Fu-Ren Hsiao

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.

Omnidirectional planar folded dipole antenna

An omnidirectional planar antenna comprising two back-to-back folded dipoles printed on a dielectric substrate is presented. A constructed prototype suitable for WLAN operation in the 5-GHz band, such as the 5.2-GHz (5150-5350 MHz) and 5.8-GHz (5725-5875 GHz) bands, is demonstrated. The constructed prototype shows a wide impedance bandwidth of larger than 1.1 GHz (about 20% centered at 5.5 GHz), and a stable antenna gain level of about 4.5 dBi, with small variations (< 2 dBi) for omnidirectional radiation, is obtained across the bandwidth. Details of the antenna design and the experimental results are presented.

A low-profile omnidirectional circularly polarized antenna for WLAN access point

Omnidirectional CP antennas have the advantage that no strict orientations between the access point, and the mobile unit are required for WLAN operation. For this reason, it can be expected that the omnidirectional CP antenna should find great application in WLAN operation. For such promising applications, we propose a novel omnidirectional CP antenna with a low profile of less than 10 % of the wavelength of the center operating frequency. The proposed antenna consists of a top-loaded cylindrical monopole for generating omnidirectional vertical linear polarization (LP) radiation and four printed arc-shaped dipoles for generating omnidirectional horizontal LP radiation. The vertical and horizontal LP radiation can further be adjusted to be of equal amplitude and a 90/spl deg/ phase difference, thereby resulting in omnidirectional CP radiation. A prototype of the proposed antenna suitable for applications in a 2.4 GHz (2400-2484 MHz) WLAN access point is constructed and studied.

Broadband very-high-permittivity dielectric resonator antenna for WLAN application

DRA with a high relative permittivity have the advantage of low profile over conventional DR antennas. The low-profile characteristic makes the very-high-permittivity DR antennas very attractive for practical applications. However, largely owing to the higher permittivity, such DR antennas usually show an insufficient impedance bandwidth for satisfying the required operating bandwidth or are hard to design for CP performance in practical applications. To overcome the problem, we propose in this article two novel designs of the very-high-permittivity DR antennas, simply by loading two narrow conducting strips of suitable lengths for broadband operation or with a regular square cross-section for achieving CP radiation. Details of the proposed broadband or CP design are described, and experimental results of the constructed prototype suitable for WLAN application are presented and discussed.

Planar inverted-F antenna with a hollow shorting cylinder for internal mobile phone antenna

Planar inverted-F antennas (PIFAs) have been very popular as an internal antenna in small handheld wireless communication devices. Recently, in many wireless devices, a digital camera is embedded and is in competition with the PIFA internal antenna for the very limited space on the system circuit board. We propose a novel design of the PIFA with a large hollow shorting cylinder for application in a mobile phone with an embedded digital camera. The hollow shorting cylinder has a large diameter (8 mm in this case), and it is easy to fit the lens of a practical embedded digital camera inside it. In this case the proposed PIFA and the embedded digital camera together occupy a minimum space, and very small or negligible coupling effects of the embedded camera with the PIFA are expected. A design example of the proposed PIFA for application in a UMTS (Universal Mobile Telecommunication System, 1920-2170 MHz) mobile phone is demonstrated. The experimental results obtained are also presented.

Omnidirectional planar dipole array antenna for WLAN access point

In this paper, a low-cost planar dipole array antenna with an omnidirectional radiation characteristic is presented. The proposed omnidirectional planar dipole array antenna comprises two 1/spl times/2 dipole arrays arranged back to back, and can be easily constructed by printing on both sides of a dielectric substrate. By selecting the central ground plane to have a small width (about 6 mm for operating at about 2.4 GHz), the proposed array antenna can have a good omnidirectional radiation pattern in the azimuthal plane (gain variations less than 2 dBi). Prototypes of the proposed antenna for WLAN operation in the 2.4 GHz band (2400-2484 MHz) were constructed and studied.

Dual-frequency PIFA with a rolled radiating arm for GSM/DCS operation

In this paper, a novel dual-frequency design of the PIFA (planar inverted-F antenna) suitable for mounting on the top edge of the system ground plane of a communication device is presented. The proposed PIFA has a rolled radiating arm, which provides two separate resonant paths for GSM/DCS operations and leads to compact size of the antenna, and shows a very low profile to the top edge of the ground plane (antenna height above the top of the ground is 8 mm only, corresponding to about 0.024 times the free-space wavelength at 900 MHz).

Harmonic control of a square microstrip antenna operated at the 1.8 GHz band

This paper presents an experimental study of the harmonic resonance suppression of a square microstrip antenna fed by using a 50 /spl Omega/ inset microstrip line with an open-circuited tuning stub. The antenna studied is operated at the 1.8 GHz band. By choosing the open-circuited tuning stub to be about 0.125 guided wavelength of the fundamental frequency and placing the tuning stub at a suitable position away from the feed point, the possible resonance of the microstrip antenna at the second harmonic frequency can be suppressed. The obtained experimental results are presented and discussed.

Dual-shorted monopole antenna for Ultra-Wideband application

A novel dual-shorted monopole antenna suitable for UWB application, especially as an internal antenna for notebook or tablet PC has been proposed. The proposed antenna has a simple structure with a dual-shorted strip and is easy to implement at a low cost. Prototypes of the proposed antenna have been constructed and studied. A very uniform surface current distribution in the proposed antenna is occurred. It effectively reduces the coupling noise and enhances the antenna receiving performance. Besides, a wide operating bandwidth of about 2.3 GHz (about 2.01-5.30 GHz) is also obtained, which can easily cover the band group 1 of the UWB system application. More experimental and simulation results will be given in the presentation.

An embedded tri-band planar inverted-F antenna with a branch-line shorting strip

By using a branch-line shorting strip, a novel planar inverted-F antenna (PIFA) suitable for the application as a GSM/DCS/PCS tri-band mobile phone internal antenna has been obtained. The proposed antenna has three resonant elements, two shorter radiating strips of slightly different lengths and one longer radiating strip, which are fabricated via stamping process and supported by a plastic holder. These three resonant elements share the branch-line shorting strip and generate three resonant modes, one on lower band from the first-order mode of the longer radiating strip for the EGSM (880-960 MHz) operation and two on upper band which is generated by the two shorter radiation strips, leading to a wide bandwidth covering the DCS (1710-1880 MHz) and PCS (1850-1990 MHz) bands. The proposed antenna has also a good radiation performance as the radiation efficiency more than 50%. Details of the antenna design and experimental results are presented and discussed