The Experts below are selected from a list of 5757 Experts worldwide ranked by ideXlab platform

Chun Hsiung Chen - One of the best experts on this subject based on the ideXlab platform.

  • new coupling scheme for microstrip bandpass filters with Quarter Wavelength resonators
    IEEE Transactions on Microwave Theory and Techniques, 2008
    Co-Authors: Tsungnan Kuo, Shihcheng Lin, Chihsueh Wang, Chun Hsiung Chen
    Abstract:

    A new coupling scheme for microstrip bandpass filters with Quarter-Wavelength (lambda/4) stepped-impedance resonators is proposed. In the proposed coupling scheme, two adjacent lambda/4 stepped-impedance resonators are coupled by directly connecting an admittance inverter between them. By properly designing the connecting position, one may adjust the coupling coefficient between two resonators so that narrow to broad bandwidth filters may easily be fabricated without coupling gaps. Here, the admittance inverter is realized by a lambda/4 stepped-impedance line. Based on the proposed coupling scheme and the conventional magnetic coupling structure, the filters with narrow or wide bandwidth may be designed and implemented. In addition, folded lines are adopted to make the filter size compact. In this study, a two-pole filter with a 3-dB bandwidth of 5.1% and two four-pole filters with 3-dB bandwidths of 33% and 51% are successfully fabricated. Good agreement between measured and simulated results is observed.

  • wide stopband microstrip bandpass filters using dissimilar Quarter Wavelength stepped impedance resonators
    IEEE Transactions on Microwave Theory and Techniques, 2006
    Co-Authors: Puhua Deng, Chihsueh Wang, Chun Hsiung Chen
    Abstract:

    Wide-stopband and compact microstrip bandpass filters (BPFs) are proposed using various dissimilar Quarter-Wavelength (/spl lambda//4) stepped-impedance resonators (SIRs) for multiple spurious suppression. The use of /spl lambda//4 SIRs is essential in widening the filter stopband and reducing the circuit size. By properly arranging the individual /spl lambda//4 SIR, which has the same fundamental resonance frequency f/sub 0/, but has different spurious (harmonic) resonance frequencies, and also carefully misaligning the maximum current density nodes, several higher order spurious resonances may be suppressed so that a BPF with wide stopband may be realized. In this study, the basic concept of multiple spurious suppression is demonstrated by thoroughly investigating the spurious characteristics of the fourth-order interdigital BPFs, which consist of two different types of /spl lambda//4 SIRs. To widen the rejection bandwidth, the fourth-order coupled-resonator BPFs based on three and four different types of /spl lambda//4 SIRs are implemented and carefully examined. Specifically, a very wide-stopband microstrip BPF composed of four dissimilar /spl lambda//4 SIRs is realized and its stopband is extended even up to 11.4f/sub 0/ with a rejection level better than 27.5 dB.

Kin-lu Wong - One of the best experts on this subject based on the ideXlab platform.

  • very low profile dual wideband loop antenna for lte tablet computer
    Microwave and Optical Technology Letters, 2015
    Co-Authors: Kin-lu Wong, Meng-ting Chen
    Abstract:

    A very-low-profile (8 mm in height), small-size (8 × 3 × 40 mm3), and dual-wideband loop antenna suitable for applications in the LTE tablet device such as a tablet computer is presented. Dual-wideband operation of the proposed loop antenna is achieved using a wideband feed structure formed by a coupling feed, a high-pass matching circuit, and a tuning inductor. The coupling feed leads to successful excitation of a Quarter-Wavelength loop mode in the desired lower band. The high-pass matching circuit causes an additional resonance occurred near the excited Quarter-Wavelength loop mode to widen the low-band bandwidth to cover the 698–960 MHz band. The tuning inductor can adjust the frequency ratio of the first two higher-order loop modes to form a wide higher band to cover the 1710–2690 MHz band. Dual-wideband operation of the proposed loop antenna for the LTE operation is hence obtained. Details of the proposed loop antenna are addressed. Working principle of the antenna, especially the function of the wideband feed structure thereof, is described. Experimental results of the fabricated prototype are also presented. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:141–146, 2015

  • Small-Size Uniplanar WWAN Tablet Computer Antenna Using a Parallel-Resonant Strip for Bandwidth Enhancement
    IEEE Transactions on Antennas and Propagation, 2013
    Co-Authors: Kin-lu Wong, Tsung-ju Wu
    Abstract:

    The technique of using a parallel-resonant (PR) strip for bandwidth enhancement of a small-size uniplanar tablet computer antenna for the WWAN operation (824-960/1710-2170 MHz) is presented. The antenna is printed on a thin FR4 substrate of small size 12 × 40 mm2, and has a simple uniplanar structure of comprising a feeding strip, a shorted strip, and a PR strip. The antenna's wide lower band is formed by the Quarter-Wavelength resonant mode of the shorted strip and an additional resonant mode generated owing to the presence of the PR strip, which occupies a very small area of about 7 × 7 mm2 only. The PR strip contributes a parallel resonance at about 1100 MHz which in turn generates an additional resonance near the Quarter-Wavelength mode of the shorted strip, thereby resulting in a new resonant mode to greatly enhance or double the bandwidth of the antenna's lower band for the GSM850/900 operation. For the antenna's upper band, it is formed by a higher-order mode of the shorted strip and a Quarter-Wavelength mode of the feeding strip, and covers the GSM1800/1900/UMTS operation. Details of the proposed antenna are presented.

  • wwan lte printed slot antenna for tablet computer application
    Microwave and Optical Technology Letters, 2012
    Co-Authors: Kin-lu Wong
    Abstract:

    A printed slot antenna comprising two Quarter-Wavelength slots of different lengths and a half-Wavelength slot for eight-band wireless wide area network/long term evolution operation in the tablet computer is presented. The two Quarter-Wavelength slots are open slots or monopole slots, and the half-Wavelength slot is aligned in-between the two Quarter-Wavelength slots. The three slots are excited using a two-strip feedline which is printed on the opposite surface of the printed slots. The proposed three-slot configuration can lead to two wide operating bands, with the lower one covering the 704–960 MHz band and the upper one covering the 1710–2690 MHz band. Good radiation efficiency for frequencies over the operating bands is obtained. The simulated body specific absorption rate values of the antenna in the bottom face, landscape and portrait orientations to the flat phantom in the body specific absorption rate testing model also meet the limit of 1.6 W/kg for 1-g tissue. Details of the results are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:44–49, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26509

  • Bandwidth Enhancement of Small-Size Planar Tablet Computer Antenna Using a Parallel-Resonant Spiral Slit
    IEEE Transactions on Antennas and Propagation, 2012
    Co-Authors: Kin-lu Wong, Yu-wei Chang, Shu-chuan Chen
    Abstract:

    An internal planar tablet computer antenna having a small size of 12 × 35 mm2 printed on a 0.8-mm thick FR4 substrate for the WWAN operation in the 824-960 and 1710-2170 MHz bands is presented. The antenna comprises a driven strip, a parasitic shorted strip and a ground pad, all printed on the small-size FR4 substrate. For bandwidth enhancement of the antenna's lower band, the antenna applies a parallel-resonant spiral slit embedded in the ground pad, which generates a parallel resonance at about 1.2 GHz and in turn results in a new resonance occurred nearby the Quarter-Wavelength mode of the parasitic shorted strip. This feature leads to a dual-resonance characteristic obtained for the antenna's lower band, making it capable of wideband operation to cover the desired 824-960 MHz with a small antenna size. The antenna's upper band is formed by the higher-order resonant mode contributed by the parasitic shorted strip and the Quarter-Wavelength resonant mode of the driven strip and can cover the desired 1710-2170 MHz band. Details of the proposed antenna and the operating principle of the parallel-resonant spiral slit are presented.

  • gsm850 900 1800 1900 umts printed monopole antenna for mobile phone application
    Microwave and Optical Technology Letters, 2008
    Co-Authors: Kin-lu Wong, Tingwei Kang
    Abstract:

    The design of a printed monopole antenna on the system circuit board of the mobile phone for achieving GSM850/900/1800/1900/UMTS operation with a small area of 10 mm × 60 mm is presented. The antenna is easy to fabricate at low cost and mainly comprises a driven strip, a coupled strip, and a high-pass matching network for providing two wide operating bands at about 900 and 1900 MHz to cover GSM850/900 and GSM1800/1900/UMTS operations, respectively. The wide lower band is controlled by the driven strip excited as a Quarter-Wavelength mode, which is further tuned to become a dual-resonance excitation by incorporating the high-pass matching network for effective bandwidth enhancement. For the wide upper band, it is formed by a Quarter-Wavelength mode excited at about 1800 MHz by the coupled strip and the higher-order mode contributed by the driven strip. Furthermore, with the proposed antenna structure, the lower and upper bands can generally be tuned separately, which is an attractive feature and makes it easy to design for practical applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3192–3198, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23936

Chingwen Tang - One of the best experts on this subject based on the ideXlab platform.

  • a compact tunable notch filter with wide constant absolute bandwidth
    IEEE Microwave and Wireless Components Letters, 2015
    Co-Authors: Chingwen Tang, Weichen Chen
    Abstract:

    A compact notch filter with a wide tunable frequency range is developed. This tunable filter is composed of two varactor-tuned resonators, shunted at input/output ports separately, and one Quarter-Wavelength transmission line connecting two varactor-tuned resonators. By enlarging impedance of the Quarter-Wavelength transmission line, the proposed tunable filter can obtain a wide and constant absolute bandwidth within the whole tunable frequency band. The measured results show that there is a wide tuning range, 124.3%. In addition, with insertion loss greater than 20 dB, a wide constant absolute bandwidth can be achieved at 450 MHz.

  • miniaturization of microstrip branch line coupler with dual transmission lines
    IEEE Microwave and Wireless Components Letters, 2008
    Co-Authors: Chingwen Tang, Mingguang Chen, Chihhung Tsai
    Abstract:

    The dual transmission lines are proposed to replace conventional Quarter-Wavelength transmission lines for a compact microstrip branch-line coupler in this study. The developed coupler can be easily fabricated on the printed circuit board without lumped element; moreover, its size is greatly reduced compared to the conventional branch-line coupler. Furthermore, simulated and measured frequency responses match well to validate the proposed coupler with dual transmission lines.

  • harmonic suppression ltcc filter with the step impedance Quarter Wavelength open stub
    IEEE Transactions on Microwave Theory and Techniques, 2004
    Co-Authors: Chingwen Tang
    Abstract:

    An effective method to design a low-temperature co-fired ceramic RF bandpass filter with suppression of the harmonic frequency is demonstrated in this paper. The second harmonic, which appears in the frequency band of 4.8-5.0 GHz, is very significant and should be reduced in the 2.4-GHz wireless local area network and Bluetooth application. This feature of harmonic frequency suppression is very important in a communication system to improve linearity, output power, intermodulation performance, etc. The harmonic-suppression filter can be easily obtained by adopting the characteristic of equivalent Quarter-Wavelength resonators. The detailed three-dimensional layout of each layer is disclosed. By analyzing the influences of the dielectric constant and layer thickness of a ceramic sheet by electromagnetic simulation, the optimal condition for the filter design can be obtained. The measured results agree well with the simulation.

Gao Wei - One of the best experts on this subject based on the ideXlab platform.

  • multiple band notched uwb antenna with band rejected elements integrated in the feed line
    IEEE Transactions on Antennas and Propagation, 2013
    Co-Authors: Fuguo Zhu, Steven Gao, R A Abdalhameed, C H See, Tim Brown, Gao Wei
    Abstract:

    To mitigate potential interferences with coexisting wireless systems operating over 3.3-3.6 GHz, 5.15-5.35 GHz, or 5.725-5.825 GHz bands, four novel band-notched antennas suitable for ultra-wideband (UWB) applications are proposed. These include UWB antennas with a single wide notched band, a single narrow notched band, dual notched bands, and triple notched bands. Each antenna comprises a half-circle shaped patch with an open rectangular slot and a half-circle shaped ground plane. Good band-notched performance is achieved by using high permittivity and low dielectric loss substrate, and inserting Quarter-Wavelength horizontal/vertical stubs or alternatively embedding Quarter-Wavelength open-ended slots within the feed line. The results of both simulation and measurement confirm that the gain suppression of the single and multiple band-notched antennas in each desired notched band are over 15 dB and 10 dB , respectively. The radiation pattern of the proposed triple band-notched design is relatively stable across the operating frequency band.

Yoke Choy Leong - One of the best experts on this subject based on the ideXlab platform.

  • a broad band Quarter Wavelength impedance transformer with three reflection zeros within passband
    IEEE Transactions on Microwave Theory and Techniques, 2004
    Co-Authors: Yoke Choy Leong
    Abstract:

    A new impedance transformer employing a transmission line and a coupled-line section is presented in this paper. It is physically a Quarter-Wavelength long, but can achieve three reflection zeros within the passband. Therefore, broad bandwidths can be obtained for a wide range of impedance ratios. The location of the reflection zeros can be synthesized through the transmission line and coupled-line parameters. Design curves for the transformer synthesis have been obtained by solving the design equations directly. Using these results, a stripline impedance transformer has been implemented. This 50-110-/spl Omega/ impedance transformer achieved over 25-dB return loss from 0.6 to 1.6 GHz.

  • a broad band Quarter Wavelength impedance transformer with three reflection zeros within passband
    International Microwave Symposium, 2004
    Co-Authors: Yoke Choy Leong
    Abstract:

    A new impedance transformer employing a transmission line and a coupled-line section is presented in this paper. It is physically a Quarter-Wavelength long, but can achieve three reflection zeros within the passband. Therefore, broad bandwidths can be obtained for a wide range of impedance ratios. The location of the reflection zeros can be synthesized through the transmission line and coupled-line parameters. Design curves for the transformer synthesis have been obtained by solving the design equations directly. Using these results, a stripline impedance transformer has been implemented. This 50-110-Ω impedance transformer achieved over 25-dB return loss from 0.6 to 1.6 GHz.