A Three-Fed Microstrip Antenna for Wideband Circular Polarization

New design of a circular microstrip antenna with three feeds for wideband circular polarization is presented. Detailed theoretical analysis proves that a circular microstrip antenna, which is excited by three central symmetrical feeds with equal amplitudes and relative 120° phase shifts, can obtain good circular polarization characteristic. A broadband 120° phase shifter is developed using the metamaterial transmission line (MM TL). It consists of a Wilkinson power divider and three phase-adjusting TLs, namely a MM TL and two microstrips. The antenna is composed of two circular patches. The primary radiating patch under the parasitic patch is excited by three feeds. The proposed antenna can provide an impedance bandwidth of 54.75% and a 3-dB axial ratio bandwidth of 47.88%. The 3-dB gain bandwidth is as large as 40%, with the peak gain 8.8 dBic. In addition, the measured and simulated symmetrical radiation patterns are in good agreement.

[1]  K. Lau,et al.  A novel wide-band circularly polarized patch antenna based on L-probe and aperture-coupling techniques , 2005, IEEE Transactions on Antennas and Propagation.

[2]  S. M. Kim,et al.  Single feed wideband circular polarised patch antenna , 2007 .

[3]  G. Eleftheriades,et al.  A broadband Wilkinson balun using microstrip metamaterial lines , 2005, IEEE Antennas and Wireless Propagation Letters.

[4]  Xianming Qing.  Broadband aperture‐coupled circularly polarized microstrip antenna fed by a three‐stub hybrid coupler , 2004 .

[5]  S. Duffy,et al.  A dual-band circularly polarized aperture-coupled stacked microstrip antenna for global positioning satellite , 1997 .

[6]  Kin-Lu Wong,et al.  Broad-band single-patch circularly polarized microstrip antenna with dual capacitively coupled feeds , 2001 .

[7]  Karu P. Esselle,et al.  Wideband Circularly Polarized Stacked Microstrip Antennas , 2007, IEEE Antennas and Wireless Propagation Letters.

[8]  G. Eleftheriades,et al.  Planar negative refractive index media using periodically L-C loaded transmission lines , 2002 .

[9]  Shau-Gang Mao,et al.  Broadband composite right/left-handed coplanar waveguide power splitters with arbitrary phase responses and balun and antenna applications , 2006 .

[10]  Kin‐Lu Wong,et al.  Printed ring slot antenna for circular polarization , 2002 .

[11]  Chao-Hsiung Tseng,et al.  A Broadband Quadrature Power Splitter Using Metamaterial Transmission Line , 2008, IEEE Microwave and Wireless Components Letters.

[12]  K. Tong,et al.  Circularly Polarized U-Slot Antenna , 2007, IEEE Transactions on Antennas and Propagation.