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Ratio Bandwidth (ratio + bandwidth)

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Engineering100%

Selected Abstracts

Probe compensated single feed circularly polarized fractal-shaped microstrip antennas

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2009
P. Nageswara Rao
Abstract A single feed circularly polarized fractal boundary microstrip antenna with improved axial ratio bandwidth is presented. The low-axial ratio bandwidth of single feed circularly polarized microstrip antenna is due to its probe reactance. In this article, the inherent disadvantage of this low-AR bandwidth is overcome by compensating the probe reactance by incorporating capacitance in the form of small patch between the radiating patch and the probe. The perturbation of the patch is done using fractal curve as boundary. The proposed antenna exhibits impedance and axial ratio bandwidths of 9 and 2.2% respectively at 2.4 GHz. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]

A T-type fractal boundary single-feed circularly polarized microstrip antenna

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2009
P. Nageswara Rao
Abstract A single-feed T-type fractal boundary microstrip antenna is presented. It is established that a very good circular polarization is realizable with 3-dB axial ratio bandwidth of 1.27% at the center frequency of 2446 MHz by changing the electrical length in two directions of the square patch by using T-type fractal curve as boundary. Further it is shown that the surface area occupied by the antenna is reduced compared to the Euclidean shaped patch antenna without much degradation in gain of the antenna. Experimental results are compared with simulated results and a very good agreement is obtained. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]

Design of a broadband dual circularly polarized square slot antenna

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2008
G. Zhao
Abstract In this article, a new design of a broadband dual circularly polarized square slot antenna loaded with metallic strips is presented. The proposed dual circular polarization (CP) radiations are achieved by loading the square slot with a T-shaped strip and two microstrip T-junctions. The designed antenna is implemented and measured. The experimental results show that the proposed antenna has good dual CP characteristics and a 3-dB axial ratio bandwidth is more than 19%. The isolation between two ports is better than 20 dB within the CP operating band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2639,2642, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23741 [source]

Low-profile dual-frequency GPS patch antenna enhanced with dual-band EBG structure

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2007
X. L. Bao
Abstract A novel low-cost low-profile dual-frequency circularly polarized patch antenna for GPS applications is presented. By stacking two square patches with truncated corners on a two-layer fractal electromagnetic bandgap structure substrate, the coverage of the entire GPS bandwidth is achieved. Two bandgaps exist for the proposed fractal EBG structure, from 1.16 to 1.32 GHz and from 1.45 to 2.10 GHz, which include the lower and upper frequency GPS band. The antenna is low-profile and has improved gain and axial ratio bandwidth, as well as broader impedance bandwidths compared to the same antenna without EBG. Good circularly polarized radiation patterns are realized. Measurements on prototypes are in good agreement with simulation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2630,2634, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22815 [source]

Compact printed semi-elliptical monopole antenna for super-wideband applications

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007
Xiao-Rong Yan
Abstract A compact semi-elliptical patch antenna fed by a tapered coplanar waveguide is introduced for super-wideband (SWB) applications. The simulated and experimental results demonstrate that the antenna possesses the desirable SWB characteristics, achieving a ratio bandwidth of 19.7:1 for VSWR , 2, and exhibits a nearly omni-directional radiation pattern, while its area is only about 0.15,l × 0.21,l, where ,l is the wavelength of the lowest operating frequency. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2061,2063, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22644 [source]

Meandering probe fed patch antenna with high gain characteristic for circularly polarized application

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007
Hau-Wah Lai
Abstract A meandering probe-fed circularly polarized stacked patch antenna with truncated corners is studied. The antenna has a wide 3-dB axial ratio bandwidth of 12%. It exhibits a stable radiation pattern across the axial ratio bandwidth. The antenna has low cross polarization and high gain, which are ,14 dB and 10 dBi, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1095,1098, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22357 [source]

Short helical antenna with extremely small pitch angle

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2007
Ze-Hai Wu
Abstract A 2-turn helical antenna with small pitch angle between 0.6° and 3° has been studied as a radiation element of circular polarization waves in this article. The antenna with pitch angle 2° exhibits a 3-dB axial ratio bandwidth of 9.8%, and the optimal axial ratio of 0.1 dB. When the pitch angle decreases to 0.6°, the 3-dB axial ratio bandwidth and the best axial ratio are 5% and 0.15 dB, respectively. Variation of on-axis axial ratio as a function of the straight wire height h has been computed, and the current along the helix is also given. Experimental verification of the antenna performance is presented. The antenna with low profile and high polarization purity characteristics is suitable for application of array antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 17,19, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22054 [source]

Probe compensated single feed circularly polarized fractal-shaped microstrip antennas

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2009
P. Nageswara Rao
Abstract A single feed circularly polarized fractal boundary microstrip antenna with improved axial ratio bandwidth is presented. The low-axial ratio bandwidth of single feed circularly polarized microstrip antenna is due to its probe reactance. In this article, the inherent disadvantage of this low-AR bandwidth is overcome by compensating the probe reactance by incorporating capacitance in the form of small patch between the radiating patch and the probe. The perturbation of the patch is done using fractal curve as boundary. The proposed antenna exhibits impedance and axial ratio bandwidths of 9 and 2.2% respectively at 2.4 GHz. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]

A shorted square-ring slot antenna with a branched slot for the 1575 MHz and 2.4 GHz dual-band operations

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009
Chin-Long Tsai
Abstract A shorted square-ring slot antenna with a branched slot is presented for the 1575 MHz and 2.4 GHz dual-band operations. This proposed antenna can be designed by two steps. First, the shorted square-ring slot antenna is designed for circular polarization in the GPS band. Then, a branched slot is added to the original structure to result linear polarization in the 2.4 GHz band. Because the added branched slot almost has no influence in the GPS band's characteristics, the design rule is very simple. The impedance and axial ratio bandwidths for the GPS band is 23.3% and 4.2%, respectively. Besides, the AR and antenna gain is 1.23 dB and 2.3 dBic at the frequency of 1575 MHz. The impedance bandwidth for the 2.4 GHz band is 4.5% and antenna gain at the center frequency of 2.445 GHz is 2.8 dBi. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 402,405, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24073 [source]