Broadband elliptical helical antennas with parasitic helix wire and variable pitch angle

Elliptical helical antennas are more suitable for satellite communications than traditional cylindrical helical antennas, whereas the circular polarization performance deteriorates, which restricts their wide applications. Two methods of improving radiation performance of axial mode helical antennas are combined and applied to elliptical helical antennas and an elliptical helical antenna with a parasitic helix wire and a variable pitch angle is proposed. A 5 coils elliptical helical antenna whose ratio of the short axis to the long axis is 0.65 is simulated by the FEKO software as an instance. It is found that the directivity is improved. Meanwhile, it has good circular polarization performance. The highest power gain is 12.86 dB within the band width of 2.2-4.2 GHz, which is 1.2 dB higher than that of a monofilar uniform elliptical helical antenna.