Tzung-Wern Chiou

A low-profile planar monopole antenna for multiband operation of mobile handsets

A novel planar monopole antenna is proposed. It has a very low profile (antenna height less than 0.04 times the operating wavelength in free space) and is capable of multiband operation. The proposed antenna has a planar rectangular radiating patch in which a folded slit is inserted at the patchs bottom edge. The folded slit separates the rectangular patch into two subpatches, one smaller inner subpatch encircled by the larger outer one. The proposed antenna is then operated with the inner subpatch resonating as a quarter-wavelength structure and the outer one resonating as both a quarter-wavelength and a half-wavelength structure. The proposed antenna, 12 mm high and 30 mm wide, has been constructed, and the obtained bandwidths cover the global system for mobile communication (890-960 MHz), digital communication system (1710-1880 MHz), personal communication system (1850-1990 MHz), and universal mobile telecommunication system (1920-2170 MHz) bands. Details of the proposed design and obtained experimental results are presented and discussed.

Low-cost broadband circularly polarized patch antenna

A novel single-feed broadband circularly polarized patch antenna is proposed. The proposed antenna has a simple structure, consisting of a corner-truncated square radiating patch, an L-shaped ground plane, and a probe feed. Through a via hole in the vertical ground of the L-shaped ground plane, the radiating patch is easily excited by a probe feed oriented in the same plane as the patch, and circular polarization (CP) radiation over a wide frequency range (>10%) is achieved. Experimental results of a constructed prototype with the center operating frequency at about 2500 MHz showed that the antenna has an impedance bandwidth (1.5:1 VSWR) of about 30%, a 3-dB axial-ratio CP bandwidth of about 10.4%, and a gain level of 8.5 dBi or larger within the CP bandwidth. In addition to the low cost of the proposed antenna due to its simple structure, the obtained CP performance is among the best that have been reported for single-feed single-element patch antennas.

Broad-band dual-polarized single microstrip patch antenna with high isolation and low cross polarization

This paper presents a new design of a broad-band dual-polarized single microstrip patch antenna with highly decoupled input ports and low cross-polarization (XP) radiation. A prototype of the proposed antenna with center frequency at 1800 MHz is presented. Both the dual linear polarizations have 10-dB return-loss impedance bandwidths greater than 14% and high decoupling between the two input ports (S/sub 21/ less than -40 dB across the entire bandwidths) is obtained. Moreover, the XP radiation in the principal planes of the dual linear polarizations is seen to be less than -20 dB.

Broad-band single-patch circularly polarized microstrip antenna with dual capacitively coupled feeds

New design of a circular microstrip antenna with dual capacitively coupled feeds for broad-band circular polarization radiation is presented. The dual feeds are with a small top-loaded disk and are connected to a Wilkinson power divider with a 90/spl deg/ phase shift between its two output feedlines. The radiating circular patch, printed on a thin substrate, is supported by nonconducting posts on a conducting ground plane and is excited capacitively through the dual feeds. With a distance less than 10% times the center operating wavelength between the circular patch and the ground plane, the present proposed antenna can provide an impedance bandwidth (VSWR /spl les/2) of about 49% and a 3-dB axial-ratio bandwidth of about 35%. The antenna gain bandwidth, defined to be within 1-dB gain variation in the axial-ratio bandwidth, is as large as 28%, with the antenna gain level at about 7.0 dBi.

Broadband dual-polarized aperture-coupled patch antennas with modified H-shaped coupling slots

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 ( 20 dB) for the two polarizations can be achieved. Details of the proposed design and experimental results are presented and discussed.

Broadband dual-polarized patch antennas fed by capacitively coupled feed and slot-coupled feed

Designs of broadband dual-polarized patch antennas fed by promising feed structures of a capacitively coupled feed and a slot-coupled feed (antenna A), two capacitively coupled feeds of a 180/spl deg/ phase shift and a slot-coupled feed (antenna B), and two capacitively coupled feeds of a 180/spl deg/ phase shift and two slot-coupled feeds (antenna C) are proposed and experimentally studied. The first two feed designs are for the excitation of a single-element broadband patch antenna, while the last design is for a two-element broadband patch antenna. These proposed patch antennas have a thick air substrate, and the 10 dB return-loss impedance bandwidths obtained for the two polarizations are all greater than 13%. High isolation ( 20 dB) in both E and H plane patterns for the two polarizations of antennas B and C are achieved.

Dual-band planar inverted F antenna for GSM/DCS mobile phones

A compact dual-band planar inverted F antenna suitable for the application as a global system for mobile communication/digital communication system (GSM/DCS) dual-band mobile phone internal antenna is proposed and implemented. The proposed antenna has three resonant elements, two meandered metallic strips of slightly different lengths and one nearly-rectangular patch, which are printed on a supporting FR4 substrate and arranged in a compact configuration. These three resonant elements share a common shorting pin, and for the GSM (890-960 MHz) operation, the proposed antenna is operated with the two meandered strips both resonated as a quarter-wavelength structure, leading to a wide bandwidth formed by two resonant modes. For the upper band of the proposed antenna, three resonant modes are generated, two from the second higher-order modes of the two meandered strips and one from the nearly-rectangular patch, leading to a wide bandwidth covering the DCS band (1710-1880 MHz). The antenna design and experimental results are presented.

Omnidirectional planar dipole array antenna

A planar dipole array antenna having good omnidirectional radiation in the azimuthal plane is presented. The planar dipole array antenna comprises two 1 /spl times/ 2 dipole arrays arranged back to back and separated by a narrow rectangular ground plane, and is easily constructed by printing on both sides of a dielectric substrate. Prototypes of the proposed antenna for WLAN operation in the 2.4 GHz band (2400-2484 MHz) were constructed and studied. Good omnidirectional radiation with gain variations less than 2 dBi in the azimuthal plane has been obtained, and the measured maximum antenna gain for operating frequencies across the 2.4 GHz band is about 5.0-6.1 dBi. Effects of the ground-plane width and the array spacing on the performance of the proposed antenna are also studied.

PIFA with a meandered and folded patch for the dual-band mobile phone application

In this communication, a novel design of the planar inverted-F antenna (PIFA) is proposed for the dual-band mobile telephone application. To reduce the antenna size, the radiating patch is meandered and folded. The studies begin with a folded-patch PIFA that has two tunable resonant modes. Next, by loading three slits on the patch, the surface current path is meandered and the antenna length is reduced significantly. The IE3D simulation software is employed for optimizing the design parameters, and the simulation results in general agree with the measured data. Results also show that, the excitation of the 900 and 1800 MHz resonant modes can be achieved for the proposed antenna with a small volume of 24/spl times/10/spl times/7.2 mm/sup 3/. Radiation patterns for both resonances are measured and shown. The maximum antenna gain is estimated to be 2.5 dBi for both 900/1800 band operations.

A compact dual-band dual-polarized patch antenna for 900/1800-MHz cellular systems

A novel compact design for achieving dual-band dual-polarized radiation suitable for applications in the 900/1800-MHz cellular systems is presented. The proposed antenna consists of a rectangular ring patch (for the 900-MHz operation) and a notched rectangular patch (for the 1800-MHz operation), which are printed on the same layer, and each patch is aperture-coupled by two H-shaped coupling slots to generate two orthogonal linearly polarized waves. By further incorporating a properly designed feed network, the proposed antenna shows good port decoupling of less than -39 dB and -34 dB for dual linear polarizations in the 900- and 1800-MHz bands, respectively. Details of the antenna design and experimental results are presented.