bluuebunny/crossref_metadata_2025 huggingface dataset:
Narrow‐slot bandpass filter based on folded substrate‐integrated waveguide with wide out‐of‐band rejection
Authors: Lei Wang , Che Wenquan , Deng Kuan , Dong Shiwei
Published: March 2008

The folded substrate‐integrated waveguide (FSIW) takes the advantages of more compact size and higher integration than the conventional SIW structures, probably resulting in a very compact design. One simple narrow‐slot bandpass filter is thus proposed and implemented to demonstrate the superiority of FSIW structure. The design strategies of the bandpass filter are introduced. One prototype with three narrow slots in the middle layer of FSIW is fabricated to demonstrate the validity of the proposed design. For the sake of measurement, one back‐to‐back stripline transition is also designed. The measured results are in good agreement with the HFSS‐simulated results, which indicates that the bandwidth is about 15%; the insertion loss is less than 1.5 dB. In addition, the rejection band of this filter is quite wide, implying very good harmonic rejection. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1155–1159, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23327
Directly modulated laser diode in the nonlinear regime for low‐cost digital frequency up‐conversion
Authors: Constant S. B. , Guennec Y. Le , Maury G. , Lourdiane M. , Cabon B.
Published: March 2008

The purpose of this article is to demonstrate the extension of the modulation bandwidth of single mode laser sources to reach the RF frequency range of wireless access networks such as ultra‐wide band systems with low‐cost solutions. In this article, we have studied optical microwave mixing using nonlinear direct modulation of a distributed feedback (DFB) laser diode. First, the nonlinear behavior of the DFB laser diode near the threshold current has been analyzed and explained based on frequency mixing measurements made with CW signals. Then, we have experimentally demonstrated frequency up‐conversion of a QPSK signal. These results were compared to eye‐diagram simulations based on the laser static and dynamic characteristics. Subsequently, the frequency up‐conversion of a WLAN IEEE 802.11a signal was experimentally demonstrated. Best conditions in terms of DFB bias current and RF input power signals have been studied. Good conversion loss and EVM results have been obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1214–1219, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23329
Observation and explanation of bending characteristics in solid core photonic crystal fibers
Authors: Ji Minning , Shi Zhidong , Lin Jianqiang
Published: March 2008

Bending loss peak is observed in the transmission spectrum of a solid core photonic crystal fiber. The loss peak is shifted from shorter wavelength to longer wavelength when the bending radius is decreased. These results are explained by a numerical calculation. They agree well with each other. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1178–1180, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23331
Internal wideband monopole antenna for MIMO access‐point applications in the WLAN/WIMAX bands
Authors: Chou Jui‐Hung , Su Saou‐Wen
Published: March 2008

A three‐antenna MIMO system capable of generating a wide operating bandwidth of 2400–5850 MHz for access‐point applications is introduced. The proposed design is based on a bent metal‐plate monopole antenna with a compact size of 20 × 20 × 14 mm3. The three antennas are equally spaced along the perimeter of a circular ground and all generate a wide bandwidth of larger than 4 GHz. With the antenna short‐circuiting facing the center of the ground, not only the overall antenna size is reduced but also good isolation of less than −20 dB can easily be obtained. Calculated envelope correlation is also less than 0.002 across the operating band. The design prototype of the antenna is discussed in detail in the article. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1146–1148, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23333
Design of compact, wide‐band bandstop filters with sharp‐rejection characteristics
Authors: Kanti Mandal Mrinal , Divyabramham Kandimalla , Sanyal Subrata
Published: March 2008

In this study, a novel transmission line configuration has been proposed to design a sharp‐rejecting, compact bandstop filter with wide rejection‐bandwidth. Signal interference technique is used to obtain transmission zeros, which provide the sharp rejection characteristic. Rejection bandwidth is controlled by the characteristic impedances of transmission lines. Filter is analyzed using transmission line model. Theoretical predictions have been verified by the measurements of two compact filters fabricated in microstrip line. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1244–1248, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23335
Modified circular monopole antenna with improved transmission performance for UWB communications
Authors: Wu Qi , Jin Ronghong , Geng Junping
Published: March 2008

This study theoretically analyses the transmission performance of UWB antennas and presents a design methodology for improving the transmission performance of printed monopoles. Using this methodology, a modified circular monopole are proposed and analyzed as the design example. Both measured and simulated results are provided and discussed for verifying the validity of proposed design methodology. In a typical lab environment, the deleterious multi‐path transmission effects on the transfer function of the example antenna pair were observed and discussed. This optimization methodology would not bring any size or cost increase to the printed monopoles, and the improvement of transmission performance is quite discernible, which appears to be a significant improvement over printed UWB monopoles. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1285–1289, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23336
A novel compact dual‐band bandpass filter using asymmetric SIRs for WLANS
Authors: Chang Yu‐Chi , Kao Chia‐Hsiung , Weng Min‐Hang , Yang Ru‐Yuan
Published: March 2008

In this article, a novel compact dual‐band bandpass filter (BPF) using asymmetric stepped impedance resonators (SIRs) has been presented for the first time. The feature of the proposed asymmetric SIR is only one step discontinuity, which is different from the conventional SIR with two step discontinuities. The frequency response of the dual‐band at 2.4/5.2 GHz can be achieved by determining the impedance ratio (K) and physical length ratio (α) of the asymmetric SIR. The coupling coefficient between the coupled asymmetric SIRs is calculated by using full‐wave simulator IE3D. A dual band BPF is designed, fabricated, and measured. The measured results are in good agreement with the full‐wave simulation results. Additionally, the BPF has a smaller circuit size in comparison of previous works. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1237–1240, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23339
Tunable ring laser based on a semiconductor optical amplifier at 1300 nm using a simple wavelength selection filter
Authors: Jeon Mansik , Kim Jeehyun , Song Jae‐Won , Lee Ho , Choi Sanghoon , Nelson J. Stuart
Published: March 2008

A simple, compact, and low cost tunable ring laser with a commercial semiconductor optical amplifier (SOA) was demonstrated. The tunable ring laser is based on an external wavelength filter cavity that is analogous with the Littman configuration with a diffraction grating, a mirror, and a simple slit. The unique structural advantage of this new system is that the slit is displaced to select a desired wavelength instead of tilting the mirror as in the Littman configuration. This allows easy control over the selected wavelength by the translating action of the slit. The full width half maximum (FWHM) wavelength turning range is 45 nm, and the wavelength resolution is about 2 pm. The demonstrated tunable ring laser has 2 mW output power. The side mode suppression ratios is 70–73 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1317–1320, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23340
Design and analysis of wideband double‐sided printed spiral‐dipole antenna with capacitive coupling
Authors: Rmili Hatem , Floc'h Jean‐Marie
Published: March 2008

A compact and wideband printed dipole antenna is presented for C‐ and X‐applications. The proposed balun‐fed antenna consists of a double‐sided printed dipole structure with a microstrip‐fed modified spiral‐dipole printed on the top side of the substrate, and a capacitive‐coupling rectangular‐patch, a connecting strip line and the ground plane printed on the bottom side. For the proposed antenna, a wide resonant band which extends from 6.27 to 12.47 GHz, with a fractional bandwidth of 66%, is observed. Details of the experimental and simulation results are presented and discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1312–1317, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23341
Internal multiband surface‐mount monopole slot chip antenna for mobile phone application
Authors: Chang Chih‐Hua , Wong Kin‐Lu
Published: March 2008

A multiband monopole slot chip antenna surface‐mountable on the system circuit board of the mobile phone is presented. The antenna comprises two monopole slots of different lengths, which are folded and attached onto a foam base in the study. With a compact volume of 30 × 10 × 8 mm3(2.4 cm3), the antenna can generate a lower band at about 900 MHz to cover GSM operation and a very wide upper band (bandwidth >1 GHz) to cover DCS/PCS/UMTS operation and 2.4 GHz WLAN operation. It is also promising to use a ceramic base of relative permittivity 7.8 to replace the foam base of the antenna. In this case, the antenna volume can be reduced to be 24 × 10 × 8 mm3(1.92 cm3) only, yet still capable of covering GSM/DCS/PCS/UMTS quad‐band operation. The proposed antenna is studied, and obtained results are presented and discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1273–1279, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23342
Quarter‐band internal antenna design using three branches for GPS, UMTS/WCDMA, ISM, and SDMB band operation
Authors: Jang Byung‐chan , Kim Che‐young , Park Jeung‐keun
Published: March 2008

A design scheme of a quarter‐band internal antenna is proposed for use in GPS, UMTS/WCDMA, ISM, and SDMB bands. The folded metal plates of the three branches are mounted on a dielectric‐coated ground plane for size miniaturization and durability. For a multiband operation the sectional antenna corresponding to each band was designed, combined, and finally trimmed. The return loss of the suggested antenna was calculated by a commercial HFSS simulator and the results are compared with measured return loss, which shows a good agreement between them. Gain and radiation pattern are also measured by the field measurement system in an anechoic chamber. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1227–1232, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23345
A singularity extraction technique for computation of antenna aperture fields from singular plane wave spectra
Authors: Cappellin Cecilia , Breinbjerg Olav , Frandsen Aksel
Published: March 2008

An effective technique for extracting the singularity of plane wave spectra in the computation of antenna aperture fields is proposed. The singular spectrum is first factorized into a product of a finite function and a singular function. The finite function is inverse Fourier transformed numerically using the Inverse Fast Fourier Transform, while the singular function is inverse Fourier transformed analytically, using the Weyl‐identity, and the two resulting spatial functions are then convolved to produce the antenna aperture field. This article formulates the theory of the singularity extraction technique and illustrates the effect of this for an array of electric Hertzian dipoles. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1308–1312, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23346
Strategies for the miniaturization of metamaterial resonators
Authors: Aznar Francisco , García‐García Joan , Gil Marta , Bonache Jordi , Martín Ferran
Published: March 2008

In this article, different possibilities to enhance the miniaturization of metamaterial resonant particles are presented and discussed. By using two metal layers connected by vias, new compact topologies useful for the synthesis of metamaterials (including left handed structures) are proposed. A comparative analysis of the different topologies, in terms of size and unloaded quality factor is carried out, and relevant conclusions are inferred. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1263–1270, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23348
Aperture‐coupled UHF RFID reader antenna for a handheld application
Authors: Lee DongHyun , Park PilJun , Kim JeongPyo , Choi JaeHoon
Published: March 2008

This article presents a new UHF RFID reader antenna for a handheld reader system. An aperture‐coupled structure is employed to cover the North American UHF RFID frequency band: 902–928 MHz. A thick high‐dielectric substrate with a relative permittivity of εr = 8 is used for the size reduction. The rectangular stubs on the proposed annular ring patch contribute to effective impedance matching and good axial ratio performance. The proposed antenna has a total volume of 100 mm × 100 mm × 9.6 mm and exhibits a maximum RHCP gain of 2.68 dBi and an average axial ratio of 1.1 dB for the application frequency band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1261–1263, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23349
Nonlinear propagation and wave mixing characteristics of pulses in semiconductor optical amplifiers
Authors: Kumar Das Narottam , Chandra Karmakar Nemai
Published: March 2008

Nonlinear propagation and wave mixing characteristics of pulses in semiconductor optical amplifiers (SOAs) are analyzed using the finite‐difference beam propagation method (FD‐BPM). From the analyzed output waveform it is found that the peak positions of pulses are shifted to the leading edge. The output spectra are red‐shifted and the dips are found at the higher frequency side in the frequency spectra. Two pulses propagate in SOAs and four‐wave mixing (FWM) characteristics are obtained. Next, all‐optical demultiplexing (DEMUX) characteristics of pulses in SOAs based on FWM are analyzed. From this analysis, it is clear that the SOAs with wider gain bandwidth are required for faster DEMUX operation. The DEMUX characteristics from the time‐multiplexed signals by the repetitive pump pulses are also analyzed. The FWM signal intensity decreases with the strong pump pulses. However, there is no pattern effect due to gain saturation of pulses, because the pump pulses are injected continuously. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1223–1227, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23350
The wide‐band scattering characteristics analysis of the satellite targets in different space attitude conditions
Authors: Rui Zeng , Lezhu Zhou , Mingzhi Li , Wei Wang
Published: March 2008

Wide‐band scattering properties of typical spin stabilized satellite and triaxial stabilized satellite are computed by using finite‐difference time‐domain (FDTD) in this study. Compacts of the attitudes on scattering properties are investigated. The results show the change of rolling attitude more easily arouses the variety of scattering characteristic of satellite target than pitch attitude change does. The calculation results may be helpful to the wide band radar for detecting, identifying, and tracking of the satellite targets. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1294–1300, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23353
Adaptive‐network‐based fuzzy inference system models for input resistance computation of circular microstrip antennas
Authors: Guney K. , Sarıkaya N.
Published: March 2008

A method based on adaptive‐network‐based fuzzy inference system (ANFIS) for computing the input resistance of circular microstrip antennas (MSAs) is presented. The ANFIS is a class of adaptive networks which are functionally equivalent to fuzzy inference systems (FISs). Seven optimization algorithms, least‐squares, nelder‐mead, genetic, differential evolution, hybrid learning, particle swarm, and simulated annealing, are used to determine optimally the design parameters of the ANFIS. The results of the ANFIS models show better agreement with the experimental results, as compared with the results of previous methods available in the literature. When the performances of ANFIS models are compared with each other, the best result is obtained from the ANFIS model trained by the least‐squares algorithm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1253–1261, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23354
Investigation of a compact and broadband balun
Authors: Li Jia‐Lin , Qu Shi‐Wei , Xue Quan
Published: March 2008

Investigations indicate that the bandwidth and circuit size of a conventional branch‐line balun can be improved, where the bandwidth improvement is achieved by introducing a quarter‐wavelength short‐stub at one of the output ports and the size reduction is implemented by meandering the branches of a conventional balun. In this article, a planar balun with broadband bandwidth and compact size is proposed and confirmed, theoretically and experimentally. The results show that a circuit area is reduced to 47.4%, and when referring to a phase difference of ±10°, a flat coupling of over 30% is achieved from measurements, and within this phase difference, the magnitude imbalance is maintained within ±0.25 dB. Both simulated results and measured data are presented, and a good performance is observed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1380–1384, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23361
Electronically tunable broadband E‐shaped patch antenna
Authors: Ansari J. A. , Brij Ram Ram
Published: March 2008

An electronically tunable broadband E‐shaped patch antenna (ESPA) is proposed and analyzed using equivalent circuit concept. The effects of notch parameters such as notch length, width, and position are analyzed to select the optimum values for broadband operation of ESPA. Under the optimum conditions of ESPA, the effect of bias voltage of tunnel diode on the performance of the antenna is also analyzed. The theoretical investigations of the proposed antenna reveal that the tunable band of operation between 1.055 GHz (bandwidth 42.54%) and 1.324 GHz (bandwidth 49.77%) can be achieved by adjusting the bias voltage only. It is noted that the radiative power of the proposed antenna can be enhanced up to 5.67 dB as compared with the E‐shaped patch antenna. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1341–1347, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23362
A uniform evaluation of the PO integral for 2D cylinders with arbitrary contour
Authors: Bondia Felipe Vico , Bataller Miguel Ferrando , Daviu Eva Antonio , Escuderos Daniel Sánchez
Published: March 2008

A new 2D fast physical optics method is presented for computing the field diffracted by a conducting cylinder with arbitrary contour. This method produces a fast solution with uniform accuracy in all frequencies and incidence/observation angles. The method is a combination of different techniques such as path deformation, Morse theory, and Fourier LS continuation. The technique presented here is also valid and uniformly accurate near the caustic singularities produced by surface points with infinite curvature radius. This method also takes into account the endpoint contributions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1418–1423, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23364
Decorrelation of two closely spaced antennas with a metamaterial AMC surface
Authors: Ferrer P. J. , González‐Arbesú J. M. , Romeu J.
Published: March 2008

A metamaterial spacer to decorrelate two closely spaced antennas has been designed and tested. The metamaterial spacer exhibits an artificial magnetic conductor (AMC) behavior around 2.6 GHz. Its performance has been checked against a simple metal spacer (PEC), providing a quasi orthogonal radiation pattern and good results in terms of decoupling and decorrelating a two‐antenna system. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1414–1417, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23365
Design of coupling structures for groove guide resonators
Authors: Bechteler Thomas F. , Kustepeli Alp , Bechteler Sevinc A.
Published: March 2008

Three different coupling structures for a groove guide resonator operating at 10 GHz are investigated. First, propagatable modes are determined analytically. Then, the efficiency of the coupling structures is investigated by means of the method of moments and measurements. Finally, a groove guide resonator is designed and the resonance spectrum for each coupling structure is computed numerically, applying the finite‐difference time‐domain method. Numerical results are compared with experimental measurements. There is good agreement between the measured and simulated data. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1406–1410, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23372
Negative reflection in a Faraday chiral medium
Authors: Mackay Tom G. , Lakhtakia Akhlesh
Published: March 2008

The four wave numbers associated with planewave propagation in a Faraday chiral medium (FCM) with relatively huge magnetoelectric coupling give rise to enhanced possibilities for negative‐phase‐velocity propagation and, therefore, negative refraction. They can also give rise to the phenomenon of negative reflection. In particular, for a nondissipative example, we deduced that an incident planewave with positive/negative phase velocity can result in a negatively reflected planewave with negative/positive phase velocity, as well as a positively reflected planewave with positive/negative phase velocity. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1368–1371, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23373
Advanced design methods for a high efficiency Doherty power amplifier
Authors: Chen Xiaoqun , Guo Yuchun , Shi Xiaowei
Published: March 2008

In this study, a special inverted Doherty topology and uneven power drive methods are proposed to optimize the efficiency and appropriate load modulation. The amplifier is optimized at large power back‐off. The power added efficiency and adjacent channel leakage ratio (ACLR) are 33.1% and −47 dBc, which improve by 3.2% and 5 dB, respectively, and its third‐order intermodulation distortion (IMD3) has 2 .5 dB improvement compared with conventional Doherty power amplifier. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1330–1333, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23375
Design and realisation of low loss air‐filled rectangular coaxial cable with bent quarter‐wavelength supporting stubs
Authors: Ke Maolong , Wang Yi , Lancaster Michael
Published: March 2008

A new type of rectangular coaxial cable, operating from 28 to 48 GHz, was designed and fabricated with thick SU8 photoresist technology. Two pairs of bent quarter‐wavelength supporting stubs were proposed to reduce the lateral dimension of the structure. A size reduction of 40% was achieved by using the bent supporting stubs design as compared with a similar one with straight supporting stubs design. An average insertion loss of 0.36 dB across the bandwidth of 28‐48 GHz was achieved, with return loss of better than − 14 dB. The use of bent supporting stubs did not compromise its microwave performance. The component is, therefore, particularly appealing for integrated components such as complex couplers or Butler matrix, where overall size reduction (with no loss of performance) and cost saving can be substantial. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1443–1446, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23377
Analysis of dielectric resonator antenna excited by a slot at the waveguide shorted end
Authors: Abdulla P. , Kakade Anandrao B. , Singh Y. K. , Chakrabarty A.
Published: March 2008

Hemispherical dielectric resonator (HDR) antenna excited with a slot at the short circuited end of waveguide is analyzed theoretically and verified experimentally. The analysis is based on numerical solution of coupled integral equations discretized using the method of moments (MoM). The HDR is modeled using exact magnetic field Green's function because of the equivalent magnetic current in the slot. The field inside the waveguide is expressed in terms of modal vectors and modal functions. For the analysis of HDR antenna part, the modal series is represented as a sum of particular and homogeneous solutions. The particular solution is computed efficiently using spectral domain approach. The scattering parameter for the HDR antenna loaded at the waveguide end slot is calculated and compared with measured and finite element method (FEM) results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1356–1359, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23382
Determination of metallic ring FSS scattering characteristics using WCIP method
Authors: Titaouine M. , Neto A. Gomes , Baudrand H. , Djahli F.
Published: March 2008

Wave concept iterative procedure (WCIP) is used for the determination of scattering characteristics of single and double metallic ring frequency selective surfaces (FSS). In the WCIP method, the analysis of the FSS is reduced to that of the unit cell. Basically, the WCIP method consists of scattering the incident waves at the interface and the reflection of the scattered waves by the closing ends of the periodic wall box containing the FSS unit cell. The use of the two dimensional fast Fourier transform algorithm results in a reduction of the running time and memory space. FSSs based on single and double metallic rings are analyzed by the WCIP method. A good agreement is observed between the WCIP results and the experimental results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1324–1328, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23383
Broadband differential fed integrated antenna
Authors: Mok Siu Yee , Mok Ka Tsun , Chan Wing Shing , Li Chung Wai
Published: March 2008

A broadband differential fed integrated antenna operating between 0.9 and 2.3 GHz suitable for future software defined radios is presented in this article. Two distributed amplifiers in push‐pull configuration are connecting directly to a modified differential fed bow‐tie antenna, which also performs the dual function of signal combining and radiation. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1320–1324, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23384
Enhanced GMRES method combined with MLFMA for solving electromagnetic wave scattering problems
Authors: Rui P. L. , Chen R. S.
Published: March 2008

For efficiently solving large dense complex linear systems that arise in the electric field integral equation (EFIE) formulation of electromagnetic wave scattering problems, the multilevel fast multipole algorithm (MLFMA) is used to speed up the matrix vector product operations, and the sparse approximate inverse (SAI) preconditioning technique is employed to accelerate the convergence rate of the generalized minimal residual (GMRES) iterative method. We show that the convergence rate can be greatly improved by augmenting to the GMRES method a few eigenvectors associated with the smallest eigenvalues of the preconditioned system. Numerical experiments indicate that this new variant GMRES method is very effective with the MLFMA and can reduce both the iteration number and the computational time significantly. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1433–1439, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23385
Low‐loss doubly metallized CPW low‐pass filter with additional transmission zeroes
Authors: Balalem Atallah , Machac Jan , Kim‐Fai Wong , Omar Abbas
Published: March 2008

This article modifies the classical CPW low‐pass filter to doubly metallized CPW, by implementing metallic patches at the backside of the substrate. Moreover, transmission zeroes are introduced by using single, dual, and tri‐resonant stubs. These stubs are built on the rear side of the substrate. The filters are compact in distinction to the standard CPW low‐pass filter and have a very low loss compared with some other structures. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1431–1433, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23386
Design of a diversity antenna with stubs for UWB applications
Authors: Hong Seokjin , Chung Kyungho , Lee Jaewon , Jung Sangwook , Lee Sang‐Sun , Choi Jaehoon
Published: March 2008

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
Bandpass filter with improved spurious performance using modified ring dielectric resonator in MIC environment
Authors: Srivastava Kumar Vaibhav , Mishra Vishwa V. , Biswas Animesh
Published: March 2008

A C‐band bandpass filter is designed using modified ring dielectric resonator in microwave integrated circuit (MIC) environment for improved spurious response. The dielectric resonator (DR) filters are generally made in cavity environment because of its good spurious response in cavity environment, but its spurious performance degrades as the filter is designed in MIC environment. In MIC environment, the smaller substrate thickness makes DR closer to ground plane and affects its resonance mode spectrum which, in turn, affects closely spaced resonant frequencies. The dense resonant mode spectrum of DR in MIC environment limits its application for filter designing. This article introduces a comparative study on filter realization with modified ring DR and conventional ring DR to show the improvement of spurious response in MIC environment. The simulated and measured results of these filters are presented to demonstrate the validity of the design procedure and improvement of spurious response. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1426–1431, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23391
A modified high linearity CMOS micromixer for UWB systems
Authors: Lin Shui‐Yang , Yang Li‐Wu , Sun Xiao‐Wei
Published: March 2008

A CMOS Micromixer for 3–5 GHz UWB receivers is presented in this article. Modified class‐AB input stage is developed to improve the LO/RF, LO/IF isolation and to reduce the mixer's noise figure. A LO buffer and an output buffer are integrated in it for on‐wafer testing. Our measurement results show that, with a 50‐Ω output loaded, it can achieve 5‐dB power conversion gain, 12.5 dB SSB NF, and 4 dBm IIP3. The mixer‐core consumes 2.6 mA of current from 1.8‐V power supply, and the on‐chip area occupied by this mixer with pads excluded is only about 350 × 400 μm2. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1463–1466, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23395
Erratum: Iterative implementation of approximate solutions for electromagnetic scattering
Authors: Nakhkash M.
Published: March 2008

Originally published Microwave Opt Technol Lett 49: 2425–2429, 2007. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1716, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23399
Electromagnetic smart screen for tunable transmission applications
Authors: Liu L. , Matitsine S. , Tan P. K.
Published: March 2008

Electromagnetic smart screen containing conductive strip array loaded with pin diodes was investigated with numerical and experimental approaches. Transmission coefficient was simulated using finite element method with validation by free space measurement. Tunable EM properties are observed between 3 and 8 GHz, which can be useful for antenna applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1510–1514, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23400
Broadband parametric representation of packaged MEMS interconnects using a state space spectral model
Authors: Naishadham K. , Muldavin J. , Piou J. E.
Published: March 2008

This article presents a robust measurement‐based spectral model, derived from an all‐pole state‐space system representation of the scattering parameters, for the broadband characterization of low‐loss packaged MEMS circuits. The proposed method is illustrated by extracting distributed transmission line parameters of a MEMS interconnect, which accounts for discontinuities and package‐specific parasitic effects. It is shown that the state space method (SSM) effectively filters out measurement noise and facilitates extraction of frequency‐dependent parameters. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1482–1485, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23402
High‐speed divide‐by‐4/5 prescalers with merged and gates using GaInP/GaAs HBT and SiGe HBT technologies
Authors: Wei Hung‐Ju , Meng Chinchun , Chang YuWen , Lin Yi‐Chen , Huang Guo‐Wei
Published: March 2008

This paper demonstrates the divide‐by‐4/5 prescalers with merged AND gates in 2‐μm GaInP/GaAs heterojunction bipolar transistor (HBT) and 0.35‐μm SiGe HBT technologies. By biasing the HBT near the peak transit‐time frequency (fT), the maximum operating frequency of a D‐type flip‐flop can be promoted. At the supply voltage of 5 V, the GaInP/GaAs prescaler operates from 30 MHz to 5.2 GHz, and the SiGe prescaler has the higher‐speed performance of 1–8 GHz at the cost of power consumption. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1498–1500, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23407
IMPATT diode integrated annular ring microstrip antenna
Authors: Kanaujia Binod K. , Singh A. K. , Vishvakarma B. R.
Published: March 2008

A theoretical investigation of IMPATT diode integrated annular ring microstrip antenna is proposed. In which the resonance frequency is controllable by means of bias voltage of IMPATT diode without altering the radii of annular ring. The investigations based on cavity model approach and results also simulated using MOM‐based IE3D simulator are carried out. The maximum frequency agility is found to be 10 MHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1491–1495, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23409
Internal ultra‐wideband slot antenna with a stepped ground plane
Authors: Lin Shun‐Yun , Huang Hong‐Ren
Published: March 2008

This article presents an ultra‐wideband antenna design useful for the internal application in compact mobile devices. It is a planar circular slot antenna fed by a 50‐Ω coplanar waveguide line through a circular patch. The antenna ground plane was bent and vertically connected to the system ground plane. Such fabrications make the whole ground plane like a step. The modified ground plane preserves the original ultrawide bandwidth (from 2.3 GHz to larger than 20 GHz) and radiation characteristics from the integration with the RF circuitry. Also, the experimental results indicate that the proposed antenna can be employed in very close proximity to the possible shielding metal cases for battery and associated RF circuitry, with almost no degradation in the antenna performances. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1487–1491, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23410
MZI‐SOA‐based 2R regeneration of OCDMA signals with multiaccess interference noise
Authors: Silveira T. , Teixeira A. , Kataoka N. , Ferreira A. , Wada N. , Wang X. , Miyazaki T. , Monteiro P.
Published: March 2008

In this work, we present 2R regeneration of coherent optical code division multiple access (OCDMA) signals with distortion provoked by multiple access interference. The regeneration scheme is based on a Mach‐Zehnder interferometer exploiting cross phase modulation in semiconductor optical amplifiers. Experimental regeneration of an 8 Chip 10 Gb/s OCDMA signal is demonstrated with improvements in the required optical signal‐to‐noise ratio and elimination of bit error rate floor. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1521–1523, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23412
Clutter reduction in synthetic aperture radar images with statistical modeling: An application to MSTAR data
Authors: Demirci Sevket , Ozdemir Caner , Akdagli Ali , Yigit Enes
Published: March 2008

In this article, an application of clutter modeling and reduction techniques to synthetic aperture radar (SAR) images of moving and stationary target acquisition and recognition data is presented. Statistical modeling of the clutter signal within these particular SAR images is demonstrated. Lognormal, Weibull, and K‐distribution models are analyzed for the amplitude distribution of high‐resolution land clutter data. Higher‐order statistics (moments and cumulants) are utilized to estimate the appropriate statistical distribution models for the clutter. Also, Kolmogorov‐Smirnov (K‐S) goodness‐of‐fit test is employed to validate the accuracy of the selected models. With the use of the determined clutter model, constant false‐alarm rate detection algorithm is applied to the SAR images of several military targets. Resultant SAR images obtained by using the proposed method show that target signatures are reliably differentiated from the clutter background. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1514–1520, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23413
Inclined slot coupled hemispherical dielectric resonator antenna
Authors: Kakade Anandrao B. , Ghosh B.
Published: March 2008

A microstrip line coupled dielectric resonator antenna with an inclined and offset slot in the common ground plane has been analyzed. Excitation of the TE111 mode in this configuration is studied. It is also seen that the slot geometry and offset can be optimized to excite the higher order TM101 mode. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1527–1530, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23414
Multiband planar antenna design for mobile handset
Authors: Sim Chow‐Yen‐Desmond
Published: March 2008

The design of a novel microstrip‐fed planar mobile phone antenna operating within the GSM/PCS/DCS band is proposed. Besides the additional ability to cover the entire wireless local area network frequency spectrum at 2.4, 5.2, and 5.8 GHz, its multiband operation also includes the GLONASS and MSS band if navigation system application is required. Impedance matching for this case is achieved by simply tuning the ground‐plane's width, one side of the taper structure and the tuning stub. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1543–1545, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23418
A coupled‐defected ground structure lowpass filter using inductive coupling for improved attenuation
Authors: Jung S. , Lim Y.‐K. , Lee H.‐Y.
Published: March 2008

A coupled‐defected ground structure (C‐DGS) with closely located DGS cells is proposed for the application of high‐performance lowpass filters (LPFs). The closely located DGS cells create the coupling of ground currents between adjacent DGS cells, and the coupling effect greatly improves the stopband characteristics because of an additional attenuation pole without structural modification. A LPF that uses the C‐DGS has an attenuation slope of 110.8 dB/GHz and a −20‐dB rejection band that ranges from 3.8 to 15.6 GHz. The C‐DGS improves the DGS circuit performance and extends the scope of DGS applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1541–1543, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23419
An optimized Doherty power amplifier using an unequal quadrature input splitter
Authors: Jung Sung‐chan , Xi Yao , Park Hyunchul , Kwon Sung‐Wook , Van Juho , Lim Kyung‐Hoon , Kim Min‐Su , Cho Hanjin , Jeong Jong‐Hyuk , Yang Youngoo
Published: March 2008

In this article, we present an optimized Doherty power amplifier using an unequal quadrature input splitter and bias control for the peaking amplifier. The linearity and efficiency performances of the Doherty power amplifier were experimentally optimized by means of unequal quadrature input power splitters, which drive unbalanced input power between the carrier and peaking amplifiers. The bias points of the peaking amplifier were also adjusted for each input splitter. A high power‐added efficiency of 33.68% and an output power of 33.95 dBm were achieved for a down‐link wide‐band code division multiple access signal excitation at a given adjacent channel leakage‐power ratio of −30 dBc. This was a significant improvement by 2.75% and 8.22% points from the conventional Doherty and class‐AB amplifiers, respectively. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1536–1539, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23420
An EBG spatial power combiner
Authors: Ooi B. L. , Leong M. S. , Zhong Z. , Wang Y. , Hui S. C. , Hristov H. , Feick R.
Published: March 2008

A new electromagnetic bandgap (EBG) spatial power combiner is proposed. The prototype consists of the design of the EBG ground holes structure, the active‐EBG coupler, and the Vivaldi antenna array. A 17 dB system gain coupled with a 5.5 GHz of impedance bandwidth and good out‐of‐band suppression has been achieved. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1534–1536, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23421
Novel design of semi‐circular slot antenna with triple‐band operation for WLAN/WIMAX communication
Authors: Wang Yau‐Der , Lu Jui‐Han , Hsiao Hai‐Ming
Published: March 2008

A novel triple‐band design of semi‐circular slot antenna for WLAN/WiMAX communication is proposed. With the use of dual arc‐shaped strips inset along the circle edge of the semi‐circular slot antenna, a new resonant mode close to 3.5 GHz for WiMAX application is easily excited. And, with the excited 2.4‐ and 5‐GHz band of the proposed semi‐circular slot antenna for WLAN applications, the triple‐band operation can be easily achieved. The obtained impedance bandwidths for triple operating bands (2.4/3.5/5 GHz) can reach 310/250/600 MHz, respectively, which is enough for WLAN/WiMAX communication. The peak antenna gains for the operating frequencies across WLAN/WiMAX bands are measured to be, respectively, 4.5, 4.2, and 5.1 dBi with the gain variations within 0.5 dBi. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1531–1534, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23422
Characterizations of a supercontinuum optical source for radio‐over‐fiber system
Authors: Wang Jianping , Liu Bosheng , Wang Dan
Published: March 2008

The generation and characterizations of supercontinuum (SC) optical source in wavelength‐division‐multiplexing radio‐over‐fiber (ROF) system is studied in this article. Factors such as the chirp and peak power of the pump pulse, the length of the SC fiber that affect the light source frequency stability are analyzed. The simulation results demonstrate that by altering the value of initial chirp, peak power and SC fiber length, the random fluctuation of the phase and intensity of the SC spectrum is different. At last by optimizing the initial value, an optimal optical source with high frequency stability as the optical source of ROF system is obtained by experiments. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1561–1565, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23430
A novel high brightness parallax barrier stereoscopy technology using a reflective crown grating
Authors: Chen Chien‐Yue , Chang Ming‐Chieh , Ke Ming‐Da , Lin Chen‐Chi , Chen Yi‐Ming
Published: March 2008

In this study, we propose a method to improve the shortcoming of parallax barrier method. As a result of a great deal of light being absorbed or diffused by barrier, brightness will be seriously decreased. Thus, we recommend an idea to effectively reuse the absorbed light, so that the periodic reflective crown grating is plated and fitted below the barrier. The light absorbed or diffused by barrier will be able to be guided back to the reflected layer in backlight and the re‐guided light can be reused again. After simulation, we find the average brightness of the periodic reflective crown grating is raised 114.47% more than traditional parallax barrier type. And we further measure the brightness of three‐dimensional display composed of the periodic reflective crown grating we designed and a 14 inch LCD panel. It is discovered that the brightness is raised by 96.33%. Besides, we put the metal reflective crown grating in between the liquid panel and the backlight, and this method can effectively avoid the loss of the recycled light reflected, which is absorbed by liquid layer. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1610–1616, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23435
Modified Sagnac interferometer for distributed disturbance detection
Authors: Wu Dong‐Fang , Zhang Tian‐Zhao , Jia Bo
Published: March 2008

A fiber optic sensor based on Sagnac interferometer for determining the position of disturbance is presented. For this application, a disturbance simultaneously imposed on two different points of sensing fiber loop could be measured and located. The method solves the problem of isolating part of fiber loop from physical field. Experimentally, longitudinal position of a disturbance is determined with an average error of 59 m over a total length of 25 km. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1608–1610, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23436