is proposed and characterized. Then, its advantages and design problems are analyzed. Finally, design instructions are setup in order to obtain a good performance of the switchless amplifier within the frequency band of interest. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1888–1890, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22631
Using WCS‐FDTD method to simulate various small aperture‐coupled metallic enclosures
Authors: Chen Juan , Wang Jianguo 
Published: May 2007

AbstractThe weakly conditionally stable finite‐difference time‐domain (WCS‐FDTD) method is employed to compute the electromagnetic coupling and shielding of various small aperture‐coupled metallic enclosures. In the WCS‐FDTD method, a larger time‐step size than allowed by the CFL stability condition limitation can be set because the algorithm of this method is weakly conditionally stable. Consequently, an increase in computational efforts caused by fine cells due to small apertures can be prevented. The results from the WCS‐FDTD method agree well with results from the conventional finite‐difference time‐domain (FDTD) method, and the required CPU time for the WCS‐FDTD method is much shorter than that for the FDTD method. Compared with the ADI‐FDTD method, the WCS‐FDTD method has better accuracy and higher efficiency, which is demonstrated by numerical examples. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1852–1858, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22633
The numerical study of pulse evolution in self‐similar parabolic pulse amplifier
Authors: Chenghou Tu , Fuyun Lu , Ting Lei , Yongnan Li , Wengang Guo , Xiaoyi Dong 
Published: May 2007

AbstractIn this article, the influences of initial pulse and gain fiber parameters on the pulse's self‐similar evolution are studied by numerical simulation. We propose and demonstrate that dispersion length is the determining factor of pulse's self‐similar evolution. For a given input pulse, if dispersion length is comparable or smaller than fiber length, it can evolve into similariton, otherwise it can not. Under the self‐similar evolution condition, increasing pulse energy and gain coefficient can accelerate self‐similar evolution, otherwise the effect is not evident. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1785–1787, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22636
Theoretical and practical experiments for a single antenna gain testing method: Application to wireless communication devices
Authors: Anguera Jaume , Sanz Alfonso , Ko Young‐Jik , Borja Carmen , Puente Carles , Soler Jordi 
Published: May 2007

AbstractA compact antenna gain measurement system suitable for wireless devices is presented. The method needs the antenna under test, a planar electric conductor, and a vector analyzer. It is possible to obtain the total gain by a reflection measurement. Several simulations show a guideline to optimize the set‐up. Finally, some wireless devices operating at GSM900, GSM1900, and Bluetooth® are tested and compared with gain obtained by a three radiation pattern method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1781–1785, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22637
Differential form approach to the analysis of electromagnetic cloaking and masking
Authors: Teixeira F. L. 
Published: May 2007

AbstractWe discuss the relationship between (a) electromagnetic masking or cloaking of objects produced by some metamaterial blueprints and (b) some invariances of Maxwell equations obviated by means of differential forms (exterior calculus). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2051–2053, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22640
A microstrip bandgap filter with the photonic band gap resonators
Authors: Wang S. , Guo M. S. , Sun C. L. , Yang H. L. , Zhao X. Z. 
Published: May 2007

AbstractA microstrip bandstop filter using four square air holes resonator at frequencies above 10 GHz has been investigated. The square air holes resonator generate a bandgap, and its operation mechanism is made clearly through the Finite Differential Time‐Domain method. The measured frequency response of the filter is in good agreement with the simulation, and the center frequency of stopband of the microstrip filter shifted to higher frequency along with the dimension of the square air holes increased. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2020–2022, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22641