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ABSTRACT: A circularly polarized (CP) composite antenna is studied in this article. The antenna unit is composed of a CP curl antenna and a CP omni-directional antenna with three pairs of tilted parasitic elements. Reasonable agreement between simulation and measurement is obtained. The proposed antenna has a 10-dB impedance bandwidth (S11 < −10 dB) of 35% and a 3-dB axial ratio (AR) bandwidth of 20%. The composite antenna and the reference antenna are compared in this article. The composite antenna can obtain a 3-dB power gain beamwidth of 110° and 3-dB AR beamwidth of 120°, when compared with those of the reference antenna with 95° and 95°, respectively. The characteristics of the composite antenna are also investigated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2461–2464, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24594
Microwave and Optical Technology Letters 07/2009; 51(10):2461 - 2464. · 0.62 Impact Factor
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ABSTRACT: The application of circular polarized log periodic dipole antenna (LPDA) as a feed for offset parabolic reflector antenna is presented in the paper. Reflector pattern characteristics are discussed for beams generated by on-focus and off-focus feed. Results demonstrate for beamwidths, gain peak, side lobe level and cross-polarization levels so as functions of the reflector geometries. The summary is given so as to allow the design of feed for a variety of offset parabolic reflectors. Final simulated results of pattern and gain peak at the single frequency f=0.8GHz in the band is also presented below.
Radar Conference, 2009 IET International; 05/2009
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ABSTRACT: The application of an array of circular polarized log periodic dipole antennas (LPDA) as feed array for a multiple-beam antenna to cover 3.5:1 bandwidths is described. Meanwhile, the use of an array of log-periodic antennas for two kinds of arrangement: rectangular grid and hexagonal grid illumination is also presented. In comparison with the rectangular grid, hexagonal grid is more efficient in beam coverage area for synchronous-orbiting communications satellites. Enhanced feed concept is used in the LPDA feed array in order to increase gain in coverage area. Finally, the simulated results for beam contour which is excite by right-hand circular polarized LPDA of both grids and enhanced beam contour over the frequency range of 0.8 GH to 2.5 GHz are demonstrated.
Millimeter Waves, 2008. GSMM 2008. Global Symposium on; 05/2008
