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Now showing items 145 - 160 of 183

  • Cylindrical-rectangular microstrip patch antenna for circular polarization

    Kin-Lu Wong   Shyh-Yeong Ke  

    The circular polarization condition for a rectangular microstrip patch antenna on a thin cylindrical substrate is investigated. The theoretical study is based on the modal-expansion theory, which is valid for the thin-substrate case. Numerical results for the aspect ratio of the cylindrical-rectangular patch, the optimal feed point for minimum voltage standing wave ratio and the 3-dB bandwidth for circularly polarized radiation are analyzed. Effects of the curvature on the circular polarization condition are also discussed.
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  • Compact dual-frequency microstrip antenna with a pair of bent slots

    Kin-Lu Wong   Kai-Ping Yang  

    A novel, compact, dual-frequency design for cutting a pair of bent slots in the centre of a rectangular patch is demonstrated. For fixed dual-frequency operation, the proposed design provides an antenna-size reduction as high as 32%compared to that of using a simple patch without the slots. Experimental results of the proposed design, with various sizes of the bent slots, are presented and analysed.
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  • Broadband dual-polarized aperture-coupled patch antennas with modified H-shaped coupling slots

    Kin-Lu Wong   Hao-Chun Tung   Tzung-Wern Chiou  

    This paper presents a new design of aperture-coupled patch antennas with modified H-shaped coupling slots for achieving dual-polarization radiation with high isolation over a wide bandwidth. By using the proposed coupling slots, whose two upper side arms are bent inward with a proper angle, the isolation between the two feeding ports of the patch antenna can. greatly be improved, compared to the case with conventional H-shaped coupling slots. Also, when using a pair of modified H-shaped coupling slots for each feeding port, the isolation can further be improved; a high degree of isolation (> -34 dB) over the entire impedance bandwidth greater than 15%and good cross-polarization level (< 20 dB) for the two polarizations can be achieved. Details of the proposed design and experimental results are presented and discussed.
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  • WLAN chip antenna mountable above the system ground plane of a mobile device

    Kin-Lu Wong   Chih-Hua Chang  

    A novel wireless local-area network (WLAN) chip antenna suitable to be mounted above the system ground plane of a mobile device is presented. The antenna in the study is easily fabricated from folding a single metal plate onto a foam base, and mainly comprises a short-circuited radiating strip and an antenna ground. The antenna ground occupies the bottom surface and two adjacent side surfaces of the foam base. When the antenna is mounted at the corner of the system ground plane, this antenna ground structure is expected to effectively reduce the antenna's possible fringing electromagnetic fields inside the mobile device. In this case, when the associated element such as the radio-frequency shielding metal case is placed under the proposed antenna, small or negligible variations in the antenna performance are obtained. Design considerations of the proposed antenna for WLAN operation in the 2.4 GHz band are described, and results of the constructed prototypes are presented.
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  • Study of an internally matched helical beam antenna

    Kin-Lu Wong   Wen-Shyang Chen  

    An internally matched helical beam antenna has been designed and constructed. The helix winding of a helical antenna was designed to be a slow wave section by placing a ground copper sheet on the inner side of the winding and inserting a dielectric sheet between the winding and the ground copper sheet to form a distributed capacitance along the antenna. By carefully adjusting the internal inductance of the helix winding and the distributed capacitance, the antenna can radiate in the axial mode and be internally matched to the 50- Omega transmission line feeding it. With this arrangement, the dimension of such an antenna can be much smaller than that for an ordinary helical beam antenna at the same operating condition. Details of the antenna design and experimental results are presented.
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  • Compact microstrip antenna with dual-frequency operation

    Kin-Lu Wong   Wen-Shan Chen  

    The characteristics of a single-feed dual-frequency compact microstrip antenna with a shorting pin are studied experimentally. Besides the compactness of the antenna, this dual-frequency design can provide a high frequency ratio of <3.0 between the two operating frequencies. Typical experimental results of the proposed antenna are presented and discussed.
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  • Internal penta-band printed loop-type mobile phone antenna

    Kin-Lu Wong   Wei-Yu Li  

    A novel internal mobile phone loop-type antenna for GSM850/GSM900/DCS/PCS/UMTS penta-band operation is presented. The antenna comprising a driven monopole and a coupled strip is very suitable to be printed on the system circuit board of the mobile phone and short-circuited to the system ground plane to form as a loop-type structure. The antenna provides two wide bands at about 900 and 1900 MHz to cover the GSM850/900 and DCS/PCS/UMTS bands; respectively. The lower band is generated by the driven monopole and coupled strip operated together as a half-wavelength loop resonant structure. The upper band is formed by two resonant modes: the first one is the driven monopole operated alone as a quarterwavelength monopole and the second one is contributed from the driven monopole and coupled strip operated together as a onewavelength loop resonant structure.
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  • Resonance and radiation of cylindrical triangular microstrip antennas

    Kin-Lu Wong   Shan-Cheng Pan  

    The characteristics of cylindrical microstrip antennas with triangular patches are studied theoretically and experimentally. The fundamental mode (TM/sub 10/ mode), having a broadside radiation pattern, is studied. A full-wave approach for the analysis of the cylindrical triangular microstrip antenna is applied, and the resonance frequency, input impedance, and far-zone radiated fields are formulated. Numerical results are calculated and an experiment is also conducted to verify the theory. A comparison of the antenna characteristics with those of the rectangular and circular patches is also given.
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  • Printed Loop Antenna With a Perpendicular Feed for Penta-Band Mobile Phone Application

    Chih-Hong Huang   Kin-Lu Wong  

    A promising printed loop antenna is described that can be mounted in perpendicular to the top edge of the system circuit board of the mobile phone for penta-band operation. The antenna comprises a loop pattern printed on a thin FR4 substrate of small size 10$\,\times\,$ 60 ${\rm mm}^{2}$ and a perpendicular feeding portion printed on the narrow top ungrounded region of the system circuit board. Since the top ungrounded region is 4 mm in length only, the antenna is very low profile to the top edge of the ground plane on the system circuit board; that is, the antenna occupies a small volume inside the mobile phone housing and is suitable to operate as an internal antenna. In addition, the antenna generates two wide operating bands centered at about 900 and 1900 MHz to cover GSM850/900 and DCS/PCS/UMTS operations, respectively.
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  • Penta-Band Printed Loop Antenna for Mobile Phone

    Chih-Hong Huang   Kin-Lu Wong  

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  • A broadband patch antenna with wide slits

    Kin-Lu Wong   Wen-Hsiu Hsu  

    Broadband patch antennas with a thick air or foam substrate have been of considerable interest owing to their simple structure, easy fabrication, and good radiation characteristics over a wide operating bandwidth. However, when such broadband patch antennas are to be excited using a probe feed, achievable bandwidth is usually limited to be less than 10%, due to the large inductance associated with the longer probe in the thick substrate layer. To overcome this problem, there are usually some compensations or modifications to be introduced in the feed arrangement or some slot loadings to be added to the radiating patch. In this article we demonstrate a new and simple broadband design of a patch antenna with a pair of wide slits. The wide slits are inserted at the boundary of a circular patch or at one of the radiating edges of a rectangular patch. The proposed broadband patch antenna can have similar wide impedance bandwidth and good radiation characteristics as those reported for a U-slotted patch antenna. Details of the antenna design and experimental results are presented and discussed.
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  • Small broadband rectangular microstrip antenna with chip-resistor loading

    Kin-Lu Wong   Yi-Fang Lin  

    Designs of a chip-resistor-loaded rectangular microstrip antenna fed using a probe feed or an inset microstrip-line feed are presented. These antenna designs have the advantages of small antenna size and wide antenna bandwidth, compared to a conventional rectangular microstrip antenna. Details of the experimental results are given.
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  • An inverted U-shaped patch antenna for compact operation

    Kin-Lu Wong   Hao-Chun Tung  

    By using a novel inverted U-shaped radiating patch in place of the conventional planar patch, compact operation of air-substrate patch antennas is presented. The inverted U-shaped patch is formed by adding two downward rims at the two radiating edges of a planar rectangular or square patch. And owing to the added rims, the excited patch's surface current paths are lengthened, which effectively lowers the antenna's resonant frequency and results in large antenna size reduction (<50%). The proposed compact design has been successfully applied to air-substrate patch antennas fed by an aperture-coupled feed. In addition to large size reduction obtained, the proposed antenna with an air-substrate thickness about 5%the wavelength of the center operating frequency can have an impedance bandwidth (10-dB return loss) greater than 9%, a peak antenna gain of about 6.4 dBi, and good broadside radiation patterns with cross-polarization levels better than 20 dB in principal planes.
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  • Infrared Wireless Communications using Complementary Sequence

    Kin-Lu Wong   Timothy J. O’Farrell  

    The performance of an infrared wireless system using direct sequence spread spectrum techniques in multipath channels depends very much on the partial correlation properties of the spreading sequences used. Ideally; a spreading sequence should have zero sidelobes in its periodic and aperiodic auto-correlation functions in order to eliminate multipath dispersion. Unfortunately; no such ideal sequence exists in the binary field. In this paper; a new spread spectrum based binary modulation scheme is proposed in which a set of complementary sequences is transmitted simultaneously such that the sum of their aperiodic auto-correlation and cross-correlation functions are impulsive or near impulsive. The system modelling and bit error rate analysis is presented. Results show that the new scheme is able to remove multipath dispersion almost completely.
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  • Internal shorted patch antenna for a UMTS folder-type mobile phone

    Kin-Lu Wong   Saou-Wen Su   Chia-Lun Tang   Shih-Huang Yeh  

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  • Analysis of a cylindrical-rectangular microstrip structure with an airgap

    Kin-Lu Wong   Yuan-Tung Cheng   Jeen-Sheen Row  

    The resonance problem of the cylindrical-rectangular microstrip structure with an airgap between the substrate layer and the ground conducting cylinder is studied by using a rigorous full-wave approach and a moment method calculation. The resonance condition is satisfied by complex resonant frequencies, which provide the information of resonant frequency and half-power bandwidth of the structure. Numerical results indicate that, with the increasing of the airgap thickness, the half-power bandwidth of the structure at the efficient radiating mode of HE/sub 0.1/ is considerably increased, which improves the narrow bandwidth characteristics of microstrip structures. Details of the numerical results, including the results for the planar rectangular microstrip structure with an airgap, are presented and analyzed.
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