Simulation Results:

The measured data is from: G. Avitabile, S. Maci, F. Bonifacio and G.Salvador, "Dual Band Circularly Polarized Patch Antenna", IEEEAP-Symposium Digest, Seattle, WA., 1994, pp.290-293.

Information on IE3D

Perfect agreement is observed between the IE3D simulation result and the measured data. Please note that the IE3D's dB[S(1,1)] and the measureddB[S(1,1)] are using different scales.

    IE3D Simulation Result          Measured Result from Literature

It was claimed in the referenced paper that the resonance at 2.3 GHz and3.235 GHz are good for circular polarization and the resonance at 2.73 GHz is not good for circular polarization. The conclusion was based upon the fact that|S21 is almost 0 at 2.3 GHz and 3.235 GHz and is almost 1 at 2.73 GHz. The above observation is verified using the IE3D. We can also look at the radiation patterns, directivity and efficiency of the antenna at the three different frequencies. When the 2-ports are excited with 90· phase difference, the antenna yields good circular polarized pattern with cross-polarization below -20dB from q = -60· to 60· at 2.3 GHz and 3.235 GHz. At 2.73 GHz, the pattern is not a circular polarization and the efficiency is absolute not acceptable.