bluuebunny/crossref_metadata_2025 huggingface dataset:
A dual‐band rejected cross monopole antenna maintaining omnidirection radiation
Authors: Chen Wen‐Shan , Lin Chi‐Huang
Published: July 2008

UWB cross semi‐elliptic monopole antenna with a dual‐band rejected characteristic is presented and experimentally studied. The proposed cross bevel‐rectangular monopole antenna is embedded with four small h‐shaped slots; it produces a design of dual‐band rejected characteristics and maintains omnidirection radiation. This technique is suitable for creating multiwideband antenna or ultrawideband (UWB) antenna with dual‐rejected band. And the proposed antenna with good omnidirection characteristic is also maintained. Details of the results for the proposed antenna are presented and discussed in this study. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2491–2493, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23712
T‐shaped compact mobile handset antenna for wideband applications
Authors: Yu Byunggil , Byun Joonho , Lee Byungje
Published: July 2008

A novel compact and wideband antenna of the mobile handset, consisting of the T‐shaped radiating elements, a coaxial feed, and a partially added high permittivity material, is proposed for wideband applications including GSM, GPS, DCS, PCS, UMTS, and WiBro bands. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2727–2730, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23713
Higher‐efficiency‐biasing technique for enhancing the performance of BJT‐distributed amplifiers
Authors: Leung Tik Shun , Chan Wing Shing
Published: July 2008

Efficiency of distributed amplifier based on bipolar junction transistors is low particularly at higher frequencies. The work presented here shows an increase in efficiency of up to three times by applying a proposed unequal biasing technique, which also eliminates the inefficient use of a dummy load at the output artificial transmission line. The proposed circuit provides a maximum power added efficiency of 27.8% which is a three‐times improvement compared with the optimized conventional distributed amplifier. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2725–2727, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23714
Design concept of a mobile handset antenna to mitigate user's hand effect
Authors: Kim Sung‐Joo , Kong Ki‐Hyun , Park Myun‐Joo , Chung Young‐Seek , Lee Byungje
Published: July 2008

A meandered loop antenna with the modified ground plane in conjunction with the balanced structure is proposed to mitigate the degradation of antenna performance when the handset is directly held by the user's hand. The antenna efficiency for a dual frequency band (AMPS and PCS) is studied under the influence of the user's hand. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2696–2698, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23715
Design of dual‐band bandpass filter using diverse quarter‐wavelength resonators for GPS/WLAN applications
Authors: Wu Hung‐Wei , Su Yan‐Kuin , Weng Min‐Hang , Yang Ru‐Yuan
Published: July 2008

The novel compact dual‐band bandpass filter (BPF) by using diverse quarter‐wavelength (λ/4) resonators for global position system (GPS)/wireless local area network (WLAN) applications is proposed for the first time. The use of two interdigital‐like λ/4 resonators of the proposed BPF effectively provides the responses for GPS/WLAN at 1.575/5.7 GHz by properly arranging the λ/4 SIRs. Full‐wave simulator IE3D is used to design the proposed BPF. Good agreement with responses of electromagnetic (EM) simulation and measurement is compared. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2694–2696, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23716
Compact planar monopole UWB antenna with band‐notched characteristic
Authors: Zhao Yu‐Long , Jiao Yong‐Chang , Zhao Gang , Zhang Li , Song Yue , Wong Zi‐Bin
Published: July 2008

A novel compact ultra‐wideband antenna with band‐notched function is proposed and implemented. The radiating patch consists of a binomial function edge and is fed by coplanar waveguide. The size of the UWB antenna is minimized to 30 × 27.4 mm2. A new type of π‐shaped slot is embedded to obtain the band‐notched characteristic in the 5 GHz WLAN band. The center frequency of the notched band can be varied from 5.2 to 5.8 GHz by properly selecting the parameter values. The measured results are in good agreement with the simulated ones. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2656–2658, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23717
Bandwidth enhancement of printed dipole antenna with tuning stub
Authors: Liu Ying , Gong Shuxi , Bu Antao
Published: July 2008

A novel design of tuning stub is presented to improve the performance of printed dipole antenna. In large antenna array, the feed network occupies large ground area, which will deteriorate the performance of antenna array and limit the design of large antenna array. The tuning stub is proposed to reduce the effect of the ground size on antenna array. The stub is approximately one‐fourth wavelength, and its size and position are optimized to control the coupling between the dipole and ground. Under the same measurement condition, the antenna with stub has bandwidth almost two times that of the reference antenna without stub. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2653–2656, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23718
Fourier‐transform phase comparator for the measurement of extrinsic Fabry–Perot interferometric sensors
Authors: Jiang Yi
Published: July 2008

A Fourier‐transform phase comparator is developed to measure fiber optic extrinsic Fabry‐Perot interferometric sensors. The phase comparator is realized by comparing the phases of two white‐light spectra, which are obtained by scanning the wavelength of the light source. The changes of a cavity length, which are concerned in most applications, can be interrogated. A linear output is obtained, and a measurement resolution of 15 pm is experimentally achieved, which is very close to the theoretical value. The technique has high resolution and a large dynamic measurement range. In addition, the measurement is not affected by various imperfections of the sensor, light source spectrum profile, and the loss of leading fiber and connectors. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2621–2625, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23719
A compact dual‐band bandpass filter using meandering stepped impedance resonators
Authors: Chen Fu‐Chang , Chu Qing‐Xin
Published: July 2008

We propose a compact dual band bandpass filter (BPF) using meandering stepped impedance resonators (SIRs). By appropriately selecting the impedance ratio (K) of the SIR, the harmonic frequencies can be tuned for generating the dual‐passband response. Using this structure, the bandwidth of each passband can be controlled independently by adjusting the coupling gap and the spur‐line length. The BPF has good dual‐passband performance at 2.4/5.25 GHz and has a very smaller area in comparison with the previous works. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2619–2621, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23720
Error analysis on single sideband modulator
Authors: Chen Lei , Shi Xiaowei , Guo Yuchun
Published: July 2008

This paper analyzes the influence of amplitude and phase error of different path on single sideband modulator (SSB) which can be used as an upconverter. Unwanted sideband suppression expression and error variables equation for maximum output sideband suppression are also deduced. The simulation curve shows the variation of sideband suppression with the amplitude and phase error of the components of SSB is given. Simulation results show that components of the amplitude and phase of the highly consistent or inconsistent amplitude and phase which meet the relationship can achieve higher sideband suppression for the SSB. The completed modulator used as an upper sideband upconverter shows −11 dB typical conversion gain with 22‐dB sideband suppression. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2590–2594, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23721
Wideband bandpass filter for MB‐OFDM application
Authors: Lee Ching‐Her , Hsu Chung‐I G. , Chen Lian‐Yu
Published: July 2008

This article presents a wideband bandpass filter (BPF) designed using novel multimode resonators (MMRs). The MMR is formed by combining two quarter‐wavelength (λ/4) stepped‐impedance resonators (SIRs) in a structure‐shared fashion. The fundamental resonant frequency of the inherent λ/4 SIR and that of the embedded half‐wavelength (λ/2) SIR were designed to locate in the passband of the BPF to achieve a wideband response. Experiments on a prototype wideband BPF were carried out for validating the filter design. The fabricated BPF was measured to have a large bandwidth of 1:2.2 with an insertion loss of less than 0.86 dB and a small group‐delay variation of not more than 0.11 ns in the passband. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2587–2590, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23722
Low‐loss MEMS switchable microstrip filters
Authors: Ong Cen Y. , Okoniewski Michal
Published: July 2008

Parallel‐coupled microstrip filters with MEMS switchable frequency responses are designed. The 15‐GHz filter switches 5.3% with minimum insertion loss of 0.7 dB, whereas the 20‐GHz filter has 12.9% switching range and minimum insertion loss of 0.6 dB. Both filters have the lowest insertion losses among MEMS tunable microwave bandpass filters to date. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2557–2561, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23723
CMOS top‐series coupling quadrature injection‐locked frequency divider
Authors: Jang Sheng‐Lyang , Wu Sheng‐Chien , Lee Chien‐Feng , Juang M.‐H.
Published: July 2008

This article presents a new divide‐by‐2 injection‐locked frequency divider (ILFD). The ILFD consists of a 2.1‐GHz top‐series quadrature voltage‐controlled oscillator (QVCO) and two NMOS switches, which are in parallel with the QVCO resonators for signal injection. The proposed CMOS ILFD uses three‐dimensional inductor to save chip area and has been implemented with the TSMC 0.18‐μm CMOS technology and the core power consumption is 9.36 mW at the supply voltage of 0.9 V. The free‐running frequency of the ILFD is tunable from 2.02 to 2.28 GHz. At the input power of −8 dBm, the total divide‐by‐2 locking range is from 3.6 to 6.05 GHz as the tuning voltage is varied from 0 to 0.9 V. The phase noise of the locked output spectrum is lower than that of free running ILFD in the ÷2 mode. The phase deviation of quadrature output is about 0.19°. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2554–2557, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23724
Determination of wave propagation properties for multilayered dielectric waveguide by semivectorial beam propagation method with Douglas scheme
Authors: Chen Chun‐Ping , Ma Zhewang , Anada Tetsuo , Hsu Jui‐Pang
Published: July 2008

An improved parabolic‐equation‐based numerical method with Douglas scheme is developed for modeling the new 3D multilayered dielectric transmission waveguides. Unlike the traditional one, such waveguides are constructed by putting the multilayered dielectric cladding with step indices property on a silicon substrate. The propagation properties of widely used polarization‐maintaining waveguides and antiresonant reflecting dielectric waveguide are investigated by this method as examples. The discussion on the numerical dispersion and radiation loss property is also included to validate this improved beam propagation method (or BPM). © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2521–2524, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23725
Numerical specific absorption rate analysis and measurement of a small indoor base station antenna
Authors: Ilvonen Sami , Toivonen Tommi , Toivo Tim , Uusitupa Tero , Laakso Ilkka
Published: July 2008

A comparison of different compliance rules for a small indoor base station antenna is presented at frequencies 1800, 2140, and 2450 MHz using a computational model. The numerical model of the antenna is validated using measurements of free space electric field values in close proximity of the antenna and specific absorption rate in a flat liquid phantom. Losses of the antenna are approximated using the measured radiation efficiency as a scaling factor between the input and output power of the antenna. The compliance distances are then computed using the reference levels for field values and equivalent power density. Obtained values are compared to the basic restriction limit in the upper torso of an anatomically realistic numerical model of a human body. The results show that in this case the reference level of maximum value of equivalent power density gives conservative compliance distances. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2516–2521, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23726
Compact multiband PIFA with a coupling feed for internal mobile phone antenna
Authors: Wong Kin‐Lu , Huang Chih‐Hong
Published: July 2008

A compact multiband PIFA (planar inverted‐F antenna) occupying a very small volume of less than 0.8 cm3 in the mobile phone for GSM/DCS/PCS/UMTS operation is presented. The PIFA uses a single resonant path only, which is close to about one‐eighth wavelength at 900 MHz. A coupling feed, different from the conventional direct feed, is proposed to excite the PIFA. In this case, the large input impedance at 900 and 1900 MHz can be greatly decreased, making it promising to excite two operating bands at about 900 and 1900 MHz to cover the desired multiband operation. Good radiation characteristics for frequencies over the operating bands are also obtained. The occupied volume of the proposed multiband PIFA is about the smallest among the reported internal multiband mobile phone antennas. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2487–2491, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23727
Printed dual band monopole antenna structures for WLAN applications
Authors: Gupta R. K. , Kumar G.
Published: July 2008

This article proposes printed dual‐band monopole antenna structures for Wireless Local Area Network (WLAN) applications in IEEE 802.11 a/b/g. The proposed antennas are fabricated on a low cost easily available FR4 substrate, which effectively covers both 2.4 and 5 GHz bands. The antenna structures are derived from an E‐shape dual‐band monopole antenna, which generates two separate resonant frequencies for the desired dual‐band operations. The one arm resonates at the 5 GHz band, whereas the other resonates at the 2.4 GHz band. The proposed antennas can easily be fed by using a 50‐Ω probe feed. The measured VSWR is <2 over the 2.4–2.5 GHz and 5.15–5.875 GHz. The radiation patterns indicate the suitability of these antennas for WLAN applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2483–2487, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23728
Design of a fishbone‐shaped antenna with a V‐slot for dual‐band operation
Authors: Kang Suk‐Youb , Min Kyeong‐Sik , Yoon Cheol , Park Hyo‐Dal
Published: July 2008

The structure of the proposed fishbone‐shaped antenna with a V‐slot for dual‐band operation makes it possible to easily design a high‐performance dual‐band antenna by adjusting the location and number of fishbones on both sides of a basic antenna with a V‐slot at the center. This design can be applied to various types of microstrip patch antennas with a centrally located V‐slot. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2509–2512, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23729
CMOS top‐series coupling quadrature injection‐locked frequency divider
Authors: Jang Sheng‐Lyang , Wu Sheng‐Chien , Lee Chien‐Feng , Juang M.‐H.
Published: July 2008

This article presents a new divide‐by‐2 injection‐locked frequency divider (ILFD). The ILFD consists of a 2.1‐GHz top‐series quadrature voltage‐controlled oscillator (QVCO) and two NMOS switches, which are in parallel with the QVCO resonators for signal injection. The proposed CMOS ILFD uses three‐dimensional inductor to save chip area and has been implemented with the TSMC 0.18‐μm CMOS technology, and the core power consumption is 9.36 mW at the supply voltage of 0.9 V. The free‐running frequency of the ILFD is tunable from 2.02 to 2.28 GHz. At the input power of −8 dBm, the total divide‐by‐2 locking range is from 3.6 to 6.05 GHz as the tuning voltage is varied from 0 to 0.9 V. The phase noise of the locked output spectrum is lower than that of free‐running ILFD in the \div\2 mode. The phase deviation of quadrature output is about 0.19°. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2702–2705, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23730
Design of a compact antenna for Bluetooth application
Authors: Yoon Joong Han
Published: July 2008

In this article, a compact antenna with stack geometry for Bluetooth application was proposed and experimentally studied. The antenna consists of a lower patch at the bottom layer, an upper patch at the top layer, and a via that connects the two layers. The effect of various parameters on the top and bottom patch antennas for Bluetooth application is investigated. From the results of the experiments, the measured impedance bandwidth, defied by VSWR 1:3, can reach an operating bandwidth of 170 MHz (2.37–2.54 GHz). Also, antenna radiation patterns and gains within the operating band were measured and studied. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2568–2572, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23731
Comment/correction: “Waves in 2D anisotropic L‐C lattice metamaterials: Phenomenology and properties”
Authors: Glass B.
Published: July 2008

In Brennan et al. (Microwave Opt Technol Lett 48 (2006), 2538–2542), in part 2, (for Y0 = 0) the unusual properties of an infinite bidimensional L‐C lattice obtaining results concerning the propagation of waves (backward and forward propagation) were discussed. The same result was obtained in Brennan et al. (Microwave Symp Dig 2005 IEEE MTT‐S Int 12–17 (2005), 1757–1760) (part II). This comment points out a more efficient performance analysis and shows that the behavior for backward (LHM) or forward (RHM) waves has no special restriction for values of the phase like φi < π/2(i = 1,2). Moreover, it must be carefully treated that the symmetry of the phase diagram (isofrequency) for the first zone of Brillouin (φi = [−π,π], with lattice periodicity 2π). Also, there is an unusual feature for the angle δ(φ1)X=const between the group and phase velocities for backward waves, where there is a discontinuity for isofrequency X = 1 at φ1 = π. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2730–2732, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23732
Miniaturized microstrip filters and diplexers for wireless communication systems
Authors: Zayniyev Damir , Budimir Djuradj , Zouganelis George
Published: July 2008

A highly miniaturized microstrip diplexer composed of pseudointerdigital quasi‐elliptical bandpass filters is proposed. Compactness of diplexer is achieved through the combination of the bandpass filters, which does not require matching network. The proposed microstrip diplexer, having a size of 30.7 × 5.6 mm at a center frequency of 2.7 GHz at channel 1 and 3.8 GHz at channel 2 is designed, fabricated, and tested. Experimental results of the fabricated microstrip diplexer are in very good agreement with the simulated results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2701–2702, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23733
CPW‐FED omnidirectional hybrid microstrip/dielectric resonator antenna
Authors: Perron Alexandre , Denidni Tayeb A. , Sebak Abdel R.
Published: July 2008

In this letter, we present a new antenna configuration in which a coplanar waveguide (CPW) is used to feed a cylindrical dielectric resonator (DR) and a subjacent circular patch to generate an omnidirectional radiation pattern. A first prototype, designed to resonate near 2.45 GHz, shows that an impedance bandwidth of 6.3% is achievable using a single layer of substrate. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2699–2701, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23734
Compact broadband monolithic 3‐dB coupler by using artificial transmission lines
Authors: Monti Giuseppina , Tarricone Luciano
Published: July 2008

This letter presents a broadband rat‐race coupler designed by using right‐handed artificial transmission lines (ATLs) combined with a composite right/left‐handed ATL; in order to limit spurious parasitic effects, by using metal–air–metal capacitor and short circuited stubs, both kinds of ATLs have been designed without lumped elements, leading to a very compact and monolithic device. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2662–2667, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23735
An augmented electric field integral equation for high‐speed interconnect analysis
Authors: Qian Zhi Guo , Chew Weng Cho
Published: July 2008

The conventional electric field integral equation (EFIE) is augmented by including charge as the extra unknown, so that the contributions of the vector potential and the scalar potential are separated to avoid the imbalance at low frequencies. With the frequency scaling and the direct enforcement of the current continuity constraint, the new augmented EFIE is free of low‐frequency breakdown for interconnect analysis. Mathematically, it can be categorized as a generalized saddle‐point problem. The new equation is verified by numerical examples. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2658–2662, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23736
The influence of the ASE noise on the cascadability of active Mach‐Zehnder interferometer switches
Authors: Martinez Jose Manuel , Herrera Javier , Ramos Francisco , Marti Javier
Published: July 2008

The influence of the ASE noise on the cascadability of SOA‐MZI structures is investigated. The experimental results show that saturation effects in the SOAs are the main cause of signal degradation, so counter‐propagation pump schemes as well as lower bias currents and optical powers are desirable when cascading several SOA‐MZI optical switches. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2629–2631, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23737
Analysis of slot‐loaded stacked disk patch antenna
Authors: Ansari J. A. , Singh Prabhakar , Dubey Satya Kesh , Khan R. U. , Vishvakarma Babau R.
Published: July 2008

In the present article circular disk loaded with slot as well as stacking with parasitic element is analyzed in which it is found that bandwidth of the antenna improves by loading it with slot as well as parasitic element. The resonance frequency and matching of the antenna depends on slot dimensions and substrate thickness (h1 and h2). The theoretical results are compared with the simulated results using IE3D. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2625–2629, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23738
Near‐zero permittivity substrates for horizontal antennas: Performance enhancement and limitations
Authors: Hirvonen Mervi , Tretyakov Sergei A.
Published: July 2008

In this letter the advantages offered by ε‐near‐zero materials as substrates for horizontal dipole antennas near a ground plane are theoretically studied. From the previous work it is known that substrates with extremely low values of permittivity dramatically enhance radiation from horizontal currents over a ground plane. On the other hand, as reported in this letter, frequency dispersion and the finite size of the substrate limit the achievable enhancement in antenna performance. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2674–2677, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23739
11.8 GHz GAINP/GAAS HBT dynamic frequency divider using HLO‐FF technique
Authors: Wei Hung‐Ju , Meng Chinchun , Chang YuWen , Huang Guo‐Wei
Published: July 2008

An integrated GaInP/GaAs heterojunction bipolar transistor (HBT) dynamic frequency divider based on HLO‐FF (high‐speed latching operating flip‐flop) structure is demonstrated at 4.1–11.8 GHz. In this experiment, a conventional static frequency divider using the same cut‐off‐frequency device is also fabricated for comparison. By biasing the HBT transistors around the peak of fT and optimizing the Iread/Ilatch ratio, the maximum operating frequency of the HLO‐FF is greatly improved due to higher slew‐rate and smaller voltage swing. The speed of HLO‐FF is faster about 48% than that of static structure. The core current is 13 mA at the supply voltage of 5 V. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2642–2645, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23740
Design of a broadband dual circularly polarized square slot antenna
Authors: Zhao G. , Chen L.‐N. , Jiao Y.‐C.
Published: July 2008

In this article, a new design of a broadband dual circularly polarized square slot antenna loaded with metallic strips is presented. The proposed dual circular polarization (CP) radiations are achieved by loading the square slot with a T‐shaped strip and two microstrip T‐junctions. The designed antenna is implemented and measured. The experimental results show that the proposed antenna has good dual CP characteristics and a 3‐dB axial ratio bandwidth is more than 19%. The isolation between two ports is better than 20 dB within the CP operating band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2639–2642, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23741
Design of a compact and wideband microstrip bandstop filter
Authors: Çakir Gonca
Published: July 2008

A novel bandstop filter (BSF), with a stop band covering GSM‐900, GSM1800, Bluetooth, and future 5 GHz applications which possesses the characteristics of compact size and wide bandwidth is proposed and fabricated. Parameters are optimized via numerical simulations. The simulations are performed via an in‐house‐prepared three dimensional (3D) finite‐difference time‐domain (FDTD) package. Measurements are carried out using an HP‐8510C network analyzer. The simulated and measured results show that the filter has wide stopband of 126% (1.7–7.8 GHz) for 3‐dB bandwidth. There is a good agreement between the simulated and experimental results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2612–2614, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23742
Application of segmentation analysis to a matched U‐slot patch antenna
Authors: Lee S. K. , Ooi S. F. , Sambell A. , Korolkiewicz E. , Scott S.
Published: July 2008

A wide impedance matching bandwidth or multi‐band response can be obtained using a single layer U‐slot rectangular antenna with a probe feed. However, the determination of the input impedance of this antenna has not been reported. In this letter using segmentation analysis a new explicit matrix input impedance formula has been derived. The U‐slot rectangular antenna is partitioned into rectangular segments and the system of coplanar matrix circuit equations is reduced by cojoining pairs of equations. The reduced system is then solved to obtain a new explicit matrix input impedance formula. This technique has the potential to be applied to other multi‐segmented antenna geometries. Two antennas operating at 2.45 GHz were fabricated, one with a substrate of thickness 1.575 mm and the other with a substrate of thickness of 3.175 mm. For both antennas there is an excellent agreement between the predicted, simulated, and measured results for the input impedance. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2608–2611, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23743
A 90‐NM CMOS low‐power down‐converter for 3‐ to 5‐GHz ultra‐wideband wireless systems
Authors: Sapone Giuseppina , Palmisano Giuseppe
Published: July 2008

This article presents the design and the measurement results of a 3‐to 5‐GHz down‐converter fabricated in a 90‐nm CMOS technology. The circuit consists of a single‐ended low‐noise amplifier and two I/Q double‐balanced mixers. A transformer‐based on‐chip single‐ended‐to‐differential conversion allows gain and noise performance to be optimized at a very low power. The down‐converter achieves a 23‐dB conversion gain, a noise figure of 3.4 dB, and an input third‐order intercept point of −8 dBm, while drawing only 9 mA from a 1.2‐V supply voltage. The down‐converter exhibits competitive performance compared to the best state‐of‐the‐art ultra‐wideband circuits in the same frequency range. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2577–2581, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23744
Varactor‐tuned microstrip bandpass filter with wide tuning range
Authors: Kim Jeongpyo , Choi Jaehoon
Published: July 2008

In this study, a tunable bandpass filter with a hairpin line resonator and loading capacitors using varactor diodes was proposed. The filter was modified by adding varactor diodes to the coupling part to compensate for losses. The designed filter had a simple structure and the characteristics of wide tuning range of 87.9% from 430 to 1105 MHz and low insertion loss of less than 4.42 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2574–2577, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23745
Optical fiber‐based macrobend free air flow sensor using a hinge joint: A preliminary report
Authors: Vijayan Anu , Thakare Vishal , Karekar R. N. , Aiyer R. C.
Published: July 2008

A novel idea of hinge joint is explored to cause macrobend in optical fiber and is explored for its use as a flow sensor. The bending of the fiber at the hinge changes the intensity of light traveling through the optical fiber. This can ideally be used in areas where air flow upto 10 lit/min needs to be monitored continuously. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2543–2546, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23746
Design of three prime‐focus 12‐mm‐wavelength horns for the Parkes radio telescope
Authors: Granet Christophe , Gough Russell
Published: July 2008

Three prime‐focus horns have been optimized to cover different frequency bands around the 12‐mm‐wavelength radio‐astronomy bands. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2537–2543, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23747
Leaky mode analysis of optical waveguides by Legendre and Laguerre pseudospectral method
Authors: Huang Chia‐Chien
Published: July 2008

In this letter, an efficient multidomain pseudospectral method is implemented to solve leaky waveguides. The exterior subdomains with the evanescent and oscillatory mode shapes, the optical fields are, respectively, expanded by Laguerre‐Gauss functions and Legendre polynomials incorporating simple Mur's absorbing boundary condition. Numerical results verify the effectiveness of the present approach and are in good agreement with exact data. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2507–2509, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23748
A novel structure of the power equalizer for millimeter wave applications
Authors: Zhang Yong
Published: July 2008

Power equalizer is often used to adjust the output power of traveling wave tubes (TWT) or high power solid state amplifiers. Traditionally, a power equalizer is composed of coaxial line with electromagnetic wave absorber or microstrip line with resistance in resonance circuit. However, those structures only adapt to microwave frequency band. In this article, a millimeter wave power equalizer is fulfilled by waveguide resonant cavity with electromagnetic wave absorber. The measured results and the simulated results show a very good agreement. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2504–2506, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23749
Finite element analysis of multiconductor transmission lines in multilayered dielectric media
Authors: Musa Sarhan M. , Sadiku Matthew N. O.
Published: July 2008

In this work, we illustrate the analysis of inhomogeneous quasi‐TEM multiconductor transmission lines in multilayered dielectric media using finite element method. We specifically determine the per unit length of capacitance and the inductance matrices of two circular wires in layer surrounded by two different dielectric layers, three conductors in three different dielectric layers, and four conductors in three different dielectric layers between two grounds. Excellent agreement with results obtained previously by integrated equation method and method of moment is demonstrated. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2743–2747, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23750
Topology gradient optimization in 2‐D and 3‐D for the design of microwave components
Authors: Khalil Hassan , Assadihaghi Atousa , Bila Stéphane , Baillargeat Dominique , Aubourg M. , Verdeyme Serge , Puech Jerome , Lapierre Luc
Published: July 2008

A numerical model defined by a finite element method coupled with a topology gradient method is used for optimizing the shape of microwave components with respect to electrical specifications. The approach, which consists in minimizing a cost function with respect to the physical property of individual topological elements, which define the shape of the component, is first described. Regarding the given electrical specifications, the technique is applied for optimizing, respectively, in 2D, the distribution of metal upon the surface of a planar component and, in 3D, the distribution of dielectric material within a waveguide component. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2739–2743, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23751
Diffusion characteristics of a joint‐proton source for the wet etch of LiNbO3
Authors: Ting Tien‐Lun , Huang Wen‐Hung , Chen Liang‐Yin , Wang Way‐Seen
Published: July 2008

Diffusion characteristics of a joint‐proton source for proton exchange in LiNbO3 are presented. With a concentration‐dependent diffusivity derived from experimental results, the diffusion process is simulated to estimate the proton‐exchanged wet‐etched depth. Good agreement between simulated and measured depth is obtained. In addition, an S‐shaped ridge waveguide is fabricated to demonstrate the improvement in power transmission efficiency. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2736–2738, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23752
Ultra‐wideband loop antenna coupled‐FED by a monopole feed for penta‐band folder‐type mobile phone
Authors: Wong Kin‐Lu , Tu Shu‐Yang
Published: July 2008

An ultra‐wideband coupled‐fed loop antenna for penta‐band operation in the folder‐type mobile phone is presented. The antenna comprises a loop strip and a monopole feed; the latter not only serves as a coupling feed for the loop strip to generate a 0.5‐wavelength loop resonant mode, but also provides a 0.25‐wavelength monopole resonant mode for enhancing the operating bandwidth of the antenna. Hence, with an occupied volume of 2.6 cm3only, the antenna can provide a very wide operating band of larger than 100% or about 1.7 GHz (from 790 to 2480 MHz), allowing the antenna to cover GSM850/900/DCS/PCS/UMTS penta‐band operation with radiation efficiencies larger than 70% for the folder‐type mobile phone in the open state (talk condition). For the antenna in the close state (idle condition), it can still provide a very wide operating band just by including a matching circuit of a series chip capacitor at the antenna's feeding point, and the radiation efficiencies over the five operating bands are still better than 53%. Details of the proposed antenna are studied. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2706–2712, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23753
Tunable all‐fiber Er3+‐doped laser based on a double‐clad Er3+/Yb3+ co‐doped fiber amplifier
Authors: Shumin Zhang , Dan Li , Guangzhen Zhao
Published: July 2008

In this study, a continuously tunable Er‐doped fiber laser based on a double‐clad Er3+/Yb3+ co‐doped fiber amplifier is demonstrated. By using the nonlinear polarization rotation technique, the tunable laser operating can be an all‐fiber structure and have tuning range, power variation, and laser line width of 15 nm, 0.37 dBm, and less than 0.06 nm, respectively. By using an Er3+/Yb3+ co‐doped fiber amplifier, the amplified spontaneous emission intensity can be more than 40 dBm suppressed over the tunable range, and the power conversion efficiency is about 10.5%. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2671–2674, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23754
Evaluation of coplanar waveguide‐to‐microstrip transitions for precision S‐parameter measurements
Authors: O'Neil Benton K. , Young Jeffery L.
Published: July 2008

The metric of unaccounted power is introduced as a sufficient condition to successful thru‐reflect‐line (TRL) calibrations for microstrip circuits. It is then demonstrated how this metric can be used both a priori, with simulation data, and a posteriori, with measured data, to evaluate the efficacy of coplanar waveguide to microstrip transitions in TRL calibrations. This demonstration is performed with four different transition topologies, two of which utilize coaxial edge mount connectors and two of which utilize ground‐signal‐ground coplanar probes. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2667–2671, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23755
Synthesis of ultrawideband bandpass filter by multisection of commensurate stepped‐impedance resonators
Authors: Chen Chun‐Ping , Ma Zhewang , Anada Tetsuo
Published: July 2008

A novel filter prototype composed of multisection of stepped impedance resonators (SIRs) is proposed to realize the ultra‐wideband bandpass (UWB) filter. The relation between the modes number and stage number of resonators is first discussed, followed by the derivation of the corresponding Chebyshev filtering function. Furthermore, the equivalent circuit model of this new filter prototype is established based on the transmission‐line theory for filter synthesis. As an example, a FCC UWB filter is synthesized with the proposed filter prototype to possess a passband from 3.1 to 10.6 GHz (fractional bandwidth is about 110%). The synthesized circuit model are further optimized by EM simulator, fabricated in microstrip line, and characterized by network analyzer. The good agreement between the measured and predicted frequency responses validates the effectiveness of newly proposed synthesis approach. In addition, the designed filter exhibits good characteristics of comparatively low insertion loss, quite sharp skirts, very flat group delay, and good stopband (especially in lower one) as well. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2635–2639, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23756
A VCO with on chip tank for IEEE 802.11a
Authors: Khemchandani S. L. , Suarez J. del Pino , Goñi‐Iturri Amaya , Diaz Roberto , Hernandez Antonio
Published: July 2008

In the last years, wireless LAN market has shown an incredible growth, exceeding expectations. This article presents a fully integrated LC voltage controlled oscillator in a low cost 0.35 μm BiCMOS process for the 5–6 GHz band, according to the IEEE 802.11a wireless LAN standard. The tank inductor has been designed by electromagnetic simulations. To test the VCO performance, a synthesizer for IEEE 802.11a has been designed. This work demonstrates the feasibility of a low cost silicon technology for the design of 5–6 GHz band circuits. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2632–2635, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23757
Simplified propagation channel characterization considering the disturbance of antennas in the case of a multipath cluster
Authors: Vu Van Yem , Kohmura Akiko , Braga A. Judson , Begaud Xavier , Huyart Bernard
Published: July 2008

In this article, a simple approach of antenna calibration for the radio propagation channel measurements in the case of a multipath cluster is presented. The method is based on the concept of “power wave transfer functions.” Practical experiments are performed for the characterization of a multipath propagation channel using printed dipole antennas, quasi‐Yagi antennas, and their array in the 2–3 GHz frequency range. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2604–2608, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23758
Compact dual‐band diversity antenna for mobile handset applications
Authors: Byun Joonho , Jo Jae‐Hoon , Lee Byungje
Published: July 2008

A dual band diversity antenna for PCS and WiMAX bands is proposed and designed with compact dimension. The proposed diversity antenna consists of two dual‐band PIFAs arranged front to front with the same structure. With polarization diversity, jointed shorting structure, and suspended line, the proposed antenna gives high radiation efficiency (>50%), high isolation (>15 dB), and low correlation coefficient (ρe < 0.05. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2600–2604, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23759
Compact paper‐clip‐shaped wire antenna for 2.4 and 5.2 GHz WLAN operation
Authors: Su Saou‐Wen , Chou Jui‐Hung , Liu Yung‐Tao
Published: July 2008

A compact dual‐WLAN‐band antenna, in the shape of a paper clip, is presented. The antenna can be easily manufactured by bending few times a single copper wire with a length of about 65 mm, and it operates in the 2.4 and 5.2 GHz bands in the WLAN environment. In addition to the simple configuration, the antenna is easily fed by a 50‐Ω mini‐coaxial cable which allows it to be flexible in a defined location for installation. An experimental prototype of the proposed antenna with the overall dimensions of about 5 mm × 23.5 mm is constructed, tested, and demonstrated. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2572–2574, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23760
The fabrication and analysis of lateral pressure fiber sensor based on fiber Bragg grating
Authors: Huang Hsi‐Shan , Liang Tsair‐Chun
Published: July 2008

This article mainly depicts the sensitivity of the pressure sensor based on fiber Bragg grating coated with polymers of different ratio hardener and silicone sealant. The result shows that when the ratio is 1:13, the effect of the sensitivity of 1.94 × 10−2/MPa can be obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2535–2537, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23761
Displacement of phase center location in circular microstrip antennas
Authors: Shafai Lotfollah , Pour Zahra Allahgholi
Published: July 2008

It is shown that the phase center of a dual‐mode circular microstrip antenna depends on the excitation of its modes. For a single mode, the phase center is located on the geometrical center of the antenna. However, if two or more modes are combined, the phase center can be moved away from the antenna center, and make its location dependent on the mode excitations. For the two adjacent TM11 and TM21 modes the problem is investigated and the dependence of the phase center location on the relative excitation of the two modes is determined. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2531–2535, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23762
Synthetic asymptote formula for coupled microstrip line on two layer grounded substrates
Authors: Tang Wanchun , Cai Wenbo , Yu Zhengyong
Published: July 2008

This article presents the derivation of simple CAD formula for coupled microstrip line on a grounded substrate of two layers by synthetic asymptote. The formulas are simple, accurate, and give good physical insights to the design properties. By simply introducing an imaginary part in the permittivity of the bottom layer substrate, the formulas in this article can be applied for coupled microstrip line of silicon‐based RFIC. Not only the even and odd mode characteristic impedances, but also the attenuation and propagation constants are compared with numerical results. Good agreements are obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2500–2504, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23763
A Kretschmann‐type absorption‐based surface plasmon resonance waveguide sensor
Authors: Shibayama Jun
Published: July 2008

The Kretschmann‐type surface plasmon resonance (SPR) waveguide sensor is numerically investigated for detecting a change in the imaginary part of the refractive index. SPR responses are found to be quite sensitive to the change, suggesting the possibility of realizing a compact absorption‐based waveguide sensor integrated into optical circuits. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2497–2500, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23764