Tian-Fu Hung

Miniaturized Dual-Band CPW-Fed Annular Slot Antenna Design With Arc-Shaped Tuning Stub

The design of a miniaturized dual-band CPW-fed annular slot antenna with arc-shaped tuning stub is proposed. The proposed feeding structure, which includes the arc-shaped tuning stub and a 50- transformer, is connected to the extremity of the CPW fed-line, achieving the dual-band input impedance matching. The return loss of the proposed design exhibits that two wide operating bands are over the bandwidths of 30.8% and 24.0%, respectively. By modifying the angle of the arc-shaped tuning stub, the first-higher order resonant mode can be shifted to the lower frequency band to combine with the fundamental mode of the annular slot, achieving the broadband operation with the bandwidth of 3048 MHz (78.4%). Moreover, the miniaturized design indicates an embedded strip is protruded from the ground plane into a slit, revealing the center frequencies of two resonant bands from 2752 to 1738 MHz (size reduction 60%) and 5022 to 3760 MHz (size reduction 44%), respectively. Two resonant bands of the prototype show the broadside radiation patterns with the maximum peak antenna gains of 3.8 dBi and 5.1 dBi, respectively.

Single-Feed Circularly Polarized Aperture-Coupled Stack Antenna With Dual-Mode Square Loop Radiator

The authors propose a compact single-feed stack antenna consisting of a square loop radiator with perturbation, an aperture-coupled structure, and a straight-strip feed line for circular polarization (CP) and unidirectional radiation applications. This perturbation applies both dual-mode and orthogonal-mode effects simultaneously in the square loop resonator to present bandwidth and CP characteristics. The stack antenna presents the desired axial ratio (AR) bands of 2.42 GHz with 3-dB bandwidth (BW) = 62 MHz (2.5%). The circular polarization is demonstrated with AR spectrum and orthogonal modes distributions. The proposed antenna is successfully simulated and measured with frequency responses, radiation patterns, and current distributions.

A Compact Size and Small Frequency Ratio CPW-Fed Circular Slot Antenna for GPS/WLAN Dual-Band and Circular Polarizations

This paper presents a novel dual-band circularly polarized CPW-fed circular slot antenna with two open-ground rings. The proposed antenna is constructed with two opened-ground rings facing in opposite directions and embedded in the circular slot and the enhanced feed strip of CPW. By way of adjusting the relevant parameters, we can obtain the dualband at 1.57GHz and 2.46GHz respectively. A smaller frequency ratio of 1.56 is presented. The measured i10dB return loss impedance bandwidth are 380MHz (24.68%) for 1.57GHz band and 210MHz (8.33%) for 2.46GHz band. The measured i3dB axial ratio bandwidth for 1.57GHz and 2.46GHz bands are 13.38% and 8.13%, the polarization of radiation patterns are RHCP and LHCP for each band and the antenna gain are 3.72 and 3.21dBic respectively.

CPW-Fed Sleeve Monopole Antenna with Complementary Sir Radiators for Dtv Signal Reception and Circularly Polarized Applications

A new circularly-polarized (CP) sleeve antenna fed by a CPW for DTV signal reception applications is presented in this paper. The CPW-fed sleeve monopole antenna consists of square loop sleeve, CPW-fed and complementary SIR radiators. The lower and upper resonance frequencies of the desired band are controlled by the complementary SIR arms, making designs of the wide-band antenna very easy. To demonstrate the idea, the proposed antenna was designed at the band with 470{863GHz (BW = 393MHz, 58.9%) for DTV UHF-bands. The antenna gains are varied about 2.2 to 4.0dBi. An omnidirectional radiation property is also shown. The CP operation for the proposed design can be achieved by properly adjusting the asymmetrical radiators. The re∞ection coe-cient, axial ratio, radiation pattern and gain of the proposed antenna were studied, and reasonable agreement between the simulated and measured results was obtained.

A circularly polarized CPW-fed square slot antenna with embedded Hilbert-curves and rectangular patches for GPS/GLONASS operations

This paper presents a circularly polarized CPW-fed square slot antenna with embedded Hilbert-curves and rectangular patches for GPS/GLONASS operations. The proposed antenna is constructed with two Hilbert-curves lines, three rectangular patches and the enhanced feed strip of CPW. By way of adjusting the relevant parameters, we can obtain the GPS band at 1.575 GHz and GLONASS band at 1.609 GHz. The measured -10 dB return loss impedance bandwidth are 480 MHz (30.48%) from 1.35 to 1.83 GHz. The measured 3 dB axial ratio bandwidth is 160 MHz (9.8%) from 1.55 to 1.71 GHz. The polarization of radiation patterns are RHCP and the antenna gain are 3.98 dBic at 1.575 GHz, 3.46 dBic at 1.609 GHz, respectively.

Design a monopole antenna with three-tier small semicircles for ultra-wideband operation

This paper presents a monopole antenna with three-tier small semicircles for ultra-wideband operation. The monopole antenna with three-tier small semicircles which can get wider bandwidth is done by etching process on the FR4 substrate with 1.6mm in thickness and 4.4 relative permittivity. The ground plane is a semicircle with larger slit which is good for impedance matching. The S11 frequency response, radiation patterns, power gain, group delay, received pulse response, and phase change are also investigated. The relevant research reports can prove that a monopole antenna with three-tier small semicircles are very suitable for applications in ultra-wideband short-range wireless devices and apply to medical image.

A dipole antenna with helix structure applied to the WLAN systems

A novel printed dipole antenna with helix structure fed by a coplanar waveguide, suitable for 2.4 GHz and 5.2~5.85 GHz WLAN application is presented and investigated in this paper. The helix structure is designed so that the antenna length has a reduction then traditional printed dipole antenna. Some effects of many important parameters on the return loss and gain value of the proposed antenna have been investigated. In order to operate as WLAN device, the dipole antenna with helix structure should be cover the operation bandwidth of the 2.4 GHz and 5.2~5.85 GHz, and omni-directional radiation patterns are achieved at two operating bands.

Gain enhancement of a circularly polarized patch antenna using a suspended patch

A circularly polarized (CP) patch antenna with gain enhancement is presented. This paper provides a technique to increase the CP gain of an antenna without changing its original configuration. A gain enhancement of 1.7 dBic is achieved by an additional suspended patch. First, we design a CP patch antenna, which works in the band of Wireless Local Area Network (WLAN) with an antenna gain of 10 dBic. Second, adding a suspended patch along the z-axis to the original antenna which the gain enhancement of the modified structure can be improved. The measured and simulated results are equivalent agreement, and they both show that the antenna gain is indeed improved about 1.7 dBic by adding a suspended patch.