A circular polarization microstrip antenna with a single feeding point is designed in this paper. The microstrip patch has a structure of Koch fractal edges, and the circular polarization is realized by inspiring two degenerate modes that are orthogonal to each other. The software CST MWS® is used to simulate the designed antenna. The simulation results indicate that circular polarization radiation could be achieved though feeding at one of the diagonal lines of the patch by a probe. Antennas considering substrate medium loss are also simulated, and the results are approximate to those with ideal substrates. According to the simulated results of the surface currents at the edges of the patch, an equivalent line current radiation model is proposed to describe the radiation characteristics of the designed antenna. A circular polarization microstrip antenna is fabricated and tested. The simulated, calculated, and the measured results agree well. The designed antenna operates at 1.575 GHz, with an impedance bandwidth of 3% for VSWR < 2, the gain of the antenna is 2.6 dB, and the axial ratio in the maximum radiation direction is 2.7 dB.
2. Han, Q. W. , S. Deng, and T. Wang, "Design and realization of single back-feed circular polarization micro-strip antenna," Journal of Chongqing University, Vol. 31, No. 1, 50-51, 2008 (inChinese).
3. Wong, K.-L. and T.-W. Chiou, "Broad-band single-patch circularly polarized microstrip antenna with dual capacitively coupled feeds," IEEE Trans. on Antennas and Propagation, Vol. 49, No. 1, 41-47, 2001.
4. Fu, S. Q. , S. J. Fang, Z. B. Wang, and X. M. Li, "Broadband circularly polarized slot antenna array fed by asymmetric CPW for L-band applications," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 1014-1016, 2009.
5. Nageswara Rao, P. and N. V. S. N. Sarma, "Fractal boundary circularly polarized single feed microstrip antenna," Electronics Letters, Vol. 44, No. 12, 2008.