Hang Wong

Design and Analysis of a Low-Profile and Broadband Microstrip Monopolar Patch Antenna

A new microstrip monopolar patch antenna is proposed and analyzed. The antenna has a wide bandwidth and a monopole like radiation pattern. Such antenna is constructed on a circular patch antenna that is shorted concentrically with a set of conductive vias. The antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the antenna, but also provides a guideline to design a broadband monopolar patch antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi.

A Dual-Polarized Magneto-Electric Dipole With Dielectric Loading

A plusmn45degdual-polarized magneto-electric dipole loaded with dielectric substrate is presented. This antenna is composed of shorted-circuited patches and planar dipoles and is fed by four Gamma-shaped probes. The height of a prototype antenna operated at 1.9 GHz is only 24 mm (0.15lambdao). A wide impedance bandwidth of 24.9% is achieved. The average gain is about 8.2 dBi and the isolation between the two ports is higher than 29 dB over the operating bandwidth. It is demonstrated that the antenna performance can be improved by adding metallic side walls.

60 GHz Plated Through Hole Printed Magneto-Electric Dipole Antenna

A wideband unidirectional antenna, which is composed of a planar electric dipole and a magnetic dipole formed by a vertically-oriented shorted patch antenna, is presented for millimeter wave applications. The antenna is realized by a plated through hole printed technique with the use of a microwave substrate and is excited by a T-shaped coupled strip feed. An impedance bandwidth of 33% (S11 ≤-15 dB) from 50 to 70 GHz is achieved. Stable radiation patterns with low cross polarizations and a stable antenna gain of ~7.5 dBi are achieved across the entire operating bandwidth. This single antenna element yields advantages of wideband, good directional radiation pattern and low fabrication cost.

A Wideband Circularly Polarized Cross-Dipole Antenna

This letter introduces a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45-GHz ISM band wireless communications. Unlike conventional cross-dipole antennas, the proposed cross dipole is designed with wide open ends such that both impedance and axial-ratio (AR) bandwidths are enhanced. In addition, to excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at the corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. The antenna is center-fed by a 50- Ω coaxial cable and is placed above a square reflector to obtain a directional CP radiation pattern. With the advantage of centered feed, symmetric CP radiation patterns can be achieved across the entire operating bandwidth. Simulated and measured results confirm the proposed antenna produced good CP characteristics. An impedance bandwidth (for VSWR ≤ 2) of about 50.2% (1.99-3.22 GHz) and the 3-dB AR bandwidth of about 27% (2.30-2.9 GHz) around the center frequency of 2.45 GHz were measured. The antenna has an average CP gain of 6.2 dBic across the operating bandwidth and the maximum gain of 6.8 dBic at the center frequency. The size of antenna is 0.45λ×0.45λ×0.24λ.

Small Circularly Polarized U-Slot Wideband Patch Antenna

A single-feed circularly polarized (CP) patch antenna at L-band is designed and built using the recently developed U-slot loaded patch technique. With the presence of the U-slot, the antenna fabricated on a high-dielectric-constant (ε_r = 10.02) substrate achieves a reasonable axial-ratio bandwidth. At the operating frequency of 1.575 GHz, the size of the patch is 0.13λ_o × 0.13λ_o, while the ground size is 0.315λ_o × 0.315λ_o and the thickness of the substrate is 0.05λ_o. The measured gain is 4.5 dBi, and axial-ratio bandwidth is 3.2%.

Wideband Shorted Bowtie Patch Antenna With Electric Dipole

A wideband directional antenna composed of a shorted bowtie patch antenna and an electric dipole is presented. Through this composition, an equivalent magnetic dipole due to the shorted bowtie patch antenna and an electric dipole are excited together. Almost equal radiation pattern in the E- and H-planes is obtained. The proposed antenna has a wide impedance bandwidth, which is over 60% for SWR. < 2 ranging from 2.16-4.13 GHz.

A Shorted Bowtie Patch Antenna With a Cross Dipole for Dual Polarization

A dual-polarized shorted bowtie antenna integrated with a cross dipole is presented. The electric cross dipole is added to generate a symmetric radiation pattern and to compensate the high back radiation due to the shorted patches. This novel dual-polarized antenna is designed for the existing DCS, PCS, and 3G mobile communication systems working between 1.71 and 2.17 GHz. Stable and symmetric radiation patterns at slanted plusmn45deg polarization have been obtained over the operating frequency bands. Measured isolation between the two input ports is over 28 dB. The gain of the proposed antenna is also stable with frequency. The average is about 6.6 dBi

Broadband Patch Antenna With a Folded Plate Pair as a Differential Feeding Scheme

A broadband differential-fed patch antenna (DFPA) with good radiation pattern is proposed and studied. Unlike conventional DFPAs, the proposed antenna employs a folded plate pair as the differential feeding scheme. The devised feeding approach subtly acts as an impedance matching media for two radiation modes of the antenna, conducing to the wide impedance bandwidth. The conceived bandwidth enhancement technique demonstrates an impedance bandwidth (SWR les2) of up to 74% which outperforms conventional broadband patch antennas of more than 20%. Meanwhile, by using a differentially-driven signal along with the introduced feeding scheme, symmetric radiation patterns, low cross-polarization levels and stable radiation patterns are realized within the band. More importantly, the antenna has a stable gain at 8.5 dBi within a wide frequency range, demonstrating the high stability of the radiation characteristics for the two radiation modes. Analysis and parametric studies of the proposed feeding structure are provided.

Small Antennas in Wireless Communications

The objective of this paper is to provide the context, physical insight, and perspective on antennas in wireless communications. Although it does not mean to be comprehensive, the four key technologies related to small antenna designs to be reviewed and discussed, including multiband planar inverted-F antennas, broadband folded patch antennas, compact differentially fed antennas, and miniature circularly polarized patch antennas, would cover a wide range of topical interests and practical applications. A brief overview of computer software for analyzing these antennas is also provided. Hopefully, this paper will be beneficial for the diverse engineering readership of the IEEE.

Dual-Mode Dual-Band Bandpass Filter Based on a Stub-Loaded Patch Resonator

This letter presents a dual-mode dual-band bandpass filter using a patch resonator with a cross slot and two different groups of stubs loaded. The cross slot with different orthogonal lengths excites orthogonal modes in the passbands and reduces the patch size. Meanwhile, the two sets of stubs can modify the filters input impedance at different frequencies and control the even and odd modes in the passbands, respectively. Utilizing these two kinds of elements, transmission poles can be realized easily in both passbands. For demonstration, a dual-band patch resonator filter working at 2.4 and 5.2 GHz is designed. The theoretical analysis is given and the simulated and measured results are presented. The good agreement verifies the proposed method.